import React, { useState, useEffect } from 'react';
import apiService from '../services/apiService';
import type { UserManagementResponse, AgencyResponse } from '../services/apiService';
import { UserIcon } from './icons/UserIcon';
import { PlusIcon } from './icons/PlusIcon';
import { ChevronDownIcon } from './icons/ChevronDownIcon';
import type { UserRole } from '../types';

const ROLE_OPTIONS: { value: UserRole; label: string }[] = [
    { value: 'super_admin', label: 'Super Admin' },
    { value: 'oversight_admin', label: 'Oversight Admin' },
    { value: 'agency_admin', label: 'Agency Admin' },
    { value: 'basic_user', label: 'Basic User' },
];

const formatDate = (iso: string) => {
    return new Date(iso).toLocaleDateString('en-US', { month: 'short', day: 'numeric', year: 'numeric' });
};

export const UserManagement: React.FC = () => {
    const [users, setUsers] = useState<UserManagementResponse[]>([]);
    const [agencies, setAgencies] = useState<AgencyResponse[]>([]);
    const [isLoading, setIsLoading] = useState(true);
    const [error, setError] = useState<string | null>(null);

    // New agency form
    const [newAgencyName, setNewAgencyName] = useState('');
    const [isCreatingAgency, setIsCreatingAgency] = useState(false);

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

    const loadData = async () => {
        setIsLoading(true);
        try {
            const [usersData, agenciesData] = await Promise.all([
                apiService.getUsers(),
                apiService.getAgencies(),
            ]);
            setUsers(usersData);
            setAgencies(agenciesData);
        } catch (err) {
            console.error('Failed to load user management data:', err);
            setError('Failed to load data. You may not have permission.');
        } finally {
            setIsLoading(false);
        }
    };

    const handleRoleChange = async (userId: string, newRole: string) => {
        try {
            const updated = await apiService.updateUser(userId, { role: newRole });
            setUsers(prev => prev.map(u => u.id === userId ? updated : u));
        } catch (err) {
            console.error('Failed to update user role:', err);
            setError('Failed to update user role.');
        }
    };

    const handleAgencyChange = async (userId: string, agencyId: string | null) => {
        try {
            const updated = await apiService.updateUser(userId, { agency_id: agencyId });
            setUsers(prev => prev.map(u => u.id === userId ? updated : u));
        } catch (err) {
            console.error('Failed to update user agency:', err);
            setError('Failed to update user agency.');
        }
    };

    const handleCreateAgency = async (e: React.FormEvent) => {
        e.preventDefault();
        if (!newAgencyName.trim()) return;

        setIsCreatingAgency(true);
        try {
            const newAgency = await apiService.createAgency(newAgencyName.trim());
            setAgencies(prev => [...prev, newAgency].sort((a, b) => a.name.localeCompare(b.name)));
            setNewAgencyName('');
        } catch (err) {
            console.error('Failed to create agency:', err);
            setError('Failed to create agency.');
        } finally {
            setIsCreatingAgency(false);
        }
    };

    if (isLoading) {
        return (
            <div className="p-8 flex items-center justify-center h-full">
                <div className="flex flex-col items-center gap-3">
                    <svg className="animate-spin h-8 w-8 text-active-blue" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24">
                        <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" />
                        <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z" />
                    </svg>
                    <p className="text-grey-700 text-sm">Loading user management...</p>
                </div>
            </div>
        );
    }

    return (
        <div className="p-4 sm:p-6 lg:p-8 h-full bg-white overflow-y-auto">
            <header className="mb-6">
                <h1 className="text-3xl lg:text-4xl font-semibold text-primary-blue">User Management</h1>
                <p className="text-base lg:text-lg text-primary-blue mt-1">
                    Manage user roles and agency assignments. Users are provisioned automatically via Azure AD.
                </p>
            </header>

            {error && (
                <div className="mb-4 p-3 bg-error/10 border border-error/30 rounded-[10px] text-error text-sm">
                    {error}
                    <button onClick={() => setError(null)} className="ml-2 font-semibold hover:underline">Dismiss</button>
                </div>
            )}

            {/* Users Table */}
            <section className="mb-10">
                <h2 className="text-xl font-semibold text-primary-blue mb-4">Users ({users.length})</h2>
                <div className="bg-white rounded-[10px] shadow-md overflow-hidden border border-grey-300">
                    <div className="overflow-x-auto">
                        <table className="min-w-full">
                            <thead className="bg-lime">
                                <tr>
                                    <th className="px-6 py-3 text-left text-xs font-bold text-black-title uppercase tracking-wider">Name</th>
                                    <th className="px-6 py-3 text-left text-xs font-bold text-black-title uppercase tracking-wider">Email</th>
                                    <th className="px-6 py-3 text-left text-xs font-bold text-black-title uppercase tracking-wider">Role</th>
                                    <th className="px-6 py-3 text-left text-xs font-bold text-black-title uppercase tracking-wider">Agency</th>
                                    <th className="px-6 py-3 text-left text-xs font-bold text-black-title uppercase tracking-wider">Created</th>
                                </tr>
                            </thead>
                            <tbody className="divide-y divide-grey-300">
                                {users.map((user, index) => (
                                    <tr key={user.id} className={index % 2 === 0 ? 'bg-white' : 'bg-grey-100'}>
                                        <td className="px-6 py-4 whitespace-nowrap">
                                            <div className="flex items-center">
                                                <div className="flex-shrink-0 h-8 w-8 rounded-full bg-info-light flex items-center justify-center text-active-blue">
                                                    <UserIcon className="h-4 w-4" />
                                                </div>
                                                <div className="ml-3">
                                                    <div className="text-sm font-medium text-black-title">{user.name}</div>
                                                </div>
                                            </div>
                                        </td>
                                        <td className="px-6 py-4 whitespace-nowrap text-sm text-black-title">
                                            {user.email}
                                        </td>
                                        <td className="px-6 py-4 whitespace-nowrap">
                                            <div className="relative max-w-[180px]">
                                                <select
                                                    value={user.role}
                                                    onChange={(e) => handleRoleChange(user.id, e.target.value)}
                                                    className="w-full bg-white border-2 border-active-blue text-black-title py-1.5 pl-3 pr-8 rounded-[10px] text-sm focus:outline-none focus:ring-2 focus:ring-active-blue appearance-none"
                                                >
                                                    {ROLE_OPTIONS.map(r => (
                                                        <option key={r.value} value={r.value}>{r.label}</option>
                                                    ))}
                                                </select>
                                                <ChevronDownIcon className="absolute right-2 top-1/2 -translate-y-1/2 h-3 w-3 text-active-blue pointer-events-none" />
                                            </div>
                                        </td>
                                        <td className="px-6 py-4 whitespace-nowrap">
                                            <div className="relative max-w-[200px]">
                                                <select
                                                    value={user.agency_id || ''}
                                                    onChange={(e) => handleAgencyChange(user.id, e.target.value || null)}
                                                    className="w-full bg-white border-2 border-active-blue text-black-title py-1.5 pl-3 pr-8 rounded-[10px] text-sm focus:outline-none focus:ring-2 focus:ring-active-blue appearance-none"
                                                >
                                                    <option value="">None (Unassigned)</option>
                                                    {agencies.map(a => (
                                                        <option key={a.id} value={a.id}>{a.name}</option>
                                                    ))}
                                                </select>
                                                <ChevronDownIcon className="absolute right-2 top-1/2 -translate-y-1/2 h-3 w-3 text-active-blue pointer-events-none" />
                                            </div>
                                        </td>
                                        <td className="px-6 py-4 whitespace-nowrap text-sm text-grey-700">
                                            {formatDate(user.created_at)}
                                        </td>
                                    </tr>
                                ))}
                                {users.length === 0 && (
                                    <tr>
                                        <td colSpan={5} className="px-6 py-8 text-center text-grey-700">
                                            No users found.
                                        </td>
                                    </tr>
                                )}
                            </tbody>
                        </table>
                    </div>
                </div>
            </section>

            {/* Agency Management */}
            <section>
                <h2 className="text-xl font-semibold text-primary-blue mb-4">Agencies ({agencies.length})</h2>
                <div className="max-w-xl">
                    <form onSubmit={handleCreateAgency} className="flex gap-2 mb-4">
                        <input
                            type="text"
                            value={newAgencyName}
                            onChange={(e) => setNewAgencyName(e.target.value)}
                            placeholder="New agency name..."
                            className="flex-grow p-2 border-2 border-grey-700 rounded-[10px] focus:ring-2 focus:ring-active-blue focus:border-active-blue transition text-black-title"
                        />
                        <button
                            type="submit"
                            disabled={!newAgencyName.trim() || isCreatingAgency}
                            className="bg-active-blue text-white font-semibold py-2 px-6 rounded-full hover:bg-active-blue/90 transition-colors disabled:bg-grey-700 disabled:cursor-not-allowed flex items-center gap-2"
                        >
                            <PlusIcon className="h-4 w-4" />
                            Add
                        </button>
                    </form>

                    <div className="space-y-2">
                        {agencies.map(agency => (
                            <div
                                key={agency.id}
                                className="flex items-center justify-between bg-grey-100 p-3 rounded-[10px] border border-grey-300"
                            >
                                <span className="text-black-title font-medium">{agency.name}</span>
                                <span className="text-xs text-grey-700">
                                    {users.filter(u => u.agency_id === agency.id).length} user(s)
                                </span>
                            </div>
                        ))}
                        {agencies.length === 0 && (
                            <div className="text-center py-6 text-grey-700 bg-grey-100 rounded-[10px]">
                                No agencies created yet.
                            </div>
                        )}
                    </div>
                </div>
            </section>
        </div>
    );
};