"""纠正已知初始日期为先开放、后发Offer；备份、事务更新，可重复执行。"""
import ast
import json
import sys
from datetime import datetime
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT))
from sqlalchemy import text
from database import engine


def main():
    tree = ast.parse((ROOT / "seed_data.py").read_text(encoding="utf-8-sig"))
    constants = {node.targets[0].id: ast.literal_eval(node.value)
                 for node in tree.body if isinstance(node, ast.Assign)
                 and isinstance(node.targets[0], ast.Name)
                 and node.targets[0].id in ("employment_data", "student_data")}
    seeds = {str(constants["student_data"][row["student_id"]-1]["student_no"]): row
             for row in constants["employment_data"]}
    snapshot = "SELECT e.*, s.student_no FROM employment e JOIN student s ON s.sid=e.student_id ORDER BY e.id"
    with engine.begin() as conn:
        before = [dict(row._mapping) for row in conn.execute(text(snapshot + " FOR UPDATE"))]
        backup = ROOT / "artifacts" / ("employment-before-offer-order-" + datetime.now().strftime("%Y%m%d-%H%M%S-%f") + ".json")
        backup.parent.mkdir(exist_ok=True)
        backup.write_text(json.dumps({"database": conn.execute(text("SELECT DATABASE()")).scalar(), "rows": before}, ensure_ascii=False, indent=2, default=str), encoding="utf-8")
        changed, skipped = [], []
        for old in before:
            seed = seeds.get(old['student_no'])
            if not seed:
                continue
            start = datetime.fromisoformat(seed['employment_start_time'])
            offer = datetime.fromisoformat(seed['offer_time'])
            assert offer >= start
            if (old['employment_start_time'], old['offer_time']) == (start, offer):
                continue
            # 只改完全匹配的旧种子日期，保留用户已编辑的记录。
            if old['company_name'] != seed['company_name'] or (old['employment_start_time'], old['offer_time']) != (offer, start):
                skipped.append(old['id'])
                continue
            conn.execute(text("UPDATE employment SET employment_start_time=:start, offer_time=:offer WHERE id=:id"), {'start':start,'offer':offer,'id':old['id']})
            changed.append(old['id'])
        after = [dict(row._mapping) for row in conn.execute(text(snapshot))]
        assert len(before) == len(after)
        for old, new in zip(before, after):
            assert old['id'] == new['id']
            if old['id'] not in changed:
                assert old == new
            else:
                assert new['offer_time'] >= new['employment_start_time']
                assert all(old[key] == new[key] for key in old if key not in ('employment_start_time','offer_time'))
    print('Backup:', backup)
    print('Updated initial record IDs:', changed)
    print('Skipped customized initial record IDs:', skipped)


if __name__ == '__main__':
    main()