[SearchSnippet][Part-1] Implement SearchSnippet/get

lib/jmap/mail/email/search_snippet/search_snippet.dart

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+import 'package:equatable/equatable.dart';
+import 'package:jmap_dart_client/http/converter/email_id_converter.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'search_snippet.g.dart';
+
+@JsonSerializable(
+  includeIfNull: false,
+  explicitToJson: true,
+  converters: [EmailIdConverter()]
+)
+class SearchSnippet with EquatableMixin {
+  final EmailId emailId;
+  final String? subject;
+  final String? preview;
+
+  SearchSnippet({
+    required this.emailId,
+    required this.subject,
+    required this.preview,
+  });
+
+  factory SearchSnippet.fromJson(Map<String, dynamic> json) => _$SearchSnippetFromJson(json);
+  Map<String, dynamic> toJson() => _$SearchSnippetToJson(this);
+
+  @override
+  List<Object?> get props => [emailId, subject, preview];
+}

lib/jmap/mail/email/search_snippet/search_snippet_get_method.dart

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+import 'package:jmap_dart_client/http/converter/account_id_converter.dart';
+import 'package:jmap_dart_client/jmap/core/capability/capability_identifier.dart';
+import 'package:jmap_dart_client/jmap/core/method/request/get_method.dart';
+import 'package:jmap_dart_client/jmap/core/method/request/query_method.dart';
+import 'package:jmap_dart_client/jmap/core/request/request_invocation.dart';
+import 'package:jmap_dart_client/jmap/core/request/result_reference.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email_filter_condition.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+class SearchSnippetGetMethod extends GetMethod with OptionalFilter, OptionalReferenceEmailIds {
+  SearchSnippetGetMethod(super.accountId);
+
+  @override
+  MethodName get methodName => MethodName('SearchSnippet/get');
+
+  @override
+  List<Object?> get props => [methodName, accountId, filter];
+
+  @override
+  Set<CapabilityIdentifier> get requiredCapabilities => {
+    CapabilityIdentifier.jmapCore,
+    CapabilityIdentifier.jmapMail
+  };
+
+  factory SearchSnippetGetMethod.fromJson(Map<String, dynamic> json) {
+    return SearchSnippetGetMethod(
+      const AccountIdConverter().fromJson(json['accountId'])
+    )
+      ..filter = json['filter'] == null
+        ? null
+        : EmailFilterCondition.fromJson(json['filter'] as Map<String, dynamic>)
+      ..referenceEmailIds = json['#emailIds'] == null
+        ? null
+        : ResultReference.fromJson(json['#emailIds'] as Map<String, dynamic>);
+  }
+
+  @override
+  Map<String, dynamic> toJson() {
+    final val = <String, dynamic>{
+      'accountId': const AccountIdConverter().toJson(accountId),
+    };
+
+    void writeNotNull(String key, dynamic value) {
+      if (value != null) {
+        val[key] = value;
+      }
+    }
+
+    writeNotNull('filter', filter?.toJson());
+    writeNotNull('#emailIds', referenceEmailIds?.toJson());
+
+    return val;
+  }
+}
+
+mixin OptionalReferenceEmailIds {
+  @JsonKey(name: '#emailIds', includeIfNull: false)
+  ResultReference? referenceEmailIds;
+
+  void addReferenceEmailIds(ResultReference resultReferenceIds) {
+    referenceEmailIds = resultReferenceIds;
+  }
+}

lib/jmap/mail/email/search_snippet/search_snippet_get_response.dart

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+import 'package:jmap_dart_client/http/converter/account_id_converter.dart';
+import 'package:jmap_dart_client/http/converter/id_converter.dart';
+import 'package:jmap_dart_client/jmap/core/id.dart';
+import 'package:jmap_dart_client/jmap/core/method/method_response.dart';
+import 'package:jmap_dart_client/jmap/mail/email/search_snippet/search_snippet.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'search_snippet_get_response.g.dart';
+
+@JsonSerializable(
+  includeIfNull: false,
+  explicitToJson: true,
+  converters: [
+    AccountIdConverter(),
+    IdConverter(),
+  ]
+)
+class SearchSnippetGetResponse extends ResponseRequiringAccountId {
+  SearchSnippetGetResponse(
+    super.accountId,
+    this.list,
+    this.notFound,
+  );
+
+  final List<SearchSnippet>? list;
+  final List<Id>? notFound;
+
+  factory SearchSnippetGetResponse.fromJson(Map<String, dynamic> json) => _$SearchSnippetGetResponseFromJson(json);
+  Map<String, dynamic> toJson() => _$SearchSnippetGetResponseToJson(this);
+
+  @override
+  List<Object?> get props => [accountId, list, notFound];
+}