<?php
require_once __DIR__ . '/db/config.php';

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

$response = ['success' => false, 'error' => 'Invalid request'];

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $project_id = $_POST['projectId'] ?? null;
    $month = $_POST['month'] ?? null;

    $metrics = [
        'wip' => $_POST['wip'] ?? null,
        'opening_balance' => $_POST['openingBalance'] ?? null,
        'billings' => $_POST['billings'] ?? null,
        'expenses' => $_POST['expenses'] ?? null,
        'cost' => $_POST['cost'] ?? null,
    ];

    if ($project_id && $month && !in_array(null, $metrics, true)) {
        try {
            $pdo = db();
            $sql = "INSERT INTO projectFinanceMonthly (projectId, month, metricName, value, is_overridden)
                    VALUES (:pid, :m, :metric, :value, 1)
                    ON DUPLICATE KEY UPDATE value = :value, is_overridden = 1";
            $stmt = $pdo->prepare($sql);

            $metric_map = [
                'wip' => 'wip',
                'opening_balance' => 'opening_balance',
                'billings' => 'billing',
                'expenses' => 'expenses',
                'cost' => 'cost'
            ];

            foreach ($metrics as $metricKey => $value) {
                if (isset($metric_map[$metricKey])) {
                    $metricName = $metric_map[$metricKey];
                    $stmt->execute([
                        ':pid' => $project_id,
                        ':m' => $month,
                        ':metric' => $metricName,
                        ':value' => $value
                    ]);
                }
            }

            // Use the newly submitted values from POST as the source of truth for calculation
            $wip = (float)($metrics['wip'] ?? 0);
            $billings = (float)($metrics['billings'] ?? 0);
            $opening_balance = (float)($metrics['opening_balance'] ?? 0);
            $expenses = (float)($metrics['expenses'] ?? 0);
            $cost = (float)($metrics['cost'] ?? 0);

            // Calculate NSR
            $nsr = $wip + $billings - $opening_balance - $expenses;

            // Calculate Margin
            $margin = ($nsr != 0) ? (($nsr - $cost) / $nsr) : 0;

            // Save NSR and Margin
            $stmt->execute([
                ':pid' => $project_id,
                ':m' => $month,
                ':metric' => 'nsr',
                ':value' => $nsr
            ]);

            $stmt->execute([
                ':pid' => $project_id,
                ':m' => $month,
                ':metric' => 'margin',
                ':value' => $margin
            ]);

            $response = [
                'success' => true,
                'wip' => $wip,
                'openingBalance' => $opening_balance,
                'billings' => $billings,
                'expenses' => $expenses,
                'cost' => $cost,
                'nsr' => $nsr,
                'margin' => $margin
            ];

        } catch (PDOException $e) {
            $response['error'] = 'Database error: ' . $e->getMessage();
            error_log($e->getMessage());
        }
    } else {
        $response['error'] = 'Missing required fields.';
    }
}

try {
    echo json_encode($response, JSON_THROW_ON_ERROR);
} catch (JsonException $e) {
    error_log('JSON encoding error: ' . $e->getMessage());
    http_response_code(500);
    echo json_encode(['success' => false, 'error' => 'Internal server error during JSON encoding.']);
}
exit;