from pathlib import Path

from django.contrib.auth.password_validation import validate_password
from django.core import signing
from rest_framework import serializers

from apps.library.services import MEDIA_FILE_SALT, VIDEO_EXTENSIONS

from .models import User


def signed_media_url(request, item):
    """A signed media URL an <img> tag can load for an authenticated user."""
    if item is None:
        return None
    user = getattr(request, "user", None)
    if user is None or not getattr(user, "is_authenticated", False):
        return None
    location = item.locations.first()
    is_video = (
        location is not None
        and Path(location.rel_path).suffix.lower() in VIDEO_EXTENSIONS
    )
    action = "thumbnail" if is_video else "raw"
    signature = signing.dumps(
        {"item": item.id, "user": user.id, "action": action},
        salt=MEDIA_FILE_SALT,
    )
    return f"/api/files/J-{item.id}/{action}/?sig={signature}"


class UserSerializer(serializers.ModelSerializer):
    e621_configured = serializers.BooleanField(read_only=True)
    can_upload = serializers.BooleanField(read_only=True)
    avatar_j_id = serializers.SerializerMethodField()
    avatar_url = serializers.SerializerMethodField()

    class Meta:
        model = User
        fields = [
            "id",
            "username",
            "email",
            "is_staff",
            "is_superuser",
            "date_joined",
            "role",
            "can_upload",
            "avatar_j_id",
            "avatar_url",
            "e621_username",
            "e621_configured",
            "preferences",
        ]
        read_only_fields = fields

    def get_avatar_j_id(self, obj):
        return f"J-{obj.avatar_id}" if obj.avatar_id else None

    def get_avatar_url(self, obj):
        return signed_media_url(self.context.get("request"), obj.avatar)


class UserListSerializer(serializers.ModelSerializer):
    avatar_j_id = serializers.SerializerMethodField()
    avatar_url = serializers.SerializerMethodField()
    uploads_count = serializers.IntegerField(read_only=True)

    class Meta:
        model = User
        fields = [
            "id",
            "username",
            "email",
            "role",
            "is_staff",
            "is_superuser",
            "date_joined",
            "avatar_j_id",
            "avatar_url",
            "uploads_count",
        ]
        read_only_fields = fields

    def get_avatar_j_id(self, obj):
        return f"J-{obj.avatar_id}" if obj.avatar_id else None

    def get_avatar_url(self, obj):
        return signed_media_url(self.context.get("request"), obj.avatar)


class UserUpdateSerializer(serializers.Serializer):
    avatar_j_id = serializers.CharField(
        required=False, allow_blank=True, allow_null=True
    )
    role = serializers.ChoiceField(choices=User.ROLE_CHOICES, required=False)


class RegisterSerializer(serializers.ModelSerializer):
    password = serializers.CharField(write_only=True, validators=[validate_password])

    class Meta:
        model = User
        fields = ["username", "email", "password"]

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


class E621CredentialsSerializer(serializers.Serializer):
    username = serializers.CharField(max_length=100, allow_blank=True)
    api_key = serializers.CharField(
        max_length=100, allow_blank=True, trim_whitespace=True
    )
    base_url = serializers.URLField(
        max_length=200, required=False, allow_blank=True
    )


class PreferencesSerializer(serializers.Serializer):
    """Per-user browse preferences; unknown keys are ignored."""

    LANDING_PAGES = ["library", "online", "pools", "followed"]

    landing_page = serializers.ChoiceField(choices=LANDING_PAGES, required=False)
    ratings = serializers.ListField(
        child=serializers.ChoiceField(choices=["s", "q", "e"]),
        required=False,
        max_length=3,
    )
    ordering = serializers.CharField(max_length=30, required=False)
    per_page = serializers.IntegerField(min_value=12, max_value=200, required=False)
    zoom = serializers.IntegerField(min_value=120, max_value=400, required=False)