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

require_once __DIR__ . '/ai/LocalAIApi.php';

function return_error($message) {
    echo json_encode(['success' => false, 'error' => $message]);
    exit;
}

// 1. Get Request Data
$chartRequest = $_POST['chart_request'] ?? '';
$filePath = $_POST['file_path'] ?? '';

if (empty($chartRequest) || empty($filePath)) {
    return_error('Missing chart request or file path.');
}

// Security check: ensure the file path is within the uploads directory
$uploadsDir = realpath(__DIR__ . '/uploads');
$realFilePath = realpath($filePath);

if (!$realFilePath || strpos($realFilePath, $uploadsDir) !== 0) {
    return_error('Invalid file path provided.');
}

// 2. Read CSV Header and Sample Rows for context
$dataSample = '';
$handle = fopen($realFilePath, 'r');
if (!$handle) {
    return_error('Failed to open the data file.');
}

$lineCount = 0;
$header = [];
while (($row = fgetcsv($handle)) !== false && $lineCount < 3) {
    if ($lineCount === 0) {
        $header = $row;
    }
    $dataSample .= implode(',', array_map(function($cell) {
        return '"' . addslashes($cell) . '"';
    }, $row)) . "\n";
    $lineCount++;
}
fclose($handle);

if (empty($dataSample)) {
    return_error('The data file appears to be empty.');
}

// 3. Prepare Prompt for AI to generate a PHP script
$prompt = <<<PROMPT
You are a PHP data processing expert. A user wants to create a chart.
Your task is to write a **complete PHP script** that reads a CSV file, processes it according to the user's request, and then **echoes a JSON object** formatted for the Chart.js library.

**User Request:** "{$chartRequest}"
**CSV File Path:** `{$realFilePath}`
**CSV Header:** `[" . implode('", "', $header) . "]`
**Data Sample:**
```csv
{$dataSample}
```

**Instructions for the script you generate:**
1.  The script **MUST** be a complete, executable PHP script starting with `<?php`.
2.  It must read the CSV file located at `{$realFilePath}`.
3.  It must process the data to fit the user's request: `{$chartRequest}`.
4.  It must support 'pie' and 'line' charts.
5.  The **ONLY** output of the script must be a single JSON object.
6.  The JSON object must have two keys: `"type"` (either `"pie"` or `"line"`) and `"data"` (the data structure for Chart.js).

**Chart.js Data Structure Examples:**

*   **For a Pie Chart:**
    `{"labels": ["Label 1", "Label 2"], "datasets": [{"data": [10, 20], "backgroundColor": ["#FF6384", "#36A2EB"]}]}`

*   **For a Line Chart:**
    `{"labels": ["Jan", "Feb"], "datasets": [{"label": "My Dataset", "data": [10, 20], "borderColor": "#FF6384", "fill": false}]}`

**IMPORTANT:** Do not include any text, explanation, or markdown formatting outside the `<?php ... ?>` block. The output must be ONLY the raw PHP code for the script.

PROMPT;

// 4. Call AI API
try {
    $resp = LocalAIApi::createResponse(
        [
            'input' => [
                ['role' => 'system', 'content' => 'You are an expert PHP script generator for data visualization.'],
                ['role' => 'user', 'content' => $prompt],
            ],
        ]
    );

    if (empty($resp['success'])) {
        return_error('AI API failed to generate the chart script.');
    }

    $aiCode = LocalAIApi::extractText($resp);
    if (empty($aiCode)) {
        return_error('AI returned an empty script.');
    }

    // Clean the AI response to get only the PHP code
    $phpCode = $aiCode;
    if (strpos($phpCode, '<?php') !== false) {
        $phpCode = substr($phpCode, strpos($phpCode, '<?php'));
    }
    if (strpos($phpCode, '?>') !== false) {
        $phpCode = substr($phpCode, 0, strpos($phpCode, '?>') + 2);
    }

    // 5. Execute the generated script and capture its output
    $tempScriptPath = __DIR__ . '/uploads/generated_script_' . uniqid() . '.php';
    file_put_contents($tempScriptPath, $phpCode);

    ob_start();
    include $tempScriptPath;
    $chartJson = ob_get_clean();
    unlink($tempScriptPath); // Clean up the script file

    $chartData = json_decode($chartJson, true);

    if (json_last_error() !== JSON_ERROR_NONE) {
        error_log("Generated script output was not valid JSON: " . $chartJson);
        return_error('The AI-generated script produced invalid data. Could not decode JSON.');
    }

    echo json_encode(['success' => true, 'chartData' => $chartData]);

} catch (Exception $e) {
    error_log('Exception in chart generation: ' . $e->getMessage());
    return_error('An unexpected error occurred while generating the chart.');
}