import { Router, Request, Response } from 'express';
import bcrypt from 'bcryptjs';
import multer from 'multer';
import path from 'path';
import { v4 as uuidv4 } from 'uuid';
import { prisma, bigintToNumber } from '../lib/prisma';
import { authMiddleware } from '../lib/auth';

const router = Router();
router.use(authMiddleware);

const str = (v: string | string[] | undefined): string =>
  Array.isArray(v) ? v[0] ?? '' : (v ?? '');

// GET /api/users — list all users (admin only, with search)
router.get('/', async (req: Request, res: Response) => {
  try {
    if (req.user!.globalRole !== 'ADMIN') {
      res.status(403).json({ error: 'Forbidden — admin only' });
      return;
    }

    const search = typeof req.query.search === 'string' ? req.query.search.trim() : '';

    // storageUsed = sum of fileSize of all assets in projects this user owns
    const users = await prisma.user.findMany({
      where: search ? {
        OR: [
          { name: { contains: search, mode: 'insensitive' } },
          { email: { contains: search, mode: 'insensitive' } },
        ],
      } : {},
      select: {
        id: true,
        email: true,
        name: true,
        globalRole: true,
        avatarUrl: true,
        active: true,
        storageQuota: true,
        createdAt: true,
        // total storage used = sum of assets in projects this user owns
        projects: {
          select: {
            id: true,
            assets: {
              select: { fileSize: true },
            },
          },
        },
        _count: {
          select: {
            memberships: true,
            comments: true,
          },
        },
      },
      orderBy: { createdAt: 'desc' },
    });

    // Compute storageUsed and ownedProjects from owned projects
    const usersWithStorage = users.map(u => ({
      ...u,
      storageUsed: u.projects.reduce(
        (sum, p) => sum + p.assets.reduce((s, a) => s + Number(a.fileSize), 0),
        0
      ),
      ownedProjects: u.projects.length,
    }));

    res.json({ users: usersWithStorage.map(bigintToNumber) });
  } catch (err) {
    console.error('List users error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// GET /api/users/me — get current user profile
router.get('/me', async (req: Request, res: Response) => {
  try {
    const user = await prisma.user.findUnique({
      where: { id: req.user!.userId },
      select: {
        id: true,
        email: true,
        name: true,
        globalRole: true,
        avatarUrl: true,
        active: true,
        createdAt: true,
        _count: {
          select: {
            memberships: true,
            comments: true,
          },
        },
      },
    });

    if (!user) {
      res.status(404).json({ error: 'User not found' });
      return;
    }

    res.json({ user });
  } catch (err) {
    console.error('Get me error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// PUT /api/users/:id/quota — update storage quota (admin only)
router.put('/:id/quota', async (req: Request, res: Response) => {
  try {
    if (req.user!.globalRole !== 'ADMIN') {
      res.status(403).json({ error: 'Forbidden — admin only' });
      return;
    }

    const { storageQuota } = req.body;

    if (typeof storageQuota !== 'number' || !Number.isInteger(storageQuota) || storageQuota < 0) {
      res.status(400).json({ error: 'storageQuota must be a non-negative integer (bytes)' });
      return;
    }

    // Allow max 1 TB
    const MAX_QUOTA = 1024 * 1024 * 1024 * 1024;
    if (storageQuota > MAX_QUOTA) {
      res.status(400).json({ error: `storageQuota cannot exceed ${MAX_QUOTA} bytes (1 TB)` });
      return;
    }

    const user = await prisma.user.findUnique({
      where: { id: str(req.params.id) },
      select: { id: true, email: true, name: true, globalRole: true, avatarUrl: true, active: true, storageUsed: true },
    });
    if (!user) {
      res.status(404).json({ error: 'User not found' });
      return;
    }

    await prisma.user.update({
      where: { id: str(req.params.id) },
      data: { storageQuota },
    });

    res.json({
      user: bigintToNumber({ ...user, storageQuota, storageUsed: user.storageUsed ?? BigInt(0) }),
    });
  } catch (err) {
    console.error('Update quota error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// PUT /api/users/me — update current user profile
router.put('/me', async (req: Request, res: Response) => {
  try {
    const { name, avatarUrl, currentPassword, newPassword } = req.body;

    if (newPassword) {
      if (!currentPassword) {
        res.status(400).json({ error: 'currentPassword is required to change password' });
        return;
      }
      if (newPassword.length < 6) {
        res.status(400).json({ error: 'New password must be at least 6 characters' });
        return;
      }
      const user = await prisma.user.findUnique({ where: { id: req.user!.userId } });
      if (!user) {
        res.status(404).json({ error: 'User not found' });
        return;
      }
      const valid = await bcrypt.compare(currentPassword, user.password);
      if (!valid) {
        res.status(401).json({ error: 'Current password is incorrect' });
        return;
      }
      const hashed = await bcrypt.hash(newPassword, 12);
      const updated = await prisma.user.update({
        where: { id: req.user!.userId },
        data: {
          name: name?.trim() || undefined,
          avatarUrl: avatarUrl ?? undefined,
          password: hashed,
        },
        select: {
          id: true,
          email: true,
          name: true,
          globalRole: true,
          avatarUrl: true,
          active: true,
        },
      });
      res.json({ user: updated });
      return;
    }

    const updated = await prisma.user.update({
      where: { id: req.user!.userId },
      data: {
        name: name?.trim() || undefined,
        avatarUrl: avatarUrl ?? undefined,
      },
      select: {
        id: true,
        email: true,
        name: true,
        globalRole: true,
        avatarUrl: true,
        active: true,
      },
    });

    res.json({ user: updated });
  } catch (err) {
    console.error('Update me error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// ── Avatar upload ────────────────────────────────────────────────────────────
const avatarStorage = multer.diskStorage({
  destination: (_req, _file, cb) => {
    cb(null, path.resolve(__dirname, '../../uploads/avatars'));
  },
  filename: (_req, file, cb) => {
    const ext = path.extname(file.originalname).toLowerCase() || '.jpg';
    cb(null, `${uuidv4()}${ext}`);
  },
});

const avatarUpload = multer({
  storage: avatarStorage,
  limits: { fileSize: 5 * 1024 * 1024 }, // 5 MB
  fileFilter: (_req, file, cb) => {
    if (['image/jpeg', 'image/png', 'image/webp', 'image/gif'].includes(file.mimetype)) {
      cb(null, true);
    } else {
      cb(new Error('Only JPEG, PNG, WebP, or GIF images are allowed'));
    }
  },
});

// POST /api/users/me/avatar — upload avatar image
router.post('/me/avatar', avatarUpload.single('avatar'), async (req: Request, res: Response) => {
  try {
    if (!req.file) {
      res.status(400).json({ error: 'No file uploaded' });
      return;
    }

    const avatarUrl = `/uploads/avatars/${req.file!.filename}`;

    const updated = await prisma.user.update({
      where: { id: req.user!.userId },
      data: { avatarUrl },
      select: { id: true, email: true, name: true, globalRole: true, avatarUrl: true, active: true },
    });

    res.json({ user: updated, avatarUrl });
  } catch (err) {
    console.error('Avatar upload error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// PUT /api/users/:id/role — change user globalRole (admin only)
router.put('/:id/role', async (req: Request, res: Response) => {
  try {
    if (req.user!.globalRole !== 'ADMIN') {
      res.status(403).json({ error: 'Forbidden — admin only' });
      return;
    }

    const { role } = req.body;
    const validRoles = ['ADMIN', 'MEMBER', 'PROJECT_USER'];
    if (!validRoles.includes(role)) {
      res.status(400).json({ error: 'Invalid globalRole. Must be ADMIN, MEMBER, or PROJECT_USER' });
      return;
    }

    const user = await prisma.user.findUnique({ where: { id: str(req.params.id) } });
    if (!user) {
      res.status(404).json({ error: 'User not found' });
      return;
    }

    // Prevent last admin from being demoted
    if (role !== 'ADMIN') {
      const adminCount = await prisma.user.count({ where: { globalRole: 'ADMIN', active: true } });
      if (adminCount <= 1 && user.globalRole === 'ADMIN') {
        res.status(400).json({ error: 'Cannot demote the last system admin' });
        return;
      }
    }

    const updated = await prisma.user.update({
      where: { id: str(req.params.id) },
      data: { globalRole: role as any },
      select: {
        id: true,
        email: true,
        name: true,
        globalRole: true,
        avatarUrl: true,
        active: true,
        createdAt: true,
      },
    });

    res.json({ user: updated });
  } catch (err) {
    console.error('Update globalRole error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// PUT /api/users/:id/active — activate/deactivate user (admin only)
router.put('/:id/active', async (req: Request, res: Response) => {
  try {
    if (req.user!.globalRole !== 'ADMIN') {
      res.status(403).json({ error: 'Forbidden — admin only' });
      return;
    }

    const { active } = req.body;
    if (typeof active !== 'boolean') {
      res.status(400).json({ error: 'active must be a boolean' });
      return;
    }

    const user = await prisma.user.findUnique({ where: { id: str(req.params.id) } });
    if (!user) {
      res.status(404).json({ error: 'User not found' });
      return;
    }

    if (user.id === req.user!.userId) {
      res.status(400).json({ error: 'Cannot deactivate your own account' });
      return;
    }

    if (!active && user.globalRole === 'ADMIN') {
      const adminCount = await prisma.user.count({ where: { globalRole: 'ADMIN', active: true } });
      if (adminCount <= 1) {
        res.status(400).json({ error: 'Cannot deactivate the last admin' });
        return;
      }
    }

    const updated = await prisma.user.update({
      where: { id: str(req.params.id) },
      data: { active },
      select: {
        id: true,
        email: true,
        name: true,
        globalRole: true,
        avatarUrl: true,
        active: true,
        createdAt: true,
      },
    });

    res.json({ user: updated });
  } catch (err) {
    console.error('Update active error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

// DELETE /api/users/:id — delete user (admin only)
router.delete('/:id', async (req: Request, res: Response) => {
  try {
    if (req.user!.globalRole !== 'ADMIN') {
      res.status(403).json({ error: 'Forbidden — admin only' });
      return;
    }

    const user = await prisma.user.findUnique({ where: { id: str(req.params.id) } });
    if (!user) {
      res.status(404).json({ error: 'User not found' });
      return;
    }

    if (user.id === req.user!.userId) {
      res.status(400).json({ error: 'Cannot delete your own account' });
      return;
    }

    await prisma.user.delete({ where: { id: str(req.params.id) } });
    res.json({ message: 'User deleted' });
  } catch (err) {
    console.error('Delete user error:', err);
    res.status(500).json({ error: 'Internal server error' });
  }
});

export default router;