/**
 * 云函数：remixManager（视频重塑记录）
 * 替代：GET/POST/DELETE /api/remixes[/:videoId[/:remixId]]
 * 支持 action：
 *   listAll
 *   listByVideo
 *   upsert
 *   delete
 */
const { requireSession, assertRequestedUserMatchesSession } = require('./_session');

async function handler(request, response) {
  try {
    await ensureTable();

    const action = pickParam(request, 'action') || 'listAll';
    const session = await requireSession(request, Psql);
    assertRequestedUserMatchesSession(request, session);
    const userId = session.userId;

    if (action === 'listAll') return listAll(response, userId);
    if (action === 'listByVideo') return listByVideo(request, response, userId);
    if (action === 'upsert') return upsertRemix(request, response, userId);
    if (action === 'delete') return deleteRemix(request, response, userId);

    return response.json({ code: 400, success: false, error: `未知 action: ${action}` });
  } catch (error) {
    console.error('remixManager failed:', error && error.message);
    return response.json({ code: error.status || 500, success: false, error: error.message });
  }
}

async function ensureTable() {
  await Psql.query(`
    CREATE TABLE IF NOT EXISTS "Remix" (
      "objectId"  VARCHAR(50) PRIMARY KEY,
      "videoId"   VARCHAR(255) NOT NULL,
      "remixId"   VARCHAR(255) NOT NULL,
      "data"      JSONB NOT NULL DEFAULT '{}',
      "userId"    VARCHAR(255) DEFAULT '',
      "createdAt" TIMESTAMPTZ  DEFAULT NOW(),
      "updatedAt" TIMESTAMPTZ  DEFAULT NOW()
    )
  `);
  await Psql.query(`DROP INDEX IF EXISTS idx_remix_pair`);
  await Psql.query(`CREATE UNIQUE INDEX IF NOT EXISTS idx_remix_user_pair ON "Remix" ("userId", "videoId", "remixId")`);
  await Psql.query(`CREATE INDEX IF NOT EXISTS idx_remix_video ON "Remix" ("videoId")`);
  await Psql.query(`CREATE INDEX IF NOT EXISTS idx_remix_user ON "Remix" ("userId")`);
}

async function listAll(response, userId) {
  const rows = await Psql.query(
    `SELECT * FROM "Remix" WHERE "userId" = $1 ORDER BY "createdAt" DESC LIMIT 5000`,
    [userId]
  );
  const grouped = {};
  for (const row of rows) {
    if (!grouped[row.videoId]) grouped[row.videoId] = [];
    grouped[row.videoId].push(rowToObj(row));
  }
  return response.json({ code: 200, success: true, data: grouped });
}

async function listByVideo(request, response, userId) {
  const videoId = pickParam(request, 'videoId');
  if (!videoId) return response.json({ code: 400, success: false, error: '缺少 videoId' });
  const rows = await Psql.query(
    `SELECT * FROM "Remix" WHERE "videoId" = $1 AND "userId" = $2 ORDER BY "createdAt" DESC`,
    [videoId, userId]
  );
  return response.json({ code: 200, success: true, data: rows.map(rowToObj) });
}

async function upsertRemix(request, response, userId) {
  const videoId = pickParam(request, 'videoId');
  const body = pickParam(request, 'remix', 'data') || request.body || {};
  const remixId = body.remixId || pickParam(request, 'remixId');
  if (!videoId || !remixId) {
    return response.json({ code: 400, success: false, error: '缺少 videoId 或 remixId' });
  }

  const now = new Date().toISOString();
  const existing = await Psql.query(
    `SELECT * FROM "Remix" WHERE "videoId"=$1 AND "remixId"=$2 AND "userId"=$3 LIMIT 1`,
    [videoId, remixId, userId]
  );
  const previous = existing.length ? rowToObj(existing[0]) : {};
  const merged = {
    ...previous,
    ...body,
    remixId,
    videoId,
    userId,
    created_at: previous.created_at || body.created_at || now,
    updated_at: now,
  };

  await Psql.query(
    `INSERT INTO "Remix" ("objectId","videoId","remixId","data","userId")
     VALUES ($1,$2,$3,$4,$5)
     ON CONFLICT ("userId","videoId","remixId") DO UPDATE SET "data"=$4, "updatedAt"=NOW()`,
    [existing[0]?.objectId || generateId(), videoId, remixId, JSON.stringify(merged), userId]
  );
  return response.json({ code: 200, success: true, data: merged });
}

async function deleteRemix(request, response, userId) {
  const videoId = pickParam(request, 'videoId');
  const remixId = pickParam(request, 'remixId');
  if (!videoId || !remixId) {
    return response.json({ code: 400, success: false, error: '缺少 videoId 或 remixId' });
  }
  const result = await Psql.query(
    `DELETE FROM "Remix" WHERE "videoId"=$1 AND "remixId"=$2 AND "userId"=$3 RETURNING "objectId"`,
    [videoId, remixId, userId]
  );
  return response.json({ code: 200, success: true, data: { videoId, remixId, deleted: result.length > 0 } });
}

function rowToObj(row) {
  const data = typeof row.data === 'string' ? JSON.parse(row.data) : (row.data || {});
  return { ...data, objectId: row.objectId, createdAt: row.createdAt, updatedAt: row.updatedAt };
}

function pickParam(request, ...names) {
  const sources = [request.params, request.body, request.query, request];
  for (const src of sources) {
    if (!src || typeof src !== 'object') continue;
    for (const name of names) {
      const value = src[name];
      if (value !== undefined && value !== null && value !== '') return value;
    }
  }
  return null;
}

function generateId() {
  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  let value = '';
  for (let i = 0; i < 10; i += 1) value += chars.charAt(Math.floor(Math.random() * chars.length));
  return value;
}