import type {
	MediaFile,
	Directory,
	FileListing,
	FileListingWithStatus,
	DirectoryWithStatus,
	Metadata,
} from "music-server-shared/types";
import { parseMap } from "music-server-shared/mapconversion";
import type { AppOptions, Playlist } from "./types";
import { joinPath, toast, unproxy } from "./utils";
import { batch, from, untrack, type ResourceActions } from "solid-js";
import { AsyncSemaphore } from "./semaphore";
import { encodePath } from "music-server-shared/utils";
import type { FlatFileListing } from "./App";
import { createStore } from "solid-js/store";
import Dexie, { liveQuery } from "dexie";

interface StoredFile {
	path: string;
	data: Blob;
	metadata: Metadata;
}

interface StoredCover {
	path: string;
	data: Blob | null;
}

interface Database extends Dexie {
	files: Dexie.Table<StoredFile, string>;
	covers: Dexie.Table<StoredCover, string>;
	playlists: Dexie.Table<Playlist, string>;
}

const db = new Dexie("music-files") as Database;
db.version(1).stores({
	files: "path",
	covers: "path",
	playlists: "name",
});

export type Progress =
	| { status: number; abort: () => void }
	| { status: "Aborted"; retry: () => void }
	| { status: "Failed"; retry: () => void; reason: string };

interface LoadingChildren {
	amount: number;
}

export type DownloadStatus = Progress | LoadingChildren | "Synced" | undefined;
export const [downloadStatusMap, setDownloadStatusMap] = createStore<Record<string, DownloadStatus>>({});

//creates entry if it doesn't exist, so reactivity works
export function getDownloadStatus(path: string): DownloadStatus {
	untrack(() => {
		if (!Object.keys(downloadStatusMap).includes(path)) setDownloadStatusMap(path, undefined);
	});
	return downloadStatusMap[path];
}

function updateRecursiveStatus(path: string, loadChange: number, includeCurrent: boolean) {
	function updateProgressAmount(path: string) {
		const currentStatus = downloadStatusMap[path];
		if (typeof currentStatus !== "object" || !("amount" in currentStatus)) {
			setDownloadStatusMap(path, loadChange > 0 ? { amount: loadChange } : undefined);
			return;
		}

		const newAmount = currentStatus.amount + loadChange;
		setDownloadStatusMap(path, newAmount > 0 ? { amount: newAmount } : undefined);
	}

	if (includeCurrent) updateProgressAmount(path);
	// Update all parent directories
	let currentPath = path;
	while (true) {
		const lastSlash = currentPath.lastIndexOf("/");
		if (lastSlash === -1) break;
		currentPath = currentPath.substring(0, lastSlash);
		updateProgressAmount(currentPath);
	}
}

function startProgress(path: string, status: DownloadStatus) {
	updateRecursiveStatus(path, 1, false);
	setDownloadStatusMap(path, status);
}

function stopProgress(path: string, status: DownloadStatus) {
	updateRecursiveStatus(path, -1, false);
	setDownloadStatusMap(path, status);
}

//initialize filetrees and download statuses from indexedDB
export async function loadDataFromDB() {
	try {
		const files = await db.files.toArray();
		for (const file of files) {
			setDownloadStatusMap(file.path, "Synced");
			updateFileTree(file.path, { metadata: file.metadata }, true);
		}
		const covers = await db.covers.toArray();
		for (const cover of covers) {
			coverCache.set(cover.path, { data: cover.data });
		}
	} catch (e) {
		toast("Loading offline files failed", "error", e);
		console.error(e);
	}
}

//contains all locally synced files
const offlineTreeRoot: Directory = {
	files: new Map(),
};
//used for caching online file listings
const onlineTreeRoot: DirectoryWithStatus = {
	files: new Map(),
	status: "Unknown",
};

//merges "Scanned" directories from "other" to "target"
function mergeTrees(target: DirectoryWithStatus, other: DirectoryWithStatus) {
	if (other.status === "Unknown") return;
	target.status = other.status;
	for (const [fileName, file] of other.files.entries()) {
		const targetFile = target.files.get(fileName);
		if (targetFile && "files" in targetFile && "files" in file) {
			mergeTrees(targetFile, file);
		} else {
			target.files.set(fileName, file);
		}
	}
}

//TODO: improve typing to avoid "as"
//overloads for typecheking
//offline tree only stores files, directories are created ad-hoc
function updateFileTree(path: string, file: MediaFile, offline: true): void;
//online tree only stores cached directory listings
function updateFileTree(path: string, file: DirectoryWithStatus, offline: false): void;
// Updates file tree structure with new data (offline or online)
function updateFileTree(path: string, file: DirectoryWithStatus | MediaFile, offline: boolean) {
	if (offline && path === "") throw new Error("Trying to update root in offline mode");
	const basePath = path.split("/").slice(0, -1).join("/");
	const fileName = path.split("/").toReversed()[0];
	const node = getDirInTree(basePath, true, offline);

	if (offline) {
		node.files.set(fileName, file);
	} else {
		if (path === "") mergeTrees(node as DirectoryWithStatus, file as DirectoryWithStatus);
		else {
			let target = node.files.get(fileName) as DirectoryWithStatus;
			if (!target) target = { files: new Map(), status: "Unknown" };
			mergeTrees(target as DirectoryWithStatus, file as DirectoryWithStatus);
			node.files.set(fileName, target);
		}
	}
}

//overloads for typechecking
function getDirInTree(path: string, create: true, offline: true): Directory;
function getDirInTree(path: string, create: true, offline: false): DirectoryWithStatus;
function getDirInTree(path: string, create: false, offline: true): Directory | null;
function getDirInTree(path: string, create: false, offline: false): DirectoryWithStatus | null;
function getDirInTree(path: string, create: true, offline: boolean): DirectoryWithStatus | Directory;
function getDirInTree(path: string, create: false, offline: boolean): DirectoryWithStatus | Directory | null;
// get a DirectoryNode from the directory tree matching the path, and optionally creating missing nodes it if they don't exist yet
function getDirInTree(path: string, create: boolean, offline: boolean): DirectoryWithStatus | Directory | null {
	let current = offline ? offlineTreeRoot : onlineTreeRoot;
	if (path === "") return current;
	const parts = path.split("/");

	for (const part of parts) {
		let next: DirectoryWithStatus | Directory | MediaFile | undefined = current.files.get(part);
		if (!next || "metadata" in next) {
			if (!create) return null;
			//if mediafile already exists, we overwrite it with a directory anyway
			if (offline) next = { files: new Map() };
			else next = { files: new Map(), status: "Unknown" };
			current.files.set(part, next);
		}
		current = next;
	}
	return current;
}

function deleteInOfflineTree(path: string): void {
	if (path === "") return;
	const basePath = path.split("/").slice(0, -1).join("/");
	const fileName = path.split("/").toReversed()[0];

	const node = getDirInTree(basePath, false, true);
	if (!node) return;

	node.files.delete(fileName);
	if (node.files.size === 0) {
		db.covers.delete(basePath); //remove stored cover for this dir if there are not files left
		deleteInOfflineTree(basePath);
	}
}

export const clearDirectoryCache = async (path: string) => {
	const node = getDirInTree(path, false, false);
	if (!node) return;

	// Save existing children before clearing
	const preservedChildren = new Map(node.files);

	node.files.clear();
	node.status = "Unknown";

	// restore any preserved subtrees where the parent directory still exist
	const newListing = await listFiles(path, false, false);
	for (const [name, child] of preservedChildren.entries()) {
		if ("files" in child && newListing.has(name)) {
			node.files.set(name, child);
		}
	}
};
async function listOnlineFiles(dir: string, recursive: boolean): Promise<FileListingWithStatus | undefined> {
	const response = await fetch(`/list/${encodePath(dir)}?recursive=${recursive}`, { credentials: "same-origin" }).catch(
		() => {},
	);
	if (response?.status === 404) {
		toast(`Directory not found: ${dir}`, "error");
		return;
	}
	if (!response || !response.ok) {
		toast(
			`Fetching files for ${dir === "" ? "root" : dir} failed${response ? `: ${response.statusText}` : ""}`,
			"error",
		);
		return;
	}

	return parseMap(await response.text()) as FileListingWithStatus;
}

function listOfflineFiles(dir: string): FileListing {
	const node = getDirInTree(dir, false, true);
	if (!node || !node.files) return new Map();
	return node.files;
}

//checks if this Directory is completely scanned, i.e. suitable for a recursive listing result
function fullyKnown(dir: DirectoryWithStatus) {
	if (dir.status === "Unknown") {
		return false;
	}
	if (dir.files.values().some((value) => "files" in value && !fullyKnown(value))) {
		return false;
	}
	return true;
}

//non-recursive listing should not include nested children
function pruneChildren(listing: FileListing) {
	const pruned = new Map();
	for (const [name, item] of listing.entries()) {
		if ("metadata" in item) pruned.set(name, item);
		else pruned.set(name, { files: new Map() });
	}
	return pruned;
}

//used for combining the online and offline results, to be able to show files that only exist locally
function combineFileListings(listing1: FileListing, listing2: FileListing): FileListing {
	const result = new Map(listing1);

	for (const [key, value2] of listing2.entries()) {
		const value1 = result.get(key);

		if (value1 && "files" in value1 && "files" in value2) {
			result.set(key, { files: combineFileListings(value1.files, value2.files) });
		} else {
			result.set(key, value2);
		}
	}

	return result;
}

// File listing logic with hybrid online/offline support
// Combines:
// 1. Direct IndexedDB lookups for offline mode
// 2. Cached online listings
// 3. Merged online+offline results
export async function listFiles(dir: string, offline: boolean, recursive: boolean): Promise<FileListing> {
	if (offline) {
		const files = listOfflineFiles(dir);
		return recursive ? files : pruneChildren(files);
	}
	const cached = getDirInTree(dir, false, false);
	if (cached !== null && cached.status === "Scanned" && (!recursive || fullyKnown(cached))) {
		const combined = combineFileListings(cached.files, listOfflineFiles(dir));
		return recursive ? combined : pruneChildren(combined);
	}
	const files = await listOnlineFiles(dir, recursive);
	if (!files) return new Map();
	updateFileTree(dir, { files, status: "Scanned" }, false);
	const combined = combineFileListings(files, listOfflineFiles(dir));
	return recursive ? combined : pruneChildren(combined);
}

const coverCache = new Map<string, { data: Blob | null }>();

//get cover art object-url for a file or directory with cache-first strategy
export async function getCover(
	dir: string,
	options: AppOptions,
	saveToDb: boolean,
	offline: boolean,
	forceRefresh = false,
) {
	try {
		const cached = coverCache.get(dir);
		if (!forceRefresh && cached !== undefined) {
			if (saveToDb) db.covers.add({ path: dir, data: cached.data }).catch(() => {});
			return cached.data === null ? undefined : URL.createObjectURL(cached.data);
		}

		if (offline) return undefined;

		const response = await fetch(`/cover/${encodePath(dir)}${options.transcodeCovers ? "?transcode=true" : ""}`, {
			method: "GET",
			credentials: "same-origin",
		}).catch(() => {});
		if (!response || response.status === 404) {
			coverCache.set(dir, { data: null });
			if (saveToDb) db.covers.add({ path: dir, data: null }).catch(() => {});
			//if cover already exists in database, update it
			else if (forceRefresh && db.covers.get(dir) !== undefined) db.covers.put({ path: dir, data: null });
			return undefined;
		}
		const blob = await response.blob();
		coverCache.set(dir, { data: blob });
		if (saveToDb) db.covers.add({ path: dir, data: blob }).catch(() => {});
		//if cover already exists in database, update it
		else if (forceRefresh && db.covers.get(dir) !== undefined) db.covers.put({ path: dir, data: blob });
		return URL.createObjectURL(blob);
	} catch {
		return undefined;
	}
}

//returns an object url to the blob if synced, otherwise the server url
export async function getSrc(
	path: string,
	options: AppOptions,
	offline: boolean,
	seekTo: number,
	forceUrl?: true,
): Promise<string>;
export async function getSrc(path: string, options: AppOptions, offline: boolean, seekTo: number, forceUrl?: boolean) {
	if (!forceUrl) {
		const dbResult = await db.files.get(path);
		if (dbResult) return URL.createObjectURL(dbResult.data);

		if (offline) {
			toast("This file is not cached, leave offline mode to play it", "error");
			return undefined;
		}
	}
	if (options.enableTranscoding) {
		return (
			`${joinPath("/transcode", encodePath(path))}` +
			`?disableChunkedTranscoding=${options.disableChunkedTranscoding}` +
			`&container=${options.container}` +
			`&audioCodec=${options.audioCodec}` +
			`&audioBitrate=${options.audioBitrate}` +
			`&videoCodec=${options.videoCodec}` +
			`&videoBitrate=${options.videoBitrate}` +
			`${seekTo === 0 ? "" : `&seekTo=${seekTo}`}`
		);
	}
	return joinPath("/download", encodePath(path));
}

export async function loadPlaylists() {
	return await db.playlists.toArray();
}

//save playlist to indexedDB, throws error if playlist with that name already exists and overwrite=false
export async function savePlaylist(playlist: Playlist, overwrite: boolean) {
	playlist.items = playlist.items.map((item) => {
		//some less space in the db by omitting ids
		return { path: item.path, metadata: unproxy(item.metadata) };
	});

	if (overwrite) {
		await db.playlists.put(playlist);
	} else {
		await db.playlists.add(playlist);
	}
}

export async function deletePlaylist(name: string) {
	await db.playlists.delete(name);
}

function collectMediaFilePaths(listing: FileListing, basePath: string): string[] {
	const paths: string[] = [];

	for (const [name, item] of listing.entries()) {
		const currentPath = joinPath(basePath, name);

		if ("metadata" in item) {
			paths.push(currentPath);
		} else if ("files" in item) {
			paths.push(...collectMediaFilePaths(item.files, currentPath));
		}
	}

	return paths;
}

//deletes file or directory(+recursive contents) from indexedDB and updates their download statuses
export async function deleteFile(
	fullPath: string,
	item: MediaFile | Directory,
	fetchFiles: ResourceActions<FlatFileListing>,
) {
	try {
		if ("metadata" in item && downloadStatusMap[fullPath] !== "Synced") return;
		startProgress(fullPath, { amount: 1 });

		let toDelete: string[];
		if ("files" in item) {
			toDelete = collectMediaFilePaths(listOfflineFiles(fullPath), fullPath);
		} else {
			toDelete = [fullPath];
		}

		await db.files.bulkDelete(toDelete); //delete file from database
		await db.covers.bulkDelete(toDelete); //delete embedded cover from database
		deleteInOfflineTree(fullPath); //delete node  from tree
		batch(() => {
			for (const path of toDelete) {
				setDownloadStatusMap(path, undefined); // set all children to unsynced
			}
		});
		fetchFiles.refetch();
	} finally {
		stopProgress(fullPath, undefined);
	}
}

const downloadSemaphore = new AsyncSemaphore(1);

//Download file to indexedDB and updates the offline file tree
//concurrency control via the downloadSemaphore
async function downloadFile(
	path: string,
	options: AppOptions,
	item: MediaFile,
	fetchFiles: ResourceActions<FlatFileListing>,
	redownload: boolean,
): Promise<void> {
	const retry = () => downloadFile(path, options, item, fetchFiles, redownload);

	const controller = new AbortController();
	let abortResolve!: () => void;
	const abortPromise = new Promise<void>((outerResolve) => {
		abortResolve = () => {
			controller.abort();
			stopProgress(
				path,
				// if it was already synced, restore it
				initialProgress === "Synced" ? "Synced" : { status: "Aborted", retry },
			);
			outerResolve();
		};
	});
	// file already downloaded or download already in progress
	const initialProgress = downloadStatusMap[path];
	if (
		(!redownload && initialProgress === "Synced") ||
		(typeof initialProgress === "object" && "bytes" in initialProgress)
	)
		return;
	startProgress(path, { status: 0, abort: abortResolve });

	try {
		//options might change at any point, update the semaphore to the current value
		downloadSemaphore.setMaxConcurrency(options.enableTranscoding ? options.maxTranscodes : options.maxDownloads);

		//make sure to only allow the set amount of parallel downloads
		const semaphorePromise = downloadSemaphore.acquire();
		await Promise.race([abortPromise, semaphorePromise]);
		try {
			const res = await fetch(await getSrc(path, options, false, 0, true), {
				signal: controller.signal,
				credentials: "same-origin",
			});

			//let the browser do the actual download
			const blobPromise = res.clone().blob();
			if (!res.ok || !res.body) throw res.statusText;
			//we just iterate over the chunks to get the current progress
			const reader = res.body.getReader();
			let received = 0;

			let lastUpdate = 0;
			while (true) {
				const { done, value } = await reader.read();
				if (done) break;
				received += value.length;

				//debouncing logic to not update UI too fast
				const now = Date.now();
				if (now - lastUpdate < 250) continue;
				lastUpdate = now;
				setDownloadStatusMap(path, { status: received, abort: abortResolve });
			}
			const blob = await blobPromise;

			await db.files.put({
				path,
				data: blob,
				metadata: unproxy(item.metadata),
			});

			updateFileTree(path, item, true);
			stopProgress(path, "Synced");
			fetchFiles.refetch();

			//iterate through all parent directories and download their covers to database
			const parts = path.split("/");
			while (true) {
				getCover(parts.join("/"), options, true, false).then((cover) => URL.revokeObjectURL(cover || ""));
				parts.pop();
				if (parts.length === 0) break;
			}
		} finally {
			downloadSemaphore.release();
		}
	} catch (e) {
		if (e && typeof e === "object" && "name" in e && e.name === "AbortError") return;
		stopProgress(
			path,
			// if it was already synced, restore it
			initialProgress === "Synced"
				? "Synced"
				: {
						status: "Failed",
						reason: e ? e.toString() : "Unknown error",
						retry,
					},
		);
	}
}

export async function download(
	fullPath: string,
	item: MediaFile | Directory,
	options: AppOptions,
	fetchFiles: ResourceActions<FlatFileListing>,
	redownload = false,
) {
	if ("metadata" in item) {
		await downloadFile(fullPath, options, item, fetchFiles, redownload || false);
	} else {
		updateRecursiveStatus(fullPath, 1, true);
		try {
			//start downloads for all children to allow them to run in parallel, then wait for the results
			const promises: Promise<unknown>[] = [];
			const listing = await listFiles(fullPath, false, false);
			batch(() => {
				for (const [childName, childItem] of listing) {
					promises.push(download(joinPath(fullPath, childName), childItem, options, fetchFiles, redownload));
				}
			});
			await Promise.allSettled(promises);
		} finally {
			updateRecursiveStatus(fullPath, -1, true);
		}
	}
}

export const storedFilesLive = from(
	liveQuery(async () => await db.files.toCollection().keys()),
	[],
);