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

$method = $_SERVER['REQUEST_METHOD'];

switch ($method) {
    case 'GET':
        // Get schedules for a specific month and year
        $year = isset($_GET['year']) ? (int)$_GET['year'] : date('Y');
        $month = isset($_GET['month']) ? (int)$_GET['month'] : date('n');

        try {
            $stmt = $pdo->prepare("SELECT staff_id, day, shift_type FROM schedules WHERE year = :year AND month = :month");
            $stmt->execute([':year' => $year, ':month' => $month]);
            $schedules = $stmt->fetchAll();
            
            // Format data for frontend: { staffId: { day: 'shift_type' } }
            $formattedData = [];
            foreach ($schedules as $row) {
                $staffId = $row['staff_id'];
                $day = $row['day'];
                $shiftType = $row['shift_type'];
                
                if (!isset($formattedData[$staffId])) {
                    $formattedData[$staffId] = [];
                }
                $formattedData[$staffId][$day] = $shiftType;
            }
            
            echo json_encode(['status' => 'success', 'data' => $formattedData]);
        } catch (PDOException $e) {
            http_response_code(500);
            echo json_encode(['status' => 'error', 'message' => $e->getMessage()]);
        }
        break;

    case 'POST':
        // Save or update a shift
        $input = json_decode(file_get_contents('php://input'), true);

        // Check if this is a bulk operation
        if (isset($input['bulk']) && is_array($input['schedules'])) {
            try {
                $pdo->beginTransaction();
                
                // Optional: clear existing month data if requested
                if (isset($input['clear_month']) && $input['clear_month']) {
                    $stmt = $pdo->prepare("DELETE FROM schedules WHERE year = :year AND month = :month");
                    $stmt->execute([
                        ':year' => $input['year'],
                        ':month' => $input['month']
                    ]);
                }

                $insertStmt = $pdo->prepare("INSERT INTO schedules (staff_id, year, month, day, shift_type) VALUES (:staff_id, :year, :month, :day, :shift_type) ON DUPLICATE KEY UPDATE shift_type = :shift_type");
                
                foreach ($input['schedules'] as $schedule) {
                    if ($schedule['shift_type'] !== '') {
                        $insertStmt->execute([
                            ':staff_id' => $schedule['staff_id'],
                            ':year' => $input['year'],
                            ':month' => $input['month'],
                            ':day' => $schedule['day'],
                            ':shift_type' => $schedule['shift_type']
                        ]);
                    }
                }
                
                $pdo->commit();
                echo json_encode(['status' => 'success', 'message' => 'Bulk schedules saved']);
            } catch (PDOException $e) {
                $pdo->rollBack();
                http_response_code(500);
                echo json_encode(['status' => 'error', 'message' => $e->getMessage()]);
            }
            exit;
        }
        
        if (!isset($input['staff_id']) || !isset($input['year']) || !isset($input['month']) || !isset($input['day'])) {
            http_response_code(400);
            echo json_encode(['status' => 'error', 'message' => 'Missing required fields']);
            exit;
        }

        $staffId = $input['staff_id'];
        $year = $input['year'];
        $month = $input['month'];
        $day = $input['day'];
        $shiftType = isset($input['shift_type']) ? $input['shift_type'] : '';

        try {
            if ($shiftType === '') {
                // If shift_type is empty, delete the record
                $stmt = $pdo->prepare("DELETE FROM schedules WHERE staff_id = :staff_id AND year = :year AND month = :month AND day = :day");
                $stmt->execute([
                    ':staff_id' => $staffId,
                    ':year' => $year,
                    ':month' => $month,
                    ':day' => $day
                ]);
            } else {
                // Insert or update (upsert)
                $stmt = $pdo->prepare("
                    INSERT INTO schedules (staff_id, year, month, day, shift_type) 
                    VALUES (:staff_id, :year, :month, :day, :shift_type)
                    ON DUPLICATE KEY UPDATE shift_type = :shift_type_update
                ");
                $stmt->execute([
                    ':staff_id' => $staffId,
                    ':year' => $year,
                    ':month' => $month,
                    ':day' => $day,
                    ':shift_type' => $shiftType,
                    ':shift_type_update' => $shiftType
                ]);
            }
            
            echo json_encode(['status' => 'success', 'message' => 'Schedule 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;
}
?>