'use client'

import { useCallback, useEffect, useState } from 'react'
import { useCurrentUser } from '@/lib/hooks/usePermissions'
import { broadcastPermissionsRefresh, usePermissions } from '@/lib/hooks/usePermissions'

interface Permission {
  id: string
  resource: string
  action: string
  description: string | null
}

interface Role {
  id: string
  name: string
  description: string | null
}

interface User {
  id: string
  name: string
  email: string
  isActive: boolean
  role: Role | null
  roleId: string | null
  createdAt: string
}

export default function UserManagementClient() {
  const [users, setUsers] = useState<User[]>([])
  const [roles, setRoles] = useState<Role[]>([])
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState<string | null>(null)
  const [showCreateModal, setShowCreateModal] = useState(false)
  const [newUserName, setNewUserName] = useState('')
  const [newUserEmail, setNewUserEmail] = useState('')
  const [newUserRoleId, setNewUserRoleId] = useState('')
  const [newUserPassword, setNewUserPassword] = useState('')
  const [newUserPasswordConfirm, setNewUserPasswordConfirm] = useState('')
  
  // Bulk role assignment
  const [selectedUsers, setSelectedUsers] = useState<string[]>([])
  const [bulkRoleId, setBulkRoleId] = useState<string>('')

  const { userId } = useCurrentUser()
  const { hasPermission, loading: permsLoading } = usePermissions()

  const fetchUsers = useCallback(async () => {
    if (!userId) return
    try {
      const res = await fetch('/api/users', {
        headers: {
          'x-user-id': userId || '',
        },
        cache: 'no-store',
      })
      if (!res.ok) throw new Error('Failed to fetch users')
      const data = await res.json()
      setUsers(data)
      setLoading(false)
    } catch (err: any) {
      setError(err.message)
      setLoading(false)
    }
  }, [userId])

  const fetchRoles = useCallback(async () => {
    if (!userId) return
    try {
      const res = await fetch('/api/roles', {
        headers: {
          'x-user-id': userId || '',
        },
        cache: 'no-store',
      })
      if (!res.ok) throw new Error('Failed to fetch roles')
      const data = await res.json()
      setRoles(data)
    } catch (err: any) {
      console.error('Error fetching roles:', err)
    }
  }, [userId])

  useEffect(() => {
    if (!userId) return
    fetchUsers()
    fetchRoles()
  }, [fetchRoles, fetchUsers, userId])

  const handleToggleUserStatus = async (user: User) => {
    try {
      const res = await fetch(`/api/users/${user.id}`, {
        method: 'PATCH',
        headers: {
          'Content-Type': 'application/json',
          'x-user-id': userId || '',
        },
        cache: 'no-store',
        body: JSON.stringify({
          isActive: !user.isActive,
        }),
      })

      if (!res.ok) throw new Error('Failed to update user status')

      await fetchUsers()
      broadcastPermissionsRefresh()
    } catch (err: any) {
      alert('Error updating user: ' + err.message)
    }
  }

  const toggleUserSelection = (userId: string) => {
    setSelectedUsers(prev =>
      prev.includes(userId)
        ? prev.filter(id => id !== userId)
        : [...prev, userId]
    )
  }

  const toggleSelectAll = () => {
    if (selectedUsers.length === users.length) {
      setSelectedUsers([])
    } else {
      setSelectedUsers(users.map(u => u.id))
    }
  }

  const handleBulkAssignRole = async () => {
    if (selectedUsers.length === 0) {
      alert('Please select at least one user')
      return
    }

    if (!bulkRoleId) {
      alert('Please select a role to assign')
      return
    }

    try {
      // Update all selected users
      await Promise.all(
        selectedUsers.map(selectedUserId =>
          fetch(`/api/users/${selectedUserId}`, {
            method: 'PATCH',
            headers: {
              'Content-Type': 'application/json',
              'x-user-id': userId || '',
            },
            cache: 'no-store',
            body: JSON.stringify({ roleId: bulkRoleId }),
          })
        )
      )

      setSelectedUsers([])
      setBulkRoleId('')
      await fetchUsers()
      broadcastPermissionsRefresh()
      alert(`Successfully assigned role to ${selectedUsers.length} user(s)`)
    } catch (err: any) {
      alert('Error assigning roles: ' + err.message)
    }
  }

  const handleCreateUser = async () => {
    if (!newUserName || !newUserEmail) {
      alert('Please enter name and email')
      return
    }

    const wantsToSetPassword = Boolean(newUserPassword || newUserPasswordConfirm)
    const canManagePasswords = !permsLoading && hasPermission('users', 'manage')
    if (wantsToSetPassword && !canManagePasswords) {
      alert('You do not have permission to set passwords. Ask an admin to set it after the user is created.')
      return
    }
    if (wantsToSetPassword) {
      if (newUserPassword.length < 8) {
        alert('Password must be at least 8 characters')
        return
      }
      if (newUserPassword !== newUserPasswordConfirm) {
        alert('Passwords do not match')
        return
      }
    }

    try {
      const res = await fetch('/api/users', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'x-user-id': userId || '',
        },
        cache: 'no-store',
        body: JSON.stringify({
          name: newUserName,
          email: newUserEmail,
          roleId: newUserRoleId || null,
        }),
      })

      if (!res.ok) {
        const data = await res.json()
        throw new Error(data.error || 'Failed to create user')
      }

      const data = await res.json().catch(() => ({} as any))
      const createdUser: User | undefined = data?.user

      if (wantsToSetPassword && createdUser?.id) {
        const pwRes = await fetch(`/api/users/${createdUser.id}/password`, {
          method: 'PATCH',
          headers: {
            'Content-Type': 'application/json',
            'x-user-id': userId || '',
          },
          cache: 'no-store',
          body: JSON.stringify({ password: newUserPassword }),
        })

        const pwData = await pwRes.json().catch(() => ({}))
        if (!pwRes.ok) {
          throw new Error(pwData?.error || 'User created, but failed to set password')
        }
      }

      setShowCreateModal(false)
      setNewUserName('')
      setNewUserEmail('')
      setNewUserRoleId('')
      setNewUserPassword('')
      setNewUserPasswordConfirm('')
      await fetchUsers()
      broadcastPermissionsRefresh()
      alert(wantsToSetPassword ? 'User created and password set successfully!' : 'User created successfully!')
    } catch (err: any) {
      alert('Error creating user: ' + err.message)
    }
  }

  const handleDeleteUser = async (user: User) => {
    if (!confirm(`Are you sure you want to delete ${user.name}? This action cannot be undone.`)) {
      return
    }

    try {
      const res = await fetch(`/api/users/${user.id}`, {
        method: 'DELETE',
        headers: {
          'x-user-id': userId || '',
        },
        cache: 'no-store',
      })

      if (!res.ok) {
        const data = await res.json()
        throw new Error(data.error || 'Failed to delete user')
      }

      await fetchUsers()
      broadcastPermissionsRefresh()
      alert('User deleted successfully!')
    } catch (err: any) {
      alert('Error deleting user: ' + err.message)
    }
  }

  const handleSetUserPassword = async (user: User) => {
    if (!userId) {
      alert('Missing user session. Please sign in again.')
      return
    }

    const pw1 = prompt(`Set a new password for ${user.email} (min 8 chars):`) || ''
    if (!pw1) return
    if (pw1.length < 8) {
      alert('Password must be at least 8 characters')
      return
    }
    const pw2 = prompt('Confirm new password:') || ''
    if (pw1 !== pw2) {
      alert('Passwords do not match')
      return
    }

    try {
      const res = await fetch(`/api/users/${user.id}/password`, {
        method: 'PATCH',
        headers: {
          'Content-Type': 'application/json',
          'x-user-id': userId || '',
        },
        cache: 'no-store',
        body: JSON.stringify({ password: pw1 }),
      })

      const data = await res.json().catch(() => ({}))
      if (!res.ok) {
        alert(data?.error || 'Failed to set password')
        return
      }
      alert('Password set successfully')
    } catch (err: any) {
      alert('Error setting password: ' + (err?.message || String(err)))
    }
  }

  if (loading) {
    return (
      <div className="flex items-center justify-center min-h-screen">
        <div className="text-lg">Loading users...</div>
      </div>
    )
  }

  if (error) {
    return (
      <div className="flex items-center justify-center min-h-screen">
        <div className="text-red-600">Error: {error}</div>
      </div>
    )
  }

  return (
    <div className="p-8">
      <div className="flex justify-between items-center mb-6">
        <h1 className="text-3xl font-bold">User Management</h1>
        <button
          onClick={() => setShowCreateModal(true)}
          className="px-4 py-2 bg-blue-600 text-white rounded-lg hover:bg-blue-700 font-medium"
        >
          + Add New User
        </button>
      </div>

      {/* Bulk Role Assignment */}
      {selectedUsers.length > 0 && (
        <div className="bg-blue-50 border border-blue-200 rounded-lg p-4 mb-6 flex items-center gap-4">
          <span className="font-medium text-blue-900">
            {selectedUsers.length} user(s) selected
          </span>
          <select
            value={bulkRoleId}
            onChange={(e) => setBulkRoleId(e.target.value)}
            className="border rounded px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500"
          >
            <option value="">Select a role to assign</option>
            {roles.map((role) => (
              <option key={role.id} value={role.id}>
                {role.name}
              </option>
            ))}
          </select>
          <button
            onClick={handleBulkAssignRole}
            disabled={!bulkRoleId}
            className="px-4 py-2 bg-blue-600 text-white rounded hover:bg-blue-700 disabled:bg-gray-300 disabled:cursor-not-allowed"
          >
            Assign Role
          </button>
          <button
            onClick={() => setSelectedUsers([])}
            className="px-4 py-2 text-gray-600 hover:text-gray-800"
          >
            Clear Selection
          </button>
        </div>
      )}

      <div className="bg-white shadow rounded-lg overflow-hidden">
        <table className="min-w-full divide-y divide-gray-200">
          <thead className="bg-gray-50">
            <tr>
              <th className="px-6 py-3 text-left">
                <input
                  type="checkbox"
                  checked={selectedUsers.length === users.length && users.length > 0}
                  onChange={toggleSelectAll}
                  className="w-4 h-4 rounded border-gray-300 focus:ring-2 focus:ring-blue-500 cursor-pointer"
                />
              </th>
              <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                User
              </th>
              <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                Email
              </th>
              <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                Role
              </th>
              <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                Status
              </th>
              <th className="px-6 py-3 text-left text-xs font-medium text-gray-500 uppercase tracking-wider">
                Actions
              </th>
            </tr>
          </thead>
          <tbody className="bg-white divide-y divide-gray-200">
            {users.map((user) => (
              <tr 
                key={user.id}
                className={selectedUsers.includes(user.id) ? 'bg-blue-50' : 'hover:bg-gray-50'}
              >
                <td className="px-6 py-4 whitespace-nowrap">
                  <input
                    type="checkbox"
                    checked={selectedUsers.includes(user.id)}
                    onChange={() => toggleUserSelection(user.id)}
                    className="w-4 h-4 rounded border-gray-300 focus:ring-2 focus:ring-blue-500 cursor-pointer"
                  />
                </td>
                <td className="px-6 py-4 whitespace-nowrap">
                  <div className="text-sm font-medium text-gray-900">{user.name}</div>
                </td>
                <td className="px-6 py-4 whitespace-nowrap">
                  <div className="text-sm text-gray-500">{user.email}</div>
                </td>
                <td className="px-6 py-4 whitespace-nowrap">
                  <span className="px-2 inline-flex text-xs leading-5 font-semibold rounded-full bg-blue-100 text-blue-800">
                    {user.role?.name || 'No Role'}
                  </span>
                </td>
                <td className="px-6 py-4 whitespace-nowrap">
                  <span
                    className={`px-2 inline-flex text-xs leading-5 font-semibold rounded-full ${
                      user.isActive
                        ? 'bg-green-100 text-green-800'
                        : 'bg-red-100 text-red-800'
                    }`}
                  >
                    {user.isActive ? 'Active' : 'Inactive'}
                  </span>
                </td>
                <td className="px-6 py-4 whitespace-nowrap text-sm font-medium">
                  {!permsLoading && hasPermission('users', 'manage') && (
                    <button
                      onClick={() => handleSetUserPassword(user)}
                      className="text-blue-600 hover:text-blue-900 mr-4"
                    >
                      Set Password
                    </button>
                  )}
                  <button
                    onClick={() => handleToggleUserStatus(user)}
                    className={
                      user.isActive
                        ? 'text-orange-600 hover:text-orange-900 mr-4'
                        : 'text-green-600 hover:text-green-900 mr-4'
                    }
                  >
                    {user.isActive ? 'Deactivate' : 'Activate'}
                  </button>
                  <button
                    onClick={() => handleDeleteUser(user)}
                    className="text-red-600 hover:text-red-900"
                  >
                    Delete
                  </button>
                </td>
              </tr>
            ))}
          </tbody>
        </table>
      </div>

      {/* Create User Modal */}
      {showCreateModal && (
        <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center z-50">
          <div className="bg-white rounded-lg p-8 max-w-md w-full">
            <h2 className="text-2xl font-bold mb-6">Add New User</h2>

            <div className="space-y-4 mb-6">
              <div>
                <label className="block text-sm font-medium mb-2">Full Name *</label>
                <input
                  type="text"
                  value={newUserName}
                  onChange={(e) => setNewUserName(e.target.value)}
                  placeholder="John Doe"
                  className="w-full border rounded px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500"
                />
              </div>

              <div>
                <label className="block text-sm font-medium mb-2">Email Address *</label>
                <input
                  type="email"
                  value={newUserEmail}
                  onChange={(e) => setNewUserEmail(e.target.value)}
                  placeholder="user@company.com"
                  className="w-full border rounded px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500"
                />
              </div>

              <div>
                <label className="block text-sm font-medium mb-2">Assign Role</label>
                <select
                  value={newUserRoleId}
                  onChange={(e) => setNewUserRoleId(e.target.value)}
                  className="w-full border rounded px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500"
                >
                  <option value="">No Role (Assign Later)</option>
                  {roles.map((role) => (
                    <option key={role.id} value={role.id}>
                      {role.name}
                    </option>
                  ))}
                </select>
              </div>

              {!permsLoading && hasPermission('users', 'manage') && (
                <>
                  <div>
                    <label className="block text-sm font-medium mb-2">Set Password (optional)</label>
                    <input
                      type="password"
                      value={newUserPassword}
                      onChange={(e) => setNewUserPassword(e.target.value)}
                      placeholder="Minimum 8 characters"
                      className="w-full border rounded px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500"
                    />
                  </div>
                  <div>
                    <label className="block text-sm font-medium mb-2">Confirm Password</label>
                    <input
                      type="password"
                      value={newUserPasswordConfirm}
                      onChange={(e) => setNewUserPasswordConfirm(e.target.value)}
                      placeholder="Re-enter password"
                      className="w-full border rounded px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500"
                    />
                  </div>
                </>
              )}
            </div>

            <div className="flex justify-end gap-3">
              <button
                onClick={() => {
                  setShowCreateModal(false)
                  setNewUserName('')
                  setNewUserEmail('')
                  setNewUserRoleId('')
                  setNewUserPassword('')
                  setNewUserPasswordConfirm('')
                }}
                className="px-4 py-2 border rounded hover:bg-gray-50"
              >
                Cancel
              </button>
              <button
                onClick={handleCreateUser}
                className="px-4 py-2 bg-blue-600 text-white rounded hover:bg-blue-700"
              >
                Create User
              </button>
            </div>
          </div>
        </div>
      )}
    </div>
  )
}