import csv
import re
from concurrent.futures.process import ProcessPoolExecutor
from pathlib import Path

from PyPDF2 import PdfReader
from loguru import logger

COA_ROOT = Path(r"D:\lgc_coa")
OUT_FP = Path(r"D:\lgc_coa_info.csv")


def extract_coa_info(fp: Path):
    reader = PdfReader(fp)
    page = reader.pages[0]

    text = page.extract_text()

    coa_cat_no = lot = None
    d = (m := re.search(r'Product code\s+Lot number\s+(?P<cat_no>\S+)\s+(?P<lot>\S+)', text)) and m.groupdict()
    d2 = (m := re.search(r'Product code\s+(?P<cat_no>\S+)\s+Lot number\s+(?P<lot>\S+)', text)) and m.groupdict()
    if d:
        coa_cat_no, lot = d['cat_no'], d['lot']
    if d2:
        coa_cat_no, lot = d2['cat_no'], d2['lot']
    ret = {
        "cat_no": (m := re.search(r"(?<=COA_)[^_]+", fp.name)) and m.group(),
        "coa_cat_no": coa_cat_no,
        "lot": lot,
        # "appearance": (m := re.search(r"Appearance\s+\n([^\n]+\n){6}([^\n]+)", text)) and m.group(2).strip(),
        "appearance": (m := re.search(r"([^\n]+(solid)|(liquid)|(oil))[^\n]+", text)) and m.group(1),
        "assay": (m := re.search(r'Assay\s?\w? [“"]as is[”"]\s+(\d+\.\d+\s?%)', text)) and m.group(1),
        "date_of_ship": (m := re.search(r'Date of shipment:\s+(\d+\s+\w+\s+\d+)', text)) and m.group(1),
        "fname": fp.name
    }
    if ret['assay'] is None or lot is None:
        logger.debug(f"assay or lot is None, ({lot}, {ret['assay']})")
        pass
    if ret['appearance'] is None:
        logger.debug(f"appearance is None")
    return ret


def main(dir_path: Path, max_workers: int=4):
    logger.info('starting')
    pdfs = dir_path.glob('./*.pdf')
    headers = ('cat_no', 'coa_cat_no', 'lot', 'appearance', 'assay', 'date_of_ship', 'fname')
    with OUT_FP.open('w', newline='', encoding='u8') as f, ProcessPoolExecutor(max_workers=max_workers) as pool:
        csv_writer = csv.DictWriter(f, fieldnames=headers)
        result = pool.map(extract_coa_info, pdfs)
        for ret in result:
            csv_writer.writerow(ret)
    logger.info('finished')


if __name__ == '__main__':
    main(COA_ROOT, max_workers=1)
    pass