'use strict';

const fs = require('fs');
const path = require('path');
const conf = require('>/conf');
const ollama = require('>/controller/ollama');
const tmdb = require('>/controller/tmdb');
const emby = require('>/controller/emby');
const ps = require('>/controller/pubsub');
const { withRetry } = require('>/controller/retry');

const VIDEO_EXT = new Set(['.mkv', '.mp4', '.avi', '.m4v', '.ts', '.wmv', '.mov']);
const SUB_EXT = new Set(['.srt', '.ass', '.ssa', '.sub', '.vtt', '.idx']);

function ext(name){ return path.extname(name).toLowerCase(); }
function isVideo(name){ return VIDEO_EXT.has(ext(name)) && !/sample/i.test(name); }
function isSub(name){ return SUB_EXT.has(ext(name)); }

// Strip characters that are illegal / awkward in file paths.
function sanitize(text){
	return String(text || '').replace(/[\/\\:*?"<>|]/g, '').replace(/\s+/g, ' ').trim();
}

function pad2(n){ return String(n).padStart(2, '0'); }

// Normalize resolution to the library's convention( 2160p/uhd -> 4k).
function normalizeRes(res){
	res = String(res || '').toLowerCase();
	if(/2160|4k|uhd/.test(res)) return '4k';
	let m = res.match(/(480|720|1080)p?/);
	return m ? `${m[1]}p` : '';
}

// "Unrated 1080p" style suffix from edition + quality.
function qualitySuffix(meta){
	let res = normalizeRes(meta.quality && meta.quality.resolution);
	return [sanitize(meta.edition), res].filter(Boolean).join(' ');
}

// --- LLM metadata extraction ----------------------------------------------

function buildExtractPrompt(today){
	return [
		`You are a media library organizer. Today's date is ${today}.`,
		`Given a torrent's raw release name, its coarse type (Movie or TV), and its list of`,
		`video file names, extract clean metadata for filing. Return STRICT JSON only:`,
		`{"mediaType":"movie"|"tv","title":"clean title, no year/quality/tags",`,
		`"year":"YYYY" or "","edition":"Extended|Director's Cut|Unrated|Uncut|Remastered|`,
		`Theatrical|IMAX|Redux|" (notable edition if present, else empty),`,
		`"quality":{"resolution":"2160p|1080p|720p|480p|","codec":"x265|x264|"},`,
		`"episodes":[{"file":"<exact name from the list>","season":<int>,"episode":<int>}]}`,
		`Movies: "episodes" is []. TV: one entry per video file, mapping each file to its`,
		`season/episode inferred from the file name (SxxExx, 1x02, etc.).`,
		`Do not invent data; leave a field empty or [] when unknown.`,
	].join('\n');
}

async function llmExtract({ name, category, files }){
	let today = new Date().toISOString().slice(0, 10);
	let user = JSON.stringify({ name, type: category, files });
	return await withRetry(
		() => ollama.chatJSON(buildExtractPrompt(today), user),
		{ label: 'ollama llmExtract' }
	);
}

// Parse + canonicalize. Returns a metadata object, or one carrying `organizeError`
// (so the caller flags the torrent instead of mis-filing it).
async function resolveMeta({ name, category, files }){
	let llm;
	try{
		llm = await llmExtract({ name, category, files });
	}catch(error){
		return { organizeError: `parse failed: ${error.message}` };
	}

	let mediaType = llm.mediaType === 'tv' || llm.mediaType === 'movie'
		? llm.mediaType
		: (category === 'TV' ? 'tv' : 'movie');

	if(!llm.title) return { organizeError: `could not determine a title for "${name}"` };

	let best = await tmdb.tmdbFindBest(llm.title, llm.year, mediaType);
	if(!best) return { organizeError: `no TMDB match for "${llm.title}" (${llm.year || '?'})` };

	return {
		mediaType,
		title: best.title,
		year: best.year,
		edition: llm.edition || '',
		quality: llm.quality || {},
		episodes: Array.isArray(llm.episodes) ? llm.episodes : [],
		tmdbId: best.tmdbId,
		imdbId: best.imdbId,
	};
}

// --- Target path building --------------------------------------------------

// Build the destination path for one video file. `episode` is the matching entry from
// meta.episodes (TV only).
function buildTarget(meta, fileName, episode){
	let title = sanitize(meta.title);
	let folder = `${title} (${meta.year})`;
	let suffix = qualitySuffix(meta);
	let e = ext(fileName);

	if(meta.mediaType === 'tv' && episode){
		let dir = path.join(conf.library.root, conf.library.tv, folder, `Season ${pad2(episode.season)}`);
		let se = `S${pad2(episode.season)}E${pad2(episode.episode)}`;
		let base = `${folder} - ${se}${suffix ? ' - ' + suffix : ''}${e}`;
		return path.join(dir, base);
	}

	let dir = path.join(conf.library.root, conf.library.movie, folder);
	let base = `${folder}${suffix ? ' - ' + suffix : ''}${e}`;
	return path.join(dir, base);
}

// If the exact target exists, disambiguate with codec then a counter.
function resolveCollision(target, meta){
	if(!fs.existsSync(target)) return target;
	let dir = path.dirname(target);
	let e = path.extname(target);
	let baseNoExt = path.basename(target, e);
	let codec = meta.quality && meta.quality.codec ? ' ' + sanitize(meta.quality.codec) : '';

	let candidate = path.join(dir, `${baseNoExt}${codec}${e}`);
	let n = 2;
	while(fs.existsSync(candidate)){
		candidate = path.join(dir, `${baseNoExt}${codec} (${n})${e}`);
		n++;
	}
	return candidate;
}

// --- Filesystem move -------------------------------------------------------

async function moveFile(src, dst){
	await fs.promises.mkdir(path.dirname(dst), { recursive: true });
	try{
		await fs.promises.rename(src, dst);
	}catch(error){
		if(error.code === 'EXDEV'){
			await fs.promises.copyFile(src, dst);
			await fs.promises.unlink(src);
		}else{
			throw error;
		}
	}
}

// Subs that belong to a given video( same basename, ignoring a language suffix).
function subsFor(videoName, subFiles, isMovie){
	if(isMovie) return subFiles;
	let stem = path.basename(videoName, ext(videoName)).toLowerCase();
	return subFiles.filter(s => path.basename(s, ext(s)).toLowerCase().startsWith(stem.slice(0, 20)));
}

// --- Orchestration ---------------------------------------------------------

// File a finished torrent into the library, then remove it from Transmission and refresh
// Emby. Returns { organized:true, ... } or { organized:false, error }.
async function fileTorrent(torrent){
	const { Torrent } = require('>/models');

	let info = (await Torrent.trClient.get(torrent.hashString, ['downloadDir', 'files', 'name'])).torrents[0];
	if(!info) return await flag(torrent, 'torrent not found in Transmission');

	let downloadDir = info.downloadDir;
	let videoFiles = info.files.filter(f => isVideo(f.name));
	let subFiles = info.files.filter(f => isSub(f.name)).map(f => f.name);
	if(!videoFiles.length) return await flag(torrent, 'no video files in torrent');

	let meta = await resolveMeta({
		name: torrent.name,
		category: torrent.category,
		files: videoFiles.map(f => f.name),
	});
	if(meta.organizeError) return await flag(torrent, meta.organizeError, meta);

	let isMovie = meta.mediaType !== 'tv';
	// Movie: file only the largest video. TV: file every episode video.
	let toFile = isMovie
		? [videoFiles.reduce((a, b) => (b.length > a.length ? b : a))]
		: videoFiles;

	let filed = [];
	let libraryPath = null;
	for(let vf of toFile){
		let episode = isMovie ? null : (meta.episodes.find(e => e.file === vf.name) || null);
		if(!isMovie && !episode) continue; // can't place an episode we couldn't map

		let dst = resolveCollision(buildTarget(meta, vf.name, episode), meta);
		await moveFile(path.join(downloadDir, vf.name), dst);
		filed.push({ path: dst, season: episode ? episode.season : null, episode: episode ? episode.episode : null });
		libraryPath = path.dirname(dst);

		// carry matching sidecar subtitles, renamed to the video's base name
		let dstBase = path.basename(dst, ext(dst));
		for(let sub of subsFor(vf.name, subFiles, isMovie)){
			try{
				await moveFile(path.join(downloadDir, sub), path.join(path.dirname(dst), dstBase + ext(sub)));
			}catch(error){ /* subs are best-effort */ }
		}
	}

	if(!filed.length) return await flag(torrent, 'could not map any video files to episodes', meta);

	// Move + stop seeding: drop the torrent and delete whatever download data is left.
	try{ await Torrent.trClient.remove(torrent.hashString, true); }catch(error){ /* already gone */ }

	torrent.organizedAt = new Date();
	torrent.metadata = { ...meta, libraryPath, files: filed };
	await torrent.save();

	try{ await emby.refresh(); }catch(error){ console.error('emby refresh failed:', error.message); }
	ps.publish('torrent:organized', { hashString: torrent.hashString, libraryPath });

	return { organized: true, libraryPath, files: filed };
}

// Re-file an already-organized torrent under a user-chosen TMDB match. Moves the files
// already in the library to their new canonical paths.
async function refileWithMatch(torrent, tmdbId, mediaType){
	if(!torrent.metadata || !Array.isArray(torrent.metadata.files) || !torrent.metadata.files.length){
		let error = new Error('NothingToRefile');
		error.message = 'This torrent has no filed media to re-match';
		error.status = 409;
		throw error;
	}

	let details = await tmdb.tmdbDetails(tmdbId, mediaType);
	let meta = {
		...torrent.metadata,
		mediaType,
		title: details.title,
		year: details.year,
		tmdbId,
		imdbId: details.imdbId,
	};
	delete meta.organizeError;

	let filed = [];
	let libraryPath = null;
	for(let entry of torrent.metadata.files){
		let old = typeof entry === 'string' ? entry : entry.path;
		let episode = (entry && entry.season != null) ? { season: entry.season, episode: entry.episode } : null;
		let dst = resolveCollision(buildTarget(meta, old, episode), meta);
		if(dst !== old) await moveFile(old, dst);
		filed.push({ path: dst, season: episode ? episode.season : null, episode: episode ? episode.episode : null });
		libraryPath = path.dirname(dst);

		let oldDir = path.dirname(old);
		try{ if(oldDir !== libraryPath) await fs.promises.rmdir(oldDir); }catch(error){ /* not empty / gone */ }
	}

	meta.files = filed;
	meta.libraryPath = libraryPath;
	torrent.metadata = meta;
	torrent.organizedAt = new Date();
	await torrent.save();

	try{ await emby.refresh(); }catch(error){ console.error('emby refresh failed:', error.message); }
	ps.publish('torrent:organized', { hashString: torrent.hashString, libraryPath });

	return { organized: true, libraryPath, files: filed };
}

// Record a problem in metadata without setting organizedAt( leaves it flagged for a
// manual "fix match").
async function flag(torrent, message, meta){
	console.error(`organize: ${torrent.hashString} skipped — ${message}`);
	torrent.metadata = { ...(meta || {}), organizeError: message };
	await torrent.save();
	return { organized: false, error: message };
}

module.exports = {
	fileTorrent,
	refileWithMatch,
	resolveMeta,
	llmExtract,
	buildTarget,
	qualitySuffix,
	normalizeRes,
	sanitize,
	moveFile,
	resolveCollision,
};