api: Add get-messages route

Author: gnprice

lib/api/core.dart

@@ -1,5 +1,6 @@
 import 'dart:convert';
 
+import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 
 abstract class Auth {
@@ -23,13 +24,30 @@ class ApiConnection {
     };
   }
 
+  Future<String> get(String route, Map<String, dynamic>? params) async {
+    final baseUrl = Uri.parse(auth.realmUrl);
+    final url = Uri(
+        scheme: baseUrl.scheme,
+        userInfo: baseUrl.userInfo,
+        host: baseUrl.host,
+        port: baseUrl.port,
+        path: "/api/v1/$route",
+        queryParameters: params?.map((k, v) => MapEntry(k, jsonEncode(v))));
+    if (kDebugMode) print("GET $url");
+    final response = await http.get(url, headers: _headers());
+    if (response.statusCode != 200) {
+      throw Exception("error on GET $route: status ${response.statusCode}");
+    }
+    return response.body;
+  }
+
   Future<String> post(String route, Map<String, dynamic>? params) async {
     final response = await http.post(
         Uri.parse("${auth.realmUrl}/api/v1/$route"),
         headers: _headers(),
         body: params?.map((k, v) => MapEntry(k, jsonEncode(v))));
     if (response.statusCode != 200) {
-      throw Exception("error on $route: status ${response.statusCode}");
+      throw Exception("error on POST $route: status ${response.statusCode}");
     }
     return response.body;
   }

lib/api/model/model.dart

@@ -156,6 +156,8 @@ abstract class Message {
     if (type == 'private') return PmMessage.fromJson(json);
     throw Exception("Message.fromJson: unexpected message type $type");
   }
+
+  Map<String, dynamic> toJson();
 }
 
 @JsonSerializable()
@@ -187,6 +189,9 @@ class StreamMessage extends Message {
 
   factory StreamMessage.fromJson(Map<String, dynamic> json) =>
       _$StreamMessageFromJson(json);
+
+  @override
+  Map<String, dynamic> toJson() => _$StreamMessageToJson(this);
 }
 
 @JsonSerializable()
@@ -231,4 +236,7 @@ class PmMessage extends Message {
 
   factory PmMessage.fromJson(Map<String, dynamic> json) =>
       _$PmMessageFromJson(json);
+
+  @override
+  Map<String, dynamic> toJson() => _$PmMessageToJson(this);
 }

lib/api/route/messages.dart

@@ -0,0 +1,46 @@
+// ignore_for_file: non_constant_identifier_names
+
+import 'dart:convert';
+
+import 'package:json_annotation/json_annotation.dart';
+
+import '../core.dart';
+import '../model/model.dart';
+
+part 'messages.g.dart';
+
+/// https://zulip.com/api/get-messages
+Future<GetMessagesResult> getMessages(ApiConnection connection, {
+  required int num_before,
+  required int num_after,
+}) async {
+  final data = await connection.get('messages', {
+    // 'narrow': [], // TODO parametrize
+    'anchor': 999999999, // TODO parametrize; needs raw for strings
+    'num_before': num_before,
+    'num_after': num_after,
+  });
+  return GetMessagesResult.fromJson(jsonDecode(data));
+}
+
+@JsonSerializable()
+class GetMessagesResult {
+  final int anchor;
+  final bool found_newest;
+  final bool found_oldest;
+  final bool found_anchor;
+  final bool history_limited;
+  final List<Message> messages;
+
+  GetMessagesResult({
+    required this.anchor,
+    required this.found_newest,
+    required this.found_oldest,
+    required this.found_anchor,
+    required this.history_limited,
+    required this.messages,
+  });
+
+  factory GetMessagesResult.fromJson(Map<String, dynamic> json) =>
+      _$GetMessagesResultFromJson(json);
+}