import { randomUUID } from "node:crypto";
import { readdir } from "node:fs/promises";
import { join } from "node:path";
import type {
  FileIdentifyCandidate,
  FileIdentifyItem,
  FilesIdentifyRequest,
  FilesIdentifyResult,
} from "@umt/contracts";
import { sql } from "@umt/db";
import { type IdentityCandidate, type ParsedRelease, parseReleasePath, queryTitles, rankCandidates } from "@umt/domain";
import { localIdentityCandidate } from "@umt/mapping";
import type { Principal } from "../../http/auth.ts";
import { actorOfP, errMessage, FilesError, type FmDeps, resolveIn } from "./common.ts";
import { kindOfName } from "./list.ts";

// 识别(只读,不落库):parseReleasePath(文件 + 父/祖父目录上下文)→ 本地召回(别名 pg_trgm + 外部身份)
// → 远端候选(catalog.lookup 能力,走 TMDB 缓存;失败只降级为提示)→ rankCandidates,每项前 5。

const TRGM = 0.45;
const LEVEL: Record<string, FileIdentifyCandidate["level"]> = {
  rule_confirmed: "high",
  multi_evidence: "medium",
  needs_confirm: "low",
};

interface Video {
  root: string;
  rel: string;
}

async function collectVideos(d: FmDeps, body: FilesIdentifyRequest): Promise<{ videos: Video[]; truncated: boolean }> {
  const max = d.options.identifyMaxVideos;
  const videos: Video[] = [];
  let truncated = false;
  for (const it of body.items) {
    const r = await resolveIn(d, it.root, it.path);
    if (!r.lst?.isDirectory() || r.isSymlink) {
      if (videos.length >= max) truncated = true;
      else videos.push({ root: it.root, rel: r.rel });
      continue;
    }
    const stack = [r.rel];
    while (stack.length > 0) {
      const rel = stack.shift()!;
      const names = (await readdir(join(r.rootReal, rel), { withFileTypes: true }).catch(() => [])).sort((a, b) =>
        a.name.localeCompare(b.name),
      );
      for (const n of names) {
        if (n.name.startsWith(".")) continue;
        const child = rel ? `${rel}/${n.name}` : n.name;
        if (n.isDirectory()) stack.push(child);
        else if (n.isFile() && kindOfName(n.name) === "video") {
          if (videos.length >= max) {
            truncated = true;
            break;
          }
          videos.push({ root: it.root, rel: child });
        }
      }
      if (truncated) break;
    }
  }
  return { videos, truncated };
}

function segments(rel: string) {
  const parts = rel.split("/");
  const file = parts.pop()!;
  const parent = parts.pop();
  const grandParent = parts.pop();
  return { file, ...(parent ? { parent } : {}), ...(grandParent ? { grandParent } : {}) };
}

export async function identify(
  d: FmDeps,
  principal: Principal | undefined,
  body: FilesIdentifyRequest,
): Promise<FilesIdentifyResult> {
  const db = d.ctx.db;
  const { videos, truncated } = await collectVideos(d, body);
  const localCache = new Map<string, IdentityCandidate[]>();
  const remoteCache = new Map<string, { list: IdentityCandidate[]; warning: string | null }>();
  const entityKinds = new Map<string, string>();

  const localFor = async (p: ParsedRelease): Promise<IdentityCandidate[]> => {
    const key = `${queryTitles(p).join("|")}|${body.hints?.tmdbId ?? ""}`;
    const hit = localCache.get(key);
    if (hit) return hit;
    const ids = new Set<string>();
    for (const q of queryTitles(p)) {
      const rows = await sql<{ media_entity_id: string }>`
        select distinct a.media_entity_id from title_alias a join media_entity e on e.id = a.media_entity_id
         where e.status not in ('merged', 'archived')
           and (a.normalized = ${q} or (length(${q}) >= 3 and similarity(a.normalized, ${q}) >= ${TRGM}))
         limit 20`.execute(db);
      for (const r of rows.rows) ids.add(r.media_entity_id);
    }
    const explicit = [
      ...p.explicitIds.map((x) => ({ provider: x.provider as string, id: x.id })),
      ...(body.hints?.tmdbId ? [{ provider: "tmdb", id: String(body.hints.tmdbId) }] : []),
    ];
    for (const x of explicit) {
      const rows = await db
        .selectFrom("external_identity")
        .select(["media_entity_id"])
        .where("provider", "=", x.provider)
        .where("external_id", "=", x.id)
        .where("status", "=", "accepted")
        .execute();
      for (const r of rows) if (r.media_entity_id) ids.add(r.media_entity_id);
    }
    const out: IdentityCandidate[] = [];
    if (ids.size > 0) {
      const list = [...ids];
      const ents = await db.selectFrom("media_entity").selectAll().where("id", "in", list).execute();
      const aliases = await db
        .selectFrom("title_alias")
        .select(["media_entity_id", "alias"])
        .where("media_entity_id", "in", list)
        .execute();
      const idents = await db
        .selectFrom("external_identity")
        .select(["media_entity_id", "provider", "external_id", "status"])
        .where("media_entity_id", "in", list)
        .execute();
      for (const e of ents) {
        entityKinds.set(e.id, e.kind);
        const c = localIdentityCandidate(
          { id: e.id, kind: e.kind, title: e.title, originalTitle: e.original_title, year: e.year },
          aliases.filter((a) => a.media_entity_id === e.id).map((a) => a.alias),
          idents
            .filter((i) => i.media_entity_id === e.id)
            .map((i) => ({ provider: i.provider, externalId: i.external_id, status: i.status })),
        );
        if (c) out.push(c);
      }
    }
    localCache.set(key, out);
    return out;
  };

  const remoteFor = async (p: ParsedRelease) => {
    const q = p.titleCn ?? p.title ?? p.titleEn;
    if (!q) return { list: [], warning: null };
    const key = `${q}|${body.hints?.year ?? p.year ?? ""}`;
    const hit = remoteCache.get(key);
    if (hit) return hit;
    let res: { list: IdentityCandidate[]; warning: string | null };
    try {
      const out = (await d.ctx.capabilities.invoke(
        "catalog.lookup",
        { query: q, includeRemote: true, limit: 10, ...(body.hints?.year ? { year: body.hints.year } : {}) },
        {
          actorId: actorOfP(principal),
          taskId: `files.identify:${randomUUID()}`,
          scopeIds: [],
          signal: AbortSignal.timeout(15_000),
          source: "web",
        },
      )) as {
        remote?: { provider: string; entityType: string; externalId: string; title: string; year: number | null }[];
      };
      const list: IdentityCandidate[] = (out.remote ?? [])
        .filter((m) => m.entityType === "movie" || m.entityType === "tv")
        .map((m) => ({
          provider: m.provider,
          entityType: m.entityType as "movie" | "tv",
          externalId: m.externalId,
          titles: [m.title],
          ...(m.year !== null ? { year: m.year } : {}),
          aliases: [],
        }));
      res = { list, warning: null };
    } catch (e) {
      res = { list: [], warning: `远端候选不可用(仅本地召回):${errMessage(e).slice(0, 200)}` };
    }
    remoteCache.set(key, res);
    return res;
  };

  const items: FileIdentifyItem[] = [];
  for (const v of videos) {
    const parsed0 = parseReleasePath(segments(v.rel));
    const parsed: ParsedRelease = {
      ...parsed0,
      ...(parsed0.year === undefined && body.hints?.year ? { year: body.hints.year } : {}),
    };
    const warnings: string[] = [];
    const local = parsed.title || parsed.explicitIds.length || body.hints?.tmdbId ? await localFor(parsed) : [];
    const remote = parsed.title ? await remoteFor(parsed) : { list: [], warning: null };
    if (remote.warning) warnings.push(remote.warning);
    if (!parsed.title) warnings.push("文件名无法解析出标题");
    // 已关联到本地作品的远端候选不重复出现
    const linked = new Set(local.flatMap((c) => (c.linkedExternalIds ?? []).map((l) => `${l.provider}:${l.id}`)));
    const all = [...local, ...remote.list.filter((c) => !linked.has(`${c.provider}:${c.externalId}`))];
    const kindHint = body.hints?.mediaKind;
    const ranked = rankCandidates(parsed, all)
      .filter((r) => r.level !== "rejected")
      .filter((r) => !kindHint || (kindHint === "movie") === (r.candidate.entityType === "movie"))
      .slice(0, 5);
    const candidates: FileIdentifyCandidate[] = ranked.map((r, i) => {
      const c = r.candidate;
      const localKind = c.localEntityId ? entityKinds.get(c.localEntityId) : undefined;
      return {
        mediaEntityId: c.localEntityId ?? null,
        provider: c.provider,
        externalId: c.localEntityId ? null : c.externalId,
        title: c.titles[0] ?? c.externalId,
        year: c.year ?? null,
        kind: (localKind ?? (c.entityType === "movie" ? "movie" : "series")) as FileIdentifyCandidate["kind"],
        level: LEVEL[r.level] ?? "low",
        score: 5 - i,
        reasons: r.evidence,
      };
    });
    const best = candidates[0];
    let contentUnitId: string | null = null;
    let contentUnit: string | null = null;
    const season = parsed.season ?? (parsed.episodes ? 1 : undefined);
    if (season !== undefined) {
      const pad = (n: number) => String(n).padStart(2, "0");
      contentUnit = parsed.episodes ? `S${pad(season)}E${pad(parsed.episodes.start)}` : `S${pad(season)}`;
      if (best?.mediaEntityId) {
        let q = db
          .selectFrom("content_unit")
          .select(["id"])
          .where("media_entity_id", "=", best.mediaEntityId)
          .where("season_number", "=", season)
          .where("status", "<>", "retired");
        q = parsed.episodes ? q.where("episode_number", "=", parsed.episodes.start) : q.where("kind", "=", "season");
        contentUnitId = (await q.executeTakeFirst())?.id ?? null;
      }
    }
    const def = v.root.startsWith("lib:") ? v.root.slice(4) : null;
    const existing = def
      ? await db
          .selectFrom("asset_location")
          .select(["media_asset_id"])
          .where("library_root_id", "=", def)
          .where("relative_path", "=", v.rel)
          .where("status", "<>", "removed")
          .executeTakeFirst()
      : undefined;
    items.push({
      root: v.root as FileIdentifyItem["root"],
      path: v.rel,
      parsed: {
        title: parsed.title ?? null,
        year: parsed.year ?? null,
        season: season ?? null,
        episodes: parsed.episodes
          ? Array.from(
              { length: Math.min(200, parsed.episodes.end - parsed.episodes.start + 1) },
              (_, i) => parsed.episodes!.start + i,
            )
          : [],
        resolution: parsed.resolution ?? null,
        source: parsed.source ?? null,
        releaseGroup: parsed.releaseGroup?.name ?? null,
        mediaKind:
          parsed.episodes || parsed.season !== undefined ? "series" : parsed.mediaTypeHint === "tv" ? "series" : null,
      },
      candidates,
      suggestion: { mediaEntityId: best?.mediaEntityId ?? null, contentUnitId, contentUnit },
      existing: { assetId: existing?.media_asset_id ?? null },
      warnings,
    });
  }
  if (videos.length === 0 && body.items.length > 0 && !truncated)
    throw new FilesError("bad_request", "所选项中没有视频文件");
  return { items, truncated };
}