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

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

$raw_input = file_get_contents('php://input');
$response = ['success' => false, 'message' => 'An error occurred.'];
$pdo = null;

try {
    $pdo = db();
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $data = json_decode($raw_input, true);

    if (empty($data['project_id']) || empty($data['overrides'])) {
        throw new Exception("Project ID or overrides data not provided.");
    }

    $project_id = $data['project_id'];
    $overrides = $data['overrides'];
    $rows_affected_total = 0;

    $pdo->beginTransaction();

    $sql = "
        INSERT INTO projectFinanceMonthly (projectId, month, opening_balance, payment, wip, expenses, cost, nsr, margin, is_confirmed)
        VALUES (:project_id, :month, :opening_balance, :payment, :wip, :expenses, :cost, :nsr, :margin, :is_confirmed)
        ON DUPLICATE KEY UPDATE
            opening_balance = VALUES(opening_balance),
            payment = VALUES(payment),
            wip = VALUES(wip),
            expenses = VALUES(expenses),
            cost = VALUES(cost),
            nsr = VALUES(nsr),
            margin = VALUES(margin),
            is_confirmed = VALUES(is_confirmed)
    ";
    $stmt = $pdo->prepare($sql);

    foreach ($overrides as $override) {
        $date = new DateTime($override['month']);
        $month = $date->format('Y-m-d');

        $params = [
            ':project_id' => $project_id,
            ':month' => $month,
            ':opening_balance' => $override['opening_balance'] ?? null,
            ':payment' => $override['payment'] ?? null,
            ':wip' => $override['wip'] ?? null,
            ':expenses' => $override['expenses'] ?? null,
            ':cost' => $override['cost'] ?? null,
            ':nsr' => $override['nsr'] ?? null,
            ':margin' => $override['margin'] ?? null,
            ':is_confirmed' => $override['is_confirmed'] ?? 0,
        ];
        $stmt->execute($params);
        $rows_affected_total += $stmt->rowCount();
    }

    if ($rows_affected_total === 0) {
        // It's possible that the data is identical, so 0 affected rows is not strictly an error.
        // We can consider it a "soft" success.
        $pdo->rollBack(); // Rollback to not leave an open transaction
        $response['success'] = true; // Report success to the frontend
        $response['message'] = 'No changes were detected. Nothing was saved.';
        echo json_encode($response);
        exit;
    }

    $pdo->commit();

    $response['success'] = true;
    $response['message'] = 'Override data saved successfully. ' . $rows_affected_total . ' records were updated.';

} catch (PDOException $e) {
    if ($pdo && $pdo->inTransaction()) {
        $pdo->rollBack();
    }
    error_log("save_override.php: PDOException caught: " . $e->getMessage());
    $response['message'] = "Database Error: " . $e->getMessage();
    http_response_code(500);
} catch (Exception $e) {
    if ($pdo && $pdo->inTransaction()) {
        $pdo->rollBack();
    }
    error_log("save_override.php: Exception caught: " . $e->getMessage());
    $response['message'] = "General Error: " . $e->getMessage();
    http_response_code(500);
}

echo json_encode($response);
?>