#!/usr/bin/env nix-shell
#!nix-shell -p ruby -i ruby
# vim: ft=ruby
#
# Run this script to update the list of GCE images
#
require "json"
require "uri"

ENV['NIX_PATH'] = "nixpkgs=channel:nixpkgs-unstable"

def render_tf
  url_map=JSON.load(`nix-instantiate --json --strict --eval ./url_map.nix`)

  out = <<~HEADER
    # DON'T EDIT, run $0 instead
    variable "url_map" {
      type = map(string)

      default = {
  HEADER

  url_map.each_pair do |version, gs_url|
    u = URI.parse(gs_url)
    # convert the gs:// URL to HTTPS URL for Terraform to consume
    #
    # Eg: "gs://nixos-cloud-images/nixos-image-18.09-x86_64-linux.raw.tar.gz"
    https_url = "https://#{u.host}.storage.googleapis.com#{u.path}"

    out += "    %- 8s = %s\n" % [ version.inspect, https_url.inspect]
  end

  out += <<~FOOTER
      }

      description = "A map of release series to actual releases"
    }
  FOOTER
end

url_map_tf = render_tf

open("url_map.tf", "w") do |f|
  f.write(url_map_tf)
end

puts url_map_tf