<?php
// Start session
session_start();

// Check if user has admin privileges
if (!isset($_SESSION['role']) || ($_SESSION['role'] !== 'admin' && $_SESSION['role'] !== 'director')) {
    echo json_encode(['status' => 'error', 'message' => 'Unauthorized access']);
    exit;
}

// Include database configuration
require_once '../../admin/database/db_config.php';

// Check if form data is submitted
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    echo json_encode(['status' => 'error', 'message' => 'Invalid request method']);
    exit;
}

// Validate required fields
if (!isset($_POST['user_id']) || empty($_POST['user_id']) ||
    !isset($_POST['document_type']) || empty($_POST['document_type']) ||
    !isset($_FILES['document_file']) || $_FILES['document_file']['error'] !== 0) {
    
    echo json_encode(['status' => 'error', 'message' => 'Missing required fields']);
    exit;
}

$user_id = intval($_POST['user_id']);
$document_type = $_POST['document_type'];
$document_description = $_POST['document_description'] ?? '';
$admin_notes = $_POST['admin_notes'] ?? '';
$status = $_POST['status'] ?? 'pending'; // Default status is pending

// Validate user exists
$user_query = "SELECT id, first_name, last_name FROM users WHERE id = ?";
$stmt = $conn->prepare($user_query);
$stmt->bind_param("i", $user_id);
$stmt->execute();
$user_result = $stmt->get_result();

if ($user_result->num_rows === 0) {
    echo json_encode(['status' => 'error', 'message' => 'User not found']);
    exit;
}

$user = $user_result->fetch_assoc();

// Validate document type
$valid_types = ['id_proof', 'educational_certificate', 'photograph', 'address_proof', 'other'];
if (!in_array($document_type, $valid_types)) {
    echo json_encode(['status' => 'error', 'message' => 'Invalid document type']);
    exit;
}

// Validate file type
$allowed_file_types = [
    'image/jpeg', 'image/png', 'image/gif', 'application/pdf', 
    'application/msword', 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
];

$file_type = $_FILES['document_file']['type'];
$file_size = $_FILES['document_file']['size'];
$file_tmp = $_FILES['document_file']['tmp_name'];
$file_name = $_FILES['document_file']['name'];

if (!in_array($file_type, $allowed_file_types)) {
    echo json_encode(['status' => 'error', 'message' => 'Invalid file type. Allowed types: JPG, PNG, GIF, PDF, DOC, DOCX']);
    exit;
}

// Validate file size (max 5MB)
if ($file_size > 5242880) {
    echo json_encode(['status' => 'error', 'message' => 'File size must be less than 5MB']);
    exit;
}

// Create directory if it doesn't exist
$upload_dir = '../../uploads/documents/' . $user_id;
if (!file_exists($upload_dir)) {
    if (!mkdir($upload_dir, 0755, true)) {
        echo json_encode(['status' => 'error', 'message' => 'Failed to create directory']);
        exit;
    }
}

// Generate unique file name
$file_extension = pathinfo($file_name, PATHINFO_EXTENSION);
$unique_filename = uniqid('doc_') . '.' . $file_extension;
$upload_path = $upload_dir . '/' . $unique_filename;
$db_file_path = 'uploads/documents/' . $user_id . '/' . $unique_filename;

// Upload file
if (!move_uploaded_file($file_tmp, $upload_path)) {
    echo json_encode(['status' => 'error', 'message' => 'Failed to upload file']);
    exit;
}

// Begin transaction
$conn->begin_transaction();

try {
    // Insert document record into database
    $insert_query = "INSERT INTO student_documents (user_id, document_type, file_path, original_filename, 
                    document_description, status, admin_notes, upload_date, uploaded_by, updated_at) 
                    VALUES (?, ?, ?, ?, ?, ?, ?, NOW(), ?, NOW())";
    
    $stmt = $conn->prepare($insert_query);
    $admin_id = $_SESSION['user_id'];
    $stmt->bind_param("isssssis", $user_id, $document_type, $db_file_path, $file_name, 
                      $document_description, $status, $admin_notes, $admin_id);
    
    if (!$stmt->execute()) {
        throw new Exception("Failed to insert document record: " . $conn->error);
    }
    
    $document_id = $conn->insert_id;
    
    // If status is verified immediately, check all documents
    if ($status === 'verified') {
        // Check if all required documents for this user are verified
        $check_query = "SELECT COUNT(*) as total, SUM(CASE WHEN status = 'verified' THEN 1 ELSE 0 END) as verified
                        FROM student_documents 
                        WHERE user_id = ? AND document_type IN ('id_proof', 'educational_certificate', 'photograph')";
        $stmt = $conn->prepare($check_query);
        $stmt->bind_param("i", $user_id);
        $stmt->execute();
        $check_result = $stmt->get_result()->fetch_assoc();
        
        // If all required documents are verified (3 documents: ID, education, photo)
        if ($check_result['total'] >= 3 && $check_result['verified'] >= 3) {
            // Update all pending applications for this user
            $app_update_query = "UPDATE enrollment_applications 
                               SET status = 'payment_pending' 
                               WHERE user_id = ? AND status = 'pending'";
            $stmt = $conn->prepare($app_update_query);
            $stmt->bind_param("i", $user_id);
            $stmt->execute();
        }
    }
    
    // Log the activity
    $activity_query = "INSERT INTO activities (user_id, user_type, activity_type, activity_description, created_at) 
                      VALUES (?, 'admin', 'document_upload', ?, NOW())";
    $stmt = $conn->prepare($activity_query);
    $activity_description = "Uploaded " . $document_type . " document for user " . $user['first_name'] . ' ' . $user['last_name'];
    $stmt->bind_param("is", $admin_id, $activity_description);
    
    if (!$stmt->execute() && $conn->errno != 1146) { // Ignore error if activities table doesn't exist
        // Just log to error log, don't throw exception for activity logging failure
        error_log("Failed to log activity: " . $conn->error);
    }
    
    // Commit transaction
    $conn->commit();
    
    echo json_encode([
        'status' => 'success',
        'message' => 'Document uploaded successfully',
        'document_id' => $document_id,
        'document_path' => $db_file_path
    ]);
    
} catch (Exception $e) {
    // Rollback transaction and remove uploaded file
    $conn->rollback();
    if (file_exists($upload_path)) {
        unlink($upload_path);
    }
    
    echo json_encode(['status' => 'error', 'message' => $e->getMessage()]);
}
?>