<?php
header('Content-Type: application/json; charset=utf-8');
require 'db.php';

$action = $_GET['action'] ?? '';

// ==========================================
// DEPARTMENTS
// ==========================================
if ($action == 'get_departments') {
    $stmt = $pdo->query("SELECT * FROM departments ORDER BY name ASC");
    echo json_encode(['status' => 'success', 'data' => $stmt->fetchAll(PDO::FETCH_ASSOC)]);
    exit;
}

if ($action == 'save_department') {
    $id = $_POST['id'] ?? '';
    $name = trim($_POST['name'] ?? '');
    
    if(!$name) {
        echo json_encode(['status' => 'error', 'message' => 'กรุณากรอกชื่อหน่วยงาน']);
        exit;
    }

    try {
        if($id) {
            $stmt = $pdo->prepare("UPDATE departments SET name = ? WHERE id = ?");
            $stmt->execute([$name, $id]);
        } else {
            $stmt = $pdo->prepare("INSERT INTO departments (name) VALUES (?)");
            $stmt->execute([$name]);
        }
        echo json_encode(['status' => 'success']);
    } catch(PDOException $e) {
        echo json_encode(['status' => 'error', 'message' => 'ชื่อหน่วยงานอาจซ้ำกัน หรือเกิดข้อผิดพลาด']);
    }
    exit;
}

if ($action == 'delete_department') {
    $id = $_POST['id'] ?? '';
    
    // Check if used
    $check = $pdo->prepare("SELECT COUNT(*) FROM employees WHERE department_id = ?");
    $check->execute([$id]);
    if($check->fetchColumn() > 0) {
        echo json_encode(['status' => 'error', 'message' => 'ไม่สามารถลบได้ เนื่องจากมีบุคลากรในหน่วยงานนี้']);
        exit;
    }
    
    $stmt = $pdo->prepare("DELETE FROM departments WHERE id = ?");
    $stmt->execute([$id]);
    echo json_encode(['status' => 'success']);
    exit;
}

// ==========================================
// EMPLOYEES
// ==========================================
if ($action == 'get_employees') {
    $stmt = $pdo->query("
        SELECT e.*, d.name as department_name 
        FROM employees e 
        LEFT JOIN departments d ON e.department_id = d.id
    ");
    $employees = $stmt->fetchAll(PDO::FETCH_ASSOC);
    
    // Format for D3 Org Chart (id and parentId must be string, parentId can be empty)
    $formatted = array_map(function($emp) {
        return [
            'id' => (string)$emp['id'],
            'parentId' => $emp['parent_id'] ? (string)$emp['parent_id'] : '',
            'name' => $emp['name'],
            'position' => $emp['position'],
            'department_id' => $emp['department_id'],
            'department' => $emp['department_name'],
            'imageUrl' => $emp['image_url']
        ];
    }, $employees);
    
    echo json_encode(['status' => 'success', 'data' => $formatted]);
    exit;
}

if ($action == 'save_employee') {
    $id = $_POST['id'] ?? '';
    $name = trim($_POST['name'] ?? '');
    $position = trim($_POST['position'] ?? '');
    $department_id = $_POST['department_id'] ?? '';
    $parent_id = !empty($_POST['parent_id']) ? $_POST['parent_id'] : null;
    $image_url = trim($_POST['image_url'] ?? '');
    
    if(!$name || !$position || !$department_id) {
        echo json_encode(['status' => 'error', 'message' => 'ข้อมูลไม่ครบถ้วน']);
        exit;
    }

    if(!$image_url) {
        $image_url = "https://ui-avatars.com/api/?name=" . urlencode($name) . "&background=f8fafc&color=1e40af&size=150";
    }

    try {
        if($id) {
            // Cannot be parent of oneself
            if ($id == $parent_id) {
                echo json_encode(['status' => 'error', 'message' => 'ไม่สามารถตั้งตัวเองเป็นหัวหน้าตัวเองได้']);
                exit;
            }
            $stmt = $pdo->prepare("UPDATE employees SET name=?, position=?, department_id=?, parent_id=?, image_url=? WHERE id=?");
            $stmt->execute([$name, $position, $department_id, $parent_id, $image_url, $id]);
        } else {
            $stmt = $pdo->prepare("INSERT INTO employees (name, position, department_id, parent_id, image_url) VALUES (?, ?, ?, ?, ?)");
            $stmt->execute([$name, $position, $department_id, $parent_id, $image_url]);
        }
        echo json_encode(['status' => 'success']);
    } catch(PDOException $e) {
        echo json_encode(['status' => 'error', 'message' => 'เกิดข้อผิดพลาด: ' . $e->getMessage()]);
    }
    exit;
}

if ($action == 'delete_employee') {
    $id = $_POST['id'] ?? '';
    
    $check = $pdo->prepare("SELECT COUNT(*) FROM employees WHERE parent_id = ?");
    $check->execute([$id]);
    if($check->fetchColumn() > 0) {
        echo json_encode(['status' => 'error', 'message' => 'ไม่สามารถลบได้ เนื่องจากมีผู้ใต้บังคับบัญชา']);
        exit;
    }
    
    $stmt = $pdo->prepare("DELETE FROM employees WHERE id = ?");
    $stmt->execute([$id]);
    echo json_encode(['status' => 'success']);
    exit;
}

echo json_encode(['status' => 'error', 'message' => 'Invalid action']);
?>