"""Entry-point module"""
import os
import random
import string
import mimetypes
from typing import Tuple
from zipfile import ZipFile, is_zipfile

from werkzeug.utils import secure_filename
from flask import (
    flash,
    request,
    url_for,
    redirect,
    Blueprint,
    render_template,
    current_app as app)

entrybp = Blueprint("entry", __name__)

def errors(request) -> Tuple[str, ...]:
    """Return a tuple of the errors found in the `request`. If no error is
    found, then an empty tuple is returned."""
    def __filetype_error__():
        return (
            ("Invalid file type provided.",)
            if request.form.get("filetype") not in ("average", "standard-error")
            else tuple())

    def __file_missing_error__():
        return (
            ("No file was uploaded.",)
            if ("qc_text_file" not in request.files or
                request.files["qc_text_file"].filename == "")
            else tuple())

    def __file_mimetype_error__():
        text_file = request.files["qc_text_file"]
        return (
            (
                ("Invalid file! Expected a tab-separated-values file, or a zip "
                 "file of the a tab-separated-values file."),)
            if text_file.mimetype
            not in ("text/tab-separated-values", "application/zip")
            else tuple())

    return (
        __filetype_error__() +
        (__file_missing_error__() or __file_mimetype_error__()))

def zip_file_errors(filepath, upload_dir) -> Tuple[str, ...]:
    """Check the uploaded zip file for errors."""
    zfile_errors = tuple()
    if is_zipfile(filepath):
        zfile = ZipFile(filepath, "r")
        infolist = zfile.infolist()
        if len(infolist) != 1:
            zfile_errors = zfile_errors + (
                ("Expected exactly one (1) member file within the uploaded zip "
                 "file. Got {len(infolist)} member files."))
        if len(infolist) == 1 and infolist[0].is_dir():
            zfile_errors = zfile_errors + (
                ("Expected a member text file in the uploaded zip file. Got a "
                 "directory/folder."))

        if len(infolist) == 1 and not infolist[0].is_dir():
            zfile.extract(infolist[0], path=upload_dir)
            mime = mimetypes.guess_type(f"{upload_dir}/{infolist[0].filename}")
            if mime[0] != "text/tab-separated-values":
                zfile_errors = zfile_errors + (
                    ("Expected the member text file in the uploaded zip file to"
                     " be a tab-separated file."))

    return zfile_errors

@entrybp.route("/", methods=["GET", "POST"])
def upload_file():
    """Enables uploading the files"""
    if request.method == "GET":
        return render_template("index.html")

    upload_dir = app.config["UPLOAD_FOLDER"]
    request_errors = errors(request)
    if request_errors:
        for error in request_errors:
            flash(error, "alert-error")
        return render_template("index.html")

    filename = secure_filename(request.files["qc_text_file"].filename)
    if not os.path.exists(upload_dir):
        os.mkdir(upload_dir)

    filepath = os.path.join(upload_dir, filename)
    request.files["qc_text_file"].save(os.path.join(upload_dir, filename))

    zip_errors = zip_file_errors(filepath, upload_dir)
    if zip_errors:
        for error in zip_errors:
            flash(error, "alert-error")
        return render_template("index.html")

    return redirect(url_for(
        "parse.parse", filename=filename,
        filetype=request.form["filetype"]))