import json
from rest_framework import serializers
from .models import Material, MaterialCategory, MaterialSubcategory


class JSONListField(serializers.ListField):
    def to_internal_value(self, data):
        if isinstance(data, str):
            try:
                data = json.loads(data)
            except json.JSONDecodeError:
                data = [data]
        return super().to_internal_value(data)


class MaterialSerializer(serializers.ModelSerializer):
    """
    材料序列化器
    """
    factory_name = serializers.CharField(source='factory.factory_name', read_only=True)
    factory_short_name = serializers.CharField(source='factory.factory_short_name', read_only=True)
    major_category_display = serializers.CharField(source='get_major_category_display', read_only=True)
    replace_type_display = serializers.CharField(source='get_replace_type_display', read_only=True)
    application_scene = JSONListField(
        child=serializers.ChoiceField(choices=Material.APPLICATION_SCENE_CHOICES),
        required=False,
        allow_empty=True
    )
    advantage = JSONListField(
        child=serializers.ChoiceField(choices=Material.ADVANTAGE_CHOICES),
        required=False,
        allow_empty=True
    )
    advantage_display = serializers.SerializerMethodField()
    application_scene_display = serializers.SerializerMethodField()
    brochure_url = serializers.SerializerMethodField()

    class Meta:
        model = Material
        fields = ['id', 'name', 'major_category', 'major_category_display', 
                  'material_category', 'material_subcategory', 'spec', 'standard',
                  'application_scene', 'application_scene_display', 'application_desc',
                  'replace_type', 'replace_type_display', 'advantage', 'advantage_display',
                  'advantage_desc', 'cost_compare', 'cost_desc', 'cases', 'brochure',
                  'brochure_url', 'quality_level', 'durability_level', 'eco_level',
                  'carbon_level', 'score_level', 'connection_method', 'construction_method',
                  'limit_condition', 'factory', 'factory_name', 'factory_short_name',
                  'status', 'created_at', 'updated_at']
        read_only_fields = ['id', 'created_at', 'updated_at']

    def get_brochure_url(self, obj):
        """
        获取宣传页图片URL
        """
        if obj.brochure:
            request = self.context.get('request')
            if request:
                return request.build_absolute_uri(obj.brochure.url)
        return None

    def _display_list(self, codes, choices):
        mapping = dict(choices)
        if not codes:
            return []
        if isinstance(codes, str):
            codes = [codes]
        return [mapping.get(code, code) for code in codes]

    def get_application_scene_display(self, obj):
        return self._display_list(obj.application_scene, Material.APPLICATION_SCENE_CHOICES)

    def get_advantage_display(self, obj):
        return self._display_list(obj.advantage, Material.ADVANTAGE_CHOICES)


class MaterialListSerializer(serializers.ModelSerializer):
    """
    材料列表序列化器（简化版）
    """
    factory_name = serializers.CharField(source='factory.factory_name', read_only=True)
    factory_short_name = serializers.CharField(source='factory.factory_short_name', read_only=True)
    major_category_display = serializers.CharField(source='get_major_category_display', read_only=True)
    status_display = serializers.CharField(source='get_status_display', read_only=True)

    class Meta:
        model = Material
        fields = ['id', 'name', 'major_category', 'major_category_display', 
                  'material_category', 'material_subcategory', 'factory', 
                  'factory_name', 'factory_short_name', 'status', 'status_display']


class MaterialCategorySerializer(serializers.ModelSerializer):
    """
    材料分类序列化器
    """
    subcategory_count = serializers.SerializerMethodField()

    class Meta:
        model = MaterialCategory
        fields = ['id', 'name', 'value', 'created_at', 'updated_at', 'subcategory_count']
        read_only_fields = ['id', 'created_at', 'updated_at', 'subcategory_count']

    def get_subcategory_count(self, obj):
        return obj.subcategories.count()


class MaterialSubcategorySerializer(serializers.ModelSerializer):
    """
    材料子分类序列化器
    """
    category_name = serializers.CharField(source='category.name', read_only=True)

    class Meta:
        model = MaterialSubcategory
        fields = ['id', 'category', 'category_name', 'name', 'value', 'created_at', 'updated_at']
        read_only_fields = ['id', 'created_at', 'updated_at', 'category_name']