part of angel3_serialize_generator;

class SerializerGenerator extends GeneratorForAnnotation<Serializable> {
  final bool autoSnakeCaseNames;

  const SerializerGenerator({this.autoSnakeCaseNames = true});

  @override
  Future<String?> generateForAnnotatedElement(
      Element element, ConstantReader annotation, BuildStep buildStep) async {
    log.fine('Running SerializerGenerator');

    if (element.kind != ElementKind.CLASS) {
      throw 'Only classes can be annotated with a @Serializable() annotation.';
    }

    var ctx = await buildContext(element as ClassElement, annotation, buildStep,
        buildStep.resolver, !autoSnakeCaseNames);

    if (ctx == null) {
      log.severe('Invalid builder context');
      throw 'Invalid builder context';
    }

    var serializers = annotation.peek('serializers')?.listValue ?? [];

    if (serializers.isEmpty) {
      log.severe("No Serializers");
      return null;
    }

    // Check if any serializer is recognized
    if (!serializers.any((s) => Serializers.all.contains(s.toIntValue()))) {
      log.severe("No recognizable Serializers");
      return null;
    }

    var lib = Library((b) {
      generateClass(
          serializers.map((s) => s.toIntValue() ?? 0).toList(), ctx, b);
      generateFieldsClass(ctx, b);
    });

    var buf = lib.accept(DartEmitter(useNullSafetySyntax: true));
    return buf.toString();
  }

  /// Generate a serializer class.
  void generateClass(
      List<int> serializers, BuildContext ctx, LibraryBuilder file) {
    log.fine('Generate serializer class');

    // Generate canonical codecs, etc.
    var pascal = ctx.modelClassNameRecase.pascalCase.replaceAll('?', '');
    var camel = ctx.modelClassNameRecase.camelCase.replaceAll('?', '');

    log.fine('Generating ${pascal}Serializer');

    if (ctx.constructorParameters.isEmpty) {
      log.fine("Constructor is empty");

      file.body.add(Code('''
const ${pascal}Serializer ${camel}Serializer = ${pascal}Serializer();

class ${pascal}Encoder extends Converter<$pascal, Map> {
  const ${pascal}Encoder();

  @override
  Map convert($pascal model) => ${pascal}Serializer.toMap(model);
}

class ${pascal}Decoder extends Converter<Map, $pascal> {
  const ${pascal}Decoder();
  
  @override
  $pascal convert(Map map) => ${pascal}Serializer.fromMap(map);
}
    '''));
    }

    file.body.add(Class((clazz) {
      clazz.name = '${pascal}Serializer';
      if (ctx.constructorParameters.isEmpty) {
        clazz.extend = TypeReference((b) => b
          ..symbol = 'Codec'
          ..types.addAll([ctx.modelClassType, refer('Map')]));

        // Add constructor, Codec impl, etc.
        clazz.constructors.add(Constructor((b) => b..constant = true));
        clazz.methods.add(Method((b) => b
          ..name = 'encoder'
          ..returns = refer('${pascal}Encoder')
          ..type = MethodType.getter
          ..annotations.add(refer('override'))
          ..body = refer('${pascal}Encoder').constInstance([]).code));
        clazz.methods.add(Method((b) => b
          ..name = 'decoder'
          ..returns = refer('${pascal}Decoder')
          ..type = MethodType.getter
          ..annotations.add(refer('override'))
          ..body = refer('${pascal}Decoder').constInstance([]).code));
      } else {
        clazz.abstract = true;
      }

      if (serializers.contains(Serializers.map)) {
        generateFromMapMethod(clazz, ctx, file);
      }

      if (serializers.contains(Serializers.map) ||
          serializers.contains(Serializers.json)) {
        generateToMapMethod(clazz, ctx, file);
      }
    }));
  }

  // Generate toMapMethod
  void generateToMapMethod(
      ClassBuilder clazz, BuildContext ctx, LibraryBuilder file) {
    var originalClassName = ctx.originalClassName;
    if (originalClassName == null) {
      log.warning('Unable to generate toMap(), classname is null');
      return;
    }
    clazz.methods.add(Method((method) {
      method
        ..static = true
        ..name = 'toMap'
        ..returns = Reference('Map<String, dynamic>')
        ..requiredParameters.add(Parameter((b) {
          b
            ..name = 'model'
            ..type = TypeReference((b) => b
              ..symbol = originalClassName
              ..isNullable = true);
        }));

      var buf = StringBuffer();

      /*
      ctx.requiredFields.forEach((key, msg) {
        if (ctx.excluded[key]?.canSerialize == false) return;
        buf.writeln('''
        if (model.$key == null) {
          throw FormatException("$msg");
        }
        ''');
      });
      */

      buf.writeln('return {');
      var i = 0;

      // Add named parameters
      for (var field in ctx.fields) {
        var type = ctx.resolveSerializedFieldType(field.name);

        // Skip excluded fields
        if (ctx.excluded[field.name]?.canSerialize == false) continue;

        var alias = ctx.resolveFieldName(field.name);

        if (i++ > 0) buf.write(', ');

        var serializedRepresentation = 'model.${field.name}';

        String serializerToMap(ReCase rc, String value) {
          // if (rc.pascalCase == ctx.modelClassName) {
          //   return '($value)?.toJson()';
          // }
          return '${rc.pascalCase.replaceAll('?', '')}Serializer.toMap($value)';
        }

        var fieldNameSerializer = ctx.fieldInfo[field.name]?.serializer;
        if (fieldNameSerializer != null) {
          var name = MirrorSystem.getName(fieldNameSerializer);
          serializedRepresentation = '$name(model.${field.name})';
        }

        // Serialize dates
        else if (dateTimeTypeChecker.isAssignableFromType(type)) {
          var question =
              field.type.nullabilitySuffix == NullabilitySuffix.question
                  ? "?"
                  : "";
          serializedRepresentation =
              'model.${field.name}$question.toIso8601String()';
        }

        // Serialize model classes via `XSerializer.toMap`
        else if (isModelClass(type)) {
          var rc = ReCase(type.getDisplayString(withNullability: true));
          serializedRepresentation = serializerToMap(rc, 'model.${field.name}');
        } else if (type is InterfaceType) {
          if (isListOfModelType(type)) {
            var name =
                type.typeArguments[0].getDisplayString(withNullability: true);
            if (name.startsWith('_')) name = name.substring(1);
            var rc = ReCase(name);
            var m = serializerToMap(rc, 'm');

            var question =
                (field.type.nullabilitySuffix == NullabilitySuffix.question)
                    ? '?'
                    : '';
            serializedRepresentation =
                'model.${field.name}$question.map((m) => $m).toList()';
            log.fine('serializedRepresentation => $serializedRepresentation');
          } else if (isMapToModelType(type)) {
            var rc = ReCase(
                type.typeArguments[1].getDisplayString(withNullability: true));
            serializedRepresentation =
                '''model.${field.name}.keys.fold({}, (map, key) {
              return (map as Map<dynamic,dynamic>?)?..[key] =
              ${serializerToMap(rc, 'model.${field.name}[key]')};
            })''';
          } else if (type.element.isEnum) {
            var convert =
                (field.type.nullabilitySuffix == NullabilitySuffix.question)
                    ? '!'
                    : '';

            serializedRepresentation = '''
            model.${field.name} != null ?
              ${type.getDisplayString(withNullability: false)}.values.indexOf(model.${field.name}$convert)
              : null
            ''';
          } else if (const TypeChecker.fromRuntime(Uint8List)
              .isAssignableFromType(type)) {
            var convert =
                (field.type.nullabilitySuffix == NullabilitySuffix.question)
                    ? '!'
                    : '';

            serializedRepresentation = '''
            model.${field.name} != null ?
              base64.encode(model.${field.name}$convert)
              : null
            ''';
          }
        }

        buf.write("'$alias': $serializedRepresentation");
      }

      buf.write('};');
      method.body = Block.of([
        Code(
            'if (model == null) { throw FormatException("Required field [model] cannot be null"); }'),
        Code(buf.toString()),
      ]);
    }));
  }

  // Generate fromMapMethod
  void generateFromMapMethod(
      ClassBuilder clazz, BuildContext ctx, LibraryBuilder file) {
    clazz.methods.add(Method((method) {
      method
        ..static = true
        ..name = 'fromMap'
        ..returns = ctx.modelClassType
        ..requiredParameters.add(
          Parameter((b) => b
            ..name = 'map'
            ..type = Reference('Map')),
        );

      // Add all `super` params
      if (ctx.constructorParameters.isNotEmpty) {
        for (var param in ctx.constructorParameters) {
          method.requiredParameters.add(Parameter((b) => b
            ..name = param.name
            ..type = convertTypeReference(param.type)));
        }
      }

      var buf = StringBuffer();

      // Required Fields
      ctx.requiredFields.forEach((key, msg) {
        if (ctx.excluded[key]?.canDeserialize == false) return;
        var name = ctx.resolveFieldName(key);
        if (msg.contains("'")) {
          buf.writeln('''
            if (map['$name'] == null) {
              throw FormatException("$msg");
            }
          ''');
        } else {
          buf.writeln('''
            if (map['$name'] == null) {
              throw FormatException('$msg');
            }
          ''');
        }
      });

      buf.writeln('return ${ctx.modelClassName}(');
      var i = 0;

      // Parameters in the constructor
      for (var param in ctx.constructorParameters) {
        if (i++ > 0) buf.write(', ');
        buf.write(param.name);
      }

      // Fields
      for (var field in ctx.fields) {
        var type = ctx.resolveSerializedFieldType(field.name);

        if (ctx.excluded[field.name]?.canDeserialize == false) continue;

        var alias = ctx.resolveFieldName(field.name);

        if (i++ > 0) buf.write(', ');

        var deserializedRepresentation =
            "map['$alias'] as ${typeToString(type)}";

        if (type.nullabilitySuffix == NullabilitySuffix.question) {
          deserializedRepresentation += '?';
        }

        var defaultValue = 'null';
        var existingDefault = ctx.defaults[field.name];

        if (existingDefault != null) {
          var d = dartObjectToString(existingDefault);
          if (d != null) {
            defaultValue = d;

            if (!deserializedRepresentation.endsWith("?")) {
              deserializedRepresentation += "?";
            }
          }
          deserializedRepresentation =
              '$deserializedRepresentation ?? $defaultValue';
        }

        var fieldNameDeserializer = ctx.fieldInfo[field.name]?.deserializer;
        if (fieldNameDeserializer != null) {
          var name = MirrorSystem.getName(fieldNameDeserializer);
          deserializedRepresentation = "$name(map['$alias'])";
        } else if (dateTimeTypeChecker.isAssignableFromType(type)) {
          if (field.type.nullabilitySuffix != NullabilitySuffix.question) {
            if (defaultValue.toLowerCase() == 'null') {
              defaultValue = 'DateTime.parse("1970-01-01 00:00:00")';
            } else {
              defaultValue = 'DateTime.parse("$defaultValue")';
            }
          }
          deserializedRepresentation = "map['$alias'] != null ? "
              "(map['$alias'] is DateTime ? (map['$alias'] as DateTime) : DateTime.parse(map['$alias'].toString()))"
              ' : $defaultValue';
        }

        // Serialize model classes via `XSerializer.toMap`
        else if (isModelClass(type)) {
          var rc = ReCase(type.getDisplayString(withNullability: true));
          deserializedRepresentation = "map['$alias'] != null"
              " ? ${rc.pascalCase.replaceAll('?', '')}Serializer.fromMap(map['$alias'] as Map)"
              ' : $defaultValue';
        } else if (type is InterfaceType) {
          if (isListOfModelType(type)) {
            if (defaultValue == 'null') {
              defaultValue = '[]';
            }
            var rc = ReCase(
                type.typeArguments[0].getDisplayString(withNullability: true));

            deserializedRepresentation = "map['$alias'] is Iterable"
                " ? List.unmodifiable(((map['$alias'] as Iterable)"
                '.whereType<Map>())'
                '.map(${rc.pascalCase.replaceAll('?', '')}Serializer.fromMap))'
                ' : $defaultValue';
          } else if (isMapToModelType(type)) {
            // TODO: This requires refractoring
            if (defaultValue == 'null') {
              defaultValue = '{}';
            }

            var rc = ReCase(
                type.typeArguments[1].getDisplayString(withNullability: true));
            deserializedRepresentation = '''
                map['$alias'] is Map
                  ? Map.unmodifiable((map['$alias'] as Map).keys.fold({}, (out, key) {
                       return out..[key] = ${rc.pascalCase.replaceAll('?', '')}Serializer
                        .fromMap(((map['$alias'] as Map)[key]) as Map);
                    }))
                  : $defaultValue
            ''';
          } else if (type.element.isEnum) {
            deserializedRepresentation = '''
            map['$alias'] is ${type.getDisplayString(withNullability: true)}
              ? (map['$alias'] as ${type.getDisplayString(withNullability: true)}) ?? $defaultValue
              :
              (
                map['$alias'] is int
                ? ${type.getDisplayString(withNullability: true)}.values[map['$alias'] as int]
                : $defaultValue
              )
            ''';

            //log.warning('Code => $deserializedRepresentation');
          } else if (const TypeChecker.fromRuntime(List)
                  .isAssignableFromType(type) &&
              type.typeArguments.length == 1) {
            if (defaultValue == 'null') {
              defaultValue = '[]';
            }
            var arg = convertTypeReference(type.typeArguments[0])
                .accept(DartEmitter(useNullSafetySyntax: true));
            deserializedRepresentation = '''
                map['$alias'] is Iterable
                  ? (map['$alias'] as Iterable).cast<$arg>().toList()
                  : $defaultValue
                ''';
          } else if (const TypeChecker.fromRuntime(Map)
                  .isAssignableFromType(type) &&
              type.typeArguments.length == 2) {
            var key = convertTypeReference(type.typeArguments[0])
                .accept(DartEmitter(useNullSafetySyntax: true));
            var value = convertTypeReference(type.typeArguments[1])
                .accept(DartEmitter(useNullSafetySyntax: true));

            if (defaultValue == 'null') {
              defaultValue = '{}';
            }
            deserializedRepresentation = '''
                map['$alias'] is Map
                  ? (map['$alias'] as Map).cast<$key, $value>()
                  : $defaultValue
                ''';
          } else if (const TypeChecker.fromRuntime(Uint8List)
              .isAssignableFromType(type)) {
            deserializedRepresentation = '''
            map['$alias'] is Uint8List
              ? (map['$alias'] as Uint8List)
              :
              (
                map['$alias'] is Iterable<int>
                  ? Uint8List.fromList((map['$alias'] as Iterable<int>).toList())
                  :
                  (
                    map['$alias'] is String
                      ? Uint8List.fromList(base64.decode(map['$alias'] as String))
                      : $defaultValue
                  )
              )
            ''';
          }
        }

        buf.write('${field.name}: $deserializedRepresentation');
      }

      buf.write(');');
      method.body = Code(buf.toString());
    }));
  }

  void generateFieldsClass(BuildContext ctx, LibraryBuilder file) {
    //log.fine('Generate serializer fields');

    file.body.add(Class((clazz) {
      clazz
        ..abstract = true
        ..name = '${ctx.modelClassNameRecase.pascalCase}Fields';

      clazz.fields.add(Field((b) {
        b
          ..static = true
          ..modifier = FieldModifier.constant
          ..type = TypeReference((b) => b
            ..symbol = 'List'
            ..types.add(refer('String')))
          ..name = 'allFields'
          ..assignment = literalConstList(
                  ctx.fields.map((f) => refer(f.name)).toList(),
                  refer('String'))
              .code;
      }));

      for (var field in ctx.fields) {
        clazz.fields.add(Field((b) {
          b
            ..static = true
            ..modifier = FieldModifier.constant
            ..type = Reference('String')
            ..name = field.name
            ..assignment = Code("'${ctx.resolveFieldName(field.name)}'");
        }));
      }
    }));
  }
}