V updater/installer script written in python.

v_updater.py

"""
Cross platform script for installing and updating V toolchain.

Requirements:
pip install requests tqdm userpath
"""


import os  # to do a lot of things
import platform  # to determine host os
import shutil  # to find the V executable
import stat  # to set file permissions
from datetime import datetime  # file modification times
from zipfile import ZipFile  # to extract v.zip

import requests  # to download V from github releases
import userpath  # for updating PATH variable
from tqdm import tqdm  # for showing progress bar


def get_v_executable():
    """
    Returns the path to the V installation folder.
    """
    path = shutil.which("v")
    if path is None:
        return ""

    folder = os.path.split(path)
    return os.path.split(folder[0])[0]  # excludes `/v` from .../vlang/v/


def get_download_url():
    """
    Returns the GitHub download URL for V according to the OS.
    """
    host_os = platform.system()
    if host_os == "Windows":
        return "https://github.com/vlang/v/releases/latest/download/v_windows.zip"
    elif host_os == "Linux":
        return "https://github.com/vlang/v/releases/latest/download/v_linux.zip"
    elif host_os == "Darwin":
        return "https://github.com/vlang/v/releases/latest/download/v_macos.zip"
    else:
        return ""


def download(max_retries: int = 5):
    """
    Downloads V from GitHub releases.
    """
    retry_counter = 0

    while retry_counter < max_retries:
        try:
            retry_counter += 1
            url = get_download_url()
            if url == "":
                print("Unable to find the download URL for your system.")
                exit(1)

            print(f"Downloading V from: {url}\n")

            location = os.path.join(os.path.expanduser("~"), "Downloads")
            os.makedirs(location, exist_ok=True)
            location = os.path.join(location, "v_temp.zip")

            headers = {}
            initial_download_value = 0
            with open(location, "ab") as f:
                pos = f.tell()
                if pos:  # file already has some content
                    last_modification_time = os.path.getmtime(location)
                    last_modification_date = datetime.fromtimestamp(last_modification_time)
                    print(
                        f"Resuming download from previous failed iteration ({last_modification_date})...\n"
                    )
                    initial_download_value = pos
                    headers["Range"] = f"bytes={pos}-"

            r = requests.get(
                url, allow_redirects=True, stream=True, timeout=30, headers=headers
            )
            r.raise_for_status()

            download_size = int(r.headers.get("content-length", 0))

            with open(location, "ab") as file, tqdm(
                desc="v_temp.zip",
                total=download_size,
                initial=initial_download_value,
                unit="iB",
                unit_scale=True,
                unit_divisor=1024,
            ) as progess_bar:
                for data in r.iter_content(chunk_size=1024):
                    size = file.write(data)
                    progess_bar.update(size)

            print()
            return  # break the while loop

        except Exception as e:
            print("Unable to download V!")
            print("Error:", e)
            if retry_counter < max_retries:
                print(f"Retrying again ({retry_counter+1}th attempt)...")
            else:
                print(
                    f"Tried downloading the file {max_retries} times, but failed. Stopping now."
                )
                cleanup(location)
                exit(1)


def install():
    """
    Installs V from the downloaded zip file.
    """
    location = get_v_executable()
    WINDOWS = platform.system() == "Windows"

    if location == "":
        proceed = input(
            "Unable to find existing V installation. Would you like to newly install V? (y/n) "
        )
        if proceed.lower().strip() != "y":
            exit(0)
        location = os.path.join(os.path.expanduser("~"), "vlang")
        download()

    else:
        proceed = input(
            f"V is already installed at {location}. Would you like to update it? (y/n) "
        )
        if proceed.lower().strip() != "y":
            exit(0)

        download()

        print(f"Removing existing installation at {location}...")
        shutil.rmtree(location, ignore_errors=True)

    print(f"Installing V at {location}...")

    zip_file_location = os.path.join(os.path.expanduser("~"), "Downloads", "v_temp.zip")
    with ZipFile(zip_file_location, "r") as zip_ref:
        zip_ref.extractall(location)

    path_location = os.path.join(location, "v")
    present_in_path = userpath.in_current_path(path_location) or userpath.in_new_path(
        path_location
    )
    executable_location = (
        os.path.join(path_location, "v.exe")
        if WINDOWS
        else os.path.join(path_location, "v")
    )

    os.chmod(executable_location, stat.S_IRWXU)

    cleanup(zip_file_location)

    if not present_in_path:
        print(
            f"V installation was successfull, updating the PATH variable to use V at `{path_location}`."
        )

        success = userpath.append(path_location)
        if success:
            print(f"Successfully added {path_location} to PATH.")

        if userpath.need_shell_restart(path_location):
            print("You need to restart your shell to use V.")

    else:
        print(f"V installation was successfull at `{path_location}`.")


def cleanup(zip_file_location):
    """
    Removes downloaded assets, if present.
    """
    try:
        print("Removing downloaded assets...")
        os.remove(zip_file_location)
    except FileNotFoundError:
        pass
    except Exception as e:
        print(f"An unknown error occured: {e}")


if __name__ == "__main__":
    install()