import json

from django.db.models import TextField, Value
from django.db.models.functions import Coalesce


def _safe_json_loads(raw):
    if raw in (None, ""):
        return None
    try:
        return json.loads(raw)
    except Exception:
        return None


def is_polygon_annotation_content(content) -> bool:
    parsed = _safe_json_loads(content)
    if isinstance(parsed, dict):
        if parsed.get("type") == "polygon":
            return True
        if isinstance(parsed.get("shapes"), list):
            return True
    if isinstance(parsed, list):
        for item in parsed:
            if not isinstance(item, dict):
                continue
            region = item.get("region")
            if isinstance(region, list) and region and isinstance(region[0], (list, tuple)):
                return True
    return False


def split_dataset_sample_annotation_content(content):
    raw = content or ""
    if not raw:
        return {"rectangle": None, "polygon": None}
    if is_polygon_annotation_content(raw):
        return {"rectangle": None, "polygon": raw}
    return {"rectangle": raw, "polygon": None}


def get_dataset_sample_annotation_content(sample) -> str:
    if sample is None:
        return ""
    polygon = getattr(sample, "polygon", None)
    rectangle = getattr(sample, "rectangle", None)
    return polygon or rectangle or ""


def get_dataset_sample_annotation_from_row(sample_row: dict) -> str:
    if not isinstance(sample_row, dict):
        return ""
    return sample_row.get("polygon") or sample_row.get("rectangle") or sample_row.get("annotation_content") or ""


def annotate_queryset_with_annotation_content(queryset, alias: str = "annotation_content"):
    return queryset.annotate(
        **{
            alias: Coalesce("polygon", "rectangle", Value("", output_field=TextField()), output_field=TextField()),
        }
    )