#!/usr/bin/env python
""" check requirements.txt for outdated packages """

import pathlib

import requests


class Requirements:
    """handle requirements.txt"""

    FILE_PATH = "tubearchivist/requirements.txt"
    LOCK = "/tmp/tubearchivist-requirements.lock"

    def __init__(self):
        self.exists = self.checked_today()
        self.all_requirements = False
        self.all_updates = False

    def checked_today(self):
        """skip requirements check when lock file exists"""
        exists = pathlib.Path(self.LOCK).exists()
        return exists

    def look_for_updates(self):
        """look through requirements and check for updates"""
        self.all_requirements = self.get_dependencies()
        self.all_updates = self.check_packages()

    def get_dependencies(self):
        """read out requirements.txt"""

        all_requirements = []
        with open(self.FILE_PATH, "r", encoding="utf-8") as f:
            dependencies = f.readlines()

        for dependency in dependencies:
            package, version = dependency.split("==")
            all_requirements.append((package, version.strip()))

        all_requirements.sort(key=lambda x: x[0].lower())

        return all_requirements

    def check_packages(self):
        """compare installed with remote version"""

        total = len(self.all_requirements)
        print(f"checking versions for {total} packages...")

        all_updates = {}

        for dependency in self.all_requirements:
            package, version_installed = dependency
            url = f"https://pypi.org/pypi/{package}/json"
            response = requests.get(url).json()
            version_remote = response["info"]["version"]
            homepage = response["info"]["home_page"]
            if version_remote != version_installed:
                to_update = {
                    package: {"from": version_installed, "to": version_remote}
                }
                all_updates.update(to_update)
                message = (
                    f"update {package} {version_installed}"
                    + f"==> {version_remote}\n    {homepage}"
                )
                print(message)

        if not all_updates:
            print("no updates found")

        # remember that
        pathlib.Path(self.LOCK).touch()

        return all_updates

    def apply_updates(self):
        """update requirements.txt file with new versions"""

        to_write = []

        for requirement in self.all_requirements:
            package, old_version = requirement

            if package in self.all_updates.keys():
                package_version = self.all_updates[package]["to"]
            else:
                package_version = old_version

            to_write.append(f"{package}=={package_version}\n")

        with open(self.FILE_PATH, "w", encoding="utf-8") as f:
            f.writelines(to_write)

        print("requirements.txt updates")


def main():
    """main to check for updates"""
    handler = Requirements()
    if handler.exists:
        return

    handler.look_for_updates()
    if handler.all_updates:
        input_response = input("\nupdate requirements.txt? [y/n] ")
        if input_response == "y":
            handler.apply_updates()
        else:
            print("skip update...")


if __name__ == "__main__":
    main()