#!/usr/bin/env python3
# -*- coding: utf8 -*-

"""
Helper script that normalizes all existing date entries in the DB's "Werk" table to the format "YYYY[-MM[-DD]]". 
"""


from flask import Flask
from dotenv import load_dotenv
import os
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy import select
import re

# initialize db exactly like in the main app
app = Flask(__name__)
load_dotenv()
app.config.from_prefixed_env()
if os.getenv("SQLALCHEMY_DATABASE_DIALECT") == "sqlite":
  app.config['SQLALCHEMY_DATABASE_URI'] = "sqlite:///" + os.path.abspath(app.root_path + "/..") + "/" + os.getenv("SQLALCHEMY_DATABASE_SQLITE_FILENAME")
else:
  exit("no SQLite database URI given; exiting")

db = SQLAlchemy()
db.init_app(app)

with app.app_context():
  db.reflect()

  class Werk(db.Model):
    __table__ = db.Model.metadata.tables['Werk']

  # iterate over ids
  for id in range(1, 54):
    werk = db.session.get(Werk, id)
    if werk is None:
      print(f"ID {id}: Werk does not exist") 
      continue

    # case: None/NULL
    if werk.Erscheinungsdatum is None:
      print(f"ID {id}: date is None; was normalized to '{werk.Erscheinungsdatum}'")
      continue

    # case: empty string
    if werk.Erscheinungsdatum == "":
      werk.Erscheinungsdatum = None
      print(f"ID {id}: date is empty string; was normalized to '{werk.Erscheinungsdatum}'")
      continue

    # case: YYYY
    if len(werk.Erscheinungsdatum) == 4:
      print(f"ID {id}: date matches format YYYY; was normalized to '{werk.Erscheinungsdatum}'")
      continue

    # case: YYYY-MM-DD
    result = re.search(r"^(\d\d\d\d)-(\d\d)-(\d\d)$", werk.Erscheinungsdatum)
    if result is not None:
      print(f"ID {id}: date matches format YYYY-MM-DD; was normalized to '{werk.Erscheinungsdatum}'")
      continue

    # case: DD.MM.YYYY
    result = re.search(r"^(\d\d)\.(\d\d)\.(\d\d\d\d)$", werk.Erscheinungsdatum)
    if result is not None:
      werk.Erscheinungsdatum = result.group(3) + "-" + result.group(2) + "-" + result.group(1)
      print(f"ID {id}: date matches format DD.MM.YYYY; was normalized to '{werk.Erscheinungsdatum}'")
      continue

    # case: DD.M.YYYY
    result = re.search(r"^(\d\d)\.(\d)\.(\d\d\d\d)$", werk.Erscheinungsdatum)
    if result is not None:
      werk.Erscheinungsdatum = result.group(3) + "-0" + result.group(2) + "-" + result.group(1)
      print(f"ID {id}: date matches format DD.M.YYYY; was normalized to '{werk.Erscheinungsdatum}'")
      continue

    print(f"ID {id}: date did not match any format")

  db.session.commit()