from django.conf import settings
from django.utils import timezone
from rest_framework import serializers
from rest_framework_gis.serializers import GeoFeatureModelSerializer

from apps.utils.storage import generate_presigned_put_url, preview_url
from .models import Splat


class SplatJobSummarySerializer(serializers.Serializer):
    """Inlined job status — used in SplatMineSerializer."""
    id = serializers.UUIDField()
    status = serializers.CharField()
    current_step = serializers.CharField()
    progress = serializers.IntegerField()
    error_message = serializers.CharField()
    queued_at = serializers.DateTimeField()
    started_at = serializers.DateTimeField()
    finished_at = serializers.DateTimeField()


class SplatCreateSerializer(serializers.ModelSerializer):
    challenge_id = serializers.UUIDField(required=False, allow_null=True)
    capture_metadata = serializers.JSONField()

    class Meta:
        model = Splat
        fields = ["challenge_id", "capture_metadata"]

    def validate_capture_metadata(self, value):
        frames = value.get("frames", [])
        min_frames = settings.MIN_CAPTURE_FRAMES
        if len(frames) < min_frames:
            raise serializers.ValidationError(
                f"capture_metadata must contain at least {min_frames} frames; "
                f"got {len(frames)}."
            )
        return value


class SplatCreateResponseSerializer(serializers.Serializer):
    """Shape of the POST /splats/ response — not a ModelSerializer."""
    id = serializers.UUIDField()
    status = serializers.CharField()
    upload_url = serializers.CharField(allow_null=True)
    upload_expires_at = serializers.DateTimeField()


class SplatMapSerializer(GeoFeatureModelSerializer):
    """GeoJSON FeatureCollection for the map tile endpoint."""
    preview_url = serializers.SerializerMethodField()

    class Meta:
        model = Splat
        geo_field = "location"
        fields = ["id", "heading", "altitude", "preview_url", "splat_file_size", "created_at"]

    def get_preview_url(self, obj):
        return preview_url(obj.preview_key)


class SplatDetailSerializer(serializers.ModelSerializer):
    coverage = serializers.SerializerMethodField()
    preview_url = serializers.SerializerMethodField()
    owner_username = serializers.CharField(source="owner.username", read_only=True)
    challenge_id = serializers.UUIDField(read_only=True)

    class Meta:
        model = Splat
        fields = [
            "id", "owner_username", "challenge_id", "status", "is_published",
            "location", "coverage", "heading", "altitude",
            "preview_url", "splat_file_size",
            "quality_score", "frame_count",
            "created_at", "updated_at",
        ]

    def get_coverage(self, obj):
        if obj.coverage:
            return obj.coverage.geojson
        return None

    def get_preview_url(self, obj):
        return preview_url(obj.preview_key)


class SplatMineSerializer(serializers.ModelSerializer):
    job = serializers.SerializerMethodField()
    preview_url = serializers.SerializerMethodField()

    class Meta:
        model = Splat
        fields = [
            "id", "status", "is_published",
            "challenge_id", "preview_url",
            "quality_score", "frame_count",
            "created_at", "updated_at",
            "job",
        ]

    def get_job(self, obj):
        try:
            j = obj.job
        except Splat.job.RelatedObjectDoesNotExist:
            return None
        return SplatJobSummarySerializer(j).data

    def get_preview_url(self, obj):
        return preview_url(obj.preview_key)