import { Elysia, t } from "elysia";
import { sql } from "kysely";
import { ALLOWED_REACTIONS, ISSUES_PER_PAGE } from "../constants.ts";
import { db, getRepo, type LabelRow } from "../db/index.ts";
import {
    requireAdmin,
    requireAuth,
    resolveSession,
} from "../middleware/session.ts";
import { renderMarkdown } from "../services/markdown.ts";
import { buildReactionCounts } from "../services/reactions.ts";
import { IssueDetail } from "../views/issues/IssueDetail.tsx";
import { IssueList } from "../views/issues/IssueList.tsx";
import { NewIssue } from "../views/issues/NewIssue.tsx";
import { html } from "../views/render.tsx";

export const issueRoutes = new Elysia()
    .guard({
        cookie: t.Cookie({ session: t.Optional(t.String()) }),
    })
    .get(
        "/:repo/issues",
        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 status =
                query.status === "closed"
                    ? ("closed" as const)
                    : query.status === "completed"
                      ? ("completed" as const)
                      : ("open" as const);
            const page = Math.max(1, query.page ?? 1);

            // Parse label filter: query.labels may be a string or array of strings
            const rawLabels = query.labels;
            const labelIds: number[] = (
                Array.isArray(rawLabels)
                    ? rawLabels
                    : rawLabels
                      ? [rawLabels]
                      : []
            )
                .map((v) => parseInt(v, 10))
                .filter((n) => !isNaN(n));

            const repoLabels = await db
                .selectFrom("labels")
                .selectAll()
                .where("repo_id", "=", repo.id)
                .orderBy("name", "asc")
                .execute();

            let countQuery = db
                .selectFrom("issues")
                .select(["issues.status", db.fn.countAll<number>().as("count")])
                .where("issues.repo_id", "=", repo.id);
            if (labelIds.length > 0) {
                countQuery = countQuery.where(({ exists, selectFrom }) =>
                    exists(
                        selectFrom("issue_labels")
                            .select("issue_labels.issue_id")
                            .whereRef(
                                "issue_labels.issue_id",
                                "=",
                                "issues.id",
                            )
                            .where("issue_labels.label_id", "in", labelIds),
                    ),
                );
            }
            const allCounts = await countQuery.groupBy("issues.status").execute();
            const counts: Record<string, number> = Object.fromEntries(
                allCounts.map((r) => [r.status, Number(r.count)]),
            );
            const totalPages = Math.max(
                1,
                Math.ceil((counts[status] ?? 0) / ISSUES_PER_PAGE),
            );
            const safePage = Math.min(page, totalPages);
            const offset = (safePage - 1) * ISSUES_PER_PAGE;

            let listQuery = db
                .selectFrom("issues")
                .leftJoin("users", "users.id", "issues.author_id")
                .select([
                    "issues.id",
                    "issues.repo_id",
                    "issues.author_id",
                    "issues.number",
                    "issues.title",
                    "issues.body",
                    "issues.status",
                    "issues.created_at",
                    "issues.updated_at",
                    "issues.edited_at",
                    "users.username as author_username",
                    "users.avatar_version as author_avatar_version",
                ])
                .where("issues.repo_id", "=", repo.id)
                .where("issues.status", "=", status);
            if (labelIds.length > 0) {
                listQuery = listQuery.where(({ exists, selectFrom }) =>
                    exists(
                        selectFrom("issue_labels")
                            .select("issue_labels.issue_id")
                            .whereRef(
                                "issue_labels.issue_id",
                                "=",
                                "issues.id",
                            )
                            .where("issue_labels.label_id", "in", labelIds),
                    ),
                );
            }
            const issues = await listQuery
                .orderBy("issues.number", "desc")
                .limit(ISSUES_PER_PAGE)
                .offset(offset)
                .execute();

            // Batch-fetch labels for displayed issues
            const issueIds = issues.map((i) => i.id);
            const issueLabelsRows =
                issueIds.length > 0
                    ? await db
                          .selectFrom("issue_labels")
                          .innerJoin(
                              "labels",
                              "labels.id",
                              "issue_labels.label_id",
                          )
                          .select([
                              "issue_labels.issue_id",
                              "labels.id",
                              "labels.name",
                              "labels.color",
                          ])
                          .where("issue_labels.issue_id", "in", issueIds)
                          .execute()
                    : [];
            const labelsByIssueId = new Map<number, LabelRow[]>();
            for (const row of issueLabelsRows) {
                const list = labelsByIssueId.get(row.issue_id) ?? [];
                list.push({ id: row.id, repo_id: repo.id, name: row.name, color: row.color, created_at: "" });
                labelsByIssueId.set(row.issue_id, list);
            }

            const labelsParam =
                labelIds.length > 0
                    ? `&labels=${labelIds.map(String).join(",")}`
                    : "";
            const pagination = {
                page: safePage,
                totalPages,
                pageUrlTemplate: `/${repo.name}/issues?status=${status}${labelsParam}&page={page}`,
            };
            return html(
                <IssueList
                    user={user}
                    repo={repo}
                    issues={
                        issues as ((typeof issues)[0] & {
                            author_username: string;
                            author_avatar_version: number | null;
                        })[]
                    }
                    status={status}
                    counts={counts}
                    pagination={pagination}
                    repoLabels={repoLabels}
                    selectedLabelIds={labelIds}
                    labelsByIssueId={labelsByIssueId}
                />,
            );
        },
        {
            query: t.Object({
                status: t.Optional(t.String()),
                page: t.Optional(t.Numeric()),
                labels: t.Optional(t.Union([t.String(), t.Array(t.String())])),
            }),
        },
    )

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

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

            const { title, body: issueBody } = body;
            if (!title?.trim()) {
                return html(
                    <NewIssue
                        user={user!}
                        repo={repo}
                        error="Title is required"
                    />,
                );
            }

            const now = new Date().toISOString();
            const { number } = await db.transaction().execute(async (trx) => {
                const { issue_seq } = await trx
                    .updateTable("repositories")
                    .set({ issue_seq: sql`issue_seq + 1` })
                    .where("id", "=", repo.id)
                    .returning("issue_seq")
                    .executeTakeFirstOrThrow();
                await trx
                    .insertInto("issues")
                    .values({
                        repo_id: repo.id,
                        author_id: user?.id,
                        number: issue_seq,
                        title: title.trim(),
                        body: issueBody ?? "",
                        status: "open",
                        created_at: now,
                        updated_at: now,
                    })
                    .execute();
                return { number: issue_seq };
            });

            return new Response(null, {
                status: 302,
                headers: { Location: `/${repo.name}/issues/${number}` },
            });
        },
        {
            body: t.Object({
                title: t.String(),
                body: t.Optional(t.String()),
            }),
        },
    )

    .get("/:repo/issues/:number", 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 issueNum = parseInt(params.number, 10);
        const issue = await db
            .selectFrom("issues")
            .leftJoin("users", "users.id", "issues.author_id")
            .select([
                "issues.id",
                "issues.repo_id",
                "issues.author_id",
                "issues.number",
                "issues.title",
                "issues.body",
                "issues.status",
                "issues.created_at",
                "issues.updated_at",
                "issues.edited_at",
                "users.username as author_username",
                "users.avatar_version as author_avatar_version",
            ])
            .where("issues.repo_id", "=", repo.id)
            .where("issues.number", "=", issueNum)
            .executeTakeFirst();
        if (!issue) return new Response("Not found", { status: 404 });

        const bodyHtml = renderMarkdown(issue.body);

        const comments = await db
            .selectFrom("issue_comments")
            .leftJoin("users", "users.id", "issue_comments.author_id")
            .select([
                "issue_comments.id",
                "issue_comments.issue_id",
                "issue_comments.author_id",
                "issue_comments.body",
                "issue_comments.created_at",
                "issue_comments.edited_at",
                "users.username as author_username",
                "users.avatar_version as author_avatar_version",
            ])
            .where("issue_comments.issue_id", "=", issue.id)
            .orderBy("issue_comments.created_at", "asc")
            .execute();

        const commentsWithHtml = comments.map((c) => ({
            ...c,
            bodyHtml: renderMarkdown(c.body),
        }));

        // Reactions on the issue itself
        const allReactions = await db
            .selectFrom("issue_reactions")
            .selectAll()
            .where("issue_id", "=", issue.id)
            .execute();

        const reactions = buildReactionCounts(allReactions, null, user?.id);
        const commentReactions = new Map(
            comments.map((c) => [
                c.id,
                buildReactionCounts(allReactions, c.id, user?.id),
            ]),
        );

        const issueLabels = await db
            .selectFrom("issue_labels")
            .innerJoin("labels", "labels.id", "issue_labels.label_id")
            .select(["labels.id", "labels.repo_id", "labels.name", "labels.color", "labels.created_at"])
            .where("issue_labels.issue_id", "=", issue.id)
            .execute();

        const repoLabels = await db
            .selectFrom("labels")
            .selectAll()
            .where("repo_id", "=", repo.id)
            .orderBy("name", "asc")
            .execute();

        return html(
            <IssueDetail
                user={user}
                repo={repo}
                issue={
                    issue as typeof issue & {
                        author_username: string;
                        author_avatar_version: number | null;
                    }
                }
                bodyHtml={bodyHtml}
                comments={
                    commentsWithHtml as ((typeof commentsWithHtml)[0] & {
                        author_username: string;
                        author_avatar_version: number | null;
                    })[]
                }
                reactions={reactions}
                commentReactions={commentReactions}
                issueLabels={issueLabels}
                repoLabels={repoLabels}
            />,
        );
    })

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

            const issueNum = parseInt(params.number, 10);
            const issue = await db
                .selectFrom("issues")
                .select(["id", "status"])
                .where("repo_id", "=", repo.id)
                .where("number", "=", issueNum)
                .executeTakeFirst();
            if (!issue) return new Response("Not found", { status: 404 });

            // Only admin can comment on closed issues
            if (issue.status === "closed" && !user?.isAdmin) {
                return new Response(null, {
                    status: 302,
                    headers: { Location: `/${repo.name}/issues/${issueNum}` },
                });
            }

            const { body: commentBody } = body;
            if (!commentBody?.trim()) {
                return new Response(null, {
                    status: 302,
                    headers: { Location: `/${repo.name}/issues/${issueNum}` },
                });
            }

            await db.transaction().execute(async (trx) => {
                const now = new Date().toISOString();
                await trx
                    .insertInto("issue_comments")
                    .values({
                        issue_id: issue.id,
                        author_id: user?.id,
                        body: commentBody.trim(),
                        created_at: now,
                    })
                    .execute();
                await trx
                    .updateTable("issues")
                    .set({ updated_at: now })
                    .where("id", "=", issue.id)
                    .execute();
            });

            return new Response(null, {
                status: 302,
                headers: { Location: `/${repo.name}/issues/${issueNum}` },
            });
        },
        {
            body: t.Object({ body: t.String() }),
        },
    )

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

            const { emoji, comment_id } = body;
            if (!ALLOWED_REACTIONS.has(emoji)) {
                return new Response("Invalid emoji", { status: 400 });
            }

            const issueNum = parseInt(params.number, 10);
            const issue = await db
                .selectFrom("issues")
                .select(["id"])
                .where("repo_id", "=", repo.id)
                .where("number", "=", issueNum)
                .executeTakeFirst();
            if (!issue) return new Response("Not found", { status: 404 });

            const commentId = comment_id ? parseInt(comment_id, 10) : null;

            // One reaction per user per target: toggle off if same emoji, replace if different
            await db.transaction().execute(async (trx) => {
                const existing = await trx
                    .selectFrom("issue_reactions")
                    .select(["id", "emoji"])
                    .where("issue_id", "=", issue.id)
                    .where((eb) =>
                        commentId !== null
                            ? eb("comment_id", "=", commentId)
                            : eb("comment_id", "is", null),
                    )
                    .where("user_id", "=", user!.id)
                    .executeTakeFirst();

                if (existing) {
                    if (existing.emoji === emoji) {
                        await trx
                            .deleteFrom("issue_reactions")
                            .where("id", "=", existing.id)
                            .execute();
                    } else {
                        await trx
                            .updateTable("issue_reactions")
                            .set({ emoji })
                            .where("id", "=", existing.id)
                            .execute();
                    }
                } else {
                    await trx
                        .insertInto("issue_reactions")
                        .values({
                            issue_id: issue.id,
                            comment_id: commentId,
                            user_id: user!.id,
                            emoji,
                        })
                        .execute();
                }
            });

            return new Response(null, {
                status: 303,
                headers: { Location: `/${repo.name}/issues/${issueNum}` },
            });
        },
        {
            body: t.Object({
                emoji: t.String(),
                comment_id: t.Optional(t.String()),
            }),
        },
    )

    .post("/:repo/issues/:number/complete", 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 });

        const issueNum = parseInt(params.number, 10);
        const issue = await db
            .selectFrom("issues")
            .select("id")
            .where("repo_id", "=", repo.id)
            .where("number", "=", issueNum)
            .executeTakeFirst();
        if (!issue) return new Response("Not found", { status: 404 });

        await db
            .updateTable("issues")
            .set({ status: "completed", updated_at: new Date().toISOString() })
            .where("id", "=", issue.id)
            .execute();

        return new Response(null, {
            status: 302,
            headers: { Location: `/${repo.name}/issues/${issueNum}` },
        });
    })

    .post("/:repo/issues/:number/close", 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 });

        const issueNum = parseInt(params.number, 10);
        const issue = await db
            .selectFrom("issues")
            .select("id")
            .where("repo_id", "=", repo.id)
            .where("number", "=", issueNum)
            .executeTakeFirst();
        if (!issue) return new Response("Not found", { status: 404 });

        await db
            .updateTable("issues")
            .set({
                status: sql`CASE WHEN status = 'open' THEN 'closed' ELSE 'open' END`,
                updated_at: new Date().toISOString(),
            })
            .where("id", "=", issue.id)
            .execute();

        return new Response(null, {
            status: 302,
            headers: { Location: `/${repo.name}/issues/${issueNum}` },
        });
    })

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

        const issueNum = parseInt(params.number, 10);
        const issue = await db
            .selectFrom("issues")
            .select(["id", "author_id"])
            .where("repo_id", "=", repo.id)
            .where("number", "=", issueNum)
            .executeTakeFirst();
        if (!issue) return new Response("Not found", { status: 404 });
        if (issue.author_id !== user?.id && !user?.isAdmin)
            return new Response("Forbidden", { status: 403 });

        await db.deleteFrom("issues").where("id", "=", issue.id).execute();

        return new Response(null, {
            status: 302,
            headers: { Location: `/${repo.name}/issues` },
        });
    })

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

            const issueNum = parseInt(params.number, 10);
            const issue = await db
                .selectFrom("issues")
                .select(["id", "author_id", "status"])
                .where("repo_id", "=", repo.id)
                .where("number", "=", issueNum)
                .executeTakeFirst();
            if (!issue) return new Response("Not found", { status: 404 });
            if (issue.author_id !== user?.id && !user?.isAdmin)
                return new Response("Forbidden", { status: 403 });
            if (issue.status !== "open" && !user?.isAdmin)
                return new Response("Forbidden", { status: 403 });

            await db
                .updateTable("issues")
                .set({
                    title: body.title.trim(),
                    body: body.edit_body ?? "",
                    edited_at: new Date().toISOString(),
                    updated_at: new Date().toISOString(),
                })
                .where("id", "=", issue.id)
                .execute();

            return new Response(null, {
                status: 302,
                headers: { Location: `/${repo.name}/issues/${issueNum}` },
            });
        },
        {
            body: t.Object({
                title: t.String(),
                edit_body: t.Optional(t.String()),
            }),
        },
    )

    .post(
        "/:repo/issues/:number/comments/:id/edit",
        async ({ params, body, cookie }) => {
            const user = await resolveSession(cookie.session.value);
            const deny = requireAuth(user);
            if (deny) return deny;
            const repo = await getRepo(params.repo, user?.isAdmin ?? false);
            if (!repo) return new Response("Not found", { status: 404 });

            const comment = await db
                .selectFrom("issue_comments")
                .select(["id", "author_id", "issue_id"])
                .where("id", "=", params.id)
                .executeTakeFirst();
            if (!comment) return new Response("Not found", { status: 404 });
            if (comment.author_id !== user?.id && !user?.isAdmin)
                return new Response("Forbidden", { status: 403 });
            const parentIssue = await db
                .selectFrom("issues")
                .select("status")
                .where("id", "=", comment.issue_id)
                .executeTakeFirst();
            if (parentIssue?.status !== "open" && !user?.isAdmin)
                return new Response("Forbidden", { status: 403 });

            const issueNum = parseInt(params.number, 10);
            await db
                .updateTable("issue_comments")
                .set({
                    body: body.edit_body.trim(),
                    edited_at: new Date().toISOString(),
                })
                .where("id", "=", comment.id)
                .execute();

            return new Response(null, {
                status: 302,
                headers: { Location: `/${repo.name}/issues/${issueNum}` },
            });
        },
        {
            params: t.Object({
                repo: t.String(),
                number: t.String(),
                id: t.Numeric(),
            }),
            body: t.Object({ edit_body: t.String() }),
        },
    )

    .post(
        "/:repo/issues/:number/labels/add",
        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 issueNum = parseInt(params.number, 10);
            const issue = await db
                .selectFrom("issues")
                .select(["id"])
                .where("repo_id", "=", repo.id)
                .where("number", "=", issueNum)
                .executeTakeFirst();
            if (!issue) return new Response("Not found", { status: 404 });

            const label = await db
                .selectFrom("labels")
                .select(["id"])
                .where("id", "=", body.label_id)
                .where("repo_id", "=", repo.id)
                .executeTakeFirst();
            if (!label) {
                return new Response(null, {
                    status: 302,
                    headers: { Location: `/${repo.name}/issues/${issueNum}` },
                });
            }

            await db
                .insertInto("issue_labels")
                .values({ issue_id: issue.id, label_id: label.id })
                .onConflict((oc) => oc.doNothing())
                .execute();

            return new Response(null, {
                status: 302,
                headers: { Location: `/${repo.name}/issues/${issueNum}` },
            });
        },
        {
            params: t.Object({ repo: t.String(), number: t.String() }),
            body: t.Object({ label_id: t.Numeric() }),
        },
    )

    .post(
        "/:repo/issues/:number/labels/remove",
        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 issueNum = parseInt(params.number, 10);
            const issue = await db
                .selectFrom("issues")
                .select(["id"])
                .where("repo_id", "=", repo.id)
                .where("number", "=", issueNum)
                .executeTakeFirst();
            if (!issue) return new Response("Not found", { status: 404 });

            await db
                .deleteFrom("issue_labels")
                .where("issue_id", "=", issue.id)
                .where("label_id", "=", body.label_id)
                .execute();

            return new Response(null, {
                status: 302,
                headers: { Location: `/${repo.name}/issues/${issueNum}` },
            });
        },
        {
            params: t.Object({ repo: t.String(), number: t.String() }),
            body: t.Object({ label_id: t.Numeric() }),
        },
    );