from rest_framework import serializers

from apps.groups.models import GroupMembership, MemberProgress, ReadingGroup


class GroupMembershipSerializer(serializers.ModelSerializer):
    user_email = serializers.CharField(source="user.email", read_only=True)
    user_id = serializers.IntegerField(source="user.id", read_only=True)
    role = serializers.CharField(read_only=True)

    class Meta:
        model = GroupMembership
        fields = ["id", "user_id", "user_email", "role", "joined_at"]


class MemberProgressSerializer(serializers.ModelSerializer):
    user_email = serializers.CharField(source="user.email", read_only=True)
    user_id = serializers.IntegerField(source="user.id", read_only=True)
    total_sections = serializers.SerializerMethodField()
    section_label = serializers.SerializerMethodField()

    class Meta:
        model = MemberProgress
        fields = [
            "id",
            "user_id",
            "user_email",
            "current_section",
            "total_sections",
            "section_label",
            "percentage",
            "time_spent_seconds",
            "last_position",
            "is_public",
            "updated_at",
        ]
        read_only_fields = ["id", "user_id", "user_email", "updated_at"]
        extra_kwargs = {
            "percentage": {"required": False, "min_value": 0.0, "max_value": 100.0},
        }

    def get_total_sections(self, obj: MemberProgress) -> int:
        return obj.total_sections()

    def get_section_label(self, obj: MemberProgress) -> str:
        ts = obj.total_sections()
        if ts:
            return f"Section {obj.current_section} of {ts}"
        return "No sections"

    def validate_percentage(self, value: float) -> float:
        if value < 0.0 or value > 100.0:
            raise serializers.ValidationError("Percentage must be between 0.0 and 100.0.")
        return value


class MemberProgressPublicSerializer(serializers.ModelSerializer):
    """Limited view for other group members — section label only, no exact position."""

    user_email = serializers.CharField(source="user.email", read_only=True)
    user_id = serializers.IntegerField(source="user.id", read_only=True)
    total_sections = serializers.SerializerMethodField()
    section_label = serializers.SerializerMethodField()

    class Meta:
        model = MemberProgress
        fields = [
            "user_id",
            "user_email",
            "current_section",
            "total_sections",
            "section_label",
            "percentage",
            "time_spent_seconds",
            "updated_at",
        ]

    def get_total_sections(self, obj: MemberProgress) -> int:
        return obj.total_sections()

    def get_section_label(self, obj: MemberProgress) -> str:
        ts = obj.total_sections()
        if ts:
            return f"Section {obj.current_section} of {ts}"
        return "No sections"


class MemberProgressUpdateSerializer(serializers.Serializer):
    current_section = serializers.IntegerField(min_value=0)
    percentage = serializers.FloatField(required=False, min_value=0.0, max_value=100.0)
    time_spent_delta = serializers.IntegerField(default=0, min_value=0)
    last_position = serializers.JSONField(required=False, default=dict)
    is_public = serializers.BooleanField(required=False)


class ReadingGroupListSerializer(serializers.ModelSerializer):
    created_by_email = serializers.CharField(source="created_by.email", read_only=True)
    ebook_title = serializers.CharField(source="ebook.title", read_only=True)
    ebook_author = serializers.CharField(source="ebook.author", read_only=True)
    member_count = serializers.SerializerMethodField()
    my_progress = serializers.SerializerMethodField()

    class Meta:
        model = ReadingGroup
        fields = [
            "id",
            "name",
            "ebook",
            "ebook_title",
            "ebook_author",
            "created_by_email",
            "description",
            "member_count",
            "my_progress",
            "created_at",
            "updated_at",
        ]

    def get_member_count(self, obj: ReadingGroup) -> int:
        return obj.memberships.count()

    def get_my_progress(self, obj: ReadingGroup) -> dict | None:
        request = self.context.get("request")
        if not request or not request.user.is_authenticated:
            return None
        try:
            mp = MemberProgress.objects.get(group=obj, user=request.user)
        except MemberProgress.DoesNotExist:
            return None
        return {
            "current_section": mp.current_section,
            "percentage": mp.percentage,
            "time_spent_seconds": mp.time_spent_seconds,
            "section_label": MemberProgressSerializer().get_section_label(mp),
        }


class ReadingGroupDetailSerializer(ReadingGroupListSerializer):
    members = serializers.SerializerMethodField()

    class Meta(ReadingGroupListSerializer.Meta):
        fields = ReadingGroupListSerializer.Meta.fields + ["members"]

    def get_members(self, obj: ReadingGroup) -> list[dict]:
        memberships = obj.memberships.select_related("user").prefetch_related("progress")
        result: list[dict] = []
        for m in memberships:
            entry: dict = {
                "id": m.id,
                "user_id": m.user.id,
                "user_email": m.user.email,
                "role": m.role,
                "joined_at": m.joined_at,
            }
            try:
                mp = m.progress
            except MemberProgress.DoesNotExist:
                entry["progress"] = None
            else:
                if mp.is_public:
                    entry["progress"] = MemberProgressPublicSerializer(mp).data
                else:
                    entry["progress"] = {"is_public": False, "note": "Private"}
            result.append(entry)
        return result


class ReadingGroupCreateSerializer(serializers.ModelSerializer):
    class Meta:
        model = ReadingGroup
        fields = ["name", "ebook", "description"]


class AdminProgressSummarySerializer(serializers.Serializer):
    group_id = serializers.IntegerField()
    group_name = serializers.CharField()
    ebook_title = serializers.CharField()
    total_members = serializers.IntegerField()
    members_started = serializers.IntegerField()
    members_finished = serializers.IntegerField()
    average_percentage = serializers.FloatField()
    average_time_spent_hours = serializers.FloatField()
    member_details = serializers.ListField(child=serializers.JSONField())