<?php
/**
 * Upload Image API
 * Accepts multipart/form-data POST with 'image' file.
 * Converts JPG/PNG to WebP (resized to max 2400px), saves to /files/img/admin_upload/{uid}.webp
 * Returns JSON: { success: true }
 */

// Allow large uploads and enough memory for GD processing
ini_set('memory_limit', '256M');
ini_set('upload_max_filesize', '50M');
ini_set('post_max_size', '55M');
ini_set('max_execution_time', '120');

const MAX_DIMENSION = 2400; 
const MAX_DIMENSION_ICON = 1000; 
const WEBP_QUALITY  = 80;

$baseDir = $_SERVER['DOCUMENT_ROOT'];

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

if (!isset($baseDir)) {
	$baseDir = $_SERVER['DOCUMENT_ROOT'];
}

require_once $baseDir . '/../scripts/session_functions.php';

ini_wkvs_session();

check_user_permission('wk_leitung');

verify_csrf();


// Only accept POST
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    echo json_encode(['success' => false, 'message' => 'Method not allowed']);
    exit;
}

$allowedTypes = ['Kampfrichter', 'Trainer', 'Wk_leitung', 'Otl', 'icon', 'logo-normal'];

if (!isset($_POST['type']) || !in_array($_POST['type'], $allowedTypes)) {
    http_response_code(400);
    echo json_encode(['success' => false, 'message' => 'Typ nicht angegeben oder nicht erlaubt']);
    exit;
}

$pngs = ['icon', 'logo-normal'];

$type = $_POST['type'];
$isIcon = in_array($type, $pngs);

// Check if $_FILES is empty entirely (can happen if post_max_size exceeded)
if (empty($_FILES)) {
    http_response_code(400);
    echo json_encode([
        'success' => false,
        'message' => 'No files received. The file may exceed the server upload limit).',
    ]);
    exit;
}

// Check specific file field
if (!isset($_FILES['image'])) {
    http_response_code(400);
    echo json_encode([
        'success' => false,
        'message' => 'No "image" field in upload. Received fields: ' . implode(', ', array_keys($_FILES)),
    ]);
    exit;
}

if ($_FILES['image']['error'] !== UPLOAD_ERR_OK) {
    http_response_code(400);
    $errors = [
        UPLOAD_ERR_INI_SIZE   => 'File exceeds upload_max_filesize',
        UPLOAD_ERR_FORM_SIZE  => 'File exceeds form MAX_FILE_SIZE',
        UPLOAD_ERR_PARTIAL    => 'File was only partially uploaded',
        UPLOAD_ERR_NO_FILE    => 'No file was uploaded',
        UPLOAD_ERR_NO_TMP_DIR => 'Missing temp directory',
        UPLOAD_ERR_CANT_WRITE => 'Failed to write to disk',
    ];
    $code = $_FILES['image']['error'];
    $msg = $errors[$code] ?? "Unknown error code: $code";
    echo json_encode(['success' => false, 'message' => $msg]);
    exit;
}

$file = $_FILES['image'];
$tmpPath = $file['tmp_name'];

// Validate MIME type
$finfo = new finfo(FILEINFO_MIME_TYPE);
$mime = $finfo->file($tmpPath);

$allowedMimes = ['image/jpeg', 'image/png', 'image/webp', 'image/gif'];
if (!in_array($mime, $allowedMimes, true)) {
    http_response_code(415);
    echo json_encode(['success' => false, 'message' => "Unsupported file type: $mime"]);
    exit;
}

// Target directory


if ($isIcon) {
    $uploadDir = $baseDir . '/intern/img/';
} else {
    $uploadDir = $baseDir . '/intern/img/login';
}

if (!is_dir($uploadDir)) {
    mkdir($uploadDir, 0755, true);
}

// Load image into GD
$srcImage = null;
switch ($mime) {
    case 'image/jpeg':
        $srcImage = @imagecreatefromjpeg($tmpPath);
        break;
    case 'image/png':
        $srcImage = @imagecreatefrompng($tmpPath);
        break;
    case 'image/webp':
        $srcImage = @imagecreatefromwebp($tmpPath);
        break;
    case 'image/gif':
        $srcImage = @imagecreatefromgif($tmpPath);
        break;
}

if (!$srcImage) {
    http_response_code(500);
    echo json_encode(['success' => false, 'message' => 'Failed to load image into GD. It may be corrupt or too large.']);
    exit;
}


// ── Resize if needed ────────────────────────────────
$origW = imagesx($srcImage);
$origH = imagesy($srcImage);

$maxDimension = ($isIcon) ? MAX_DIMENSION_ICON : MAX_DIMENSION;

if ($origW > $maxDimension || $origH > $maxDimension) {
    // Calculate new dimensions keeping aspect ratio
    if ($origW >= $origH) {
        $newW = $maxDimension;
        $newH = intval(round($origH * ($maxDimension / $origW)));
    } else {
        $newH = $maxDimension;
        $newW = intval(round($origW * ($maxDimension / $origH)));
    }

    $resized = imagecreatetruecolor($newW, $newH);

    // Preserve transparency
    imagealphablending($resized, false);
    imagesavealpha($resized, true);
    $transparent = imagecolorallocatealpha($resized, 0, 0, 0, 127);
    imagefill($resized, 0, 0, $transparent);

    imagecopyresampled($resized, $srcImage, 0, 0, 0, 0, $newW, $newH, $origW, $origH);
    imagedestroy($srcImage);
    $srcImage = $resized;
} else {
    // Still preserve transparency
    imagepalettetotruecolor($srcImage);
    imagealphablending($srcImage, true);
    imagesavealpha($srcImage, true);
}

if ($isIcon) {
    // ── Save as PNG ────────────────────────────────────
    $filename = $type . '.png';
    $destPath = $uploadDir . '/' . $filename;
    $webPath  = '/intern/img/' . $filename;

    $pngCompression = 6;

    $success = imagepng($srcImage, $destPath, $pngCompression);
} else {
    // ── Save as WebP ────────────────────────────────────
    $filename = 'bg' . $_POST['type'] . '.webp';
    $destPath = $uploadDir . '/' . $filename;
    $webPath  = '/intern/img/admin_upload/' . $filename;

    $success = imagewebp($srcImage, $destPath, WEBP_QUALITY);
}

imagedestroy($srcImage);

if (!$success) {
    http_response_code(500);
    echo json_encode(['success' => false, 'message' => 'Failed to convert to WebP']);
    exit;
}

echo json_encode([
    'success'  => true
]);