<?php
ini_set('display_errors', 0);
error_reporting(0);

require_once 'db/config.php';

// Function to send a consistent JSON response, aggressively cleaning any output.
function send_json_response($data) {
    // Ensure no stray output is included.
    if (ob_get_level() > 0) {
        ob_end_clean();
    }
    header('Content-Type: application/json');
    echo json_encode($data);
    exit(); // Terminate immediately
}

// Set a global exception handler to catch any uncaught errors
set_exception_handler(function($exception) {
    error_log($exception->getMessage());
    send_json_response(['success' => false, 'message' => 'A server error occurred: ' . $exception->getMessage()]);
});

$response_data = [
    'success' => false,
    'message' => 'An unknown error occurred.',
    // Initialize all fields JS expects to avoid 'undefined' issues
    'wip' => 0,
    'openingBalance' => 0,
    'billings' => 0,
    'expenses' => 0,
    'cost' => 0,
    'nsr' => 0,
    'margin' => 0,
];

ob_clean(); // Clear any pre-existing output
try {
    $data = $_POST;

    $projectId = $data['projectId'] ?? null;
    $month = $data['month'] ?? null;

    if (!$projectId || !$month) {
        send_json_response(['success' => false, 'message' => 'Missing project ID or month.']);
    }

    $pdo = db();

    $metrics_from_form = [
        'wip' => $data['wip'] ?? 0,
        'opening_balance' => $data['openingBalance'] ?? 0,
        'billing' => $data['billings'] ?? 0,
        'expenses' => $data['expenses'] ?? 0,
        'cost' => $data['cost'] ?? 0,
    ];

    $pdo->beginTransaction();

    // Check if records exist, if not, INSERT them. Otherwise, UPDATE.
    $select_sql = "SELECT COUNT(*) FROM projectFinanceMonthly WHERE projectId = :projectId AND month = :month AND metricName = :metricName";
    $select_stmt = $pdo->prepare($select_sql);

    $update_sql = "UPDATE projectFinanceMonthly SET value = :value, is_overridden = 1 WHERE projectId = :projectId AND month = :month AND metricName = :metricName";
    $update_stmt = $pdo->prepare($update_sql);

    $insert_sql = "INSERT INTO projectFinanceMonthly (projectId, month, metricName, value, is_overridden) VALUES (:projectId, :month, :metricName, :value, 1)";
    $insert_stmt = $pdo->prepare($insert_sql);

    foreach ($metrics_from_form as $metricName => $value) {
        $select_stmt->execute([
            'projectId' => $projectId,
            'month' => $month,
            'metricName' => $metricName
        ]);
        $exists = $select_stmt->fetchColumn() > 0;

        if ($exists) {
            $update_stmt->execute([
                'value' => $value,
                'projectId' => $projectId,
                'month' => $month,
                'metricName' => $metricName,
            ]);
        } else {
            $insert_stmt->execute([
                'projectId' => $projectId,
                'month' => $month,
                'metricName' => $metricName,
                'value' => $value,
            ]);
        }
    }

    $pdo->commit();

    // Recalculate NSR and Margin
    $billing = floatval($metrics_from_form['billing']);
    $expenses = floatval($metrics_from_form['expenses']);
    $cost = floatval($metrics_from_form['cost']);
    $wip = floatval($metrics_from_form['wip']);
    $opening_balance = floatval($metrics_from_form['opening_balance']);

    $nsr = $wip + $billing - $opening_balance - $expenses;
    $margin = ($nsr > 0) ? (($nsr - $cost) / $nsr) : 0;


    // Fetch the updated data to send back
    $stmt = $pdo->prepare("SELECT metricName, value FROM projectFinanceMonthly WHERE projectId = ? AND month = ?");
    $stmt->execute([$projectId, $month]);
    $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);

    $response_data['success'] = true;
    $response_data['message'] = 'Override saved successfully.';

    foreach ($rows as $row) {
        // Map db snake_case to form's camelCase
        if ($row['metricName'] === 'opening_balance') {
            $response_data['openingBalance'] = $row['value'];
        } else if ($row['metricName'] === 'billing') {
            $response_data['billings'] = $row['value'];
        } else {
            // Directly map other metrics like 'wip', 'expenses'
            $response_data[$row['metricName']] = $row['value'];
        }
    }

    $response_data['nsr'] = $nsr;
    $response_data['margin'] = $margin;

    send_json_response($response_data);

} catch (Exception $e) {
    if (isset($pdo) && $pdo->inTransaction()) {
        $pdo->rollBack();
    }
    // Log the error and send a JSON response directly
    error_log($e->getMessage());
    send_json_response(['success' => false, 'message' => 'A server error occurred: ' . $e->getMessage()]);
}