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

$method = $_SERVER['REQUEST_METHOD'];

// Ensure table exists
try {
    $pdo->exec("
        CREATE TABLE IF NOT EXISTS `oncall_days` (
            `day_of_week` int(11) NOT NULL,
            `staff_id` int(11) NOT NULL,
            PRIMARY KEY (`day_of_week`),
            CONSTRAINT `fk_oncall_staff` FOREIGN KEY (`staff_id`) REFERENCES `staff` (`id`) ON DELETE CASCADE
        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
    ");
} catch (PDOException $e) {}

switch ($method) {
    case 'GET':
        try {
            $stmt = $pdo->query("SELECT day_of_week, staff_id FROM oncall_days");
            $data = $stmt->fetchAll(PDO::FETCH_KEY_PAIR); // returns [day_of_week => staff_id]
            
            // If empty, return defaults 1->1, 2->2... 
            if (empty($data)) {
                $data = [1 => 1, 2 => 2, 3 => 3, 4 => 4, 5 => 5];
            }

            echo json_encode(['status' => 'success', 'data' => $data]);
        } catch (PDOException $e) {
            http_response_code(500);
            echo json_encode(['status' => 'error', 'message' => $e->getMessage()]);
        }
        break;

    case 'POST':
        $input = json_decode(file_get_contents('php://input'), true);
        
        if (!isset($input['day_of_week']) || !isset($input['staff_id'])) {
            http_response_code(400);
            echo json_encode(['status' => 'error', 'message' => 'Missing required fields']);
            exit;
        }

        try {
            $stmt = $pdo->prepare("
                INSERT INTO oncall_days (day_of_week, staff_id) 
                VALUES (:day_of_week, :staff_id)
                ON DUPLICATE KEY UPDATE staff_id = :staff_id_update
            ");
            $stmt->execute([
                ':day_of_week' => $input['day_of_week'],
                ':staff_id' => $input['staff_id'],
                ':staff_id_update' => $input['staff_id']
            ]);
            
            echo json_encode(['status' => 'success', 'message' => 'On-call updated successfully']);
        } catch (PDOException $e) {
            http_response_code(500);
            echo json_encode(['status' => 'error', 'message' => $e->getMessage()]);
        }
        break;

    default:
        http_response_code(405);
        echo json_encode(['status' => 'error', 'message' => 'Method not allowed']);
        break;
}
?>