<?php
// api.php

header('Content-Type: application/json');

function load_env($path) {
    if (!file_exists($path)) {
        error_log(".env file not found at " . $path);
        return;
    }
    $lines = file($path, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
    foreach ($lines as $line) {
        if (strpos(trim($line), '#') === 0) {
            continue;
        }
        list($name, $value) = explode('=', $line, 2);
        $name = trim($name);
        $value = trim($value);
        if (!array_key_exists($name, $_SERVER) && !array_key_exists($name, $_ENV)) {
            putenv(sprintf('%s=%s', $name, $value));
            $_ENV[$name] = $value;
            $_SERVER[$name] = $value;
        }
    }
}

function get_csv_sample($filePath) {
    $sample = [];
    $handle = fopen($filePath, 'r');
    if ($handle === false) {
        return null;
    }
    $headers = fgetcsv($handle);
    $sample[] = implode(',', $headers);

    $i = 0;
    while (($row = fgetcsv($handle)) !== false && $i < 5) {
        $sample[] = implode(',', $row);
        $i++;
    }
    fclose($handle);
    return implode('\n', $sample);
}

function call_openai_api($inputSample, $outputSample) {
    $apiKey = getenv('OPENAI_API_KEY');
    if (!$apiKey) {
        return ['error' => 'OpenAI API key not configured.'];
    }

    $prompt = "I have two CSV files. I want to convert the input file to the output file format.\n\n";
    $prompt .= "Here is a sample of the input CSV file:\n---\n" . $inputSample . "\n---\n\n";
    $prompt .= "Here is a sample of the output CSV file:\n---\n" . $outputSample . "\n---\n\n";
    $prompt .= "Please generate a PHP script that contains a single function `convert_csv($input_file_path, $output_file_path)`.\n";
    $prompt .= "This function should read the data from the `$input_file_path`, transform it into the format of the output sample, and write the result to `$output_file_path`.\n";
    $prompt .= "The script should handle CSV headers correctly. Do not include any explanations, just the raw PHP code starting with `<?php`.";

    $data = [
        'model' => 'gpt-5',
        'messages' => [
            [
                'role' => 'user',
                'content' => $prompt
            ]
        ]
    ];

    $ch = curl_init('https://api.openai.com/v1/chat/completions');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Content-Type: application/json',
        'Authorization: Bearer ' . $apiKey
    ]);

    $response = curl_exec($ch);
    $httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if ($httpcode != 200) {
        return ['error' => 'Failed to connect to OpenAI API. Response: ' . $response];
    }

    $result = json_decode($response, true);

    if (isset($result['choices'][0]['message']['content'])) {
        $php_code = $result['choices'][0]['message']['content'];
        // Clean up the response to get only the code
        if (strpos($php_code, '```php') !== false) {
            $php_code = substr($php_code, strpos($php_code, '```php') + 5);
            $php_code = substr($php_code, 0, strrpos($php_code, '```'));
        }
        if (strpos($php_code, '<?php') === false) {
            $php_code = "<?php\n" . $php_code;
        }
        return ['success' => true, 'code' => $php_code];
    }

    return ['error' => 'Could not extract PHP code from OpenAI response.', 'details' => $result];
}

load_env(__DIR__ . '/.env');
$action = $_POST['action'] ?? $_GET['action'] ?? '';

if ($action === 'build_mapping') {
    if (!isset($_FILES['inputSample']) || !isset($_FILES['outputSample'])) {
        echo json_encode(['success' => false, 'error' => 'Input and output sample files are required.']);
        exit;
    }

    $inputTmpPath = $_FILES['inputSample']['tmp_name'];
    $outputTmpPath = $_FILES['outputSample']['tmp_name'];

    $inputSampleContent = get_csv_sample($inputTmpPath);
    $outputSampleContent = get_csv_sample($outputTmpPath);

    if ($inputSampleContent === null || $outputSampleContent === null) {
        echo json_encode(['success' => false, 'error' => 'Failed to read sample files.']);
        exit;
    }

    $result = call_openai_api($inputSampleContent, $outputSampleContent);

    if (isset($result['error'])) {
        echo json_encode(['success' => false, 'error' => $result['error'], 'details' => $result['details'] ?? null]);
        exit;
    }

    $mappingDir = __DIR__ . '/mappings';
    if (!is_dir($mappingDir)) {
        mkdir($mappingDir, 0775, true);
    }
    $mappingFile = 'mappings/mapping_' . time() . '.php';
    file_put_contents($mappingFile, $result['code']);

    echo json_encode(['success' => true, 'mapping_file' => $mappingFile]);
    exit;
}

if ($action === 'convert') {
    if (!isset($_FILES['fullInputFile']) || !isset($_POST['mappingFile'])) {
        echo json_encode(['success' => false, 'error' => 'Input file and mapping file are required.']);
        exit;
    }

    $mappingFile = $_POST['mappingFile'];
    if (!file_exists($mappingFile)) {
        echo json_encode(['success' => false, 'error' => 'Mapping file not found.']);
        exit;
    }

    require_once $mappingFile;

    if (!function_exists('convert_csv')) {
        echo json_encode(['success' => false, 'error' => 'Invalid mapping file: convert_csv function not found.']);
        exit;
    }

    $inputTmpPath = $_FILES['fullInputFile']['tmp_name'];
    $outputDir = __DIR__ . '/outputs';
     if (!is_dir($outputDir)) {
        mkdir($outputDir, 0775, true);
    }
    $outputFile = $outputDir . '/converted_' . time() . '.csv';

    try {
        convert_csv($inputTmpPath, $outputFile);
        echo json_encode(['success' => true, 'download_url' => basename($outputFile)]);
    } catch (Exception $e) {
        echo json_encode(['success' => false, 'error' => 'Error during conversion: ' . $e->getMessage()]);
    }
    exit;
}


echo json_encode(['success' => false, 'error' => 'No action specified.']);