"""Read-only migration audit by default; apply creates a consistent backup first.

Use backend/venv/Scripts/python.exe scripts/assistant_migrate.py --dry-run.
Restore produces a separate recovered database, never overwrites post-release writes.
"""
import argparse
import json
import sqlite3
import sys
from datetime import datetime
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT / "backend"))


def audit(path):
    if not path.is_file():
        return {"database": str(path), "exists": False, "action": "initialize-demo-instance", "dangling_references": []}
    with sqlite3.connect(path.as_uri() + "?mode=ro", uri=True) as db:
        tables = {r[0] for r in db.execute("SELECT name FROM sqlite_master WHERE type='table'")}
        counts = {name: db.execute('SELECT count(*) FROM "' + name + '"').fetchone()[0] for name in tables if name in ("projects", "runs", "snapshots", "reports", "experiences", "assistant_objects", "assistant_jobs")}
        dangling = []
        if "assistant_objects" in tables:
            objects = {(r[0], r[1]): json.loads(r[2]) for r in db.execute("SELECT kind,id,body FROM assistant_objects")}
            for (kind, key), body in objects.items():
                for field, target in (("snapshot_id", "snapshot"), ("input_snapshot_id", "input_snapshot"), ("run_id", "run"), ("document_ids", "document")):
                    if kind not in ("run", "report", "report_final", "project", "experience_application"):
                        continue
                    values = body.get(field)
                    for value in (values if isinstance(values, list) else [values]):
                        if value and (target, value) not in objects:
                            dangling.append({"kind": kind, "id": key, "field": field, "missing": value})
        return {"database": str(path), "exists": True, "counts": counts, "integrity": db.execute("PRAGMA integrity_check").fetchone()[0], "dangling_references": dangling}


def backup(source, target):
    if target.exists() or source == target:
        raise ValueError("备份目标已存在或与源相同，拒绝覆盖")
    target.parent.mkdir(parents=True, exist_ok=True)
    original = sqlite3.connect(source.as_uri() + "?mode=ro", uri=True)
    output = sqlite3.connect(target)
    try:
        original.backup(output)
    finally:
        output.close()
        original.close()


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--database", type=Path, default=ROOT / "backend/xingbang_data/project_assistant.sqlite3")
    parser.add_argument("--dry-run", action="store_true")
    parser.add_argument("--apply", action="store_true")
    parser.add_argument("--restore-copy", type=Path, help="Output recovered DB alongside current DB; never replace live data")
    args = parser.parse_args()
    path = args.database.resolve()
    if not path.is_relative_to(ROOT):
        raise ValueError("迁移数据库须位于当前工作区")
    before = audit(path)
    if before.get("integrity", "ok") != "ok" or before["dangling_references"]:
        print(json.dumps(before, ensure_ascii=False, indent=2))
        return 1
    if args.restore_copy:
        target = args.restore_copy.resolve()
        if not target.is_relative_to(ROOT) or target == path:
            raise ValueError("恢复副本须为工作区内的新路径")
        backup(path, target)
        print(json.dumps({"restored_copy": str(target), "live_data_untouched": True, "audit": audit(target)}, ensure_ascii=False, indent=2))
        return 0
    if args.apply and not args.dry_run:
        if path.exists():
            target = ROOT / ("_backup_pre_assistant_migration_" + datetime.now().strftime("%Y%m%d_%H%M%S")) / path.name
            backup(path, target)
            before["backup"] = str(target)
        from services.project_assistant import ProjectAssistantService
        ProjectAssistantService(path)
        result = {"before": before, "after": audit(path), "legacy_tables": "preserved-read-only"}
    else:
        result = {"mode": "dry-run", **before, "writes": 0}
    print(json.dumps(result, ensure_ascii=False, indent=2))
    return 0


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