#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
Collect the measles dataset

See the README file for more information.

Author: G.J.J. van den Burg
License: This file is part of TCPD, see the top-level LICENSE file.
Copyright: 2019, The Alan Turing Institute

"""

import argparse
import clevercsv
import hashlib
import json
import os

from functools import wraps
from urllib.request import urlretrieve

DAT_URL = "https://web.archive.org/web/20191128124615if_/https://ms.mcmaster.ca/~bolker/measdata/ewmeas.dat"

MD5_DAT = "143d1dacd791df963674468c8b005bf9"
MD5_JSON = "e42afd03be893fc7deb98514c94fa4c7"

NAME_DAT = "ewmeas.dat"
NAME_JSON = "measles.json"


class ValidationError(Exception):
    def __init__(self, filename):
        message = (
            "Validating the file '%s' failed. \n"
            "Please raise an issue on the GitHub page for this project "
            "if the error persists." % filename
        )
        super().__init__(message)


def check_md5sum(filename, checksum):
    with open(filename, "rb") as fp:
        data = fp.read()
    h = hashlib.md5(data).hexdigest()
    return h == checksum


def validate(checksum):
    """Decorator that validates the target file."""

    def validate_decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            target = kwargs.get("target_path", None)
            if os.path.exists(target) and check_md5sum(target, checksum):
                return
            out = func(*args, **kwargs)
            if not os.path.exists(target):
                raise FileNotFoundError("Target file expected at: %s" % target)
            if not check_md5sum(target, checksum):
                raise ValidationError(target)
            return out

        return wrapper

    return validate_decorator


@validate(MD5_DAT)
def download_zip(target_path=None):
    urlretrieve(DAT_URL, target_path)


@validate(MD5_JSON)
def write_json(dat_path, target_path=None):
    with open(dat_path, "r", newline="", encoding="ascii") as fp:
        reader = clevercsv.reader(
            fp, delimiter=" ", quotechar="", escapechar=""
        )
        rows = list(reader)

    as_dicts = {t: int(x) for t, x in rows}

    time = sorted(as_dicts.keys())
    values = [as_dicts[t] for t in time]
    series = [{"label": "V1", "type": "int", "raw": values}]

    data = {
        "name": "measles",
        "longname": "Measles cases (England & Wales)",
        "n_obs": len(time),
        "n_dim": len(series),
        "time": {
            "type": "string",
            "format": "%Y-%F",
            "index": list(range(len(time))),
            "raw": time,
        },
        "series": series,
    }

    with open(target_path, "w") as fp:
        json.dump(data, fp, indent="\t")


def collect(output_dir="."):
    dat_path = os.path.join(output_dir, NAME_DAT)
    json_path = os.path.join(output_dir, NAME_JSON)

    download_zip(target_path=dat_path)
    write_json(dat_path, target_path=json_path)


def clean(output_dir="."):
    dat_path = os.path.join(output_dir, NAME_DAT)
    json_path = os.path.join(output_dir, NAME_JSON)

    if os.path.exists(dat_path):
        os.unlink(dat_path)
    if os.path.exists(json_path):
        os.unlink(json_path)


def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "-o", "--output-dir", help="output directory to use", default="."
    )
    parser.add_argument(
        "action",
        choices=["collect", "clean"],
        help="Action to perform",
        default="collect",
        nargs="?",
    )
    return parser.parse_args()


def main(output_dir="."):
    args = parse_args()
    if args.action == "collect":
        collect(output_dir=args.output_dir)
    elif args.action == "clean":
        clean(output_dir=args.output_dir)


if __name__ == "__main__":
    main()