from __future__ import annotations

from rest_framework import serializers

from apps.groups.models import (
    FrequencyChoice,
    GroupMeeting,
    GroupMembership,
    NotificationPreference,
    PaceNotification,
    ReadingGroup,
)
from apps.groups.services.pace import PaceStatus


class NotificationPreferenceSerializer(serializers.ModelSerializer):
    class Meta:
        model = NotificationPreference
        fields = [
            "pace_notifications_enabled",
            "reminder_enabled",
            "frequency",
        ]

    def validate_frequency(self, value: str) -> str:
        valid = {choice[0] for choice in FrequencyChoice.choices}
        if value not in valid:
            raise serializers.ValidationError(
                f"Frequency must be one of: {', '.join(valid)}"
            )
        return value


class GroupMeetingSerializer(serializers.ModelSerializer):
    group_name = serializers.CharField(source="group.name", read_only=True)

    class Meta:
        model = GroupMeeting
        fields = [
            "id",
            "group",
            "group_name",
            "title",
            "scheduled_at",
            "target_section",
            "target_section_label",
            "created_at",
        ]
        read_only_fields = ["id", "created_at"]

    def validate_target_section(self, value: int) -> int:
        if value < 0:
            raise serializers.ValidationError("Target section must be non-negative.")
        return value


class ReadingGroupSerializer(serializers.ModelSerializer):
    member_count = serializers.SerializerMethodField()
    meeting_count = serializers.SerializerMethodField()

    class Meta:
        model = ReadingGroup
        fields = [
            "id",
            "name",
            "description",
            "book",
            "ebook",
            "created_by",
            "created_at",
            "member_count",
            "meeting_count",
        ]
        read_only_fields = ["id", "created_by", "created_at"]

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

    def get_meeting_count(self, obj: ReadingGroup) -> int:
        return obj.meetings.count()


class GroupMembershipSerializer(serializers.ModelSerializer):
    user_email = serializers.CharField(source="user.email", read_only=True)
    group_name = serializers.CharField(source="group.name", read_only=True)

    class Meta:
        model = GroupMembership
        fields = ["id", "user", "user_email", "group", "group_name", "role", "joined_at"]
        read_only_fields = ["id", "joined_at"]


class PaceNotificationSerializer(serializers.ModelSerializer):
    status_display = serializers.CharField(source="get_status_display", read_only=True)

    class Meta:
        model = PaceNotification
        fields = [
            "id",
            "user",
            "meeting",
            "ebook",
            "status",
            "status_display",
            "current_section",
            "target_section",
            "ahead_behind_delta",
            "created_at",
        ]
        read_only_fields = ["id", "created_at"]


class PaceStatusSerializer(serializers.Serializer):
    meeting_id = serializers.IntegerField()
    meeting_title = serializers.CharField()
    scheduled_at = serializers.CharField()
    target_section = serializers.IntegerField()
    target_section_label = serializers.CharField()
    current_section = serializers.IntegerField()
    ahead_behind_delta = serializers.IntegerField()
    status = serializers.CharField()
    days_until_meeting = serializers.IntegerField()
    sections_to_catch_up = serializers.IntegerField()
    ebook_id = serializers.IntegerField()
    ebook_title = serializers.CharField()


class ReminderSerializer(serializers.Serializer):
    meeting_id = serializers.IntegerField()
    meeting_title = serializers.CharField()
    scheduled_at = serializers.CharField()
    target_section = serializers.IntegerField()
    target_section_label = serializers.CharField()
    group_name = serializers.CharField()
    hours_until = serializers.IntegerField()
    ebook_id = serializers.IntegerField()
    ebook_title = serializers.CharField()