feature: querying and displaying upcoming movies

android/app/src/main/AndroidManifest.xml

@@ -15,6 +15,8 @@
                  the Android process has started. This theme is visible to the user
                  while the Flutter UI initializes. After that, this theme continues
                  to determine the Window background behind the Flutter UI. -->
+            <!-- Required to fetch data from the internet. -->
+            <uses-permission android:name="android.permission.INTERNET" />
             <meta-data
               android:name="io.flutter.embedding.android.NormalTheme"
               android:resource="@style/NormalTheme"

lib/api/api_manager.dart

@@ -0,0 +1,61 @@
+import 'dart:async';
+
+import 'package:http/http.dart' as http;
+
+class RateLimitStatus {
+  int consecutiveCount = 0;
+  Duration timeout = const Duration(seconds: 1);
+}
+
+class ApiManager {
+  String baseUrl;
+  Future<void> ongoingRequest = Future.value();
+  int consecutiveRateLimitExceeded = 0;
+  Duration rateLimitTimeout = Duration.zero;
+  DateTime? lastRequest;
+
+  ApiManager(this.baseUrl);
+
+  Future<http.Response> get(String path) async {
+    Future<void> waitingForRequest = ongoingRequest;
+    Completer completer = Completer();
+    try {
+      ongoingRequest = completer.future;
+      await waitingForRequest;
+
+      DateTime? lastRequestLocal = lastRequest;
+      if (consecutiveRateLimitExceeded > 0 &&
+          lastRequestLocal != null &&
+          DateTime.now().isBefore(lastRequestLocal.add(rateLimitTimeout))) {
+        throw Exception("Too many requests");
+      }
+
+      http.Response response = await http.get(Uri.parse(baseUrl + path));
+      lastRequest = DateTime.now();
+      if (response.statusCode == 429) {
+        consecutiveRateLimitExceeded++;
+        if (consecutiveRateLimitExceeded == 1) {
+          rateLimitTimeout = const Duration(seconds: 1);
+        } else {
+          rateLimitTimeout *= 2;
+        }
+        String? retryAfter = response.headers["Retry-After"];
+        if (retryAfter != null) {
+          int? retryAfterSeconds = int.tryParse(retryAfter);
+          if (retryAfterSeconds != null) {
+            Duration retryAfterDuration = Duration(seconds: retryAfterSeconds);
+            if (retryAfterDuration > rateLimitTimeout) {
+              rateLimitTimeout = retryAfterDuration;
+            }
+          }
+        }
+        throw Exception("Too many requests");
+      } else {
+        consecutiveRateLimitExceeded = 0;
+      }
+      return response;
+    } finally {
+      completer.complete();
+    }
+  }
+}

lib/api/movie_api.dart

@@ -0,0 +1,7 @@
+import 'package:release_schedule/model/movie.dart';
+
+abstract class MovieApi<CustomMovieData extends MovieData> {
+  Future<List<CustomMovieData>> getUpcomingMovies([int count]);
+  Future<List<CustomMovieData>> searchForMovies(String searchTerm);
+  Future<void> addMovieDetails(List<CustomMovieData> movies);
+}

lib/api/wikidata_movie_api.dart

@@ -0,0 +1,76 @@
+import 'dart:convert';
+
+import 'package:http/http.dart';
+import 'package:release_schedule/api/api_manager.dart';
+import 'package:release_schedule/api/movie_api.dart';
+import 'package:release_schedule/model/movie.dart';
+
+class WikidataMovieData extends MovieData {
+  int entityId;
+  WikidataMovieData(String title, DateTime releaseDate, this.entityId)
+      : super(title, releaseDate);
+
+  @override
+  bool same(MovieData other) {
+    return other is WikidataMovieData && entityId == other.entityId;
+  }
+}
+
+String createUpcomingMovieQuery(int limit) {
+  return """
+SELECT
+  ?movie
+  ?movieLabel
+  (MIN(?releaseDate) as ?minReleaseDate)
+WHERE {
+  ?movie wdt:P31 wd:Q11424;         # Q11424 is the item for "film"
+         wdt:P577 ?releaseDate;      # P577 is the "publication date" property
+         wdt:P1476 ?title.
+  FILTER (xsd:date(?releaseDate) >= xsd:date(NOW()))
+
+  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
+}
+GROUP BY ?movie ?movieLabel
+ORDER BY ?minReleaseDate
+LIMIT $limit""";
+}
+
+class WikidataMovieApi implements MovieApi<WikidataMovieData> {
+  ApiManager searchApi = ApiManager("https://www.wikidata.org/w/api.php");
+  ApiManager queryApi =
+      ApiManager("https://query.wikidata.org/sparql?format=json");
+
+  @override
+  Future<void> addMovieDetails(List<WikidataMovieData> movies) {
+    // TODO: implement addMovieDetails
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<List<WikidataMovieData>> getUpcomingMovies([int count = 100]) async {
+    Response response = await queryApi
+        .get("&query=${Uri.encodeComponent(createUpcomingMovieQuery(count))}");
+    if (response.statusCode != 200) {
+      throw Exception(
+          "The Wikidata request for upcoming movies failed with status ${response.statusCode} ${response.reasonPhrase}");
+    }
+    Map<String, dynamic> result = jsonDecode(response.body);
+    List<dynamic> entries = result["results"]["bindings"];
+    List<WikidataMovieData> movies = [];
+    for (Map<String, dynamic> entry in entries) {
+      String identifier =
+          RegExp(r"Q\d+$").firstMatch(entry["movie"]["value"])![0]!;
+      movies.add(WikidataMovieData(
+          entry["movieLabel"]["value"] as String,
+          DateTime.parse(entry["minReleaseDate"]["value"] as String),
+          int.parse(identifier.substring(1))));
+    }
+    return movies;
+  }
+
+  @override
+  Future<List<WikidataMovieData>> searchForMovies(String searchTerm) {
+    // TODO: implement searchForMovies
+    throw UnimplementedError();
+  }
+}

lib/main.dart

@@ -1,125 +1,55 @@
 import 'package:flutter/material.dart';
+import 'package:release_schedule/api/movie_api.dart';
+import 'package:release_schedule/api/wikidata_movie_api.dart';
+import 'package:release_schedule/model/movie_manager.dart';
+import 'package:release_schedule/view/movie_list.dart';
 
 void main() {
   runApp(const MyApp());
+  movieManager.loadUpcomingMovies();
 }
 
 class MyApp extends StatelessWidget {
   const MyApp({super.key});
 
-  // This widget is the root of your application.
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      title: 'Flutter Demo',
+      title: 'Movie Schedule',
+      themeMode: ThemeMode.dark,
+      darkTheme: ThemeData.dark(useMaterial3: true),
       theme: ThemeData(
-        // This is the theme of your application.
-        //
-        // TRY THIS: Try running your application with "flutter run". You'll see
-        // the application has a blue toolbar. Then, without quitting the app,
-        // try changing the seedColor in the colorScheme below to Colors.green
-        // and then invoke "hot reload" (save your changes or press the "hot
-        // reload" button in a Flutter-supported IDE, or press "r" if you used
-        // the command line to start the app).
-        //
-        // Notice that the counter didn't reset back to zero; the application
-        // state is not lost during the reload. To reset the state, use hot
-        // restart instead.
-        //
-        // This works for code too, not just values: Most code changes can be
-        // tested with just a hot reload.
         colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
         useMaterial3: true,
       ),
-      home: const MyHomePage(title: 'Flutter Demo Home Page'),
+      home: HomePage(),
     );
   }
 }
 
-class MyHomePage extends StatefulWidget {
-  const MyHomePage({super.key, required this.title});
+class HomePage extends StatelessWidget {
+  final MovieApi api = WikidataMovieApi();
 
-  // This widget is the home page of your application. It is stateful, meaning
-  // that it has a State object (defined below) that contains fields that affect
-  // how it looks.
-
-  // This class is the configuration for the state. It holds the values (in this
-  // case the title) provided by the parent (in this case the App widget) and
-  // used by the build method of the State. Fields in a Widget subclass are
-  // always marked "final".
-
-  final String title;
-
-  @override
-  State<MyHomePage> createState() => _MyHomePageState();
-}
-
-class _MyHomePageState extends State<MyHomePage> {
-  int _counter = 0;
-
-  void _incrementCounter() {
-    setState(() {
-      // This call to setState tells the Flutter framework that something has
-      // changed in this State, which causes it to rerun the build method below
-      // so that the display can reflect the updated values. If we changed
-      // _counter without calling setState(), then the build method would not be
-      // called again, and so nothing would appear to happen.
-      _counter++;
-    });
-  }
+  HomePage({super.key});
 
   @override
   Widget build(BuildContext context) {
-    // This method is rerun every time setState is called, for instance as done
-    // by the _incrementCounter method above.
-    //
-    // The Flutter framework has been optimized to make rerunning build methods
-    // fast, so that you can just rebuild anything that needs updating rather
-    // than having to individually change instances of widgets.
     return Scaffold(
-      appBar: AppBar(
-        // TRY THIS: Try changing the color here to a specific color (to
-        // Colors.amber, perhaps?) and trigger a hot reload to see the AppBar
-        // change color while the other colors stay the same.
-        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
-        // Here we take the value from the MyHomePage object that was created by
-        // the App.build method, and use it to set our appbar title.
-        title: Text(widget.title),
+      appBar: AppBar(title: const Text("Release Schedule")),
+      body: AnimatedBuilder(
+        animation: movieManager,
+        // future: api.getUpcomingMovies(),
+        builder: (context, widget) {
+          return MovieList(movieManager.movies);
+          // var data = snapshot.data;
+          // if (snapshot.hasData && data != null) {
+          //   return MovieList(data);
+          // } else if (snapshot.hasError) {
+          //   return ErrorWidget(snapshot.error ?? "Something went wrong");
+          // }
+          // return const Center(child: CircularProgressIndicator());
+        },
       ),
-      body: Center(
-        // Center is a layout widget. It takes a single child and positions it
-        // in the middle of the parent.
-        child: Column(
-          // Column is also a layout widget. It takes a list of children and
-          // arranges them vertically. By default, it sizes itself to fit its
-          // children horizontally, and tries to be as tall as its parent.
-          //
-          // Column has various properties to control how it sizes itself and
-          // how it positions its children. Here we use mainAxisAlignment to
-          // center the children vertically; the main axis here is the vertical
-          // axis because Columns are vertical (the cross axis would be
-          // horizontal).
-          //
-          // TRY THIS: Invoke "debug painting" (choose the "Toggle Debug Paint"
-          // action in the IDE, or press "p" in the console), to see the
-          // wireframe for each widget.
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[
-            const Text(
-              'You have pushed the button this many times:',
-            ),
-            Text(
-              '$_counter',
-              style: Theme.of(context).textTheme.headlineMedium,
-            ),
-          ],
-        ),
-      ),
-      floatingActionButton: FloatingActionButton(
-        onPressed: _incrementCounter,
-        tooltip: 'Increment',
-        child: const Icon(Icons.add),
-      ), // This trailing comma makes auto-formatting nicer for build methods.
     );
   }
 }

lib/model/movie.dart

@@ -0,0 +1,75 @@
+import 'package:flutter/material.dart';
+
+class Review {
+  String score;
+  String by;
+  DateTime asOf;
+  int count;
+
+  Review(this.score, this.by, this.asOf, this.count);
+}
+
+typedef ReleaseDateInCountry = (String country, DateTime date);
+typedef TitleInCountry = (String country, String title);
+
+class MovieData extends ChangeNotifier {
+  final String title;
+  final DateTime releaseDate;
+  bool _hasDetails = false;
+  List<ReleaseDateInCountry> _releaseDates = [];
+  List<String> _genres = [];
+  List<TitleInCountry> _titles = [];
+  List<Review> _reviews = [];
+
+  List<ReleaseDateInCountry>? get releaseDates {
+    return _releaseDates;
+  }
+
+  List<String>? get genres {
+    return _genres;
+  }
+
+  List<TitleInCountry>? get titles {
+    return _titles;
+  }
+
+  List<Review>? get reviews {
+    return _reviews;
+  }
+
+  bool get hasDetails {
+    return _hasDetails;
+  }
+
+  void setDetails(
+      {List<ReleaseDateInCountry>? releaseDates,
+      List<String>? genres,
+      List<TitleInCountry>? titles,
+      List<Review>? reviews}) {
+    if (releaseDates != null) {
+      _releaseDates = releaseDates;
+    }
+    if (genres != null) {
+      _genres = genres;
+    }
+    if (titles != null) {
+      _titles = titles;
+    }
+    if (reviews != null) {
+      _reviews = reviews;
+    }
+    _hasDetails = true;
+    notifyListeners();
+  }
+
+  @override
+  String toString() {
+    return "$title (${releaseDate.year}${_genres.isNotEmpty ? "; ${_genres.join(", ")}" : ""})";
+  }
+
+  bool same(MovieData other) {
+    return title == other.title && releaseDate == other.releaseDate;
+  }
+
+  MovieData(this.title, this.releaseDate);
+}

lib/model/movie_manager.dart

@@ -0,0 +1,73 @@
+import 'package:flutter/material.dart';
+import 'package:release_schedule/api/movie_api.dart';
+import 'package:release_schedule/api/wikidata_movie_api.dart';
+import 'package:release_schedule/model/movie.dart';
+
+T? firstWhereOrNull<T>(List<T> list, bool Function(T element) test) {
+  try {
+    return list.firstWhere(test);
+  } catch (e) {
+    return null;
+  }
+}
+
+final movieManager = MovieManager(WikidataMovieApi());
+
+class MovieManager<CustomMovieData extends MovieData> extends ChangeNotifier {
+  final List<CustomMovieData> movies = List.empty(growable: true);
+  final MovieApi<CustomMovieData> api;
+
+  MovieManager(this.api);
+
+  List<CustomMovieData> addMovies(List<CustomMovieData> additionalMovies) {
+    List<CustomMovieData> actualMovies = [];
+    bool added = false;
+    for (var movie in additionalMovies) {
+      CustomMovieData? existing =
+          firstWhereOrNull(movies, (element) => movie.same(element));
+      if (existing == null) {
+        movies.add(movie);
+        added = true;
+        actualMovies.add(movie);
+      } else {
+        actualMovies.add(existing);
+      }
+    }
+    if (added) {
+      notifyListeners();
+    }
+    return actualMovies;
+  }
+
+  /// Only search locally cached movies.
+  localSearch(String search) {}
+
+  /// Online search for movies.
+  Future<List<CustomMovieData>> search(String search) async {
+    List<CustomMovieData> movies = await api.searchForMovies(search);
+    return addMovies(movies);
+  }
+
+  expandDetails(List<CustomMovieData> movies) {
+    api.addMovieDetails(movies);
+  }
+
+  loadUpcomingMovies() async {
+    List<CustomMovieData> movies = await api.getUpcomingMovies();
+    addMovies(movies);
+  }
+}
+
+class LiveSearch<CustomMovieData extends MovieData> extends ChangeNotifier {
+  String searchTerm = "";
+  List<CustomMovieData> searchResults = [];
+  Duration minTimeBetweenRequests = const Duration(milliseconds: 500);
+  Duration minTimeAfterChangeToRequest = const Duration(milliseconds: 200);
+  final MovieManager manager;
+
+  LiveSearch(this.manager);
+
+  updateSearch(String search) {
+    searchTerm = search;
+  }
+}

lib/view/movie_item.dart

@@ -0,0 +1,78 @@
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:release_schedule/model/movie.dart';
+
+String durationApproximatedInWords(Duration duration) {
+  int seconds = duration.inSeconds;
+  int minutes = duration.inMinutes;
+  int hours = duration.inHours;
+  int days = duration.inDays;
+  int weeks = (days / 7).floor();
+  int months = (days / 30).floor();
+  int years = (days / 365).floor();
+  int centuries = (years / 100).floor();
+  if (duration == Duration.zero) {
+    return "now";
+  }
+  if (seconds == 0) {
+    return "now";
+  }
+  if (seconds < 60) {
+    return seconds > 1 ? "$seconds seconds" : "a second";
+  }
+  if (minutes < 60) {
+    return minutes > 1 ? "$minutes minutes" : "a minute";
+  }
+  if (hours < 24) {
+    return hours > 1 ? "$hours hours" : "an hour";
+  }
+  if (days < 7) {
+    return days > 1 ? "$days days" : "a day";
+  }
+  if (months == 0) {
+    return weeks > 1 ? "$weeks weeks" : "a week";
+  }
+  if (years == 0) {
+    return months > 1 ? "$months months" : "a month";
+  }
+  if (years < 100) {
+    return years > 1 ? "$years years" : "a year";
+  }
+  return centuries > 1 ? "$centuries centuries" : "a century";
+}
+
+String durationToRelativeTimeString(Duration duration) {
+  if (duration.isNegative) {
+    return "${durationApproximatedInWords(-duration)} ago";
+  } else {
+    return "in ${durationApproximatedInWords(duration)}";
+  }
+}
+
+String dateRelativeToNow(DateTime date) {
+  DateTime dateOnly = DateTime.utc(date.year, date.month, date.day);
+  DateTime now = DateTime.now().toUtc();
+  DateTime today = DateTime.utc(now.year, now.month, now.day);
+  Duration diff = dateOnly.difference(today);
+  return durationToRelativeTimeString(diff);
+}
+
+class MovieItem extends StatelessWidget {
+  final MovieData movie;
+  const MovieItem(this.movie, {super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final format = DateFormat(DateFormat.YEAR_MONTH_DAY);
+
+    return AnimatedBuilder(
+      animation: movie,
+      builder: (context, widget) {
+        return ListTile(
+            title: Text(movie.title),
+            subtitle: Text(
+                "${dateRelativeToNow(movie.releaseDate)}, ${format.format(movie.releaseDate)}"));
+      },
+    );
+  }
+}

lib/view/movie_list.dart

@@ -0,0 +1,18 @@
+import 'package:flutter/material.dart';
+import 'package:release_schedule/model/movie.dart';
+import 'package:release_schedule/view/movie_item.dart';
+
+class MovieList extends StatelessWidget {
+  final List<MovieData> movies;
+  const MovieList(this.movies, {super.key});
+
+  @override
+  Widget build(Object context) {
+    return ListView.builder(
+      itemCount: movies.length,
+      itemBuilder: (context, index) {
+        return MovieItem(movies[index]);
+      },
+    );
+  }
+}

pubspec.lock

@@ -75,6 +75,30 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  http:
+    dependency: "direct main"
+    description:
+      name: http
+      sha256: "759d1a329847dd0f39226c688d3e06a6b8679668e350e2891a6474f8b4bb8525"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
+  http_parser:
+    dependency: transitive
+    description:
+      name: http_parser
+      sha256: "2aa08ce0341cc9b354a498388e30986515406668dbcc4f7c950c3e715496693b"
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.0.2"
+  intl:
+    dependency: "direct main"
+    description:
+      name: intl
+      sha256: "3bc132a9dbce73a7e4a21a17d06e1878839ffbf975568bc875c60537824b0c4d"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.18.1"
   lints:
     dependency: transitive
     description:
@@ -168,6 +192,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.6.0"
+  typed_data:
+    dependency: transitive
+    description:
+      name: typed_data
+      sha256: facc8d6582f16042dd49f2463ff1bd6e2c9ef9f3d5da3d9b087e244a7b564b3c
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.3.2"
   vector_math:
     dependency: transitive
     description:

pubspec.yaml

@@ -35,6 +35,8 @@ dependencies:
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.2
+  http: ^1.1.0
+  intl: ^0.18.1
 
 dev_dependencies:
   flutter_test: