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Update file_handler.dart
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@PrimozRatej
PrimozRatej committed Nov 19, 2024
1 parent 2677e66 commit 3bada98
Showing 1 changed file with 118 additions and 97 deletions.
215 changes: 118 additions & 97 deletions lib/util/file_handler.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -14,141 +14,162 @@ class FileHandler {
final Function(File file, String filename) onSuccess;
final Function(double progress)? onProgress;
final Function()? onStart;

static const String _jsCode = """
function downloadFile(url) {
fetch(url, {
headers: {
// Include necessary headers for authentication if needed
'Authorization': 'Bearer <your_token>'
}
})
.then(response => {
const reader = response.body.getReader();
const contentLength = response.headers.get('Content-Length');
let receivedLength = 0;
let chunks = []; // array of received binary chunks (comprises the body)
return new ReadableStream({
start(controller) {
function push() {
reader.read().then(({ done, value }) => {
if (done) {
const blob = new Blob(chunks); // Create blob from chunks
const fileReader = new FileReader();
fileReader.readAsDataURL(blob);
fileReader.onloadend = function() {
const base64data = fileReader.result;
// Send the base64 content to Flutter
window.flutter_inappwebview.callHandler('downloadFile', base64data);
}
return;
}
chunks.push(value); // Store received chunk
receivedLength += value.length;
if (contentLength) {
// Calculate progress percentage
const progress = (receivedLength / contentLength) * 100;
// Send the progress to Flutter
window.flutter_inappwebview.callHandler('onProgress', progress);
}
push(); // Call the push function again to read the next chunk
});
}
push(); // Start reading the data
}
});
})
.catch(error => console.error('Error downloading file:', error));
}
""";
function downloadFile(url) {
fetch(url)
.then(async response => {
const reader = response.body.getReader();
const contentLength = response.headers.get('Content-Length');
let receivedLength = 0;
try {
while (true) {
const { done, value } = await reader.read();
if (done) {
window.flutter_inappwebview.callHandler('onDownloadComplete');
break;
}
receivedLength += value.length;
// Convert chunk to Base64
const base64Chunk = arrayBufferToBase64(value.buffer);
window.flutter_inappwebview.callHandler('onChunk', base64Chunk);
if (contentLength) {
const progress = (receivedLength / contentLength) * 100;
window.flutter_inappwebview.callHandler('onProgress', progress);
}
}
} catch (error) {
console.error('Stream error:', error);
window.flutter_inappwebview.callHandler('onError', error.toString());
}
})
.catch(error => {
console.error('Fetch error:', error);
window.flutter_inappwebview.callHandler('onError', error.toString());
});
}
const FileHandler(
{required this.controller,
required this.downloadStartRequest,
required this.onSuccess,
this.filename,
this.onError,
this.onProgress,
this.onStart});
function arrayBufferToBase64(buffer) {
let binary = '';
const bytes = new Uint8Array(buffer);
const len = bytes.byteLength;
download() {
for (let i = 0; i < len; i++) {
binary += String.fromCharCode(bytes[i]);
}
return btoa(binary);
}
""";

const FileHandler({
required this.controller,
required this.downloadStartRequest,
required this.onSuccess,
this.filename,
this.onError,
this.onProgress,
this.onStart,
});

void download() {
PermissionHandler.runWithPermissionCheck(
permissions: [],
action: () => _download(),
);
}

_download() async {
Future<void> _download() async {
try {
if (onStart != null) {
onStart!();
}
onStart?.call();

Directory? directory = await _getDownloadDirectory();
if (directory == null) throw Exception("no_download_folder_found");

String endFilename = filename ?? downloadStartRequest.suggestedFilename ?? await _generateFilename();
String filePath = await _generateUniqueFilePath(directory, endFilename);
File file = File(filePath);
IOSink fileSink = file.openWrite();

// Inject JavaScript for file download
await controller.evaluateJavascript(source: _jsCode);
await controller.evaluateJavascript(source: "downloadFile('${downloadStartRequest.url.toString()}');");
controller.addJavaScriptHandler(
handlerName: 'downloadFile',
callback: (args) async {
String base64Data = args[0];
var (file, filename) = await _saveFile(base64Data);
onSuccess(file, filename);
});
await controller.evaluateJavascript(
source: "downloadFile('${downloadStartRequest.url}');",
);

// Handle chunked data
controller.addJavaScriptHandler(
handlerName: 'onProgress',
callback: (args) {
double progress = double.parse(args[0].toString());
if (onProgress != null) {
onProgress!(progress);
}
});
} catch (er) {
if (er is Exception && onError != null) {
onError!(er);
}
handlerName: 'onChunk',
callback: (args) async {
String base64Chunk = args[0];
List<int> chunkBytes = base64Decode(base64Chunk);
fileSink.add(chunkBytes); // Write to file
},
);

// Handle progress
controller.addJavaScriptHandler(
handlerName: 'onProgress',
callback: (args) {
double progress = double.parse(args[0].toString());
onProgress?.call(progress);
},
);

// Handle download completion
controller.addJavaScriptHandler(
handlerName: 'onDownloadComplete',
callback: (args) async {
await fileSink.close();
onSuccess(file, endFilename);
},
);

// Handle errors
controller.addJavaScriptHandler(
handlerName: 'onError',
callback: (args) async {
String errorMessage = args[0].toString();
await fileSink.close();
file.deleteSync();
onError?.call(Exception(errorMessage));
},
);
} catch (e) {
if (e is Exception) onError?.call(e);
}
}

Future<(File file, String filename)> _saveFile(String base64Data) async {
// Decode base64 string to binary data
final decodedBytes = base64Decode(base64Data.split(",").last); // In case there's a base64 header
final decodedBytes = base64Decode(base64Data.split(",").last);

// Get the directory for storing files
Directory? directory = await _getDownloadDirectory();
if (directory == null) throw Exception("no_download_folder_found");
// Set a default filename if not provided
String endFilename = filename ?? downloadStartRequest.suggestedFilename ?? await _generateFilename();

// Generate a unique file path
String endFilename = filename ?? downloadStartRequest.suggestedFilename ?? await _generateFilename();
String filePath = await _generateUniqueFilePath(directory, endFilename);

// Write the decoded data to the file
File file = File(filePath);
await file.writeAsBytes(decodedBytes);
if (!await file.exists()) throw Exception("file_was_not_created");

return (file, endFilename);
}

Future<String> _generateFilename() async {
PackageInfo packageInfo = await PackageInfo.fromPlatform();
String appName = packageInfo.appName;
String filename = '${appName}file';

// Replace spaces with underscores
filename = filename.replaceAll(' ', '_');

return filename;
String appName = packageInfo.appName.replaceAll(' ', '_');
return '${appName}file';
}

Future<String> _generateUniqueFilePath(Directory directory, String baseFilename) async {
String filePath = '${directory.path}/$baseFilename';
int counter = 1;

while (File(filePath).existsSync()) {
// Append a number in parentheses to the baseFilename
String newFilename = '($counter)$baseFilename';
filePath = '${directory.path}/$newFilename';
counter++;
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