import { readFileSync, rmSync } from "node:fs";
import path from "node:path";
import { Elysia, t } from "elysia";
import { fileTypeFromBuffer } from "file-type";
import { sql } from "kysely";
import config from "../config.ts";
import {
    BINARY_DETECT_BYTES,
    BRANCHES_PER_PAGE,
    COMMITS_PER_PAGE,
    MAX_BRANCH_NAME_LENGTH,
    MAX_LABEL_NAME_LENGTH,
    paths,
    REPOS_PER_PAGE,
    TAGS_PER_PAGE,
    VALID_REPO_NAME_RE,
    YEAR_SECONDS,
} from "../constants.ts";
import { db } from "../db/index.ts";
import { contentDisposition } from "../lib/contentDisposition.ts";
import { redirect } from "../lib/redirect.ts";
import { requireAdmin, resolveSession } from "../middleware/session.ts";
import { git, repoPath, type TreeEntry } from "../services/git.ts";
import {
    hasBinaryContent,
    prepareDiff,
    serveFile,
} from "../services/highlightWorker.ts";
import { renderMarkdown } from "../services/markdown.ts";
import { ensureRepoRecord, repoDiskExists } from "../services/repoSync.ts";
import { html } from "../views/render.tsx";
import { BranchList } from "../views/repos/BranchList.tsx";
import { CommitDetail } from "../views/repos/CommitDetail.tsx";
import { CommitLog } from "../views/repos/CommitLog.tsx";
import { FileBlob } from "../views/repos/FileBlob.tsx";
import { FileEdit } from "../views/repos/FileEdit.tsx";
import { FileTree } from "../views/repos/FileTree.tsx";
import { NewFileForm } from "../views/repos/NewFileForm.tsx";
import { NewRepo } from "../views/repos/NewRepo.tsx";
import { RepoHome } from "../views/repos/RepoHome.tsx";
import { RepoList } from "../views/repos/RepoList.tsx";
import { RepoSettings } from "../views/repos/RepoSettings.tsx";
import { TagList } from "../views/repos/TagList.tsx";

async function getRepo(name: string, isAdmin: boolean) {
    if (!repoDiskExists(name)) return null;
    const repo = await ensureRepoRecord(name);
    if (repo.is_private && !isAdmin) return null;
    return repo;
}

/**
 * Read a byte range out of a streaming source without ever holding
 * the full content in memory. Used by the /raw endpoint to honour
 * HTTP Range headers against `git show`'s pipe.
 */
function sliceStream(
    source: ReadableStream<Uint8Array>,
    start: number,
    length: number,
    onDone: () => void,
): ReadableStream<Uint8Array> {
    const reader = source.getReader();
    let skipped = 0;
    let emitted = 0;
    let finished = false;
    const finish = () => {
        if (finished) return;
        finished = true;
        reader.cancel().catch(() => {});
        onDone();
    };
    return new ReadableStream<Uint8Array>({
        async pull(controller) {
            while (emitted < length) {
                const { value, done } = await reader.read();
                if (done) {
                    controller.close();
                    finish();
                    return;
                }
                let chunk = value;
                if (skipped < start) {
                    const drop = Math.min(start - skipped, chunk.length);
                    skipped += drop;
                    chunk = chunk.subarray(drop);
                    if (chunk.length === 0) continue;
                }
                const remaining = length - emitted;
                if (chunk.length > remaining)
                    chunk = chunk.subarray(0, remaining);
                emitted += chunk.length;
                controller.enqueue(chunk);
                if (emitted >= length) {
                    controller.close();
                    finish();
                }
                return;
            }
            controller.close();
            finish();
        },
        cancel() {
            finish();
        },
    });
}

/** Wrap a process stdout stream so the underlying process is killed on
 *  close or cancel. Without this, a client disconnect partway through a
 *  large blob leaves `git cat-file` running until its pipe back-pressures. */
function streamWithKill(
    source: ReadableStream<Uint8Array>,
    proc: { kill: () => void },
): ReadableStream<Uint8Array> {
    const reader = source.getReader();
    let killed = false;
    const finish = () => {
        if (killed) return;
        killed = true;
        reader.cancel().catch(() => {});
        proc.kill();
    };
    return new ReadableStream<Uint8Array>({
        async pull(controller) {
            try {
                const { value, done } = await reader.read();
                if (done) {
                    controller.close();
                    finish();
                    return;
                }
                controller.enqueue(value);
            } catch (err) {
                controller.error(err);
                finish();
            }
        },
        cancel() {
            finish();
        },
    });
}

async function mimeForContent(
    filename: string,
    content: Buffer,
): Promise<string> {
    const result = await fileTypeFromBuffer(content);
    if (result) return result.mime;

    const typeFromName = Bun.file(filename).type;
    if (typeFromName !== "application/octet-stream") {
        return typeFromName;
    }

    return hasBinaryContent(content.subarray(0, BINARY_DETECT_BYTES))
        ? "application/octet-stream"
        : "text/plain; charset=utf-8";
}

const README_NAMES = ["README.md", "readme.md", "README", "readme"];

async function readReadme(
    repo: string,
    ref: string,
    dir = "",
    knownEntries: TreeEntry[],
): Promise<{ content: Buffer; filename: string } | null> {
    const prefix = dir ? `${dir}/` : "";
    // Fast path: we already have the tree listing — find the README name and
    // fetch only that one file, avoiding up to 3 wasted git-show calls.
    const entryNames = new Set(knownEntries.map((e) => e.name));
    const name = README_NAMES.find((n) => entryNames.has(n));
    if (!name) return null;
    const content = await git.show(repo, ref, `${prefix}${name}`);
    return content ? { content, filename: `${prefix}${name}` } : null;
}

export const repoRoutes = new Elysia()
    .get("/allowed_signers", () => {
        return new Response(readFileSync(paths.ALLOWED_SIGNERS_PATH), {
            headers: { "Content-Type": "text/plain; charset=utf-8" },
        });
    })
    .guard({
        cookie: t.Cookie({
            session: t.Optional(t.String()),
            repo_sort: t.Optional(t.String()),
        }),
    })
    .post(
        "/sort",
        ({ body }) => {
            const sort = body.sort === "name" ? "name" : "created";
            const secure = config.PUBLIC_HTTPS ? "; Secure" : "";
            return redirect(
                "/",
                `repo_sort=${sort}; Path=/; SameSite=Lax${secure}; Max-Age=${YEAR_SECONDS}`,
            );
        },
        { body: t.Object({ sort: t.String() }) },
    )
    .get(
        "/",
        async ({ cookie, query }) => {
            const user = await resolveSession(cookie.session.value);
            const search = query.q?.trim() || undefined;
            const page = Math.max(1, query.page ?? 1);
            const sort = cookie.repo_sort.value === "name" ? "name" : "created";

            const isAdmin = user?.isAdmin ?? false;

            const searchPattern = search
                ? `%${search.replace(/[\\%_]/g, "\\$&")}%`
                : undefined;

            const countResult = await db
                .selectFrom("repositories")
                .select(db.fn.countAll<number>().as("count"))
                .where((eb) =>
                    isAdmin
                        ? eb.or([
                              eb("is_private", "=", 0),
                              eb("is_private", "=", 1),
                          ])
                        : eb("is_private", "=", 0),
                )
                .$if(!!searchPattern, (qb) =>
                    qb.where(
                        sql<boolean>`("name" LIKE ${searchPattern} ESCAPE '\\' OR "description" LIKE ${searchPattern} ESCAPE '\\')`,
                    ),
                )
                .executeTakeFirst();

            const totalCount = Number(countResult?.count ?? 0);
            const totalPages = Math.max(
                1,
                Math.ceil(totalCount / REPOS_PER_PAGE),
            );
            const safePage = Math.min(page, totalPages);

            const repos = await db
                .selectFrom("repositories")
                .selectAll()
                .where((eb) =>
                    isAdmin
                        ? eb.or([
                              eb("is_private", "=", 0),
                              eb("is_private", "=", 1),
                          ])
                        : eb("is_private", "=", 0),
                )
                .$if(!!searchPattern, (qb) =>
                    qb.where(
                        sql<boolean>`("name" LIKE ${searchPattern} ESCAPE '\\' OR "description" LIKE ${searchPattern} ESCAPE '\\')`,
                    ),
                )
                .orderBy("is_pinned", "desc")
                .$if(sort === "name", (qb) => qb.orderBy("name", "asc"))
                .$if(sort === "created", (qb) =>
                    qb.orderBy("created_at", "desc"),
                )
                .limit(REPOS_PER_PAGE)
                .offset((safePage - 1) * REPOS_PER_PAGE)
                .execute();

            const searchParam = search
                ? `&q=${encodeURIComponent(search)}`
                : "";
            const pagination = {
                page: safePage,
                totalPages,
                pageUrlTemplate: `/?page={page}${searchParam}`,
            };

            return html(
                <RepoList
                    user={user}
                    repos={repos}
                    search={search}
                    sort={sort}
                    pagination={pagination}
                />,
            );
        },
        {
            query: t.Object({
                q: t.Optional(t.String()),
                page: t.Optional(t.Numeric()),
            }),
        },
    )

    .get("/new", async ({ cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const deny = requireAdmin(user);
        if (deny) return deny;
        return html(<NewRepo user={user!} />);
    })

    .post(
        "/new",
        async ({ body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;

            const { name, description, is_private, default_branch } = body;

            if (!VALID_REPO_NAME_RE.test(name)) {
                return html(
                    <NewRepo user={user!} error="Invalid repository name" />,
                );
            }

            const branch = (default_branch?.trim() || "main").replace(
                /[^a-zA-Z0-9._/-]/g,
                "",
            );

            const existing = await db
                .selectFrom("repositories")
                .select("id")
                .where("name", "=", name)
                .executeTakeFirst();
            if (existing) {
                return html(
                    <NewRepo
                        user={user!}
                        error="Repository name already taken"
                    />,
                );
            }

            const now = new Date().toISOString();
            await db
                .insertInto("repositories")
                .values({
                    name,
                    description: description || null,
                    is_private: is_private === "1" ? 1 : 0,
                    default_branch: branch,
                    created_at: now,
                })
                .execute();

            // Initialise the git repo after the DB record is committed.  If
            // git.init fails we roll back the DB record so the two stay in sync.
            try {
                await git.init(name, branch);
            } catch (err) {
                await db
                    .deleteFrom("repositories")
                    .where("name", "=", name)
                    .execute();
                throw err;
            }
            return new Response(null, {
                status: 302,
                headers: { Location: `/${name}` },
            });
        },
        {
            body: t.Object({
                name: t.String(),
                description: t.Optional(t.String()),
                is_private: t.Optional(t.String()),
                default_branch: t.Optional(t.String()),
            }),
        },
    )

    .get("/:repo", async ({ params, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });

        const hasContent = await git.hasCommits(repo.name);
        let readmeHtml: string | null = null;
        let readmePath: string | undefined;
        let entries: Awaited<ReturnType<typeof git.lsTree>> = [];
        let branches: string[] = [];
        let tags: string[] = [];

        if (hasContent) {
            const [lsResult, branchResult, tagResult, resolved] =
                await Promise.all([
                    git.lsTree(repo.name, repo.default_branch),
                    git.branches(repo.name),
                    git.tags(repo.name),
                    git.resolveRef(repo.name, repo.default_branch),
                ]);
            entries = lsResult;
            branches = branchResult;
            tags = tagResult;
            const readme = await readReadme(
                repo.name,
                repo.default_branch,
                "",
                lsResult,
            );
            if (readme) {
                const key = resolved
                    ? `readme:${repo.name}:${resolved}:`
                    : undefined;
                readmeHtml = renderMarkdown(
                    readme.content.toString("utf-8"),
                    key,
                    {
                        repo: repo.name,
                        ref: repo.default_branch,
                        dir: "",
                    },
                );
                readmePath = readme.filename;
            }
        }

        return html(
            <RepoHome
                user={user}
                repo={repo}
                entries={entries}
                readmeHtml={readmeHtml}
                readmePath={readmePath}
                hasContent={hasContent}
                branches={branches}
                tags={tags}
            />,
        );
    })

    .get(
        "/:repo/branch-switch",
        async ({ params, query, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const repo = await getRepo(params.repo, user?.isAdmin ?? false);
            if (!repo) return new Response("Not found", { status: 404 });

            const ref = query.rev?.trim();
            if (!ref)
                return new Response(null, {
                    status: 302,
                    headers: { Location: `/${repo.name}` },
                });

            const view = query.view;
            const subpath = query.path ?? "";

            if (view === "commits") {
                return new Response(null, {
                    status: 302,
                    headers: { Location: `/${repo.name}/commits/${ref}` },
                });
            }
            if (view === "blob" && subpath) {
                return new Response(null, {
                    status: 302,
                    headers: {
                        Location: `/${repo.name}/blob/${ref}/${subpath}`,
                    },
                });
            }
            const location = subpath
                ? `/${repo.name}/tree/${ref}/${subpath}`
                : `/${repo.name}/tree/${ref}`;
            return new Response(null, {
                status: 302,
                headers: { Location: location },
            });
        },
        {
            query: t.Object({
                rev: t.Optional(t.String()),
                view: t.Optional(t.String()),
                path: t.Optional(t.String()),
            }),
        },
    )

    .get("/:repo/tree/:ref", async ({ params, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });

        const resolved = await git.resolveRef(repo.name, params.ref);
        if (!resolved) return new Response("Not found", { status: 404 });

        const [entries, branches, tags] = await Promise.all([
            git.lsTree(repo.name, params.ref),
            git.branches(repo.name),
            git.tags(repo.name),
        ]);
        const readme = await readReadme(repo.name, params.ref, "", entries);
        const readmeHtml = readme
            ? renderMarkdown(
                  readme.content.toString("utf-8"),
                  `readme:${repo.name}:${resolved}:`,
                  { repo: repo.name, ref: params.ref, dir: "" },
              )
            : null;
        return html(
            <FileTree
                user={user}
                repo={repo}
                ref={params.ref}
                subpath=""
                entries={entries}
                branches={branches}
                tags={tags}
                readmeHtml={readmeHtml}
                readmePath={readme?.filename}
            />,
        );
    })

    .get("/:repo/tree/:ref/*", async ({ params, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });

        const resolved = await git.resolveRef(repo.name, params.ref);
        if (!resolved) return new Response("Not found", { status: 404 });

        const subpath = decodeURIComponent(params["*"]);
        const [entries, branches, tags] = await Promise.all([
            git.lsTree(repo.name, params.ref, subpath),
            git.branches(repo.name),
            git.tags(repo.name),
        ]);
        if (entries.length === 0) {
            // Could be a file — redirect to blob
            return new Response(null, {
                status: 302,
                headers: {
                    Location: `/${repo.name}/blob/${params.ref}/${subpath}`,
                },
            });
        }
        const readme = await readReadme(
            repo.name,
            params.ref,
            subpath,
            entries,
        );
        const readmeHtml = readme
            ? renderMarkdown(
                  readme.content.toString("utf-8"),
                  `readme:${repo.name}:${resolved}:${subpath}`,
                  { repo: repo.name, ref: params.ref, dir: subpath },
              )
            : null;
        return html(
            <FileTree
                user={user}
                repo={repo}
                ref={params.ref}
                subpath={subpath}
                entries={entries}
                branches={branches}
                tags={tags}
                readmeHtml={readmeHtml}
                readmePath={readme?.filename}
            />,
        );
    })

    .get("/:repo/blob/:ref/*", async ({ params, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });

        const filePath = decodeURIComponent(params["*"]);
        // Size-gate before reading the blob into memory: holding a
        // huge content buffer (and then running shiki/marked over it)
        // is the cheapest DOS vector against unauthenticated users on
        // a public repo.
        const size = await git.getFileSize(repo.name, params.ref, filePath);
        const filename = path.basename(filePath);
        if (size !== null && size > config.MAX_RENDER_BYTES) {
            const [branches, tags] = await Promise.all([
                git.branches(repo.name),
                git.tags(repo.name),
            ]);
            return html(
                <FileBlob
                    user={user}
                    repo={repo}
                    ref={params.ref}
                    filePath={filePath}
                    view={{ type: "download", size }}
                    branches={branches}
                    tags={tags}
                    markdownHtml={undefined}
                />,
            );
        }
        const [content, branches, tags, commitSHA] = await Promise.all([
            git.show(repo.name, params.ref, filePath),
            git.branches(repo.name),
            git.tags(repo.name),
            git.resolveRef(repo.name, params.ref),
        ]);
        if (!content || !commitSHA)
            return new Response("Not found", { status: 404 });

        const [view, markdownHtml] = await Promise.all([
            serveFile(
                content,
                filename,
                `${repo.name}:${commitSHA}:${filePath}`,
            ),
            /\.mdx?$/i.test(filename)
                ? Promise.resolve(
                      renderMarkdown(
                          content.toString("utf-8"),
                          `${repo.name}:${commitSHA}:${filePath}`,
                          {
                              repo: repo.name,
                              ref: params.ref,
                              dir:
                                  path.dirname(filePath) === "."
                                      ? ""
                                      : path.dirname(filePath),
                          },
                      ),
                  )
                : Promise.resolve(undefined),
        ]);
        return html(
            <FileBlob
                user={user}
                repo={repo}
                ref={params.ref}
                filePath={filePath}
                view={view}
                branches={branches}
                tags={tags}
                markdownHtml={markdownHtml}
            />,
        );
    })

    .get("/:repo/raw/:ref/*", async ({ params, cookie, request }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });

        const filePath = decodeURIComponent(params["*"]);
        // Resolve the file's blob hash and size up front. cat-file -s
        // is O(1) and lets us stream the blob below without ever
        // holding it whole in memory — old code did
        // `await arrayBuffer()` and sliced for Range, peaking at
        // file_size × concurrent_requests of RSS.
        const total = await git.getFileSize(repo.name, params.ref, filePath);
        if (total === null) return new Response("Not found", { status: 404 });
        if (
            config.MAX_RAW_DOWNLOAD_BYTES > 0 &&
            total > config.MAX_RAW_DOWNLOAD_BYTES
        ) {
            return new Response("File exceeds raw download size limit", {
                status: 413,
            });
        }

        const filename = path.basename(filePath);
        // We use `cat-file blob` rather than `git show` so the bytes
        // streamed exactly match what `cat-file -s` reported above —
        // `git show` can apply smudge filters / autocrlf, which would
        // make Content-Length wrong on filtered repos.
        const blobArgs = [
            "git",
            "-C",
            repoPath(repo.name),
            "cat-file",
            "blob",
            `${params.ref}:${filePath}`,
        ];

        // Sniff content-type from the first bytes only — same idea as
        // the old mimeForContent but without buffering the full blob.
        const sniffStream = Bun.spawn(blobArgs, {
            stdout: "pipe",
            stderr: "ignore",
        });
        const sniffReader = sniffStream.stdout.getReader();
        const { value: firstChunk } = await sniffReader.read();
        sniffReader.cancel().catch(() => {});
        sniffStream.kill();
        const head = firstChunk
            ? Buffer.from(firstChunk.subarray(0, BINARY_DETECT_BYTES))
            : Buffer.alloc(0);
        const contentType = await mimeForContent(filename, head);

        const rangeHeader = request.headers.get("Range");
        const fullProc = Bun.spawn(blobArgs, {
            stdout: "pipe",
            stderr: "ignore",
        });
        if (rangeHeader) {
            const match = rangeHeader.match(/bytes=(\d*)-(\d*)/);
            if (match) {
                const start = match[1] ? parseInt(match[1], 10) : 0;
                const end = match[2] ? parseInt(match[2], 10) : total - 1;
                const clampedEnd = Math.min(end, total - 1);
                const length = clampedEnd - start + 1;
                // sliceStream kills fullProc once the slice is exhausted or
                // the consumer cancels — without this, requesting a tiny
                // range from a huge blob leaves `git cat-file` running.
                const sliced = sliceStream(fullProc.stdout, start, length, () =>
                    fullProc.kill(),
                );
                return new Response(sliced, {
                    status: 206,
                    headers: {
                        "Content-Type": contentType,
                        "Content-Range": `bytes ${start}-${clampedEnd}/${total}`,
                        "Accept-Ranges": "bytes",
                        "Content-Length": String(length),
                    },
                });
            }
        }

        // Wrap the full stream too so a client disconnect during a large
        // download kills the underlying git process instead of leaving it
        // wedged on a back-pressured pipe.
        return new Response(streamWithKill(fullProc.stdout, fullProc), {
            headers: {
                "Content-Type": contentType,
                "Content-Disposition": contentDisposition("inline", filename),
                "Content-Length": String(total),
                "Accept-Ranges": "bytes",
            },
        });
    })

    .get("/:repo/edit/:ref/*", async ({ params, query, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const deny = requireAdmin(user);
        if (deny) return deny;
        const repo = await getRepo(params.repo, true);
        if (!repo) return new Response("Not found", { status: 404 });

        const filePath = decodeURIComponent(params["*"]);
        const branches = await git.branches(repo.name);
        if (!branches.includes(params.ref))
            return new Response("Not found", { status: 404 });

        const content = await git.show(repo.name, params.ref, filePath);
        if (!content) return new Response("Not found", { status: 404 });

        if (hasBinaryContent(content.subarray(0, 8000)))
            return new Response("Not found", { status: 404 });

        const queryError =
            typeof query.error === "string" ? query.error : undefined;
        return html(
            <FileEdit
                user={user!}
                repo={repo}
                ref={params.ref}
                filePath={filePath}
                content={content.toString("utf-8")}
                queryError={queryError}
            />,
        );
    })

    .post(
        "/:repo/edit/:ref/*",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const filePath = decodeURIComponent(params["*"]);
            const branches = await git.branches(repo.name);
            if (!branches.includes(params.ref))
                return new Response("Not found", { status: 404 });

            const newPath = body.new_path?.trim() || undefined;
            const targetPath =
                newPath && newPath !== filePath ? newPath : filePath;

            if (
                newPath &&
                newPath !== filePath &&
                (newPath.startsWith("/") ||
                    newPath.includes("..") ||
                    newPath.includes("\0"))
            ) {
                return redirect(
                    `/${repo.name}/edit/${params.ref}/${filePath}?error=${encodeURIComponent("Invalid file path.")}`,
                );
            }

            const defaultMessage =
                targetPath !== filePath
                    ? `Rename ${path.basename(filePath)} to ${path.basename(targetPath)}`
                    : `Edited ${path.basename(filePath)}`;
            const message = body.message?.trim() || defaultMessage;
            const content = (body.content ?? "").replaceAll("\r\n", "\n");

            const commit = await git.editFile(
                repo.name,
                params.ref,
                filePath,
                content,
                message,
                config.COMMITTER_NAME,
                config.COMMITTER_EMAIL,
                newPath,
            );

            return new Response(null, {
                status: 302,
                headers: {
                    Location: `/${repo.name}/commit/${commit}`,
                },
            });
        },
        {
            body: t.Object({
                content: t.Optional(t.String()),
                message: t.Optional(t.String()),
                new_path: t.Optional(t.String()),
            }),
        },
    )

    .get(
        "/:repo/commits/:ref",
        async ({ params, cookie, query }) => {
            const user = await resolveSession(cookie.session.value);
            const repo = await getRepo(params.repo, user?.isAdmin ?? false);
            if (!repo) return new Response("Not found", { status: 404 });

            // Cursor-based pagination — O(1) regardless of history depth.
            // `after` = SHA of the last commit on the previous page (resume cursor).
            // `prev`  = the `after` value used on the page that linked here, so we can
            //           reconstruct a "← Newer" link without a full history traversal.
            const after = query.after?.trim() || null;
            const prev = query.prev?.trim() || null;

            const [rawCommits, branches, tags] = await Promise.all([
                // When `after` is set: start at that SHA and skip it (--skip=1 is O(1)),
                // then fetch LIMIT+1 to detect whether another page exists.
                after
                    ? git.log(repo.name, after, COMMITS_PER_PAGE + 1, 1)
                    : git.log(repo.name, params.ref, COMMITS_PER_PAGE + 1, 0),
                git.branches(repo.name),
                git.tags(repo.name),
            ]);

            const hasNext = rawCommits.length > COMMITS_PER_PAGE;
            const commits = rawCommits.slice(0, COMMITS_PER_PAGE);

            // Build cursor URLs.
            // "Older" advances past the last commit on this page.
            // "Newer" goes back one page using the `prev` cursor saved in the URL,
            //   or to the first page if we're on page 2.
            const base = `/${repo.name}/commits/${params.ref}`;
            const olderUrl = hasNext
                ? `${base}?after=${commits[commits.length - 1]?.hash}&prev=${after ?? ""}`
                : null;
            const newerUrl = after
                ? prev
                    ? `${base}?after=${prev}`
                    : base
                : null;

            return html(
                <CommitLog
                    user={user}
                    repo={repo}
                    ref={params.ref}
                    commits={commits}
                    branches={branches}
                    tags={tags}
                    olderUrl={olderUrl}
                    newerUrl={newerUrl}
                />,
            );
        },
        {
            query: t.Object({
                after: t.Optional(t.String()),
                prev: t.Optional(t.String()),
            }),
        },
    )

    .get("/:repo/commit/:sha", async ({ params, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });

        const [meta, rawDiff] = await Promise.all([
            git.commitMeta(repo.name, params.sha),
            git.diff(repo.name, params.sha),
        ]);
        if (!meta) return new Response("Commit not found", { status: 404 });
        // Reject oversized diffs after generation but before highlighting.
        // Avoids running marked / shiki / DOMPurify over a multi-megabyte
        // diff which would synchronously stall the worker pool.
        if (rawDiff.length > config.MAX_RENDER_BYTES) {
            return html(
                <CommitDetail
                    user={user}
                    repo={repo}
                    sha={params.sha}
                    meta={meta}
                    files={[]}
                    tooLarge={rawDiff.length}
                />,
            );
        }
        const files = await prepareDiff(
            rawDiff,
            `commit:${repo.name}:${params.sha}`,
            repo.name,
        );
        return html(
            <CommitDetail
                user={user}
                repo={repo}
                sha={params.sha}
                meta={meta}
                files={files}
            />,
        );
    })

    .get("/:repo/settings", async ({ params, query, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const deny = requireAdmin(user);
        if (deny) return deny;
        const repo = await getRepo(params.repo, true);
        if (!repo) return new Response("Not found", { status: 404 });
        const branches = await git.branches(repo.name);
        const [labels, secrets] = await Promise.all([
            db
                .selectFrom("labels")
                .selectAll()
                .where("repo_id", "=", repo.id)
                .orderBy("name", "asc")
                .execute(),
            db
                .selectFrom("ci_secrets")
                .select(["id", "name", "description", "created_at"])
                .where("repo_id", "=", repo.id)
                .orderBy("name", "asc")
                .execute(),
        ]);
        const success =
            typeof query.success === "string" ? query.success : undefined;
        const error = typeof query.error === "string" ? query.error : undefined;
        return html(
            <RepoSettings
                user={user!}
                repo={repo}
                branches={branches}
                labels={labels}
                secrets={secrets}
                success={success}
                error={error}
            />,
        );
    })

    .post(
        "/:repo/settings",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const {
                description,
                is_private,
                is_pinned,
                allow_user_labels,
                default_branch,
                issue_template,
                patch_template,
            } = body;

            const branches = await git.branches(repo.name);
            const newBranch = default_branch?.trim() || repo.default_branch;

            // Validate the selected branch exists (only if repo has commits)
            if (branches.length > 0 && !branches.includes(newBranch)) {
                return redirect(
                    `/${repo.name}/settings?error=${encodeURIComponent(`Branch "${newBranch}" does not exist.`)}`,
                );
            }

            await db
                .updateTable("repositories")
                .set({
                    description: description?.trim() || null,
                    is_private: is_private === "1" ? 1 : 0,
                    is_pinned: is_pinned === "1" ? 1 : 0,
                    allow_user_labels: allow_user_labels === "1" ? 1 : 0,
                    default_branch: newBranch,
                    issue_template: issue_template?.trim() || null,
                    patch_template: patch_template?.trim() || null,
                })
                .where("id", "=", repo.id)
                .execute();

            // Keep git HEAD in sync if the branch actually exists
            if (branches.includes(newBranch)) {
                await git
                    .setHead(repo.name, newBranch)
                    .catch((e) =>
                        console.error(
                            `setHead failed for ${repo.name}/${newBranch}:`,
                            e,
                        ),
                    );
            }

            return redirect(`/${repo.name}/settings?success=Settings+saved.`);
        },
        {
            body: t.Object({
                description: t.Optional(t.String()),
                is_private: t.Optional(t.String()),
                is_pinned: t.Optional(t.String()),
                allow_user_labels: t.Optional(t.String()),
                default_branch: t.Optional(t.String()),
                issue_template: t.Optional(t.String()),
                patch_template: t.Optional(t.String()),
            }),
        },
    )

    .post("/:repo/settings/delete", async ({ params, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const deny = requireAdmin(user);
        if (deny) return deny;
        const repo = await getRepo(params.repo, true);
        if (!repo) return new Response("Not found", { status: 404 });

        // Remove the on-disk repo first. If this fails (e.g. permission error),
        // we abort before touching the DB so the repo remains accessible.
        rmSync(repoPath(repo.name), { recursive: true, force: true });
        await db.deleteFrom("repositories").where("id", "=", repo.id).execute();

        return new Response(null, { status: 302, headers: { Location: "/" } });
    })

    .post(
        "/:repo/settings/labels",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const name = body.name?.trim();
            const color = body.color?.trim();

            if (!name || name.length > MAX_LABEL_NAME_LENGTH) {
                return redirect(
                    `/${repo.name}/settings?error=${encodeURIComponent("Label name must be 1–50 characters.")}`,
                );
            }
            if (!color || !/^#[0-9a-fA-F]{6}$/.test(color)) {
                return redirect(
                    `/${repo.name}/settings?error=${encodeURIComponent("Invalid color.")}`,
                );
            }

            try {
                await db
                    .insertInto("labels")
                    .values({
                        repo_id: repo.id,
                        name,
                        color,
                        created_at: new Date().toISOString(),
                    })
                    .execute();
            } catch {
                return redirect(
                    `/${repo.name}/settings?error=${encodeURIComponent("A label with that name already exists.")}`,
                );
            }

            return redirect(`/${repo.name}/settings?success=Label+created.`);
        },
        {
            body: t.Object({
                name: t.String(),
                color: t.String(),
            }),
        },
    )

    .post(
        "/:repo/settings/labels/delete",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const label = await db
                .selectFrom("labels")
                .select(["id", "repo_id"])
                .where("id", "=", body.id)
                .executeTakeFirst();

            if (!label || label.repo_id !== repo.id) {
                return redirect(
                    `/${repo.name}/settings?error=${encodeURIComponent("Label not found.")}`,
                );
            }

            await db.deleteFrom("labels").where("id", "=", body.id).execute();

            return redirect(`/${repo.name}/settings?success=Label+deleted.`);
        },
        {
            body: t.Object({ id: t.Numeric() }),
        },
    )

    // ── Branches ──────────────────────────────────────────────────────────────

    .get("/:repo/branches", async ({ params, query, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });
        const allBranches = await git.branchesWithInfo(repo.name);
        const page = Math.max(1, parseInt(String(query.page ?? "1"), 10) || 1);
        const totalPages = Math.max(
            1,
            Math.ceil(allBranches.length / BRANCHES_PER_PAGE),
        );
        const safePage = Math.min(page, totalPages);
        const branches = allBranches.slice(
            (safePage - 1) * BRANCHES_PER_PAGE,
            safePage * BRANCHES_PER_PAGE,
        );
        const success =
            typeof query.success === "string" ? query.success : undefined;
        const error = typeof query.error === "string" ? query.error : undefined;
        return html(
            <BranchList
                user={user}
                repo={repo}
                branches={branches}
                page={safePage}
                totalPages={totalPages}
                success={success}
                error={error}
            />,
        );
    })

    .post(
        "/:repo/branches/create",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const name = body.name?.trim() ?? "";
            const sourceRef = body.source_ref?.trim() ?? "";

            if (
                !name ||
                !/^[a-zA-Z0-9._][a-zA-Z0-9._\-/]*$/.test(name) ||
                name.includes("..") ||
                name.length > MAX_BRANCH_NAME_LENGTH
            ) {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent("Invalid branch name.")}`,
                );
            }
            if (!sourceRef) {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent("Source ref is required.")}`,
                );
            }

            const result = await git.createBranch(repo.name, name, sourceRef);
            if (result === "ok") {
                return redirect(
                    `/${repo.name}/branches?success=${encodeURIComponent(`Branch "${name}" created.`)}`,
                );
            }
            if (result === "already_exists") {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent(`Branch "${name}" already exists.`)}`,
                );
            }
            if (result === "bad_ref") {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent(`"${sourceRef}" is not a valid ref.`)}`,
                );
            }
            return redirect(
                `/${repo.name}/branches?error=${encodeURIComponent("Failed to create branch.")}`,
            );
        },
        {
            body: t.Object({
                name: t.String(),
                source_ref: t.String(),
            }),
        },
    )

    .post(
        "/:repo/branches/delete",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const name = body.name?.trim() ?? "";
            if (!name) {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent("Branch name is required.")}`,
                );
            }
            if (name === repo.default_branch) {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent("Cannot delete the default branch.")}`,
                );
            }

            const result = await git.deleteBranch(repo.name, name);
            if (result === "ok") {
                return redirect(
                    `/${repo.name}/branches?success=${encodeURIComponent(`Branch "${name}" deleted.`)}`,
                );
            }
            if (result === "not_found") {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent(`Branch "${name}" not found.`)}`,
                );
            }
            return redirect(
                `/${repo.name}/branches?error=${encodeURIComponent("Failed to delete branch.")}`,
            );
        },
        {
            body: t.Object({ name: t.String() }),
        },
    )

    .post(
        "/:repo/branches/rename",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const oldName = body.old_name?.trim() ?? "";
            const newName = body.new_name?.trim() ?? "";

            if (
                !newName ||
                !/^[a-zA-Z0-9._][a-zA-Z0-9._\-/]*$/.test(newName) ||
                newName.includes("..") ||
                newName.length > MAX_BRANCH_NAME_LENGTH
            ) {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent("Invalid branch name.")}`,
                );
            }

            const result = await git.renameBranch(repo.name, oldName, newName);
            if (result === "ok") {
                // Keep default_branch in DB in sync if we renamed it
                if (oldName === repo.default_branch) {
                    await db
                        .updateTable("repositories")
                        .set({ default_branch: newName })
                        .where("id", "=", repo.id)
                        .execute();
                    await git
                        .setHead(repo.name, newName)
                        .catch((e) =>
                            console.error(
                                `setHead failed for ${repo.name}/${newName}:`,
                                e,
                            ),
                        );
                }
                return redirect(
                    `/${repo.name}/branches?success=${encodeURIComponent(`Branch renamed to "${newName}".`)}`,
                );
            }
            if (result === "not_found") {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent(`Branch "${oldName}" not found.`)}`,
                );
            }
            if (result === "already_exists") {
                return redirect(
                    `/${repo.name}/branches?error=${encodeURIComponent(`Branch "${newName}" already exists.`)}`,
                );
            }
            return redirect(
                `/${repo.name}/branches?error=${encodeURIComponent("Failed to rename branch.")}`,
            );
        },
        {
            body: t.Object({
                old_name: t.String(),
                new_name: t.String(),
            }),
        },
    )

    // ── Tags ──────────────────────────────────────────────────────────────────

    .get("/:repo/tags", async ({ params, query, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const repo = await getRepo(params.repo, user?.isAdmin ?? false);
        if (!repo) return new Response("Not found", { status: 404 });
        const [allTags, releases] = await Promise.all([
            git.tagsWithInfo(repo.name),
            db
                .selectFrom("releases")
                .select(["id", "tag_name"])
                .where("repo_id", "=", repo.id)
                .where("tag_name", "is not", null)
                .execute(),
        ]);
        const tagReleaseMap = new Map<string, number>();
        for (const r of releases) {
            if (r.tag_name) tagReleaseMap.set(r.tag_name, r.id);
        }
        const page = Math.max(1, parseInt(String(query.page ?? "1"), 10) || 1);
        const totalPages = Math.max(
            1,
            Math.ceil(allTags.length / TAGS_PER_PAGE),
        );
        const safePage = Math.min(page, totalPages);
        const tags = allTags.slice(
            (safePage - 1) * TAGS_PER_PAGE,
            safePage * TAGS_PER_PAGE,
        );
        const success =
            typeof query.success === "string" ? query.success : undefined;
        const error = typeof query.error === "string" ? query.error : undefined;
        return html(
            <TagList
                user={user}
                repo={repo}
                tags={tags}
                tagReleaseMap={tagReleaseMap}
                page={safePage}
                totalPages={totalPages}
                success={success}
                error={error}
            />,
        );
    })

    .post(
        "/:repo/tags/create",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const tagName = body.name?.trim() ?? "";
            const ref = body.ref?.trim() ?? "";
            const message = body.message?.trim() || undefined;

            if (!tagName || !/^[a-zA-Z0-9._\-+]+$/.test(tagName)) {
                return redirect(
                    `/${repo.name}/tags?error=${encodeURIComponent("Invalid tag name.")}`,
                );
            }
            if (!ref) {
                return redirect(
                    `/${repo.name}/tags?error=${encodeURIComponent("Target ref is required.")}`,
                );
            }

            const result = await git.createTag(
                repo.name,
                tagName,
                ref,
                message,
                message ? config.COMMITTER_NAME : undefined,
                message ? config.COMMITTER_EMAIL : undefined,
            );
            if (result === "ok") {
                return redirect(
                    `/${repo.name}/tags?success=${encodeURIComponent(`Tag "${tagName}" created.`)}`,
                );
            }
            if (result === "already_exists") {
                return redirect(
                    `/${repo.name}/tags?error=${encodeURIComponent(`Tag "${tagName}" already exists.`)}`,
                );
            }
            if (result === "bad_ref") {
                return redirect(
                    `/${repo.name}/tags?error=${encodeURIComponent(`"${ref}" is not a valid ref.`)}`,
                );
            }
            return redirect(
                `/${repo.name}/tags?error=${encodeURIComponent("Failed to create tag.")}`,
            );
        },
        {
            body: t.Object({
                name: t.String(),
                ref: t.String(),
                message: t.Optional(t.String()),
            }),
        },
    )

    .post(
        "/:repo/tags/delete",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const tagName = body.name?.trim() ?? "";
            if (!tagName) {
                return redirect(
                    `/${repo.name}/tags?error=${encodeURIComponent("Tag name is required.")}`,
                );
            }

            const result = await git.deleteTag(repo.name, tagName);
            if (result === "ok") {
                return redirect(
                    `/${repo.name}/tags?success=${encodeURIComponent(`Tag "${tagName}" deleted.`)}`,
                );
            }
            if (result === "not_found") {
                return redirect(
                    `/${repo.name}/tags?error=${encodeURIComponent(`Tag "${tagName}" not found.`)}`,
                );
            }
            return redirect(
                `/${repo.name}/tags?error=${encodeURIComponent("Failed to delete tag.")}`,
            );
        },
        {
            body: t.Object({ name: t.String() }),
        },
    )

    // ── File creation ─────────────────────────────────────────────────────────

    .get("/:repo/new-file/:ref", async ({ params, query, cookie }) => {
        const user = await resolveSession(cookie.session.value);
        const deny = requireAdmin(user);
        if (deny) return deny;
        const repo = await getRepo(params.repo, true);
        if (!repo) return new Response("Not found", { status: 404 });
        const dir = typeof query.dir === "string" ? query.dir : "";
        const error = typeof query.error === "string" ? query.error : undefined;
        return html(
            <NewFileForm
                user={user!}
                repo={repo}
                ref={params.ref}
                dir={dir}
                error={error}
            />,
        );
    })

    .post(
        "/:repo/new-file/:ref",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const filePath = body.path?.trim() ?? "";
            const content = body.content ?? "";
            const message = body.message?.trim() || `Add ${filePath}`;

            if (
                !filePath ||
                filePath.startsWith("/") ||
                filePath.includes("..") ||
                filePath.includes("\0")
            ) {
                return redirect(
                    `/${repo.name}/new-file/${params.ref}?error=${encodeURIComponent("Invalid file path.")}`,
                );
            }

            // Ensure we're on a branch
            const branches = await git.branches(repo.name);
            if (branches.length > 0 && !branches.includes(params.ref)) {
                return redirect(
                    `/${repo.name}/new-file/${params.ref}?error=${encodeURIComponent("Can only create files on a branch.")}`,
                );
            }

            try {
                const commit = await git.createFile(
                    repo.name,
                    params.ref,
                    filePath,
                    content,
                    message,
                    config.COMMITTER_NAME,
                    config.COMMITTER_EMAIL,
                );
                return redirect(`/${repo.name}/commit/${commit}`);
            } catch {
                return redirect(
                    `/${repo.name}/new-file/${params.ref}?error=${encodeURIComponent("Failed to create file.")}`,
                );
            }
        },
        {
            body: t.Object({
                path: t.String(),
                content: t.Optional(t.String()),
                message: t.Optional(t.String()),
            }),
        },
    )

    // ── File deletion ─────────────────────────────────────────────────────────

    .post(
        "/:repo/delete-file/:ref/*",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAdmin(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, true);
            if (!repo) return new Response("Not found", { status: 404 });

            const filePath = decodeURIComponent(params["*"]);
            const message = body.message?.trim() || `Delete ${filePath}`;

            try {
                const commit = await git.deleteFile(
                    repo.name,
                    params.ref,
                    filePath,
                    message,
                    config.COMMITTER_NAME,
                    config.COMMITTER_EMAIL,
                );
                return redirect(`/${repo.name}/commit/${commit}`);
            } catch {
                return redirect(
                    `/${repo.name}/blob/${params.ref}/${filePath}?error=${encodeURIComponent("Failed to delete file.")}`,
                );
            }
        },
        {
            body: t.Object({
                message: t.Optional(t.String()),
            }),
        },
    );