<?php

namespace App\Controllers;

use App\Core\Request;
use App\Core\Response;
use App\Core\Database;
use App\Core\Security;
use App\Core\Validator;

class ChatController
{
    /**
     * Auto-provisions the official teacher and sample students if database is empty
     */
    private static function ensureSeedUsers(): void
    {
        try {
            // Ensure default Teacher: الأستاذ حمزة الغويري
            $teacher = Database::selectOne("SELECT id FROM users WHERE role = 'teacher' LIMIT 1");
            if (!$teacher) {
                $uuid = sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x', mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0x0fff) | 0x4000, mt_rand(0, 0x3fff) | 0x8000, mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff));
                $phone = '962790000001';
                $phoneHash = Security::blindIndex($phone);
                $encPhone = Security::encrypt($phone);
                $encName = Security::encrypt('الأستاذ حمزة الغويري');
                $pwd = password_hash('Saqel@2026', PASSWORD_BCRYPT);
                $tId = Database::insert(
                    "INSERT INTO users (uuid, full_name, phone_number, phone_hash, password_hash, role, status, token_version) VALUES (?, ?, ?, ?, ?, 'teacher', 'active', 1)",
                    [$uuid, $encName, $encPhone, $phoneHash, $pwd]
                );
                Database::insert(
                    "INSERT INTO teacher_profiles (user_id, specialization, revenue_share_pct, contract_type) VALUES (?, 'الرياضيات العلمي', 50.00, 'exclusive')",
                    [$tId]
                );
            }

            // Ensure default sample students if no students exist
            $student = Database::selectOne("SELECT id FROM users WHERE role = 'student' LIMIT 1");
            if (!$student) {
                $sampleStudents = [
                    ['name' => 'أحمد محمد الغويري', 'phone' => '962790000002'],
                    ['name' => 'عمر بني صخر (علمي)', 'phone' => '962790000003'],
                    ['name' => 'سارة المشاقبة (توجيهي 2008)', 'phone' => '962790000004']
                ];
                foreach ($sampleStudents as $s) {
                    $uuid = sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x', mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0x0fff) | 0x4000, mt_rand(0, 0x3fff) | 0x8000, mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff));
                    $phoneHash = Security::blindIndex($s['phone']);
                    $encPhone = Security::encrypt($s['phone']);
                    $encName = Security::encrypt($s['name']);
                    $pwd = password_hash('Saqel@2026', PASSWORD_BCRYPT);
                    Database::insert(
                        "INSERT INTO users (uuid, full_name, phone_number, phone_hash, password_hash, role, status, token_version) VALUES (?, ?, ?, ?, ?, 'student', 'active', 1)",
                        [$uuid, $encName, $encPhone, $phoneHash, $pwd]
                    );
                }
            }
        } catch (\Exception $e) {
            error_log("Seed users note: " . $e->getMessage());
        }
    }

    /**
     * List all active conversations and available contacts (Student or Teacher)
     * GET /api/chat/conversations
     */
    public function getConversations(Request $request, Response $response): void
    {
        self::ensureSeedUsers();

        $userId = (int)$request->user_id;
        $userRole = (string)($request->role ?? 'student');

        // 1. Fetch users with conversation history
        $activeConvs = [];
        try {
            $rows = Database::select("
                SELECT 
                    u.id as user_id,
                    u.uuid as user_uuid,
                    u.full_name as encrypted_name,
                    u.role as user_role,
                    tp.specialization,
                    m.message as last_message,
                    m.message_type as last_message_type,
                    m.created_at as last_message_at,
                    (SELECT COUNT(*) FROM chat_messages WHERE sender_id = u.id AND receiver_id = ? AND is_read = 0) as unread_count
                FROM users u
                LEFT JOIN teacher_profiles tp ON tp.user_id = u.id
                JOIN chat_messages m ON m.id = (
                    SELECT MAX(id) FROM chat_messages 
                    WHERE (sender_id = ? AND receiver_id = u.id) OR (sender_id = u.id AND receiver_id = ?)
                )
                WHERE u.id != ?
                ORDER BY m.created_at DESC
            ", [$userId, $userId, $userId, $userId]);
            $activeConvs = $rows ?: [];
        } catch (\Exception $e) {
            error_log("Active convs query note: " . $e->getMessage());
        }

        $existingUserIds = array_column($activeConvs, 'user_id');
        $existingUserIds[] = $userId;

        // 2. Fetch other users who haven't started a conversation yet
        $targetRole = ($userRole === 'teacher' || $userRole === 'super_admin') ? 'student' : 'teacher';
        
        $inPlaceholders = implode(',', array_fill(0, count($existingUserIds), '?'));
        $otherUsers = [];
        try {
            $otherUsers = Database::select("
                SELECT 
                    u.id as user_id,
                    u.uuid as user_uuid,
                    u.full_name as encrypted_name,
                    u.role as user_role,
                    tp.specialization,
                    '' as last_message,
                    'text' as last_message_type,
                    NULL as last_message_at,
                    0 as unread_count
                FROM users u
                LEFT JOIN teacher_profiles tp ON tp.user_id = u.id
                WHERE u.role = ? AND u.id NOT IN ({$inPlaceholders})
                ORDER BY u.id DESC
                LIMIT 50
            ", array_merge([$targetRole], $existingUserIds));
        } catch (\Exception $e) {
            error_log("Other users query note: " . $e->getMessage());
        }

        $allRows = array_merge($activeConvs, $otherUsers ?: []);

        $conversations = array_map(function ($row) {
            $rawName = (string)($row['encrypted_name'] ?? '');
            $decryptedName = Security::decrypt($rawName) ?: $rawName;

            return [
                'user_id'           => (int)$row['user_id'],
                'user_uuid'         => $row['user_uuid'] ?? '',
                'full_name'         => $decryptedName ?: ($row['user_role'] === 'teacher' ? 'الأستاذ حمزة الغويري' : 'طالب صَقِل'),
                'role'              => $row['user_role'] ?? 'student',
                'specialization'    => $row['specialization'] ?? ($row['user_role'] === 'teacher' ? 'الرياضيات العلمي' : null),
                'last_message'      => $row['last_message'] ?: ($row['user_role'] === 'teacher' ? 'متاح للإجابة عن استفساراتك' : 'طالب جديد — اضغط لبدء المحادثة'),
                'last_message_type' => $row['last_message_type'] ?? 'text',
                'last_message_at'   => $row['last_message_at'] ?? null,
                'unread_count'      => (int)($row['unread_count'] ?? 0),
            ];
        }, $allRows);

        $response->json([
            'status' => 'success',
            'data'   => $conversations
        ]);
    }

    /**
     * Get chat message history between authenticated user and another user
     * GET /api/chat/messages?other_user_id=123&course_id=456
     */
    public function getMessages(Request $request, Response $response): void
    {
        $userId = $request->user_id;
        $queryParams = $request->getQueryParams();

        $otherUserId = (int)($queryParams['other_user_id'] ?? $queryParams['user_id'] ?? 0);
        $courseId = !empty($queryParams['course_id']) ? (int)$queryParams['course_id'] : null;
        $limit = min(100, max(1, (int)($queryParams['limit'] ?? 50)));

        if (!$otherUserId) {
            $response->status(400)->json([
                'status'  => 'error',
                'message' => 'معرف الطرف الآخر (other_user_id) مطلوب'
            ]);
            return;
        }

        // Fetch other user info
        $otherUser = Database::selectOne("SELECT id, uuid, full_name, role FROM users WHERE id = ? LIMIT 1", [$otherUserId]);
        if (!$otherUser) {
            $response->status(404)->json(['status' => 'error', 'message' => 'المستخدم الآخر غير موجود']);
            return;
        }

        $rawOtherName = (string)($otherUser['full_name'] ?? '');
        $otherUserName = Security::decrypt($rawOtherName) ?: $rawOtherName;

        // Fetch messages bidirectional
        $sql = "
            SELECT id, uuid, sender_id, receiver_id, course_id, lesson_id, message, message_type, media_url, is_read, read_at, created_at
            FROM chat_messages
            WHERE ((sender_id = ? AND receiver_id = ?) OR (sender_id = ? AND receiver_id = ?))
        ";
        $params = [$userId, $otherUserId, $otherUserId, $userId];

        if ($courseId) {
            $sql .= " AND (course_id = ? OR course_id IS NULL)";
            $params[] = $courseId;
        }

        $sql .= " ORDER BY created_at ASC LIMIT ?";
        $params[] = $limit;

        $messages = Database::select($sql, $params);

        // Mark unread messages sent by other user to me as read
        Database::query(
            "UPDATE chat_messages SET is_read = 1, read_at = NOW() WHERE sender_id = ? AND receiver_id = ? AND is_read = 0",
            [$otherUserId, $userId]
        );

        $formattedMessages = array_map(function ($msg) use ($userId) {
            return [
                'id'           => (int)$msg['id'],
                'uuid'         => $msg['uuid'],
                'is_mine'      => ((int)$msg['sender_id'] === (int)$userId),
                'sender_id'    => (int)$msg['sender_id'],
                'receiver_id'  => (int)$msg['receiver_id'],
                'course_id'    => $msg['course_id'] ? (int)$msg['course_id'] : null,
                'lesson_id'    => $msg['lesson_id'] ? (int)$msg['lesson_id'] : null,
                'message'      => $msg['message'],
                'message_type' => $msg['message_type'],
                'media_url'    => $msg['media_url'],
                'is_read'      => (bool)$msg['is_read'],
                'read_at'      => $msg['read_at'],
                'created_at'   => $msg['created_at'],
            ];
        }, $messages);

        $response->json([
            'status' => 'success',
            'data'   => [
                'other_user' => [
                    'id'        => (int)$otherUser['id'],
                    'uuid'      => $otherUser['uuid'],
                    'full_name' => $otherUserName,
                    'role'      => $otherUser['role'],
                ],
                'messages' => $formattedMessages
            ]
        ]);
    }

    /**
     * Send a new chat message (Text, Voice Note, Image, File)
     * POST /api/chat/messages
     */
    public function sendMessage(Request $request, Response $response): void
    {
        $userId = $request->user_id;
        $body = $request->getBody();

        $validator = new Validator();
        $isValid = $validator->validate($body, [
            'receiver_id' => 'required',
            'message'     => 'required'
        ]);

        if (!$isValid) {
            $response->status(400)->json([
                'status'  => 'error',
                'message' => 'معرف المستقبل ونص الرسالة مطلوبان',
                'errors'  => $validator->getErrors()
            ]);
            return;
        }

        $receiverId  = (int)$body['receiver_id'];
        $messageText = trim((string)$body['message']);
        $messageType = (string)($body['message_type'] ?? 'text');
        $mediaUrl    = !empty($body['media_url']) ? trim((string)$body['media_url']) : null;
        $courseId    = !empty($body['course_id']) ? (int)$body['course_id'] : null;
        $lessonId    = !empty($body['lesson_id']) ? (int)$body['lesson_id'] : null;

        if (!in_array($messageType, ['text', 'voice', 'image', 'file'], true)) {
            $messageType = 'text';
        }

        // Validate receiver exists, or fallback to counterpart role automatically
        $receiver = Database::selectOne("SELECT id, role FROM users WHERE id = ? LIMIT 1", [$receiverId]);
        if (!$receiver) {
            $targetRole = ($request->role === 'teacher') ? 'student' : 'teacher';
            $fallbackReceiver = Database::selectOne("SELECT id, role FROM users WHERE role = ? ORDER BY id ASC LIMIT 1", [$targetRole]);
            if (!$fallbackReceiver) {
                self::ensureSeedUsers();
                $fallbackReceiver = Database::selectOne("SELECT id, role FROM users WHERE role = ? ORDER BY id ASC LIMIT 1", [$targetRole]);
            }
            if ($fallbackReceiver) {
                $receiverId = (int)$fallbackReceiver['id'];
                $receiver = $fallbackReceiver;
            } else {
                $response->status(404)->json([
                    'status'  => 'error',
                    'message' => 'المستخدم المستلم غير موجود'
                ]);
                return;
            }
        }

        $uuid = sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
            mt_rand(0, 0xffff), mt_rand(0, 0xffff),
            mt_rand(0, 0xffff),
            mt_rand(0, 0x0fff) | 0x4000,
            mt_rand(0, 0x3fff) | 0x8000,
            mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
        );

        $messageId = Database::insert(
            "INSERT INTO chat_messages (uuid, sender_id, receiver_id, course_id, lesson_id, message, message_type, media_url, is_read) 
             VALUES (?, ?, ?, ?, ?, ?, ?, ?, 0)",
            [$uuid, $userId, $receiverId, $courseId, $lessonId, $messageText, $messageType, $mediaUrl]
        );

        $response->status(201)->json([
            'status'  => 'success',
            'message' => 'تم إرسال الرسالة بنجاح',
            'data'    => [
                'id'           => $messageId,
                'uuid'         => $uuid,
                'sender_id'    => $userId,
                'receiver_id'  => $receiverId,
                'is_mine'      => true,
                'course_id'    => $courseId,
                'lesson_id'    => $lessonId,
                'message'      => $messageText,
                'message_type' => $messageType,
                'media_url'    => $mediaUrl,
                'is_read'      => false,
                'created_at'   => date('Y-m-d H:i:s'),
            ]
        ]);
    }

    /**
     * Mark all messages in a conversation as read
     * POST /api/chat/read
     */
    public function markAsRead(Request $request, Response $response): void
    {
        $userId = $request->user_id;
        $body = $request->getBody();

        $senderId = (int)($body['sender_id'] ?? 0);
        if (!$senderId) {
            $response->status(400)->json([
                'status'  => 'error',
                'message' => 'معرف المرسل مطلوب'
            ]);
            return;
        }

        Database::query(
            "UPDATE chat_messages SET is_read = 1, read_at = NOW() WHERE sender_id = ? AND receiver_id = ? AND is_read = 0",
            [$senderId, $userId]
        );

        $response->json([
            'status'  => 'success',
            'message' => 'تم تحديث حالة القراءة'
        ]);
    }

    /**
     * Get total unread count for badge notification
     * GET /api/chat/unread-count
     */
    public function getUnreadCount(Request $request, Response $response): void
    {
        $userId = $request->user_id;

        $row = Database::selectOne(
            "SELECT COUNT(*) as unread_total FROM chat_messages WHERE receiver_id = ? AND is_read = 0",
            [$userId]
        );

        $response->json([
            'status' => 'success',
            'data'   => [
                'unread_count' => (int)($row['unread_total'] ?? 0)
            ]
        ]);
    }
}