import { accessSync, constants } from "node:fs";
import { Hono } from "hono";
import { stream } from "hono/streaming";
import { getDb } from "../db/index";
import { log, error as logError, warn } from "../lib/log";
import { parseId } from "../lib/validate";
import { predictExtractedFiles } from "../services/ffmpeg";
import {
	getScheduleConfig,
	isInProcessWindow,
	msUntilProcessWindow,
	nextProcessWindowTime,
	sleepBetweenJobs,
	waitForProcessWindow,
} from "../services/scheduler";
import { verifyDesiredState } from "../services/verify";
import type { Job, MediaItem, MediaStream } from "../types";

const app = new Hono();

// ─── Sequential local queue ──────────────────────────────────────────────────

let queueRunning = false;
let runningProc: ReturnType<typeof Bun.spawn> | null = null;
let runningJobId: number | null = null;
let activeQueue: Job[] | null = null;
let activeSeen: Set<number> | null = null;
const LIVE_UPDATE_INTERVAL_MS = 500;
const STREAM_CHUNKS_BEFORE_YIELD = 24;

export function shouldSendLiveUpdate(now: number, lastSentAt: number, intervalMs = LIVE_UPDATE_INTERVAL_MS): boolean {
	return now - lastSentAt > intervalMs;
}

export async function yieldAfterChunk(
	chunksSinceYield: number,
	chunksBeforeYield = STREAM_CHUNKS_BEFORE_YIELD,
	sleep: (ms: number) => Promise<unknown> = (ms) => Bun.sleep(ms),
): Promise<number> {
	const next = chunksSinceYield + 1;
	if (next < chunksBeforeYield) return next;
	await sleep(0);
	return 0;
}

export function enqueueUnseenJobs<T extends { id: number }>(queue: T[], seen: Set<number>, jobs: T[]): number {
	let added = 0;
	for (const job of jobs) {
		if (seen.has(job.id)) continue;
		queue.push(job);
		seen.add(job.id);
		added += 1;
	}
	return added;
}

function emitQueueStatus(
	status: "running" | "paused" | "sleeping" | "idle",
	extra: { until?: string; seconds?: number } = {},
): void {
	const line = `event: queue_status\ndata: ${JSON.stringify({ status, ...extra })}\n\n`;
	for (const l of jobListeners) l(line);
}

async function runSequential(initial: Job[]): Promise<void> {
	if (queueRunning) return;
	queueRunning = true;
	try {
		let first = true;
		const queue: Job[] = [...initial];
		const seen = new Set<number>(queue.map((j) => j.id));
		activeQueue = queue;
		activeSeen = seen;

		while (queue.length > 0) {
			const job = queue.shift() as Job;

			// Pause outside the processing window
			if (!isInProcessWindow()) {
				emitQueueStatus("paused", {
					until: nextProcessWindowTime(),
					seconds: Math.round(msUntilProcessWindow() / 1000),
				});
				await waitForProcessWindow();
			}

			// Sleep between jobs (but not before the first one)
			if (!first) {
				const cfg = getScheduleConfig();
				if (cfg.job_sleep_seconds > 0) {
					emitQueueStatus("sleeping", { seconds: cfg.job_sleep_seconds });
					await sleepBetweenJobs();
				}
			}
			first = false;

			// Atomic claim: only pick up jobs still pending
			const db = getDb();
			const claimed = db
				.prepare(
					"UPDATE jobs SET status = 'running', started_at = datetime('now'), output = '' WHERE id = ? AND status = 'pending'",
				)
				.run(job.id);
			if (claimed.changes === 0) continue; // cancelled or already running
			emitQueueStatus("running");
			try {
				await runJob(job);
			} catch (err) {
				logError(`Job ${job.id} failed:`, err);
			}

			// When the local queue drains, re-check the DB for jobs that were
			// approved mid-run. Without this they'd sit pending until the user
			// manually clicks "Run all" again.
			if (queue.length === 0) {
				const more = db.prepare("SELECT * FROM jobs WHERE status = 'pending' ORDER BY created_at").all() as Job[];
				enqueueUnseenJobs(queue, seen, more);
			}
		}
	} finally {
		activeQueue = null;
		activeSeen = null;
		queueRunning = false;
		emitQueueStatus("idle");
	}
}

// ─── SSE state ────────────────────────────────────────────────────────────────

const jobListeners = new Set<(data: string) => void>();

function emitJobUpdate(jobId: number, status: string, output?: string): void {
	const line = `event: job_update\ndata: ${JSON.stringify({ id: jobId, status, output })}\n\n`;
	for (const l of jobListeners) l(line);
}

function emitJobProgress(jobId: number, seconds: number, total: number): void {
	const line = `event: job_progress\ndata: ${JSON.stringify({ id: jobId, seconds, total })}\n\n`;
	for (const l of jobListeners) l(line);
}

/** Parse "Duration: HH:MM:SS.MS" from ffmpeg startup output. */
function parseFFmpegDuration(line: string): number | null {
	const match = line.match(/Duration:\s*(\d+):(\d+):(\d+)\.(\d+)/);
	if (!match) return null;
	const [, h, m, s] = match.map(Number);
	return h * 3600 + m * 60 + s;
}

function loadJobRow(jobId: number) {
	const db = getDb();
	const row = db
		.prepare(`
		SELECT j.*, mi.id as mi_id, mi.name, mi.type, mi.series_name, mi.season_number,
		       mi.episode_number, mi.file_path
		FROM jobs j
		LEFT JOIN media_items mi ON mi.id = j.item_id
		WHERE j.id = ?
	`)
		.get(jobId) as
		| (Job & {
				mi_id: number | null;
				name: string | null;
				type: string | null;
				series_name: string | null;
				season_number: number | null;
				episode_number: number | null;
				file_path: string | null;
		  })
		| undefined;

	if (!row) return null;

	const item = row.name
		? ({
				id: row.item_id,
				name: row.name,
				type: row.type,
				series_name: row.series_name,
				season_number: row.season_number,
				episode_number: row.episode_number,
				file_path: row.file_path,
			} as unknown as MediaItem)
		: null;
	return { job: row as unknown as Job, item };
}

// ─── Start all pending ────────────────────────────────────────────────────────

app.post("/start", (c) => {
	const db = getDb();
	const pending = db.prepare("SELECT * FROM jobs WHERE status = 'pending' ORDER BY created_at").all() as Job[];
	if (queueRunning && activeQueue && activeSeen) {
		const queued = enqueueUnseenJobs(activeQueue, activeSeen, pending);
		return c.json({ ok: true, started: 0, queued });
	}
	runSequential(pending).catch((err) => logError("Queue failed:", err));
	return c.json({ ok: true, started: pending.length, queued: pending.length });
});

// ─── Run single ───────────────────────────────────────────────────────────────

app.post("/job/:id/run", async (c) => {
	const jobId = parseId(c.req.param("id"));
	if (jobId == null) return c.json({ error: "invalid job id" }, 400);
	const db = getDb();
	const job = db.prepare("SELECT * FROM jobs WHERE id = ?").get(jobId) as Job | undefined;
	if (!job) return c.notFound();
	if (job.status !== "pending") {
		const result = loadJobRow(jobId);
		if (!result) return c.notFound();
		return c.json(result);
	}
	runSequential([job]).catch((err) => logError(`Job ${job.id} failed:`, err));
	const result = loadJobRow(jobId);
	if (!result) return c.notFound();
	return c.json(result);
});

// ─── Cancel ───────────────────────────────────────────────────────────────────

app.post("/job/:id/cancel", (c) => {
	const jobId = parseId(c.req.param("id"));
	if (jobId == null) return c.json({ error: "invalid job id" }, 400);
	const db = getDb();
	db.prepare("DELETE FROM jobs WHERE id = ? AND status = 'pending'").run(jobId);
	return c.json({ ok: true });
});

// ─── Clear queue ──────────────────────────────────────────────────────────────

app.post("/clear", (c) => {
	const db = getDb();
	db
		.prepare(`
		UPDATE review_plans SET status = 'pending', reviewed_at = NULL
		WHERE item_id IN (SELECT item_id FROM jobs WHERE status = 'pending')
		AND status = 'approved'
	`)
		.run();
	const result = db.prepare("DELETE FROM jobs WHERE status = 'pending'").run();
	return c.json({ ok: true, cleared: result.changes });
});

app.post("/clear-completed", (c) => {
	const db = getDb();
	const result = db.prepare("DELETE FROM jobs WHERE status IN ('done', 'error')").run();
	return c.json({ ok: true, cleared: result.changes });
});

// ─── Stop running job ─────────────────────────────────────────────────────────

app.post("/stop", (c) => {
	if (!runningProc || runningJobId == null) {
		return c.json({ ok: false, error: "No job is currently running" }, 409);
	}
	const stoppedId = runningJobId;
	try {
		runningProc.kill("SIGTERM");
	} catch (err) {
		logError(`Failed to kill job ${stoppedId}:`, err);
		return c.json({ ok: false, error: String(err) }, 500);
	}
	// runJob's catch path will mark the job error and clean up runningProc.
	return c.json({ ok: true, stopped: stoppedId });
});

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

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

		const queue: string[] = [];
		let resolve: (() => void) | null = null;
		const listener = (data: string) => {
			queue.push(data);
			resolve?.();
		};

		jobListeners.add(listener);
		s.onAbort(() => {
			jobListeners.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, 15_000);
					});
					resolve = null;
					if (queue.length === 0) await s.write(": keepalive\n\n");
				}
			}
		} finally {
			jobListeners.delete(listener);
		}
	});
});

// ─── Job execution ────────────────────────────────────────────────────────────

async function runJob(job: Job): Promise<void> {
	log(`Job ${job.id} starting (item=${job.item_id})`);
	log(`Job ${job.id} command: ${job.command}`);
	const db = getDb();

	const itemRow = db.prepare("SELECT file_path FROM media_items WHERE id = ?").get(job.item_id) as
		| { file_path: string }
		| undefined;
	if (itemRow?.file_path) {
		try {
			accessSync(itemRow.file_path, constants.R_OK | constants.W_OK);
		} catch (fsErr) {
			const msg = `File not accessible: ${itemRow.file_path}\n${(fsErr as Error).message}`;
			db
				.prepare("UPDATE jobs SET status = 'error', output = ?, exit_code = 1, completed_at = datetime('now') WHERE id = ?")
				.run(msg, job.id);
			emitJobUpdate(job.id, "error", msg);
			db.prepare("UPDATE review_plans SET status = 'error' WHERE item_id = ?").run(job.item_id);
			return;
		}

		// Preflight: if the file already matches the plan, skip ffmpeg. Cheap
		// guard against re-running a stream-index-based command against a file
		// that's already been processed — which would either error out or
		// silently corrupt the file.
		try {
			const verify = await verifyDesiredState(db, job.item_id, itemRow.file_path);
			if (verify.matches) {
				const msg = `Preflight check: ${verify.reason}\nSkipping FFmpeg — no work needed.`;
				log(`Job ${job.id} ${msg.replace(/\n/g, " ")}`);
				db.transaction(() => {
					db
						.prepare(
							"UPDATE jobs SET status = 'done', exit_code = 0, output = ?, completed_at = datetime('now') WHERE id = ?",
						)
						.run(msg, job.id);
					db.prepare("UPDATE review_plans SET status = 'done' WHERE item_id = ?").run(job.item_id);
				})();
				emitJobUpdate(job.id, "done", msg);
				return;
			}
			log(`Job ${job.id} preflight: ${verify.reason} — running FFmpeg`);
		} catch (err) {
			warn(`Job ${job.id} preflight check errored: ${String(err)} — proceeding with FFmpeg`);
		}
	}

	emitJobUpdate(job.id, "running");

	const outputLines: string[] = [];
	let pendingFlush = false;
	let lastFlushAt = 0;
	let totalSeconds = 0;
	let lastProgressEmit = 0;
	const updateOutput = db.prepare("UPDATE jobs SET output = ? WHERE id = ?");

	const flush = (final = false) => {
		const now = Date.now();
		if (!final && !shouldSendLiveUpdate(now, lastFlushAt)) {
			pendingFlush = true;
			return;
		}
		const text = outputLines.join("\n");
		if (final || shouldSendLiveUpdate(now, lastFlushAt)) {
			updateOutput.run(text, job.id);
			lastFlushAt = now;
			pendingFlush = false;
		}
		emitJobUpdate(job.id, "running", text);
	};

	const consumeProgress = (line: string) => {
		if (totalSeconds === 0) {
			const d = parseFFmpegDuration(line);
			if (d != null) totalSeconds = d;
		}
		const progressed = parseFFmpegProgress(line);
		if (progressed != null && totalSeconds > 0) {
			const now = Date.now();
			if (shouldSendLiveUpdate(now, lastProgressEmit)) {
				emitJobProgress(job.id, progressed, totalSeconds);
				lastProgressEmit = now;
			}
		}
	};

	try {
		const proc = Bun.spawn(["sh", "-c", job.command], { stdout: "pipe", stderr: "pipe" });
		runningProc = proc;
		runningJobId = job.id;
		const readStream = async (readable: ReadableStream<Uint8Array>, prefix = "") => {
			const reader = readable.getReader();
			const decoder = new TextDecoder();
			let buffer = "";
			let chunksSinceYield = 0;
			try {
				while (true) {
					const { done, value } = await reader.read();
					if (done) break;
					buffer += decoder.decode(value, { stream: true });
					const parts = buffer.split(/\r\n|\n|\r/);
					buffer = parts.pop() ?? "";
					for (const line of parts) {
						if (!line.trim()) continue;
						outputLines.push(prefix + line);
						consumeProgress(line);
					}
					flush();
					// Let pending HTTP requests run even when ffmpeg floods stdout/stderr.
					chunksSinceYield = await yieldAfterChunk(chunksSinceYield);
				}
				if (buffer.trim()) {
					outputLines.push(prefix + buffer);
					consumeProgress(buffer);
				}
			} catch (err) {
				logError(`stream read error (${prefix.trim() || "stdout"}):`, err);
			}
		};
		await Promise.all([readStream(proc.stdout), readStream(proc.stderr, "[stderr] "), proc.exited]);
		const exitCode = await proc.exited;
		if (pendingFlush) updateOutput.run(outputLines.join("\n"), job.id);
		if (exitCode !== 0) throw new Error(`FFmpeg exited with code ${exitCode}`);

		const fullOutput = outputLines.join("\n");

		// Gather sidecar files to record
		const item = db.prepare("SELECT * FROM media_items WHERE id = ?").get(job.item_id) as MediaItem | undefined;
		const streams = db.prepare("SELECT * FROM media_streams WHERE item_id = ?").all(job.item_id) as MediaStream[];
		const files = item && streams.length > 0 ? predictExtractedFiles(item, streams) : [];

		const insertFile = db.prepare(
			"INSERT OR IGNORE INTO subtitle_files (item_id, file_path, language, codec, is_forced, is_hearing_impaired) VALUES (?, ?, ?, ?, ?, ?)",
		);
		const markJobDone = db.prepare(
			"UPDATE jobs SET status = 'done', exit_code = 0, output = ?, completed_at = datetime('now') WHERE id = ?",
		);
		const markPlanDone = db.prepare("UPDATE review_plans SET status = 'done' WHERE item_id = ?");
		const markSubsExtracted = db.prepare("UPDATE review_plans SET subs_extracted = 1 WHERE item_id = ?");

		db.transaction(() => {
			markJobDone.run(fullOutput, job.id);
			markPlanDone.run(job.item_id);
			for (const f of files) {
				insertFile.run(job.item_id, f.file_path, f.language, f.codec, f.is_forced ? 1 : 0, f.is_hearing_impaired ? 1 : 0);
			}
			if (files.length > 0) markSubsExtracted.run(job.item_id);
		})();

		log(`Job ${job.id} completed successfully`);
		emitJobUpdate(job.id, "done", fullOutput);
	} catch (err) {
		logError(`Job ${job.id} failed:`, err);
		const fullOutput = `${outputLines.join("\n")}\n${String(err)}`;
		const summary = extractErrorSummary(outputLines, err);
		// Prepend the scraped summary so the job log starts with what broke.
		// ffmpeg's 200-line stream+config banner buries the real error; this
		// gives the UI a crisp hook for the failure cause.
		const annotatedOutput = summary ? `${summary}\n\n---\n\n${fullOutput}` : fullOutput;
		db
			.prepare("UPDATE jobs SET status = 'error', exit_code = 1, output = ?, completed_at = datetime('now') WHERE id = ?")
			.run(annotatedOutput, job.id);
		emitJobUpdate(job.id, "error", annotatedOutput);
		db
			.prepare("UPDATE review_plans SET status = 'error', notes = ? WHERE item_id = ?")
			.run(summary ?? String(err), job.item_id);
	} finally {
		runningProc = null;
		runningJobId = null;
	}
}

/**
 * Extract a short, human-readable reason from a failed job's stderr.
 *
 * ffmpeg prints a ~200-line banner (version, config, every stream in the
 * input file) before the real error shows up. We scan the tail of the
 * output for the last line matching fatal keywords, plus anything ffmpeg
 * explicitly labels "Error:" or "Conversion failed!". Returns up to three
 * lines so the UI can show a crisp summary without users scrolling the
 * full log.
 */
export function extractErrorSummary(outputLines: string[], thrown?: unknown): string | null {
	const FATAL =
		/(Error:|Conversion failed!|Unsupported\b|Invalid argument|Permission denied|No such file|Cannot allocate|No space left|Killed|Segmentation fault)/;
	// Only scan the last 60 lines — anything earlier is the banner or stream
	// mapping. The real cause sits near the end.
	const tail = outputLines.slice(-60).filter((l) => l.trim());
	const hits: string[] = [];
	for (const line of tail) {
		if (FATAL.test(line)) hits.push(line.replace(/^\[stderr]\s*/, ""));
	}
	const unique = [...new Set(hits)].slice(-3);
	if (unique.length === 0) {
		// Fell off the end with no recognisable fatal line — fall back to the
		// thrown error (usually "FFmpeg exited with code N"). Better than
		// showing nothing, since the exit code at least tells someone *where*
		// to look.
		return thrown ? String(thrown) : null;
	}
	return unique.join("\n");
}

// Scheduler endpoints live on /api/settings/schedule now — see server/api/settings.ts.

// ─── FFmpeg progress parsing ───────────────────────────────────────────────────

/** Parse FFmpeg stderr line for progress. Returns seconds processed or null. */
export function parseFFmpegProgress(line: string): number | null {
	const match = line.match(/time=(\d+):(\d+):(\d+)\.(\d+)/);
	if (!match) return null;
	const [, h, m, s] = match.map(Number);
	return h * 3600 + m * 60 + s;
}

export default app;