image_chooser.py

#!/usr/bin/env python3
# Written by Andrew Scheller, May 2021
# Released under the WTFPL

# This is a fun little script that provides an interactive text-based menu for
# the user to select an image from; once an image has been selected it prints
# the "choices path" that was navigated to get to that image, and the URL that
# the image can be downloaded from (e.g. using wget)
#
# Alternatively, if given a "choices path" it runs non-interactively and
# prints out the image download URL corresponding to that option. For example,
# image_chooser.py "Raspberry Pi OS (other)" "Raspberry Pi OS Lite (32-bit)"
# will print out the URL of the latest RasPiOS Lite image (which is
# https://downloads.raspberrypi.org/raspios_lite_armhf/images/raspios_lite_armhf-2021-03-25/2021-03-04-raspios-buster-armhf-lite.zip
# at the time of writing)

BASE_JSON_URL = 'https://downloads.raspberrypi.org/os_list_imagingutility_v2.json'

import urllib.request
import json
import sys
import re

json_cache = {}
def read_json_list(url):
    if url not in json_cache:
        with urllib.request.urlopen(url) as response:
            json_cache[url] = json.loads(response.read())['os_list']
    return json_cache[url]

# Allow optional custom BASE_JSON_URL to be supplied
if len(sys.argv) > 1 and (sys.argv[1].startswith('http://') or sys.argv[1].startswith('https://')):
    BASE_JSON_URL = sys.argv.pop(1)

if len(sys.argv) > 1:
    # Noninteracative mode - use supplied "choices path" to find image
    choices = sys.argv[1:]
    options = read_json_list(BASE_JSON_URL)
    found = False
    while choices:
        choice = choices.pop(0)
        options_lookup = {item['name']: index for index, item in enumerate(options)}
        if choice in options_lookup:
            chosen = options[options_lookup[choice]]
            if 'subitems_url' in chosen:
                options = read_json_list(chosen['subitems_url'])
            elif 'subitems' in chosen:
                options = chosen['subitems']
            else:
                found = True
                # print the selected image url
                print(chosen['url'])
                if choices:
                    raise Exception("Found OS before reaching end of choices")
                break
        else:
            raise Exception("\"%s\" not found in %s" % (choice, [item['name'] for item in options]))
    if not found:
        raise Exception("No matching OS found")
else:
    # Interactive mode - display menu for user to navigate
    title = "Select an Operating System"
    options = read_json_list(BASE_JSON_URL)
    parents = []
    while True:
        print(title)
        min_index = 1
        if parents:
            print(" [%d] Go back to: %s" % (0, parents[-1][0]))
            min_index = 0
        for index, item in enumerate(options):
            prefix = " [%d] %s: " % (index + 1, 'MENU' if 'subitems_url' in item or 'subitems' in item else 'IMAGE')
            print("%s%s" % (prefix, item['name']))
            if 'description' in item:
                print("%s%s" % (' ' * len(prefix), item['description']))
        max_index = len(options)

        choice = 'invalid'
        while choice != 'q' and choice != 'quit' and not (re.match('^\d+$', choice) and (min_index <= int(choice) <= max_index)):
            choice = input("Choose option (%d to %d, or q to quit) ? " % (min_index, max_index))
        if choice == 'q' or choice == 'quit':
            break

        choice = int(choice)
        if choice == 0:
            title, options = parents.pop()
        else:
            parents.append((title, options))
            chosen = options[choice - 1]
            title = chosen['name']
            if 'subitems_url' in chosen:
                options = read_json_list(chosen['subitems_url'])
            elif 'subitems' in chosen:
                options = chosen['subitems']
            else:
                choices = [p[0] for p in parents[1:]]
                choices.append(title)
                # print the selected "choices path"
                print(' '.join("\"%s\"" % c for c in choices))
                # print the selected image url
                print(chosen['url'])
                break