from rest_framework import serializers
from apps.support.models import SupportRoom, SupportMessage
from utils import absolute_https_url


class SupportMessageSerializer(serializers.ModelSerializer):
    sender_name = serializers.SerializerMethodField()
    timestamp_ms = serializers.SerializerMethodField()

    class Meta:
        model = SupportMessage
        fields = (
            'id',
            'room',
            'sender_type',
            'sender_name',
            'content',
            'is_read',
            'created_at',
            'timestamp_ms',
        )
        read_only_fields = fields

    def get_sender_name(self, obj: SupportMessage) -> str:
        if obj.sender_type == SupportMessage.SenderType.SUPPORT:
            if obj.sender and obj.sender.fullname:
                return obj.sender.fullname
            return 'Support Specialist'
        if obj.sender and obj.sender.fullname:
            return obj.sender.fullname
        return 'You'

    def get_timestamp_ms(self, obj: SupportMessage) -> int:
        if not obj.created_at:
            return 0
        return int(obj.created_at.timestamp() * 1000)


class SendSupportMessageSerializer(serializers.Serializer):
    content = serializers.CharField(
        required=True,
        allow_blank=False,
        max_length=4000,
        trim_whitespace=True,
    )


class SupportRoomSerializer(serializers.ModelSerializer):
    class Meta:
        model = SupportRoom
        fields = (
            'id',
            'status',
            'unread_by_user',
            'last_message_at',
            'created_at',
        )
        read_only_fields = fields


def serialize_admin_chat_user(user, request=None) -> dict:
    if not user:
        return {
            'id': 0,
            'email': '',
            'fullname': 'Unknown User',
            'avatar': '',
            'phone_number': '',
            'language': '',
            'gender': '',
            'user_type': 'client',
            'is_guest': True,
        }

    is_guest = getattr(user, 'is_guest', False) or not bool(user.email)
    fullname = (user.fullname or '').strip()
    if not fullname:
        if user.email:
            fullname = user.email.split('@')[0]
        else:
            fullname = f"Guest #{user.id}"

    avatar_url = ''
    if getattr(user, 'avatar', None):
        try:
            avatar_url = (
                absolute_https_url(user.avatar.url, request)
                if request
                else user.avatar.url
            ) or ''
        except Exception:
            avatar_url = ''

    return {
        'id': user.id,
        'email': user.email or '',
        'fullname': fullname,
        'avatar': avatar_url,
        'phone_number': str(user.phone_number) if getattr(user, 'phone_number', None) else '',
        'language': str(user.language) if getattr(user, 'language', None) else '',
        'gender': user.gender or '',
        'user_type': 'guest' if is_guest else (user.user_type or 'client'),
        'is_guest': is_guest,
    }


def detect_content_type(content: str) -> str:
    if not content:
        return 'text'
    lower = content.lower().strip()
    if lower.startswith(('http://', 'https://', '/media/')):
        if any(lower.endswith(ext) for ext in ('.png', '.jpg', '.jpeg', '.gif', '.webp', '.svg')):
            return 'image'
        if any(lower.endswith(ext) for ext in ('.mp3', '.wav', '.ogg', '.webm', '.m4a')):
            return 'audio'
        if any(lower.endswith(ext) for ext in ('.mp4', '.mov', '.mkv')):
            return 'video'
    return 'text'


class AdminSupportMessageSerializer(serializers.ModelSerializer):
    room_id = serializers.IntegerField(read_only=True)
    sender = serializers.SerializerMethodField()
    content_type = serializers.SerializerMethodField()
    sent_at = serializers.SerializerMethodField()
    updated_at = serializers.SerializerMethodField()
    is_deleted = serializers.SerializerMethodField()

    class Meta:
        model = SupportMessage
        fields = (
            'id',
            'room_id',
            'sender_type',
            'sender',
            'content',
            'content_type',
            'sent_at',
            'updated_at',
            'is_read',
            'is_deleted',
        )
        read_only_fields = fields

    def get_sender(self, obj: SupportMessage) -> dict:
        request = self.context.get('request')
        if obj.sender_type == SupportMessage.SenderType.SUPPORT:
            sender_user = obj.sender or (request.user if request and request.user.is_authenticated else None)
            data = serialize_admin_chat_user(sender_user, request=request)
            if not sender_user:
                data['fullname'] = 'Support Specialist'
            return data
        sender_user = obj.sender or (obj.room.user if obj.room_id else None)
        return serialize_admin_chat_user(sender_user, request=request)

    def get_content_type(self, obj: SupportMessage) -> str:
        return detect_content_type(obj.content)

    def get_sent_at(self, obj: SupportMessage) -> str:
        return obj.created_at.isoformat() if obj.created_at else ''

    def get_updated_at(self, obj: SupportMessage) -> str:
        return obj.created_at.isoformat() if obj.created_at else ''

    def get_is_deleted(self, obj: SupportMessage) -> bool:
        return False


class AdminSupportRoomSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField()
    room_type = serializers.SerializerMethodField()
    initiator = serializers.SerializerMethodField()
    recipient = serializers.SerializerMethodField()
    participants = serializers.SerializerMethodField()
    unread_messages_count = serializers.IntegerField(source='unread_by_admin', read_only=True)
    last_message = serializers.SerializerMethodField()

    class Meta:
        model = SupportRoom
        fields = (
            'id',
            'name',
            'room_type',
            'status',
            'initiator',
            'recipient',
            'participants',
            'unread_messages_count',
            'last_message',
            'created_at',
            'updated_at',
        )
        read_only_fields = fields

    def get_name(self, obj: SupportRoom) -> str:
        request = self.context.get('request')
        user_data = serialize_admin_chat_user(obj.user, request=request)
        return user_data['fullname']

    def get_room_type(self, obj: SupportRoom) -> str:
        return 'private'

    def get_initiator(self, obj: SupportRoom) -> dict:
        request = self.context.get('request')
        return serialize_admin_chat_user(obj.user, request=request)

    def get_recipient(self, obj: SupportRoom) -> dict:
        request = self.context.get('request')
        specialist = obj.assigned_to or (request.user if request and request.user.is_authenticated else None)
        return serialize_admin_chat_user(specialist, request=request)

    def get_participants(self, obj: SupportRoom) -> list:
        return [self.get_initiator(obj), self.get_recipient(obj)]

    def get_last_message(self, obj: SupportRoom):
        last_msg = getattr(obj, '_prefetched_last_message', None)
        if last_msg is None:
            last_msg = obj.messages.order_by('-id').first()
        if not last_msg:
            return None
        return {
            'id': last_msg.id,
            'content': last_msg.content,
            'content_type': detect_content_type(last_msg.content),
            'sent_at': last_msg.created_at.isoformat() if last_msg.created_at else '',
            'sender_type': last_msg.sender_type,
        }