This script prints a list of URLs required to download all the minecraft resources that the new launcher can access (jars, libraries, assets) Redirect stdout to a file to do something useful with it.

mcresources.py

"""
This script prints a list of URLs required to download all the minecraft
resources that the new launcher can access (jars, libraries, assets)

Redirect stdout to a file to do something useful with it.

Will store cached json indexes in

    versions.json
    versions/*.json
    assets/*.json

Create those two directories.

Deduplication:

    python mcresources.py | sort -t: -k2 | uniq > all_resources.txt
"""

import os
import json
import requests

VERSIONS_JSON = "http://s3.amazonaws.com/Minecraft.Download/versions/versions.json"
VERSION_JSON = "http://s3.amazonaws.com/Minecraft.Download/versions/%s/%s.json"
ASSET_INDEX = "https://s3.amazonaws.com/Minecraft.Download/indexes/%s.json"

CLIENT_JAR = "http://s3.amazonaws.com/Minecraft.Download/versions/%s/%s.jar"
SERVER_JAR = "http://s3.amazonaws.com/Minecraft.Download/versions/%s/minecraft_server.%s.jar"
SERVER_EXE = "http://s3.amazonaws.com/Minecraft.Download/versions/%s/minecraft_server.%s.exe"

LIBRARY_JAR = "https://libraries.minecraft.net/%s/%s/%s/%s-%s.jar"
NATIVE_JAR = "https://libraries.minecraft.net/%s/%s/%s/%s-%s-%s.jar"

ASSET_DOWNLOAD = "http://resources.download.minecraft.net/%s/%s"

ALL_OS = ['osx', 'linux', 'windows']

def print_sha(url):
    print(url)
    print(url + ".sha1")

def fetch_json(url, filename):
    print(url)
    if os.path.exists(filename):
        return json.load(open(filename))
    else:
        response = requests.get(url)
        open(filename, "w").write(response.content)
        return response.json()

def parse_rules(rules):
    if not rules:
        return set(ALL_OS)

    allowed_os = set()

    for rule in rules:
        action = rule['action']
        change = set()
        if 'os' in rule:
            # when filtering out versions
            if not (action == 'disallow' and 'version' in rule['os']):
                change.add(rule['os']['name'])
        else:
            change = set(ALL_OS)

        if action == 'allow':
            allowed_os |= change
        else:
            allowed_os -= change
    return allowed_os

def parse_libraries(libs):
    for lib in libs:
        package, name, version = lib['name'].split(":")
        package = package.replace(".", "/")
        jar = LIBRARY_JAR % (package, name, version, name, version)

        if 'natives' in lib:
            allowed_os = parse_rules(lib.get('rules', []))

            for os_name, value in lib['natives'].items():
                if os_name not in allowed_os:
                    continue

                jar = (NATIVE_JAR % (package, name, version, name, version, value))

                if '${arch}' in value:
                    for arch in ("32", "64"):
                        jar_arch = jar.replace("${arch}", arch)
                        print_sha(jar_arch)
                else:
                    print_sha(jar)
        else:
            print_sha(jar)

def get_assets(asset_types):
    for asset_type in asset_types:
        index = fetch_json(
            ASSET_INDEX % asset_type,
            "assets/%s.json" % asset_type)

        for i in index['objects'].values():
            print(ASSET_DOWNLOAD % (i['hash'][:2], i['hash']))

def main():
    all_versions_json = fetch_json(VERSIONS_JSON, "versions.json")

    versions = [x['id'] for x in all_versions_json['versions']]

    asset_types = set()

    for version in versions:
        print(CLIENT_JAR % (version, version))
        print(SERVER_JAR % (version, version))
        print(SERVER_EXE % (version, version))

        version_json = fetch_json(
            VERSION_JSON % (version, version),
            "versions/%s.json" % version)

        parse_libraries(version_json['libraries'])

        asset_types.add(version_json.get('assets', 'legacy'))

    get_assets(asset_types)


if __name__ == '__main__':
    main()