import React, { useState, useEffect } from 'react';
import { X, Plus, Edit2, Trash2, Loader, AlertCircle, CheckCircle, User, Mail, Shield } from 'lucide-react';
import { useAuth } from '../contexts/AuthContext';

const API_BASE = process.env.REACT_APP_API_BASE || 'http://localhost:3001/api';

export default function UserManagement({ onClose }) {
    const { user: currentUser } = useAuth();
    const [users, setUsers] = useState([]);
    const [loading, setLoading] = useState(true);
    const [error, setError] = useState(null);
    const [showAddUser, setShowAddUser] = useState(false);
    const [editingUser, setEditingUser] = useState(null);
    const [formData, setFormData] = useState({
        username: '',
        email: '',
        password: '',
        role: 'viewer'
    });
    const [formError, setFormError] = useState('');
    const [formSuccess, setFormSuccess] = useState('');

    useEffect(() => {
        fetchUsers();
    }, []);

    const fetchUsers = async () => {
        try {
            const response = await fetch(`${API_BASE}/users`, {
                credentials: 'include'
            });
            if (!response.ok) throw new Error('Failed to fetch users');
            const data = await response.json();
            setUsers(data);
        } catch (err) {
            setError(err.message);
        } finally {
            setLoading(false);
        }
    };

    const handleSubmit = async (e) => {
        e.preventDefault();
        setFormError('');
        setFormSuccess('');

        try {
            const url = editingUser
                ? `${API_BASE}/users/${editingUser.id}`
                : `${API_BASE}/users`;

            const method = editingUser ? 'PATCH' : 'POST';

            const body = { ...formData };
            if (editingUser && !body.password) {
                delete body.password;
            }

            const response = await fetch(url, {
                method,
                headers: { 'Content-Type': 'application/json' },
                credentials: 'include',
                body: JSON.stringify(body)
            });

            const data = await response.json();

            if (!response.ok) {
                throw new Error(data.error || 'Operation failed');
            }

            setFormSuccess(editingUser ? 'User updated successfully' : 'User created successfully');
            fetchUsers();

            setTimeout(() => {
                setShowAddUser(false);
                setEditingUser(null);
                setFormData({ username: '', email: '', password: '', role: 'viewer' });
                setFormSuccess('');
            }, 1500);
        } catch (err) {
            setFormError(err.message);
        }
    };

    const handleEdit = (user) => {
        setEditingUser(user);
        setFormData({
            username: user.username,
            email: user.email,
            password: '',
            role: user.role
        });
        setShowAddUser(true);
        setFormError('');
        setFormSuccess('');
    };

    const handleDelete = async (userId) => {
        if (!window.confirm('Are you sure you want to delete this user?')) {
            return;
        }

        try {
            const response = await fetch(`${API_BASE}/users/${userId}`, {
                method: 'DELETE',
                credentials: 'include'
            });

            const data = await response.json();

            if (!response.ok) {
                throw new Error(data.error || 'Delete failed');
            }

            fetchUsers();
        } catch (err) {
            alert(err.message);
        }
    };

    const handleToggleActive = async (user) => {
        try {
            const response = await fetch(`${API_BASE}/users/${user.id}`, {
                method: 'PATCH',
                headers: { 'Content-Type': 'application/json' },
                credentials: 'include',
                body: JSON.stringify({ is_active: !user.is_active })
            });

            const data = await response.json();

            if (!response.ok) {
                throw new Error(data.error || 'Update failed');
            }

            fetchUsers();
        } catch (err) {
            alert(err.message);
        }
    };

    const getRoleBadgeColor = (role) => {
        switch (role) {
            case 'admin':
                return 'bg-red-100 text-red-800';
            case 'editor':
                return 'bg-blue-100 text-blue-800';
            default:
                return 'bg-gray-100 text-gray-800';
        }
    };

    return (
        <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center z-50 p-4">
            <div className="bg-white rounded-lg shadow-xl max-w-4xl w-full max-h-[90vh] overflow-hidden flex flex-col">
                <div className="p-6 border-b border-gray-200 flex justify-between items-center">
                    <div>
                        <h2 className="text-2xl font-bold text-gray-900">User Management</h2>
                        <p className="text-gray-600">Manage user accounts and permissions</p>
                    </div>
                    <button
                        onClick={onClose}
                        className="text-gray-400 hover:text-gray-600 p-2"
                    >
                        <X className="w-6 h-6" />
                    </button>
                </div>

                <div className="p-6 overflow-y-auto flex-1">
                    {!showAddUser && (
                        <button
                            onClick={() => {
                                setShowAddUser(true);
                                setEditingUser(null);
                                setFormData({ username: '', email: '', password: '', role: 'viewer' });
                                setFormError('');
                                setFormSuccess('');
                            }}
                            className="mb-6 px-4 py-2 bg-[#0476D9] text-white rounded-lg hover:bg-[#0360B8] transition-colors flex items-center gap-2 shadow-md"
                        >
                            <Plus className="w-5 h-5" />
                            Add User
                        </button>
                    )}

                    {showAddUser && (
                        <div className="mb-6 p-6 bg-gray-50 rounded-lg border border-gray-200">
                            <h3 className="text-lg font-semibold mb-4">
                                {editingUser ? 'Edit User' : 'Add New User'}
                            </h3>

                            {formError && (
                                <div className="mb-4 p-3 bg-red-50 border border-red-200 rounded-lg flex items-center gap-2">
                                    <AlertCircle className="w-5 h-5 text-red-600" />
                                    <span className="text-sm text-red-700">{formError}</span>
                                </div>
                            )}

                            {formSuccess && (
                                <div className="mb-4 p-3 bg-green-50 border border-green-200 rounded-lg flex items-center gap-2">
                                    <CheckCircle className="w-5 h-5 text-green-600" />
                                    <span className="text-sm text-green-700">{formSuccess}</span>
                                </div>
                            )}

                            <form onSubmit={handleSubmit} className="space-y-4">
                                <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
                                    <div>
                                        <label className="block text-sm font-medium text-gray-700 mb-1">
                                            Username *
                                        </label>
                                        <div className="relative">
                                            <User className="w-5 h-5 text-gray-400 absolute left-3 top-1/2 transform -translate-y-1/2" />
                                            <input
                                                type="text"
                                                required
                                                value={formData.username}
                                                onChange={(e) => setFormData({ ...formData, username: e.target.value })}
                                                className="w-full pl-10 pr-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-[#0476D9] focus:border-transparent"
                                            />
                                        </div>
                                    </div>

                                    <div>
                                        <label className="block text-sm font-medium text-gray-700 mb-1">
                                            Email *
                                        </label>
                                        <div className="relative">
                                            <Mail className="w-5 h-5 text-gray-400 absolute left-3 top-1/2 transform -translate-y-1/2" />
                                            <input
                                                type="email"
                                                required
                                                value={formData.email}
                                                onChange={(e) => setFormData({ ...formData, email: e.target.value })}
                                                className="w-full pl-10 pr-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-[#0476D9] focus:border-transparent"
                                            />
                                        </div>
                                    </div>

                                    <div>
                                        <label className="block text-sm font-medium text-gray-700 mb-1">
                                            Password {editingUser ? '(leave blank to keep current)' : '*'}
                                        </label>
                                        <input
                                            type="password"
                                            required={!editingUser}
                                            value={formData.password}
                                            onChange={(e) => setFormData({ ...formData, password: e.target.value })}
                                            className="w-full px-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-[#0476D9] focus:border-transparent"
                                        />
                                    </div>

                                    <div>
                                        <label className="block text-sm font-medium text-gray-700 mb-1">
                                            Role *
                                        </label>
                                        <div className="relative">
                                            <Shield className="w-5 h-5 text-gray-400 absolute left-3 top-1/2 transform -translate-y-1/2" />
                                            <select
                                                value={formData.role}
                                                onChange={(e) => setFormData({ ...formData, role: e.target.value })}
                                                className="w-full pl-10 pr-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-[#0476D9] focus:border-transparent"
                                            >
                                                <option value="viewer">Viewer (read-only)</option>
                                                <option value="editor">Editor (can add CVEs, upload docs)</option>
                                                <option value="admin">Admin (full access)</option>
                                            </select>
                                        </div>
                                    </div>
                                </div>

                                <div className="flex gap-3 pt-2">
                                    <button
                                        type="submit"
                                        className="px-4 py-2 bg-[#0476D9] text-white rounded-lg hover:bg-[#0360B8] transition-colors"
                                    >
                                        {editingUser ? 'Update User' : 'Create User'}
                                    </button>
                                    <button
                                        type="button"
                                        onClick={() => {
                                            setShowAddUser(false);
                                            setEditingUser(null);
                                        }}
                                        className="px-4 py-2 bg-gray-200 text-gray-700 rounded-lg hover:bg-gray-300 transition-colors"
                                    >
                                        Cancel
                                    </button>
                                </div>
                            </form>
                        </div>
                    )}

                    {loading ? (
                        <div className="text-center py-12">
                            <Loader className="w-8 h-8 text-[#0476D9] mx-auto animate-spin" />
                            <p className="text-gray-600 mt-2">Loading users...</p>
                        </div>
                    ) : error ? (
                        <div className="text-center py-12">
                            <AlertCircle className="w-8 h-8 text-red-500 mx-auto" />
                            <p className="text-red-600 mt-2">{error}</p>
                        </div>
                    ) : (
                        <div className="overflow-x-auto">
                            <table className="w-full">
                                <thead>
                                    <tr className="border-b border-gray-200">
                                        <th className="text-left py-3 px-4 text-sm font-medium text-gray-700">User</th>
                                        <th className="text-left py-3 px-4 text-sm font-medium text-gray-700">Role</th>
                                        <th className="text-left py-3 px-4 text-sm font-medium text-gray-700">Status</th>
                                        <th className="text-left py-3 px-4 text-sm font-medium text-gray-700">Last Login</th>
                                        <th className="text-right py-3 px-4 text-sm font-medium text-gray-700">Actions</th>
                                    </tr>
                                </thead>
                                <tbody>
                                    {users.map((user) => (
                                        <tr key={user.id} className="border-b border-gray-100 hover:bg-gray-50">
                                            <td className="py-3 px-4">
                                                <div>
                                                    <p className="font-medium text-gray-900">{user.username}</p>
                                                    <p className="text-sm text-gray-500">{user.email}</p>
                                                </div>
                                            </td>
                                            <td className="py-3 px-4">
                                                <span className={`px-2 py-1 rounded text-xs font-medium ${getRoleBadgeColor(user.role)}`}>
                                                    {user.role.charAt(0).toUpperCase() + user.role.slice(1)}
                                                </span>
                                            </td>
                                            <td className="py-3 px-4">
                                                <button
                                                    onClick={() => handleToggleActive(user)}
                                                    disabled={user.id === currentUser.id}
                                                    className={`px-2 py-1 rounded text-xs font-medium ${
                                                        user.is_active
                                                            ? 'bg-green-100 text-green-800'
                                                            : 'bg-red-100 text-red-800'
                                                    } ${user.id === currentUser.id ? 'opacity-50 cursor-not-allowed' : 'cursor-pointer hover:opacity-80'}`}
                                                >
                                                    {user.is_active ? 'Active' : 'Inactive'}
                                                </button>
                                            </td>
                                            <td className="py-3 px-4 text-sm text-gray-500">
                                                {user.last_login
                                                    ? new Date(user.last_login).toLocaleString()
                                                    : 'Never'}
                                            </td>
                                            <td className="py-3 px-4">
                                                <div className="flex justify-end gap-2">
                                                    <button
                                                        onClick={() => handleEdit(user)}
                                                        className="p-2 text-gray-600 hover:bg-gray-100 rounded"
                                                        title="Edit user"
                                                    >
                                                        <Edit2 className="w-4 h-4" />
                                                    </button>
                                                    <button
                                                        onClick={() => handleDelete(user.id)}
                                                        disabled={user.id === currentUser.id}
                                                        className={`p-2 text-red-600 hover:bg-red-50 rounded ${
                                                            user.id === currentUser.id ? 'opacity-50 cursor-not-allowed' : ''
                                                        }`}
                                                        title="Delete user"
                                                    >
                                                        <Trash2 className="w-4 h-4" />
                                                    </button>
                                                </div>
                                            </td>
                                        </tr>
                                    ))}
                                </tbody>
                            </table>
                        </div>
                    )}
                </div>
            </div>
        </div>
    );
}