feat: set up FFI

Signed-off-by: Sphericalkat <me@kat.bio>

.fvmrc

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+{
+  "flutter": "stable"
+}

.gitignore

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+# https://dart.dev/guides/libraries/private-files
+# Created by `dart pub`
+.dart_tool/
+
+# Avoid committing pubspec.lock for library packages; see
+# https://dart.dev/guides/libraries/private-files#pubspeclock.
+pubspec.lock
+
+# FVM Version Cache
+.fvm/

.vscode/settings.json

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+{
+  "dart.flutterSdkPath": ".fvm/versions/stable"
+}

CHANGELOG.md

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+## 1.0.0
+
+- Initial version.

README.md

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+<!-- 
+This README describes the package. If you publish this package to pub.dev,
+this README's contents appear on the landing page for your package.
+
+For information about how to write a good package README, see the guide for
+[writing package pages](https://dart.dev/guides/libraries/writing-package-pages). 
+
+For general information about developing packages, see the Dart guide for
+[creating packages](https://dart.dev/guides/libraries/create-library-packages)
+and the Flutter guide for
+[developing packages and plugins](https://flutter.dev/developing-packages). 
+-->
+
+TODO: Put a short description of the package here that helps potential users
+know whether this package might be useful for them.
+
+## Features
+
+TODO: List what your package can do. Maybe include images, gifs, or videos.
+
+## Getting started
+
+TODO: List prerequisites and provide or point to information on how to
+start using the package.
+
+## Usage
+
+TODO: Include short and useful examples for package users. Add longer examples
+to `/example` folder. 
+
+```dart
+const like = 'sample';
+```
+
+## Additional information
+
+TODO: Tell users more about the package: where to find more information, how to 
+contribute to the package, how to file issues, what response they can expect 
+from the package authors, and more.

analysis_options.yaml

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+# This file configures the static analysis results for your project (errors,
+# warnings, and lints).
+#
+# This enables the 'recommended' set of lints from `package:lints`.
+# This set helps identify many issues that may lead to problems when running
+# or consuming Dart code, and enforces writing Dart using a single, idiomatic
+# style and format.
+#
+# If you want a smaller set of lints you can change this to specify
+# 'package:lints/core.yaml'. These are just the most critical lints
+# (the recommended set includes the core lints).
+# The core lints are also what is used by pub.dev for scoring packages.
+
+include: package:lints/recommended.yaml
+
+# Uncomment the following section to specify additional rules.
+
+# linter:
+#   rules:
+#     - camel_case_types
+
+# analyzer:
+#   exclude:
+#     - path/to/excluded/files/**
+
+# For more information about the core and recommended set of lints, see
+# https://dart.dev/go/core-lints
+
+# For additional information about configuring this file, see
+# https://dart.dev/guides/language/analysis-options

example/readability_example.dart

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+import 'package:readability/readability.dart';
+
+void main() {
+  var parser = ReadabilityParser();
+  Article article = parser.parse('https://www.bbc.com/sport/football/articles/cl7y4z82z2do');
+  print(article.toString());
+}

lib/readability.dart

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+/// Support for doing something awesome.
+///
+/// More dartdocs go here.
+library;
+
+export 'src/readability_parser.dart';
+export 'src/article.dart';
+
+// TODO: Export any libraries intended for clients of this package.

lib/src/article.dart

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+
+class Article {
+  final String? title;
+  final String? author;
+  final int length;
+  final String? excerpt;
+  final String? siteName;
+  final String? imageUrl;
+  final String? faviconUrl;
+  final String? content;
+  final String? textContent;
+  final String? language;
+  final String? publishedTime;
+
+  Article({
+    required this.title,
+    required this.author,
+    required this.length,
+    required this.excerpt,
+    required this.siteName,
+    required this.imageUrl,
+    required this.faviconUrl,
+    required this.content,
+    required this.textContent,
+    required this.language,
+    required this.publishedTime,
+  });
+
+  @override
+  String toString() {
+    return 'Article{title: $title,\n author: $author,\n length: $length,\n excerpt: $excerpt,\n siteName: $siteName,\n imageUrl: $imageUrl,\n faviconUrl: $faviconUrl,\n content: $content,\n textContent: $textContent,\n language: $language,\n publishedTime: $publishedTime}';
+  }
+}

lib/src/readability_parser.dart

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+import 'dart:ffi' as ffi;
+import 'dart:ffi';
+import 'package:ffi/ffi.dart';
+import 'dart:io' show Platform;
+
+import 'package:readability/src/article.dart';
+
+final class CArticle extends Struct {
+  external Pointer<Utf8> title;
+  external Pointer<Utf8> author;
+  @Int32()
+  external int length;
+  external Pointer<Utf8> excerpt;
+  external Pointer<Utf8> site_name;
+  external Pointer<Utf8> image_url;
+  external Pointer<Utf8> favicon_url;
+  external Pointer<Utf8> content;
+  external Pointer<Utf8> text_content;
+  external Pointer<Utf8> language;
+  external Pointer<Utf8> published_time;
+  external Pointer<Utf8> err;
+
+  @Int32()
+  external int success;
+}
+
+typedef ParseFunc = CArticle Function(Pointer<Utf8> url);
+typedef ParseDart = CArticle Function(Pointer<Utf8> url);
+
+typedef FreeArticleFunc = Void Function(CArticle article);
+typedef FreeArticleDart = void Function(CArticle article);
+
+class ReadabilityParser {
+  late final DynamicLibrary _lib;
+  late final ParseDart _parse;
+  late final FreeArticleDart _freeArticle;
+
+  ReadabilityParser() {
+    _lib = ffi.DynamicLibrary.open(_getDylibPath());
+    _parse = _lib.lookupFunction<ParseFunc, ParseDart>('Parse');
+    _freeArticle =
+        _lib.lookupFunction<FreeArticleFunc, FreeArticleDart>('FreeArticle');
+  }
+
+  Article parse(String url) {
+    // Convert the URL to a native string.
+    final urlPtr = url.toNativeUtf8();
+
+    // Call the native function.
+    final article = _parse(urlPtr);
+
+    // Free the memory allocated for the URL.
+    malloc.free(urlPtr);
+
+
+    // Convert the native article to a Dart article.
+    final articleDart = Article(
+      title: article.title == nullptr ? null : article.title.toDartString(),
+      author: article.author == nullptr ? null : article.author.toDartString(),
+      length: article.length,
+      excerpt: article.excerpt == nullptr ? null : article.excerpt.toDartString(),
+      siteName: article.site_name == nullptr ? null : article.site_name.toDartString(),
+      imageUrl: article.image_url == nullptr ? null : article.image_url.toDartString(),
+      faviconUrl: article.favicon_url == nullptr ? null : article.favicon_url.toDartString(),
+      content: article.content == nullptr ? null : article.content.toDartString(),
+      textContent: article.text_content == nullptr ? null : article.text_content.toDartString(),
+      language: article.language == nullptr ? null : article.language.toDartString(),
+      publishedTime: article.published_time == nullptr ? null : article.published_time.toDartString(),
+    );
+
+    // Free the memory allocated for the article.
+    _freeArticle(article);
+
+    return articleDart;
+  }
+}
+
+String _getDylibPath() {
+  if (Platform.isWindows) {
+    return 'native/windows/x64/readability.dll';
+  } else if (Platform.isMacOS) {
+    return 'native/macos/x64/readability.dylib';
+  } else if (Platform.isLinux) {
+    return 'native/linux/x86-64/libreadability.so';
+  } else {
+    throw UnsupportedError('This platform is not supported.');
+  }
+}

native/linux/x86-64/libreadability.h

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+/* Code generated by cmd/cgo; DO NOT EDIT. */
+
+/* package command-line-arguments */
+
+
+#line 1 "cgo-builtin-export-prolog"
+
+#include <stddef.h>
+
+#ifndef GO_CGO_EXPORT_PROLOGUE_H
+#define GO_CGO_EXPORT_PROLOGUE_H
+
+#ifndef GO_CGO_GOSTRING_TYPEDEF
+typedef struct { const char *p; ptrdiff_t n; } _GoString_;
+#endif
+
+#endif
+
+/* Start of preamble from import "C" comments.  */
+
+
+#line 3 "main.go"
+
+#include <stdlib.h>
+
+typedef struct {
+	char* title;
+	char* author;
+	int length;
+	char* excerpt;
+	char* site_name;
+	char* image_url;
+	char* favicon_url;
+	char* content; // HTML content
+	char* text_content; // text content
+	char* language;
+	char* published_time;
+	char* err;
+	int success;
+} CArticle;
+
+#line 1 "cgo-generated-wrapper"
+
+
+/* End of preamble from import "C" comments.  */
+
+
+/* Start of boilerplate cgo prologue.  */
+#line 1 "cgo-gcc-export-header-prolog"
+
+#ifndef GO_CGO_PROLOGUE_H
+#define GO_CGO_PROLOGUE_H
+
+typedef signed char GoInt8;
+typedef unsigned char GoUint8;
+typedef short GoInt16;
+typedef unsigned short GoUint16;
+typedef int GoInt32;
+typedef unsigned int GoUint32;
+typedef long long GoInt64;
+typedef unsigned long long GoUint64;
+typedef GoInt64 GoInt;
+typedef GoUint64 GoUint;
+typedef size_t GoUintptr;
+typedef float GoFloat32;
+typedef double GoFloat64;
+#ifdef _MSC_VER
+#include <complex.h>
+typedef _Fcomplex GoComplex64;
+typedef _Dcomplex GoComplex128;
+#else
+typedef float _Complex GoComplex64;
+typedef double _Complex GoComplex128;
+#endif
+
+/*
+  static assertion to make sure the file is being used on architecture
+  at least with matching size of GoInt.
+*/
+typedef char _check_for_64_bit_pointer_matching_GoInt[sizeof(void*)==64/8 ? 1:-1];
+
+#ifndef GO_CGO_GOSTRING_TYPEDEF
+typedef _GoString_ GoString;
+#endif
+typedef void *GoMap;
+typedef void *GoChan;
+typedef struct { void *t; void *v; } GoInterface;
+typedef struct { void *data; GoInt len; GoInt cap; } GoSlice;
+
+#endif
+
+/* End of boilerplate cgo prologue.  */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern CArticle Parse(char* url);
+extern void FreeArticle(CArticle article);
+
+#ifdef __cplusplus
+}
+#endif

pubspec.yaml

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+name: readability
+description: A starting point for Dart libraries or applications.
+version: 1.0.0
+# repository: https://github.com/my_org/my_repo
+
+environment:
+  sdk: ^3.4.3
+
+# Add regular dependencies here.
+dependencies:
+  ffi: ^2.1.2
+  # path: ^1.8.0
+
+dev_dependencies:
+  lints: ^3.0.0
+  test: ^1.24.0

test/readability_test.dart

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+import 'package:readability/readability.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('A group of tests', () {
+    final ReadabilityParser parser = ReadabilityParser();
+
+    setUp(() {
+      // Additional setup goes here.
+    });
+
+    test('First Test', () {
+      final Article article = parser.parse('https://www.bbc.com/sport/football/articles/cl7y4z82z2do');
+      expect(article.title, isNotNull);
+    });
+  });
+}