qrm2/utils/resources_manager.py

"""
Resources manager for qrm2.
---
Copyright (C) 2021 classabbyamp, 0x5c

This file is part of qrm2 and is released under the terms of
the GNU General Public License, version 2.
"""


from pathlib import Path

import requests

from utils.resources_models import Index


class ResourcesManager:
    def __init__(self, basedir: Path, url: str, versions: dict):
        self.basedir = basedir
        self.url = url
        self.versions = versions
        self.index: Index = self.sync_start(basedir)

    def parse_index(self, index: str):
        """Parses the index."""
        return Index.parse_raw(index)

    def sync_fetch(self, filepath: str):
        """Fetches files in sync mode."""
        self.print_msg(f"Fetching {filepath}", "sync")
        with requests.get(self.url + filepath) as resp:
            return resp.content

    def sync_start(self, basedir: Path) -> Index:
        """Takes cares of constructing the local resources repository and initialising the RM."""
        self.print_msg("Initialising ResourceManager", "sync")
        self.ensure_dir(basedir)
        try:
            raw = self.sync_fetch("index.json")
            new_index: Index = self.parse_index(raw)
            with (basedir / "index.json").open("wb") as file:
                file.write(raw)
        except (requests.RequestException, OSError) as ex:
            self.print_msg(f"There was an issue fetching the index: {ex.__class__.__name__}: {ex}", "sync")
            if (basedir / "index.json").exists():
                self.print_msg("Old file exist, using old resources", "fallback")
                with (basedir / "index.json").open("r") as file:
                    old_index = self.parse_index(file.read())
                for res, ver in self.versions.items():
                    for file in old_index[res][ver]:
                        if not (basedir / file.filename).exists():
                            self.print_msg(f"Error: {file.filename} is missing", "fallback")
                            raise SystemExit(1)
                return old_index
            raise SystemExit(1)
        for res, ver in self.versions.items():
            for file in new_index[res][ver]:
                try:
                    with (basedir / file.filename).open("wb") as f:
                        f.write(self.sync_fetch(file.filename))
                except (requests.RequestException, OSError) as ex:
                    ex_cls = ex.__class__.__name__
                    self.print_msg(f"There was an issue fetching {file.filename}: {ex_cls}: {ex}", "sync")
                    if not (basedir / file.filename).exists():
                        raise SystemExit(1)
                    self.print_msg("Old file exists, using it", "fallback")
        return new_index

    def ensure_dir(self, basedir: Path) -> bool:
        """Ensures that the resources/ directory is present. Creates as necessary."""
        if basedir.is_file():
            raise FileExistsError(f"'{basedir}' is not a directory!")
        if not basedir.exists():
            self.print_msg("Creating resources directory")
            basedir.mkdir()
            return True
        return False

    def print_msg(self, msg: str, mode: str = None):
        """Formats and prints messages for the resources manager."""
        message = "RM: "
        message += msg
        if mode:
            message += f" ({mode})"
        print(message)