import { Hono } from "hono";
import { stream } from "hono/streaming";
import { getAllConfig, getConfig, getDb, setConfig } from "../db/index";
import { log, error as logError, warn } from "../lib/log";
import { getAllItems, getDevItems } from "../services/jellyfin";
import { loadLibrary as loadRadarrLibrary, isUsable as radarrUsable } from "../services/radarr";
import { upsertJellyfinItem } from "../services/rescan";
import { isInScanWindow, msUntilScanWindow, nextScanWindowTime, waitForScanWindow } from "../services/scheduler";
import { loadLibrary as loadSonarrLibrary, isUsable as sonarrUsable } from "../services/sonarr";

const app = new Hono();

/**
 * Validate a scan `limit` input. Must be a positive integer or absent —
 * NaN/negatives/non-numerics would disable the progress cap
 * (`processed >= NaN` never trips) or produce bogus totals via
 * `Math.min(NaN, …)`. Exported for unit tests.
 */
export function parseScanLimit(raw: unknown): { ok: true; value: number | null } | { ok: false } {
	if (raw == null || raw === "") return { ok: true, value: null };
	const n = typeof raw === "number" ? raw : Number(raw);
	if (!Number.isInteger(n) || n <= 0) return { ok: false };
	return { ok: true, value: n };
}

type ScanStatusFilter = "all" | "pending" | "scanned" | "error";
type ScanTypeFilter = "all" | "movie" | "episode";
type ScanSourceFilter = "all" | "scan" | "webhook";

export interface ScanItemsQuery {
	offset: number;
	limit: number;
	search: string;
	status: ScanStatusFilter;
	type: ScanTypeFilter;
	source: ScanSourceFilter;
}

function parsePositiveInt(raw: unknown, fallback: number): number {
	const n = typeof raw === "number" ? raw : Number(raw);
	if (!Number.isFinite(n)) return fallback;
	if (!Number.isInteger(n)) return fallback;
	return n;
}

function clamp(n: number, min: number, max: number): number {
	if (n < min) return min;
	if (n > max) return max;
	return n;
}

function parseOneOf<T extends readonly string[]>(raw: unknown, allowed: T, fallback: T[number]): T[number] {
	if (typeof raw !== "string") return fallback;
	const lowered = raw.toLowerCase();
	return (allowed as readonly string[]).includes(lowered) ? (lowered as T[number]) : fallback;
}

export function parseScanItemsQuery(raw: Record<string, unknown>): ScanItemsQuery {
	const limit = clamp(parsePositiveInt(raw.limit, 50), 1, 200);
	const offset = Math.max(0, parsePositiveInt(raw.offset, 0));
	const search = typeof raw.q === "string" ? raw.q.trim() : "";
	return {
		offset,
		limit,
		search,
		status: parseOneOf(raw.status, ["all", "pending", "scanned", "error"] as const, "all"),
		type: parseOneOf(raw.type, ["all", "movie", "episode"] as const, "all"),
		source: parseOneOf(raw.source, ["all", "scan", "webhook"] as const, "all"),
	};
}

export function buildScanItemsWhere(query: ScanItemsQuery): { sql: string; args: unknown[] } {
	const clauses: string[] = [];
	const args: unknown[] = [];
	if (query.status !== "all") {
		clauses.push("scan_status = ?");
		args.push(query.status);
	}
	if (query.type !== "all") {
		clauses.push("lower(type) = ?");
		args.push(query.type);
	}
	if (query.source !== "all") {
		clauses.push("ingest_source = ?");
		args.push(query.source);
	}
	if (query.search.length > 0) {
		clauses.push("(lower(name) LIKE ? OR lower(file_path) LIKE ?)");
		const needle = `%${query.search.toLowerCase()}%`;
		args.push(needle, needle);
	}
	return {
		sql: clauses.length > 0 ? `WHERE ${clauses.join(" AND ")}` : "",
		args,
	};
}

// ─── State ────────────────────────────────────────────────────────────────────

let scanAbort: AbortController | null = null;
const scanListeners = new Set<(data: string) => void>();

function emitSse(type: string, data: unknown): void {
	const line = `event: ${type}\ndata: ${JSON.stringify(data)}\n\n`;
	for (const listener of scanListeners) listener(line);
}

function currentScanLimit(): number | null {
	const v = getConfig("scan_limit");
	return v ? Number(v) : null;
}

function parseLanguageList(raw: string | null, fallback: string[]): string[] {
	if (!raw) return fallback;
	try {
		const parsed = JSON.parse(raw);
		return Array.isArray(parsed) ? parsed.filter((v): v is string => typeof v === "string") : fallback;
	} catch {
		return fallback;
	}
}

// ─── Status ───────────────────────────────────────────────────────────────────

app.get("/", (c) => {
	const db = getDb();
	const running = getConfig("scan_running") === "1";
	const total = (db.prepare("SELECT COUNT(*) as n FROM media_items").get() as { n: number }).n;
	const scanned = (
		db.prepare("SELECT COUNT(*) as n FROM media_items WHERE scan_status = 'scanned'").get() as { n: number }
	).n;
	const errors = (db.prepare("SELECT COUNT(*) as n FROM media_items WHERE scan_status = 'error'").get() as { n: number })
		.n;
	const recentItems = db
		.prepare(
			"SELECT name, type, scan_status, file_path, last_scanned_at, ingest_source FROM media_items ORDER BY COALESCE(last_scanned_at, created_at) DESC, id DESC LIMIT 5",
		)
		.all() as {
		name: string;
		type: string;
		scan_status: string;
		file_path: string;
		last_scanned_at: string | null;
		ingest_source: string | null;
	}[];

	return c.json({ running, progress: { scanned, total, errors }, recentItems, scanLimit: currentScanLimit() });
});

app.get("/items", (c) => {
	const db = getDb();
	const query = parseScanItemsQuery({
		offset: c.req.query("offset"),
		limit: c.req.query("limit"),
		q: c.req.query("q"),
		status: c.req.query("status"),
		type: c.req.query("type"),
		source: c.req.query("source"),
	});
	const where = buildScanItemsWhere(query);
	const rows = db
		.prepare(
			`
			SELECT id, jellyfin_id, name, type, series_name, season_number, episode_number,
			       scan_status, original_language, orig_lang_source, container, file_size, file_path,
			       last_scanned_at, ingest_source
			FROM media_items
			${where.sql}
			ORDER BY COALESCE(last_scanned_at, created_at) DESC, id DESC
			LIMIT ? OFFSET ?
		`,
		)
		.all(...where.args, query.limit, query.offset) as Array<{
		id: number;
		jellyfin_id: string;
		name: string;
		type: string;
		series_name: string | null;
		season_number: number | null;
		episode_number: number | null;
		scan_status: string;
		original_language: string | null;
		orig_lang_source: string | null;
		container: string | null;
		file_size: number | null;
		file_path: string;
		last_scanned_at: string | null;
		ingest_source: string | null;
	}>;
	const total = (db.prepare(`SELECT COUNT(*) as n FROM media_items ${where.sql}`).get(...where.args) as { n: number }).n;
	return c.json({ rows, total, hasMore: query.offset + rows.length < total, query });
});

// ─── Start ────────────────────────────────────────────────────────────────────

app.post("/start", async (c) => {
	const db = getDb();
	// Atomic claim: only succeed if scan_running is not already '1'.
	const claim = db.prepare("UPDATE config SET value = '1' WHERE key = 'scan_running' AND value != '1'").run();
	if (claim.changes === 0) {
		return c.json({ ok: false, error: "Scan already running" }, 409);
	}

	const body = await c.req.json<{ limit?: unknown }>().catch(() => ({ limit: undefined }));
	const formLimit = parseScanLimit(body.limit);
	const envLimit = parseScanLimit(process.env.SCAN_LIMIT);
	if (!formLimit.ok || !envLimit.ok) {
		db.prepare("UPDATE config SET value = '0' WHERE key = 'scan_running'").run();
		return c.json({ ok: false, error: "limit must be a positive integer" }, 400);
	}
	const limit: number | null = formLimit.value ?? envLimit.value ?? null;
	setConfig("scan_limit", limit != null ? String(limit) : "");

	runScan(limit).catch((err) => {
		logError("Scan failed:", err);
		setConfig("scan_running", "0");
		emitSse("error", { message: String(err) });
	});

	return c.json({ ok: true });
});

// ─── Stop ─────────────────────────────────────────────────────────────────────

app.post("/stop", (c) => {
	scanAbort?.abort();
	setConfig("scan_running", "0");
	return c.json({ ok: true });
});

// ─── SSE ──────────────────────────────────────────────────────────────────────

app.get("/events", (c) => {
	return stream(c, async (s) => {
		c.header("Content-Type", "text/event-stream");
		c.header("Cache-Control", "no-cache");
		c.header("Connection", "keep-alive");

		const queue: string[] = [];
		let resolve: (() => void) | null = null;

		const listener = (data: string) => {
			queue.push(data);
			resolve?.();
		};

		scanListeners.add(listener);
		s.onAbort(() => {
			scanListeners.delete(listener);
		});

		try {
			while (!s.closed) {
				if (queue.length > 0) {
					await s.write(queue.shift()!);
				} else {
					await new Promise<void>((res) => {
						resolve = res;
						setTimeout(res, 25_000);
					});
					resolve = null;
					if (queue.length === 0) await s.write(": keepalive\n\n");
				}
			}
		} finally {
			scanListeners.delete(listener);
		}
	});
});

// ─── Core scan logic ──────────────────────────────────────────────────────────

async function runScan(limit: number | null = null): Promise<void> {
	log(`Scan started${limit ? ` (limit: ${limit})` : ""}`);
	scanAbort = new AbortController();
	const { signal } = scanAbort;
	const isDev = process.env.NODE_ENV === "development";
	const db = getDb();

	if (isDev) {
		// Order matters only if foreign keys are enforced without CASCADE; we
		// have ON DELETE CASCADE on media_streams/review_plans/stream_decisions/
		// subtitle_files/jobs, so deleting media_items would be enough. List
		// them explicitly for clarity and to survive future schema drift.
		db.prepare("DELETE FROM jobs").run();
		db.prepare("DELETE FROM subtitle_files").run();
		db.prepare("DELETE FROM stream_decisions").run();
		db.prepare("DELETE FROM review_plans").run();
		db.prepare("DELETE FROM media_streams").run();
		db.prepare("DELETE FROM media_items").run();
	}

	const cfg = getAllConfig();
	const jellyfinCfg = { url: cfg.jellyfin_url, apiKey: cfg.jellyfin_api_key, userId: cfg.jellyfin_user_id };
	const audioLanguages = parseLanguageList(cfg.audio_languages ?? null, []);
	const radarrCfg = { url: cfg.radarr_url, apiKey: cfg.radarr_api_key };
	const sonarrCfg = { url: cfg.sonarr_url, apiKey: cfg.sonarr_api_key };
	// 'enabled' in config means the user toggled it on. Only actually use it
	// if the URL+key pass URL parsing — otherwise we'd hit ERR_INVALID_URL on
	// every item. Refuse to call invalid endpoints rather than spamming logs.
	const radarrEnabled = cfg.radarr_enabled === "1" && radarrUsable(radarrCfg);
	const sonarrEnabled = cfg.sonarr_enabled === "1" && sonarrUsable(sonarrCfg);

	if (cfg.radarr_enabled === "1" && !radarrEnabled) {
		warn(`Radarr is enabled in config but URL/API key is invalid (url='${cfg.radarr_url}') — skipping Radarr lookups`);
	}
	if (cfg.sonarr_enabled === "1" && !sonarrEnabled) {
		warn(`Sonarr is enabled in config but URL/API key is invalid (url='${cfg.sonarr_url}') — skipping Sonarr lookups`);
	}

	// Pre-load both libraries once so per-item lookups are O(1) cache hits
	// instead of HTTP round-trips. The previous code called /api/v3/movie
	// (the entire library!) once per item that didn't match by tmdbId.
	const [radarrLibrary, sonarrLibrary] = await Promise.all([
		radarrEnabled ? loadRadarrLibrary(radarrCfg) : Promise.resolve(null),
		sonarrEnabled ? loadSonarrLibrary(sonarrCfg) : Promise.resolve(null),
	]);

	log(
		`External language sources: radarr=${radarrEnabled ? `enabled (${cfg.radarr_url}, ${radarrLibrary?.byTmdbId.size ?? 0} movies in library)` : "disabled"}, sonarr=${sonarrEnabled ? `enabled (${cfg.sonarr_url}, ${sonarrLibrary?.byTvdbId.size ?? 0} series in library)` : "disabled"}`,
	);
	let processed = 0;
	let errors = 0;
	let total = 0;

	const rescanCfg = {
		audioLanguages,
		radarr: radarrEnabled ? radarrCfg : null,
		sonarr: sonarrEnabled ? sonarrCfg : null,
		radarrLibrary,
		sonarrLibrary,
	};

	let radarrMisses = 0;
	let radarrHits = 0;
	let sonarrMisses = 0;
	let sonarrHits = 0;
	let missingProviderIds = 0;

	const itemSource = isDev
		? getDevItems(jellyfinCfg)
		: getAllItems(jellyfinCfg, (_fetched, jellyfinTotal) => {
				total = limit != null ? Math.min(limit, jellyfinTotal) : jellyfinTotal;
			});
	for await (const jellyfinItem of itemSource) {
		if (signal.aborted) break;
		if (!isDev && limit != null && processed >= limit) break;
		if (!jellyfinItem.Name || !jellyfinItem.Path) {
			warn(`Skipping item without name/path: id=${jellyfinItem.Id}`);
			continue;
		}

		// Honour the scan window between items so overnight-only setups don't hog
		// Jellyfin during the day. Checked between items rather than mid-item so
		// we don't leave a partial upsert sitting in flight.
		if (!isInScanWindow()) {
			emitSse("paused", {
				until: nextScanWindowTime(),
				seconds: Math.round(msUntilScanWindow() / 1000),
			});
			await waitForScanWindow();
			if (signal.aborted) break;
			emitSse("resumed", {});
		}

		processed++;
		emitSse("progress", { scanned: processed, total, current_item: jellyfinItem.Name, errors, running: true });

		try {
			const result = await upsertJellyfinItem(db, jellyfinItem, rescanCfg);
			if (result.radarrHit) radarrHits++;
			if (result.radarrMiss) radarrMisses++;
			if (result.sonarrHit) sonarrHits++;
			if (result.sonarrMiss) sonarrMisses++;
			if (result.missingProviderId) missingProviderIds++;
			emitSse("log", { name: jellyfinItem.Name, type: jellyfinItem.Type, status: "scanned", file: jellyfinItem.Path });
		} catch (err) {
			errors++;
			logError(`Error scanning ${jellyfinItem.Name}:`, err);
			try {
				db
					.prepare("UPDATE media_items SET scan_status = 'error', scan_error = ? WHERE jellyfin_id = ?")
					.run(String(err), jellyfinItem.Id);
			} catch (dbErr) {
				// Failed to persist the error status — log it so the incident
				// doesn't disappear silently. We can't do much more; the outer
				// loop continues so the scan still finishes.
				logError(`Failed to record scan error for ${jellyfinItem.Id}:`, dbErr);
			}
			emitSse("log", { name: jellyfinItem.Name, type: jellyfinItem.Type, status: "error", file: jellyfinItem.Path });
		}
	}

	setConfig("scan_running", "0");
	log(`Scan complete: ${processed} scanned, ${errors} errors`);
	log(
		`  language sources: radarr hits=${radarrHits} misses=${radarrMisses}, sonarr hits=${sonarrHits} misses=${sonarrMisses}, no provider id=${missingProviderIds}`,
	);
	emitSse("complete", { scanned: processed, total, errors });
}

export default app;