from django.conf import settings
from rest_framework import serializers

from config.exceptions import AppError
from apps.user.models import Institution, Department


class CmsInstitutionSerializer(serializers.ModelSerializer):
    """CMS 机构（医院）序列化器。

    - `code` 显式声明以去掉默认 UniqueValidator，改用自定义错误码校验唯一性。
    - `banner_url` 返回可访问的完整 URL（未配置时为空串，便于管理端识别「未设图」）。
    """
    code = serializers.CharField(max_length=100)
    banner_url = serializers.SerializerMethodField()

    class Meta:
        model = Institution
        fields = [
            'id', 'code', 'name', 'type', 'level',
            'province', 'city', 'banner_url', 'created_at', 'updated_at',
        ]
        read_only_fields = ['id', 'created_at', 'updated_at']

    def get_banner_url(self, obj):
        if not obj.banner_url:
            return ''
        value = obj.banner_url
        if value.startswith(('http://', 'https://')):
            return value
        request = self.context.get('request')
        prefix = getattr(settings, 'STATIC_PUBLIC_PREFIX', '').rstrip('/')
        path = prefix + '/' + settings.STATIC_URL.strip('/') + '/' + value.lstrip('/')
        return request.build_absolute_uri(path) if request else path

    def validate_code(self, value):
        value = (value or '').strip()
        if not value:
            raise AppError('CMS_VALIDATION_ERROR', '机构编码不能为空', status_code=400)
        # 唯一性按 all_objects（含已停用）判定：编码唯一约束对软删行仍生效，
        # 否则同编码重建会在写库时撞唯一约束抛 500。
        qs = Institution.all_objects.filter(code=value)
        if self.instance is not None:
            qs = qs.exclude(pk=self.instance.pk)
        if qs.exists():
            raise AppError('CMS_INSTITUTION_CODE_EXISTS',
                           '机构编码已存在（含已停用机构），如需复用请先恢复或更换编码',
                           status_code=400)
        return value


class CmsDepartmentSerializer(serializers.ModelSerializer):
    """CMS 科室（全局表，与机构无关）。"""
    name = serializers.CharField(max_length=100)

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

    def validate_name(self, value):
        value = (value or '').strip()
        if not value:
            raise AppError('CMS_VALIDATION_ERROR', '科室名称不能为空', status_code=400)
        # 唯一性按 all_objects（含已停用）判定，避免同名重建在写库时撞唯一约束抛 500。
        qs = Department.all_objects.filter(name=value)
        if self.instance is not None:
            qs = qs.exclude(pk=self.instance.pk)
        if qs.exists():
            raise AppError('CMS_DEPARTMENT_NAME_EXISTS',
                           '科室名称已存在（含已停用科室），如需复用请先恢复或更换名称',
                           status_code=400)
        return value