/**
 * 云函数：systemStorageManager
 *
 * 通用业务实体、审计和迁移状态的云端入口。
 * 数据主存储为 Parse 项目命名空间 Class：
 * - VideoWorkflowEntity
 * - VideoWorkflowAudit
 * - VideoWorkflowMigration
 *
 * 所有数据归属都通过 _session.js 从 Parse sessionToken 解析得到。
 */
const { requireSession, requireAdmin, assertRequestedUserMatchesSession } = require('./_session');
const {
  VIDEO_WORKFLOW_CLASSES,
  createParseClassStore,
  parseUserFields,
  parseUserWhere,
} = require('./_parseClassStore');

async function handler(request, response) {
  try {
    const action = pickParam(request, 'action') || 'list';
    if (action === 'adminInspect') {
      const adminSession = await requireAdmin(request, Psql);
      const store = createParseClassStore({ sessionToken: adminSession.sessionToken });
      return adminInspect(request, response, adminSession, store);
    }

    const session = await requireSession(request, Psql);
    assertRequestedUserMatchesSession(request, session);
    const store = createParseClassStore({ sessionToken: session.sessionToken });
    const userId = session.userId;

    if (action === 'list') return listEntities(request, response, userId, store);
    if (action === 'get') return getEntity(request, response, userId, store);
    if (action === 'upsert') return upsertEntity(request, response, userId, store);
    if (action === 'patch') return patchEntity(request, response, userId, store);
    if (action === 'delete') return deleteEntity(request, response, userId, store);
    if (action === 'purge') return purgeEntity(request, response, userId, store);
    if (action === 'audit') return writeAudit(request, response, userId, store);
    if (action === 'auditList') return listAudits(request, response, userId, store);
    if (action === 'stats') return getStats(request, response, userId, store);
    if (action === 'migrationGet') return getMigration(request, response, userId, store);
    if (action === 'migrationSet') return setMigration(request, response, userId, store);

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

async function listEntities(request, response, userId, store) {
  const entityType = requiredText(request, 'entityType', 'type');
  const status = pickParam(request, 'status') || 'active';
  const limit = safeLimit(pickParam(request, 'limit'), 100, 1000);
  const where = parseUserWhere(userId, {
    entityType,
    ...(status ? { status } : {}),
  });
  const rows = await store.list(VIDEO_WORKFLOW_CLASSES.entity, where, { order: '-updatedAt', limit });
  return response.json({ code: 200, success: true, data: rows.map(rowToEntity) });
}

async function getEntity(request, response, userId, store) {
  const entityType = requiredText(request, 'entityType', 'type');
  const entityId = requiredText(request, 'entityId', 'id', 'bizId');
  const row = await findEntity(store, userId, entityType, entityId);
  return response.json({ code: 200, success: true, data: row ? rowToEntity(row) : null });
}

async function upsertEntity(request, response, userId, store) {
  const entityType = requiredText(request, 'entityType', 'type');
  const entityId = requiredText(request, 'entityId', 'id', 'bizId');
  const data = normalizeObject(pickParam(request, 'data', 'entity') || {});
  // 行状态只表达存储生命周期，业务状态继续放在 data.status，避免 completed/failed 等业务态污染刷新查询。
  const status = pickParam(request, 'status') || 'active';
  const schemaVersion = Number(pickParam(request, 'schemaVersion') || data.schemaVersion || 1);
  const spaceId = pickParam(request, 'spaceId') || data.spaceId || '';
  const row = await saveEntity(store, { userId, entityType, entityId, data, status, schemaVersion, spaceId });
  return response.json({ code: 200, success: true, data: rowToEntity(row) });
}

async function patchEntity(request, response, userId, store) {
  const entityType = requiredText(request, 'entityType', 'type');
  const entityId = requiredText(request, 'entityId', 'id', 'bizId');
  const patch = normalizeObject(pickParam(request, 'patch', 'data') || {});
  const previousRow = await findEntity(store, userId, entityType, entityId);
  const previous = previousRow ? normalizeObject(previousRow.data) : {};
  const status = pickParam(request, 'status') || previousRow?.status || 'active';
  const row = await saveEntity(store, {
    userId,
    entityType,
    entityId,
    data: { ...previous, ...patch, id: entityId },
    status,
    schemaVersion: Number(patch.schemaVersion || previousRow?.schemaVersion || 1),
    spaceId: patch.spaceId || previousRow?.spaceId || '',
  });
  return response.json({ code: 200, success: true, data: rowToEntity(row) });
}

async function deleteEntity(request, response, userId, store) {
  const entityType = requiredText(request, 'entityType', 'type');
  const entityId = requiredText(request, 'entityId', 'id', 'bizId');
  const row = await findEntity(store, userId, entityType, entityId);
  if (row?.objectId) {
    await store.update(VIDEO_WORKFLOW_CLASSES.entity, row.objectId, { status: 'deleted' });
  }
  return response.json({ code: 200, success: true, data: { entityType, entityId, deleted: true } });
}

async function purgeEntity(request, response, userId, store) {
  const entityType = requiredText(request, 'entityType', 'type');
  const entityId = requiredText(request, 'entityId', 'id', 'bizId');
  const reason = String(pickParam(request, 'reason') || '').trim();
  if (!reason) {
    return response.json({ code: 400, success: false, error: '清理必须提供 reason' });
  }
  const row = await findEntity(store, userId, entityType, entityId);
  const purgedAt = new Date().toISOString();
  const data = { purged: true, purgedAt, reason, id: entityId, userId };
  let purged = false;
  if (row?.objectId) {
    await store.update(VIDEO_WORKFLOW_CLASSES.entity, row.objectId, {
      status: 'purged',
      data,
    });
    purged = true;
  }
  await createAudit(store, userId, {
    entityType,
    entityId,
    action: 'purge',
    summary: `清理 ${entityType}:${entityId}`,
    detail: { reason, purged },
  });
  return response.json({
    code: 200,
    success: true,
    data: { entityType, entityId, purged },
  });
}

async function writeAudit(request, response, userId, store) {
  const action = requiredText(request, 'auditAction', 'eventAction', 'name');
  const entityType = pickParam(request, 'entityType') || '';
  const entityId = pickParam(request, 'entityId', 'id') || '';
  const summary = String(pickParam(request, 'summary') || '').slice(0, 500);
  const detail = normalizeObject(pickParam(request, 'detail') || {});
  const row = await createAudit(store, userId, { entityType, entityId, action, summary, detail });
  return response.json({ code: 200, success: true, data: rowToAudit(row) });
}

async function listAudits(request, response, userId, store) {
  const limit = safeLimit(pickParam(request, 'limit'), 50, 200);
  const entityType = String(pickParam(request, 'entityType') || '').trim();
  const where = parseUserWhere(userId, entityType ? { entityType } : {});
  const rows = await store.list(VIDEO_WORKFLOW_CLASSES.audit, where, { order: '-createdAt', limit });
  return response.json({ code: 200, success: true, data: rows.map(rowToAudit) });
}

async function getStats(request, response, userId, store) {
  const [entityRows, auditRows, migrationRows] = await Promise.all([
    listAll(store, VIDEO_WORKFLOW_CLASSES.entity, parseUserWhere(userId, {}), 5000),
    listAll(store, VIDEO_WORKFLOW_CLASSES.audit, parseUserWhere(userId, {}), 1000),
    listAll(store, VIDEO_WORKFLOW_CLASSES.migration, parseUserWhere(userId, {}), 1000),
  ]);
  return response.json({
    code: 200,
    success: true,
    data: buildStats(entityRows, auditRows, migrationRows),
  });
}

async function adminInspect(request, response, adminSession, store) {
  const targetUserId = String(pickParam(request, 'targetUserId', 'inspectUserId') || '').trim();
  const limit = safeLimit(pickParam(request, 'limit'), 100, 500);
  const userWhere = targetUserId ? { ownerId: targetUserId } : {};
  const [entityRows, auditRows, migrationRows] = await Promise.all([
    listAll(store, VIDEO_WORKFLOW_CLASSES.entity, parseUserWhereForAdmin(userWhere), limit * 20),
    listAll(store, VIDEO_WORKFLOW_CLASSES.audit, parseUserWhereForAdmin(userWhere), limit * 20),
    listAll(store, VIDEO_WORKFLOW_CLASSES.migration, parseUserWhereForAdmin(userWhere), limit * 20),
  ]);
  const users = {};
  const ensureUser = (userId) => {
    if (!users[userId]) {
      users[userId] = {
        userId,
        totalEntities: 0,
        entityTypes: {},
        auditCount: 0,
        latestAuditAt: '',
        migrations: { total: 0, failedRows: 0, byStatus: {} },
        latestUpdatedAt: '',
      };
    }
    return users[userId];
  };

  for (const row of entityRows) {
    const user = ensureUser(row.ownerId || '');
    const entityType = row.entityType || '';
    const status = row.status || 'active';
    if (!entityType || !user.userId) continue;
    if (!user.entityTypes[entityType]) user.entityTypes[entityType] = { total: 0, byStatus: {} };
    user.entityTypes[entityType].total += 1;
    user.entityTypes[entityType].byStatus[status] = (user.entityTypes[entityType].byStatus[status] || 0) + 1;
    user.totalEntities += 1;
    const latest = row.updatedAt || '';
    if (latest && String(latest) > String(user.latestUpdatedAt || '')) user.latestUpdatedAt = latest;
  }
  for (const row of auditRows) {
    const user = ensureUser(row.ownerId || '');
    if (!user.userId) continue;
    user.auditCount += 1;
    const latest = row.createdAt || '';
    if (latest && String(latest) > String(user.latestAuditAt || '')) user.latestAuditAt = latest;
  }
  for (const row of migrationRows) {
    const user = ensureUser(row.ownerId || '');
    if (!user.userId) continue;
    const status = row.status || 'unknown';
    user.migrations.total += 1;
    user.migrations.byStatus[status] = (user.migrations.byStatus[status] || 0) + 1;
    user.migrations.failedRows += Number(row.failedCount || 0);
  }

  const rows = Object.values(users)
    .sort((a, b) => b.totalEntities - a.totalEntities || String(b.latestUpdatedAt || '').localeCompare(String(a.latestUpdatedAt || '')))
    .slice(0, limit);
  return response.json({
    code: 200,
    success: true,
    data: {
      adminUserId: adminSession.userId,
      targetUserId,
      users: rows,
      generatedAt: new Date().toISOString(),
    },
  });
}

async function getMigration(request, response, userId, store) {
  const migrationKey = requiredText(request, 'migrationKey');
  const sourceKey = requiredText(request, 'sourceKey');
  const row = await findMigration(store, userId, migrationKey, sourceKey);
  return response.json({ code: 200, success: true, data: row ? rowToMigration(row) : null });
}

async function setMigration(request, response, userId, store) {
  const migrationKey = requiredText(request, 'migrationKey');
  const sourceKey = requiredText(request, 'sourceKey');
  const status = pickParam(request, 'status') || 'completed';
  const migratedCount = Number(pickParam(request, 'migratedCount') || 0);
  const failedCount = Number(pickParam(request, 'failedCount') || 0);
  const detail = normalizeObject(pickParam(request, 'detail') || {});
  const where = parseUserWhere(userId, { migrationKey, sourceKey });
  const payload = {
    ...parseUserFields(userId),
    migrationKey,
    sourceKey,
    status,
    migratedCount,
    failedCount,
    detail,
  };
  const row = await upsertMigrationWithDetailFallback(store, where, payload);
  return response.json({ code: 200, success: true, data: rowToMigration(row) });
}

async function upsertMigrationWithDetailFallback(store, where, payload) {
  try {
    return await store.upsertByQuery(VIDEO_WORKFLOW_CLASSES.migration, where, payload);
  } catch (error) {
    if (!isParseFieldTypeMismatch(error) || typeof payload.detail === 'string') {
      throw error;
    }
    return store.upsertByQuery(VIDEO_WORKFLOW_CLASSES.migration, where, {
      ...payload,
      detail: safeStringify(payload.detail),
    });
  }
}

async function saveEntity(store, { userId, entityType, entityId, data, status, schemaVersion, spaceId }) {
  const rawData = normalizeObject(data);
  const payload = { ...rawData, id: rawData.id || entityId, userId };
  const where = parseUserWhere(userId, { entityType, entityId });
  return store.upsertByQuery(VIDEO_WORKFLOW_CLASSES.entity, where, {
    ...parseUserFields(userId),
    entityType,
    entityId,
    status: status || 'active',
    schemaVersion: schemaVersion || 1,
    spaceId: spaceId || '',
    data: payload,
  });
}

async function findEntity(store, userId, entityType, entityId) {
  return store.findFirst(VIDEO_WORKFLOW_CLASSES.entity, parseUserWhere(userId, { entityType, entityId }), { limit: 1 });
}

async function findMigration(store, userId, migrationKey, sourceKey) {
  return store.findFirst(VIDEO_WORKFLOW_CLASSES.migration, parseUserWhere(userId, { migrationKey, sourceKey }), { limit: 1 });
}

async function createAudit(store, userId, { entityType, entityId, action, summary, detail }) {
  return store.create(VIDEO_WORKFLOW_CLASSES.audit, {
    ...parseUserFields(userId),
    entityType: entityType || '',
    entityId: entityId || '',
    action,
    summary: String(summary || '').slice(0, 500),
    detail: safeStringify(detail || {}),
  });
}

async function listAll(store, className, where, maxRows) {
  const all = [];
  const pageSize = 1000;
  for (let skip = 0; skip < maxRows; skip += pageSize) {
    const rows = await store.list(className, where, { order: '-updatedAt', limit: Math.min(pageSize, maxRows - skip), skip });
    all.push(...rows);
    if (rows.length < pageSize || all.length >= maxRows) break;
  }
  return all.slice(0, maxRows);
}

function buildStats(entityRows, auditRows, migrationRows) {
  const entityTypes = {};
  let totalEntities = 0;
  for (const row of entityRows) {
    const entityType = row.entityType || '';
    const status = row.status || 'active';
    if (!entityType) continue;
    if (!entityTypes[entityType]) entityTypes[entityType] = { total: 0, byStatus: {} };
    entityTypes[entityType].total += 1;
    entityTypes[entityType].byStatus[status] = (entityTypes[entityType].byStatus[status] || 0) + 1;
    totalEntities += 1;
  }
  const migrations = { total: 0, byStatus: {} };
  for (const row of migrationRows) {
    const status = row.status || 'unknown';
    migrations.total += 1;
    migrations.byStatus[status] = (migrations.byStatus[status] || 0) + 1;
  }
  return {
    totalEntities,
    entityTypes,
    auditCount: auditRows.length,
    migrations,
    generatedAt: new Date().toISOString(),
  };
}

function parseUserWhereForAdmin(extra = {}) {
  return { projectKey: 'video-workflow', ...extra };
}

function rowToEntity(row) {
  const data = normalizeObject(row.data);
  return {
    id: row.entityId,
    entityId: row.entityId,
    type: row.entityType,
    entityType: row.entityType,
    status: row.status || 'active',
    schemaVersion: row.schemaVersion,
    spaceId: row.spaceId || '',
    data,
    createdAt: row.createdAt,
    updatedAt: row.updatedAt,
  };
}

function rowToMigration(row) {
  return {
    id: row.objectId,
    migrationKey: row.migrationKey,
    sourceKey: row.sourceKey,
    status: row.status,
    migratedCount: Number(row.migratedCount || 0),
    failedCount: Number(row.failedCount || 0),
    detail: normalizeObject(row.detail),
    createdAt: row.createdAt,
    updatedAt: row.updatedAt,
  };
}

function rowToAudit(row) {
  return {
    id: row.objectId,
    entityType: row.entityType || '',
    entityId: row.entityId || '',
    action: row.action,
    summary: row.summary || '',
    detail: normalizeObject(row.detail),
    createdAt: row.createdAt,
  };
}

function requiredText(request, ...names) {
  const value = pickParam(request, ...names);
  const text = String(value || '').trim();
  if (!text) {
    const error = new Error(`缺少 ${names[0]}`);
    error.status = 400;
    throw error;
  }
  return text;
}

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 normalizeObject(value) {
  if (typeof value === 'string') {
    try { return JSON.parse(value); } catch { return {}; }
  }
  if (!value || typeof value !== 'object' || Array.isArray(value)) return {};
  return value;
}

function safeLimit(value, fallback, max) {
  const parsed = parseInt(value || fallback, 10);
  return Number.isFinite(parsed) ? Math.min(Math.max(parsed, 1), max) : fallback;
}

function safeStringify(value) {
  const text = JSON.stringify(normalizeObject(value));
  return text.length > 8000 ? `${text.slice(0, 7997)}...` : text;
}

function isParseFieldTypeMismatch(error) {
  const message = String(error?.message || error?.detail?.error || '').toLowerCase();
  return Number(error?.status || 0) === 400
    && (message.includes('schema') || message.includes('type') || message.includes('expected'));
}