"""Explicitly remove attachments belonging to conversations without v2 image observations.

The command is dry-run by default. It only mutates data when ``--apply`` is
provided, and it never removes CAD task artifacts.
"""

from __future__ import annotations

import argparse
import shutil
from pathlib import Path
import sys

BACKEND_ROOT = Path(__file__).resolve().parents[1]
if str(BACKEND_ROOT) not in sys.path:
    sys.path.insert(0, str(BACKEND_ROOT))

from app.services.storage import read_json, write_json
from app.settings import get_settings


def _has_v2_observation(record: dict) -> bool:
    for message in record.get("messages") or []:
        if not isinstance(message, dict):
            continue
        for part in message.get("parts") or []:
            if not isinstance(part, dict) or part.get("type") != "data-cad-image-analysis":
                continue
            data = part.get("data")
            if isinstance(data, dict) and str(data.get("schemaVersion") or data.get("schema_version") or "") == "cad.image-observation.v2":
                return True
    return False


def plan_cleanup(root: Path) -> list[tuple[Path, str]]:
    planned: list[tuple[Path, str]] = []
    for conversation_dir in sorted(root.glob("conv_*")):
        record_path = conversation_dir / "conversation.json"
        record = read_json(record_path)
        if not isinstance(record, dict) or _has_v2_observation(record):
            continue
        uploads = conversation_dir / "uploads"
        if uploads.is_dir():
            planned.append((uploads, "legacy upload directory"))
        planning = conversation_dir / "planning"
        if planning.is_dir():
            planned.append((planning, "legacy planning directory"))
        if record.get("attachments"):
            planned.append((record_path, "remove legacy attachment metadata and image-analysis parts"))
    return planned


def apply_cleanup(root: Path) -> int:
    changed = 0
    for conversation_dir in sorted(root.glob("conv_*")):
        record_path = conversation_dir / "conversation.json"
        record = read_json(record_path)
        if not isinstance(record, dict) or _has_v2_observation(record):
            continue
        for relative in ("uploads", "planning"):
            target = conversation_dir / relative
            if target.is_dir():
                shutil.rmtree(target)
                changed += 1
        record["attachments"] = []
        for message in record.get("messages") or []:
            if not isinstance(message, dict):
                continue
            message["parts"] = [
                part for part in message.get("parts") or []
                if not (isinstance(part, dict) and part.get("type") == "data-cad-image-analysis")
            ]
        write_json(record_path, record)
        changed += 1
    return changed


def main() -> int:
    parser = argparse.ArgumentParser(description="Remove legacy conversation attachments")
    parser.add_argument("--apply", action="store_true", help="perform deletion; default is dry-run")
    parser.add_argument("--dry-run", action="store_true", help="list deletion targets without changing files")
    args = parser.parse_args()
    root = get_settings().conversation_root.resolve()
    if root.name != "conversations":
        raise SystemExit(f"Refusing unexpected conversation root: {root}")
    planned = plan_cleanup(root)
    for path, reason in planned:
        print(f"{'DELETE' if args.apply else 'WOULD DELETE'} {path} ({reason})")
    if not args.apply:
        print(f"Dry-run: {len(planned)} targets. Re-run with --apply to delete.")
        return 0
    print(f"Deleted {apply_cleanup(root)} conversation records/directories.")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())