from rest_framework import serializers
from django.contrib.auth import authenticate
from django.contrib.auth.password_validation import validate_password
from django.core.exceptions import ValidationError

from role.models import Role
from role.serializers import RoleSerializer
from branch.serializers import BranchSerializer
from .models import User, LoginSession


class RegisterSerializer(serializers.ModelSerializer):
    password = serializers.CharField(write_only=True, required=True, validators=[validate_password])
    password2 = serializers.CharField(write_only=True, required=True)
    
    role_id = serializers.PrimaryKeyRelatedField(
        queryset=Role.objects.all(), source='role', write_only=True
    )
    
    role = RoleSerializer(read_only=True)

    class Meta:
        model = User
        fields = ('id', 'username', 'email', 'first_name', 'last_name', 'password', 'password2', 'role_id', 'role', 'branch', 'date_created')

    def validate(self, data):
        if data['password'] != data['password2']:
            raise serializers.ValidationError({"password": "Password fields didn't match."})
        return data

    def create(self, validated_data):
        validated_data.pop('password2')
        user = User.objects.create_user(**validated_data)
        return user


class LoginSerializer(serializers.Serializer):
    username = serializers.CharField(required=True)
    password = serializers.CharField(write_only=True, required=True)
    branch_id = serializers.IntegerField(required=False, allow_null=True)

    def validate(self, data):
        user = authenticate(username=data['username'], password=data['password'])
        if not user:
            raise serializers.ValidationError("Invalid credentials.")
        
        # Check if user is admin (check for 'Admin' role)
        is_admin = user.role and user.role.name.lower() == 'admin'
        
        # Require branch_id only for non-admin users
        if not is_admin and not data.get('branch_id'):
            raise serializers.ValidationError({"branch_id": "branch_id is required for non-admin users."})
        
        data['user'] = user
        return data


class ChangePasswordSerializer(serializers.Serializer):
    old_password = serializers.CharField(write_only=True, required=True)
    new_password = serializers.CharField(write_only=True, required=True, validators=[validate_password])
    new_password2 = serializers.CharField(write_only=True, required=True)

    def validate(self, data):
        if data['new_password'] != data['new_password2']:
            raise serializers.ValidationError({"new_password": "Password fields didn't match."})
        return data

    def validate_old_password(self, value):
        user = self.context['request'].user
        if not user.check_password(value):
            raise serializers.ValidationError("Old password is not correct.")
        return value


class ForgotPasswordSerializer(serializers.Serializer):
    email = serializers.EmailField(required=True)

    def validate_email(self, value):
        try:
            User.objects.get(email=value)
        except User.DoesNotExist:
            raise serializers.ValidationError("User with this email does not exist.")
        return value


class ResetPasswordSerializer(serializers.Serializer):
    token = serializers.CharField(required=True)
    new_password = serializers.CharField(write_only=True, required=True, validators=[validate_password])
    new_password2 = serializers.CharField(write_only=True, required=True)

    def validate(self, data):
        if data['new_password'] != data['new_password2']:
            raise serializers.ValidationError({"new_password": "Password fields didn't match."})
        return data


class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'username', 'email', 'first_name', 'last_name', 'branch', 'date_created', 'role')


class LoginSessionSerializer(serializers.ModelSerializer):
    user = UserSerializer(read_only=True)
    branch = BranchSerializer(read_only=True)
    
    class Meta:
        model = LoginSession
        fields = ('id', 'user', 'branch', 'login_time', 'logout_time', 'ip_address', 'user_agent')


class LoginResponseSerializer(serializers.Serializer):
    message = serializers.CharField()
    access = serializers.CharField()
    refresh = serializers.CharField()
    user = UserSerializer()
    # session = LoginSessionSerializer()