import re

from rest_framework import serializers
from .models import User, Role, TeacherStudentRelation, Institution, Department


class UserSerializer(serializers.ModelSerializer):
    institution_name = serializers.CharField(source='institution.name', read_only=True)
    department_name = serializers.CharField(source='department.name', read_only=True)

    class Meta:
        model = User
        fields = [
            'id', 'username', 'real_name', 'phone', 'avatar',
            'gender', 'role_type', 'institution', 'institution_name',
            'department', 'department_name', 'title_name', 'practice_years',
            'major', 'training_stage', 'learning_target', 'competency_profile',
            'weak_dimensions', 'strong_dimensions', 'ai_preference',
            'total_training_count', 'total_case_count', 'current_level',
            'status', 'last_login_time', 'created_at', 'updated_at'
        ]
        extra_kwargs = {
            'password': {'write_only': True},
        }


class UserCreateSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = [
            'id', 'username', 'password', 'real_name', 'phone',
            'gender', 'role_type', 'institution', 'department',
            'title_name', 'major', 'training_stage', 'status'
        ]
        extra_kwargs = {
            'password': {'write_only': True},
        }

    def create(self, validated_data):
        user = User.objects.create_user(**validated_data)
        return user


class UserUpdateSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = [
            'real_name', 'phone', 'avatar', 'gender', 'role_type',
            'institution', 'department', 'title_name', 'practice_years',
            'major', 'training_stage', 'learning_target', 'status'
        ]


class ProfileUpdateSerializer(serializers.ModelSerializer):
    """个人信息更新（移动端个人中心）——仅允许用户自助修改的字段。

    白名单字段：username / real_name / phone / avatar / gender / department /
    title_name / major / practice_years / training_stage / learning_target。
    机构（institution）、角色（role_type）、is_superuser 等不在字段内，无法被用户修改。
    """
    # 显式声明以去掉 ModelSerializer 自动加的 UniqueValidator，改用自定义唯一性校验
    username = serializers.CharField(max_length=50)
    phone = serializers.CharField(max_length=20, required=False, allow_blank=True)

    class Meta:
        model = User
        fields = [
            'username', 'real_name', 'phone', 'avatar', 'gender',
            'department', 'title_name', 'major', 'practice_years',
            'training_stage', 'learning_target',
        ]

    def validate_username(self, value):
        value = (value or '').strip()
        if not value:
            raise serializers.ValidationError('用户名不能为空')
        if User.objects.filter(username=value).exclude(pk=self.instance.pk).exists():
            raise serializers.ValidationError('用户名已被占用')
        return value

    def validate_phone(self, value):
        value = (value or '').strip()
        if value:
            if not re.match(r'^1[3-9]\d{9}$', value):
                raise serializers.ValidationError('手机号格式不合法')
            if User.objects.filter(phone=value).exclude(pk=self.instance.pk).exists():
                raise serializers.ValidationError('手机号已被占用')
        return value


class StudentProfileConfigSerializer(serializers.Serializer):
    """医学生信息配置（首次进入系统）——科室、专业职称、执业年限。

    科室为全局表，用户可自由选择想学习的科室，不再校验机构归属。
    """
    department = serializers.PrimaryKeyRelatedField(
        queryset=Department.objects.all(), help_text='科室 ID（全局科室）'
    )
    title_name = serializers.CharField(max_length=50, help_text='专业职称，如：住院医师')
    practice_years = serializers.CharField(max_length=20, help_text='执业年限，如：1-3年')


class UserPasswordSerializer(serializers.Serializer):
    """密码修改序列化器"""
    old_password = serializers.CharField(required=True, write_only=True)
    new_password = serializers.CharField(required=True, write_only=True, min_length=6)


class RoleSerializer(serializers.ModelSerializer):
    class Meta:
        model = Role
        fields = '__all__'


class TeacherStudentRelationSerializer(serializers.ModelSerializer):
    teacher_name = serializers.CharField(source='teacher.real_name', read_only=True)
    student_name = serializers.CharField(source='student.real_name', read_only=True)

    class Meta:
        model = TeacherStudentRelation
        fields = '__all__'


class InstitutionSerializer(serializers.ModelSerializer):
    class Meta:
        model = Institution
        fields = '__all__'


class DepartmentSerializer(serializers.ModelSerializer):
    class Meta:
        model = Department
        fields = '__all__'