<?php
/**
 * Kling AI Video Generation API for Lux Studio
 * Handles Kling video generation: Text-to-Video, Image-to-Video, Video Extension, Lip Sync
 */

// Suppress HTML error output to prevent breaking JSON responses
error_reporting(E_ALL);
ini_set('display_errors', 0);
ini_set('log_errors', 1);
set_time_limit(600);
ini_set('memory_limit', '512M');
ini_set('post_max_size', '100M');
ini_set('upload_max_filesize', '100M');

header('Content-Type: application/json');
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST, GET, OPTIONS');
header('Access-Control-Allow-Headers: Content-Type');

// Handle preflight requests
if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    http_response_code(200);
    exit;
}

// Load configuration
require_once 'config.php';

class KlingAPI {
    private $accessKey;
    private $secretKey;
    private $baseUrl = 'https://api-singapore.klingai.com';

    public function __construct($accessKey, $secretKey) {
        $this->accessKey = $accessKey;
        $this->secretKey = $secretKey;
    }

    /**
     * Generate HS256 JWT token for Kling API authentication
     * Pure PHP implementation - no external libraries required
     */
    private function generateJWT() {
        $header = json_encode(['alg' => 'HS256', 'typ' => 'JWT']);
        $now = time();
        $payload = json_encode([
            'iss' => $this->accessKey,
            'exp' => $now + 1800,  // 30 minute expiry
            'nbf' => $now - 5     // Valid from 5 seconds ago (clock skew tolerance)
        ]);

        $b64Header = $this->base64UrlEncode($header);
        $b64Payload = $this->base64UrlEncode($payload);

        $signature = hash_hmac('sha256', "$b64Header.$b64Payload", $this->secretKey, true);
        $b64Signature = $this->base64UrlEncode($signature);

        return "$b64Header.$b64Payload.$b64Signature";
    }

    /**
     * URL-safe Base64 encoding
     */
    private function base64UrlEncode($data) {
        return rtrim(strtr(base64_encode($data), '+/', '-_'), '=');
    }

    /**
     * Make an authenticated request to the Kling API
     */
    private function makeRequest($method, $endpoint, $payload = null) {
        $url = $this->baseUrl . $endpoint;
        $jwt = $this->generateJWT();

        $headers = [
            'Content-Type: application/json',
            'Authorization: Bearer ' . $jwt
        ];

        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_TIMEOUT => 120,
            CURLOPT_HTTPHEADER => $headers
        ]);

        if ($method === 'POST') {
            curl_setopt($ch, CURLOPT_POST, true);
            if ($payload !== null) {
                curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));
            }
        }

        $response = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $curlError = curl_error($ch);
        curl_close($ch);

        if ($curlError) {
            throw new Exception("Kling API connection error: $curlError");
        }

        $decoded = json_decode($response, true);

        if ($httpCode === 401 || (isset($decoded['code']) && $decoded['code'] >= 1000 && $decoded['code'] <= 1004)) {
            throw new Exception('Kling API authentication failed. Check your KLING_ACCESS_KEY and KLING_SECRET_KEY in .env');
        }

        if ($httpCode === 429 || (isset($decoded['code']) && $decoded['code'] >= 1302 && $decoded['code'] <= 1304)) {
            throw new Exception('Kling API rate limit or concurrent task limit exceeded. Please wait and try again.');
        }

        if (isset($decoded['code']) && $decoded['code'] >= 1200 && $decoded['code'] <= 1201) {
            $detail = $decoded['message'] ?? 'Unknown parameter error';
            throw new Exception("Kling API invalid parameters: $detail");
        }

        if ($httpCode >= 500) {
            throw new Exception('Kling server error. Please try again.');
        }

        if ($httpCode !== 200 && $httpCode !== 201) {
            $msg = $decoded['message'] ?? "HTTP $httpCode";
            throw new Exception("Kling API error: $msg");
        }

        return $decoded;
    }

    /**
     * Text-to-Video generation
     */
    public function textToVideo($prompt, $opts = []) {
        $payload = [
            'prompt' => $prompt,
            'model_name' => $opts['model_name'] ?? 'kling-v2-6',
            'mode' => $opts['mode'] ?? 'std',
            'duration' => $opts['duration'] ?? '5',
            'aspect_ratio' => $opts['aspect_ratio'] ?? '16:9',
            'cfg_scale' => floatval($opts['cfg_scale'] ?? 0.5)
        ];

        if (!empty($opts['negative_prompt'])) {
            $payload['negative_prompt'] = $opts['negative_prompt'];
        }

        if (!empty($opts['sound']) && $opts['sound'] === 'on') {
            $payload['sound'] = 'on';
        }

        // Camera control - only include if a preset is selected
        if (!empty($opts['camera_control']) && $opts['camera_control'] !== 'none') {
            $payload['camera_control'] = [
                'type' => 'predefined',
                'config' => $opts['camera_control']
            ];
        }

        error_log("Kling T2V request: model={$payload['model_name']}, mode={$payload['mode']}, duration={$payload['duration']}");

        $response = $this->makeRequest('POST', '/v1/videos/text2video', $payload);

        return $this->extractTaskInfo($response, 'text2video');
    }

    /**
     * Image-to-Video generation
     */
    public function imageToVideo($images, $prompt, $opts = []) {
        $payload = [
            'model_name' => $opts['model_name'] ?? 'kling-v2-6',
            'mode' => $opts['mode'] ?? 'std',
            'duration' => $opts['duration'] ?? '5',
            'aspect_ratio' => $opts['aspect_ratio'] ?? '16:9',
            'cfg_scale' => floatval($opts['cfg_scale'] ?? 0.5)
        ];

        if (!empty($prompt)) {
            $payload['prompt'] = $prompt;
        }

        if (!empty($opts['negative_prompt'])) {
            $payload['negative_prompt'] = $opts['negative_prompt'];
        }

        if (!empty($opts['sound']) && $opts['sound'] === 'on') {
            $payload['sound'] = 'on';
        }

        // Camera control
        if (!empty($opts['camera_control']) && $opts['camera_control'] !== 'none') {
            $payload['camera_control'] = [
                'type' => 'predefined',
                'config' => $opts['camera_control']
            ];
        }

        // Start frame image (required)
        if (isset($images[0])) {
            $imageData = $this->cleanBase64($images[0]['data']);
            $payload['image'] = $imageData;
        }

        // Optional end frame image
        if (isset($images[1])) {
            $tailData = $this->cleanBase64($images[1]['data']);
            $payload['image_tail'] = $tailData;
        }

        error_log("Kling I2V request: model={$payload['model_name']}, images=" . count($images));

        $response = $this->makeRequest('POST', '/v1/videos/image2video', $payload);

        return $this->extractTaskInfo($response, 'image2video');
    }

    /**
     * Extend an existing Kling video
     */
    public function extendVideo($videoId, $opts = []) {
        $payload = [
            'video_id' => $videoId
        ];

        if (!empty($opts['prompt'])) {
            $payload['prompt'] = $opts['prompt'];
        }

        if (!empty($opts['negative_prompt'])) {
            $payload['negative_prompt'] = $opts['negative_prompt'];
        }

        if (isset($opts['cfg_scale'])) {
            $payload['cfg_scale'] = floatval($opts['cfg_scale']);
        }

        error_log("Kling Extend request: videoId=$videoId");

        $response = $this->makeRequest('POST', '/v1/videos/video-extend', $payload);

        return $this->extractTaskInfo($response, 'video-extend');
    }

    /**
     * Lip Sync generation (image + audio → talking head video)
     */
    public function lipSync($imageData, $audioData, $opts = []) {
        $payload = [
            'image' => $this->cleanBase64($imageData),
            'sound_file' => $this->cleanBase64($audioData)
        ];

        if (!empty($opts['prompt'])) {
            $payload['prompt'] = $opts['prompt'];
        }

        if (!empty($opts['mode'])) {
            $payload['mode'] = $opts['mode'];
        }

        error_log("Kling Lip Sync request: mode=" . ($opts['mode'] ?? 'std'));

        $response = $this->makeRequest('POST', '/v1/videos/avatar', $payload);

        return $this->extractTaskInfo($response, 'avatar');
    }

    /**
     * Check the status of a Kling task
     */
    public function checkStatus($taskId, $taskType) {
        // Map task types to their status endpoints
        $endpointMap = [
            'text2video' => '/v1/videos/text2video/',
            'image2video' => '/v1/videos/image2video/',
            'video-extend' => '/v1/videos/video-extend/',
            'avatar' => '/v1/videos/avatar/'
        ];

        $endpoint = ($endpointMap[$taskType] ?? '/v1/videos/text2video/') . $taskId;

        $response = $this->makeRequest('GET', $endpoint);

        return $response;
    }

    /**
     * Download a video from Kling CDN and save locally
     */
    public function downloadAndSaveVideo($url) {
        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_TIMEOUT => 120
        ]);

        $videoData = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        $curlError = curl_error($ch);
        curl_close($ch);

        if ($curlError || $httpCode !== 200 || !$videoData) {
            throw new Exception("Failed to download video from Kling CDN: HTTP $httpCode");
        }

        $filename = 'video_' . date('Ymd_His') . '_' . bin2hex(random_bytes(4)) . '.mp4';
        $videoDir = __DIR__ . '/generated_videos';

        if (!is_dir($videoDir)) {
            mkdir($videoDir, 0755, true);
        }

        $filepath = $videoDir . '/' . $filename;
        file_put_contents($filepath, $videoData);

        return $filename;
    }

    /**
     * Extract task ID and type from Kling API response
     */
    private function extractTaskInfo($response, $taskType) {
        // Kling API returns: { "code": 0, "message": "...", "request_id": "...", "data": { "task_id": "...", "task_status": "submitted" } }
        if (isset($response['data']['task_id'])) {
            return [
                'taskId' => $response['data']['task_id'],
                'taskType' => $taskType,
                'status' => $response['data']['task_status'] ?? 'submitted'
            ];
        }

        // Also check for task_id at top level
        if (isset($response['task_id'])) {
            return [
                'taskId' => $response['task_id'],
                'taskType' => $taskType,
                'status' => $response['task_status'] ?? 'submitted'
            ];
        }

        throw new Exception('Kling API returned unexpected response: ' . json_encode($response));
    }

    /**
     * Clean base64 data - remove data URI prefix and whitespace
     */
    private function cleanBase64($data) {
        $data = preg_replace('/^data:[^;]+;base64,/', '', $data);
        $data = preg_replace('/\s+/', '', $data);
        return $data;
    }
}

// =============================================================================
// Request Handler
// =============================================================================

try {
    $action = $_POST['action'] ?? $_GET['action'] ?? null;

    if (!$action) {
        throw new Exception('No action specified');
    }

    // Validate Kling credentials
    if (!defined('KLING_ACCESS_KEY') || empty(KLING_ACCESS_KEY) || !defined('KLING_SECRET_KEY') || empty(KLING_SECRET_KEY)) {
        throw new Exception('Kling API credentials not configured. Please set KLING_ACCESS_KEY and KLING_SECRET_KEY in your .env file.');
    }

    $api = new KlingAPI(KLING_ACCESS_KEY, KLING_SECRET_KEY);

    // =========================================================================
    // Action: generate (Text-to-Video or Image-to-Video)
    // =========================================================================
    if ($action === 'generate') {
        $prompt = $_POST['prompt'] ?? '';
        $modelName = $_POST['modelName'] ?? 'kling-v2-6';
        $duration = $_POST['duration'] ?? '5';
        $aspectRatio = $_POST['aspectRatio'] ?? '16:9';
        $mode = $_POST['mode'] ?? 'std';
        $cfgScale = $_POST['cfgScale'] ?? '0.5';
        $sound = $_POST['sound'] ?? 'off';
        $negativePrompt = $_POST['negativePrompt'] ?? '';
        $cameraControl = $_POST['cameraControl'] ?? 'none';

        // Validate model
        $validModels = ['kling-v3', 'kling-v3-omni', 'kling-v2-6', 'kling-v2-5-turbo', 'kling-v2-1-master', 'kling-v1-6'];
        if (!in_array($modelName, $validModels)) {
            $modelName = 'kling-v2-6';
        }

        // Validate duration
        if (!in_array($duration, ['5', '10'])) {
            $duration = '5';
        }

        // Validate aspect ratio
        if (!in_array($aspectRatio, ['16:9', '9:16', '1:1'])) {
            $aspectRatio = '16:9';
        }

        // Validate mode
        if (!in_array($mode, ['std', 'pro'])) {
            $mode = 'std';
        }

        $opts = [
            'model_name' => $modelName,
            'mode' => $mode,
            'duration' => $duration,
            'aspect_ratio' => $aspectRatio,
            'cfg_scale' => $cfgScale,
            'sound' => $sound,
            'negative_prompt' => trim($negativePrompt),
            'camera_control' => $cameraControl
        ];

        // Collect reference images
        $referenceImages = [];
        $refCount = intval($_POST['referenceImageCount'] ?? 0);
        for ($i = 0; $i < min($refCount, 2); $i++) {
            if (isset($_POST["referenceImage_$i"])) {
                $referenceImages[] = [
                    'data' => $_POST["referenceImage_$i"],
                    'mime_type' => $_POST["referenceImageType_$i"] ?? 'image/jpeg'
                ];
            }
        }

        // Branch: T2V or I2V based on reference images
        if (!empty($referenceImages)) {
            if (empty($prompt)) {
                $prompt = '';  // Prompt is optional for I2V
            }
            $result = $api->imageToVideo($referenceImages, $prompt, $opts);
        } else {
            if (empty($prompt)) {
                throw new Exception('Prompt is required for text-to-video generation');
            }
            $result = $api->textToVideo($prompt, $opts);
        }

        echo json_encode([
            'success' => true,
            'status' => 'pending',
            'taskId' => $result['taskId'],
            'taskType' => $result['taskType'],
            'message' => 'Kling video generation started. Polling for status.'
        ]);
        exit;
    }

    // =========================================================================
    // Action: extend (Video Extension)
    // =========================================================================
    if ($action === 'extend') {
        $videoId = $_POST['videoId'] ?? null;
        $prompt = $_POST['prompt'] ?? '';
        $cfgScale = $_POST['cfgScale'] ?? '0.5';
        $negativePrompt = $_POST['negativePrompt'] ?? '';

        if (!$videoId) {
            throw new Exception('Video ID is required for video extension');
        }

        $opts = [
            'prompt' => trim($prompt),
            'negative_prompt' => trim($negativePrompt),
            'cfg_scale' => $cfgScale
        ];

        $result = $api->extendVideo($videoId, $opts);

        echo json_encode([
            'success' => true,
            'status' => 'pending',
            'taskId' => $result['taskId'],
            'taskType' => 'video-extend',
            'message' => 'Video extension started. Polling for status.'
        ]);
        exit;
    }

    // =========================================================================
    // Action: lipsync (Lip Sync Generation)
    // =========================================================================
    if ($action === 'lipsync') {
        $imageData = $_POST['image'] ?? null;
        $audioData = $_POST['audioFile'] ?? null;
        $prompt = $_POST['prompt'] ?? '';
        $mode = $_POST['mode'] ?? 'std';

        if (!$imageData) {
            throw new Exception('Face image is required for lip sync');
        }

        if (!$audioData) {
            throw new Exception('Audio file is required for lip sync');
        }

        if (!in_array($mode, ['std', 'pro'])) {
            $mode = 'std';
        }

        $opts = [
            'prompt' => trim($prompt),
            'mode' => $mode
        ];

        $result = $api->lipSync($imageData, $audioData, $opts);

        echo json_encode([
            'success' => true,
            'status' => 'pending',
            'taskId' => $result['taskId'],
            'taskType' => 'avatar',
            'message' => 'Lip sync generation started. Polling for status.'
        ]);
        exit;
    }

    // =========================================================================
    // Action: check_status (Poll task status for any workflow)
    // =========================================================================
    if ($action === 'check_status') {
        $taskId = $_POST['taskId'] ?? null;
        $taskType = $_POST['taskType'] ?? 'text2video';

        if (!$taskId) {
            throw new Exception('Task ID is required');
        }

        $response = $api->checkStatus($taskId, $taskType);

        // Extract status from response
        $taskStatus = $response['data']['task_status'] ?? 'processing';
        $taskStatusMsg = $response['data']['task_status_msg'] ?? '';

        if ($taskStatus === 'succeed') {
            // Task completed - extract video URL
            $videos = $response['data']['task_result']['videos'] ?? [];

            if (empty($videos)) {
                throw new Exception('Kling generation completed but no video was returned');
            }

            $videoUrl = $videos[0]['url'] ?? null;
            $videoDuration = $videos[0]['duration'] ?? null;

            if (!$videoUrl) {
                throw new Exception('Kling generation completed but video URL is missing');
            }

            // Download from Kling CDN and save locally (CDN URLs are temporary)
            $filename = $api->downloadAndSaveVideo($videoUrl);

            echo json_encode([
                'success' => true,
                'status' => 'complete',
                'video' => [
                    'url' => '/generated_videos/' . $filename,
                    'filename' => $filename,
                    'mime_type' => 'video/mp4',
                    'duration' => $videoDuration
                ],
                'taskId' => $taskId
            ]);
        } elseif ($taskStatus === 'failed') {
            throw new Exception('Kling video generation failed: ' . ($taskStatusMsg ?: 'Unknown error'));
        } else {
            // Still processing (submitted, processing)
            echo json_encode([
                'success' => true,
                'status' => 'pending',
                'taskStatus' => $taskStatus,
                'message' => 'Kling video generation in progress...'
            ]);
        }
        exit;
    }

    // =========================================================================
    // Action: download_video (Proxy download from Kling CDN)
    // =========================================================================
    if ($action === 'download_video') {
        $videoUrl = $_POST['videoUrl'] ?? null;

        if (!$videoUrl) {
            throw new Exception('Video URL is required');
        }

        $filename = $api->downloadAndSaveVideo($videoUrl);

        echo json_encode([
            'success' => true,
            'video' => [
                'url' => '/generated_videos/' . $filename,
                'filename' => $filename,
                'mime_type' => 'video/mp4'
            ]
        ]);
        exit;
    }

    throw new Exception('Invalid action: ' . $action);

} catch (Exception $e) {
    http_response_code(500);

    error_log("Exception in kling_api.php: " . $e->getMessage());
    error_log("Stack trace: " . $e->getTraceAsString());

    echo json_encode([
        'success' => false,
        'error' => $e->getMessage(),
        'debug' => [
            'file' => basename($e->getFile()),
            'line' => $e->getLine(),
            'timestamp' => date('Y-m-d H:i:s')
        ]
    ]);
    exit;
}