#!/usr/bin/env ruby
# frozen_string_literal: true

require "fileutils"
require "json"
require "open3"
require "pathname"
require "tmpdir"
require "yaml"

ROOT = Pathname(__dir__).expand_path

def executable(env_name, command)
  override = ENV[env_name]
  return File.expand_path(override) if override && File.executable?(override)

  ENV.fetch("PATH", "").split(File::PATH_SEPARATOR).each do |directory|
    candidate = File.join(directory, command)
    return candidate if File.file?(candidate) && File.executable?(candidate)
  end
  nil
end

def literal(value)
  case value
  when String then JSON.generate(value)
  when TrueClass then "true"
  when FalseClass then "false"
  when Numeric then value.to_s
  when Array then "[#{value.map { |item| literal(item) }.join(",")}]"
  else raise "Cannot convert #{value.inspect} to OpenSCAD"
  end
end

def run!(*command, env: {})
  stdout, stderr, status = Open3.capture3(env, *command)
  return if status.success?

  warn [stdout, stderr].reject(&:empty?).join("\n")
  raise "Command failed (#{status.exitstatus}): #{command.first}"
end

config = YAML.safe_load_file(ROOT.join("case.yml"), permitted_classes: [],
                             permitted_symbols: [], aliases: false)
openscad = executable("OPENSCAD", "openscad")
blender = executable("BLENDER", "blender")
abort "OpenSCAD not found; install it or set OPENSCAD" unless openscad
abort "Blender not found; install it or set BLENDER" unless blender

parameters = config.fetch("parameters").merge(
  "extra_cutouts" => config.fetch("resolved").fetch("extra_cutouts")
)
parts = %w[body lid] + config.fetch("outputs").fetch("coupons")
buttons = %w[button_a button_b button_c button_reset]
if parameters["top_profile"] == "oled128x64" &&
   buttons.any? { |name| parameters[name] }
  parts << "buttons"
end

stage = Pathname(Dir.mktmpdir(".rebuild-", ROOT.to_s))
begin
  exports = stage.join("exports")
  previews = stage.join("previews")
  scratch = stage.join("meshes")
  FileUtils.mkdir_p([exports, previews, scratch])
  model = ROOT.join("source/feather_case.scad")
  renderer = ROOT.join("source/render_stl_previews.py")

  export = lambda do |output, part, overrides = {}|
    values = parameters.merge(overrides).merge("part" => part)
    command = [openscad, "-o", output.to_s]
    values.each { |name, value| command.concat(["-D", "#{name}=#{literal(value)}"]) }
    run!(*command, model.to_s)
  end

  config.fetch("outputs").fetch("formats").each do |format|
    directory = exports.join(format)
    FileUtils.mkdir_p(directory)
    parts.each do |part|
      puts "Exporting #{part}.#{format}…"
      export.call(directory.join("#{part}.#{format}"), part)
    end
  end

  assembly = scratch.join("assembly.stl")
  puts "Preparing assembly preview…"
  export.call(assembly, "assembly",
              "exploded_view" => config.fetch("outputs").fetch("assembly_exploded_view"),
              "show_references" => false)
  render_env = {"DISPLAY" => nil, "WAYLAND_DISPLAY" => nil}
  run!(blender, "--background", "-noaudio", "--python", renderer.to_s, "--",
       assembly.to_s, previews.to_s, "assembly", env: render_env)
  parts.each do |part|
    puts "Rendering #{part} preview…"
    mesh = scratch.join("#{part}.stl")
    export.call(mesh, part) unless mesh.file?
    run!(blender, "--background", "-noaudio", "--python", renderer.to_s, "--",
         mesh.to_s, previews.to_s, part, "iso", env: render_env)
  end

  backup = ROOT.join(".build-old-#{Process.pid}")
  FileUtils.mkdir_p(backup)
  %w[exports previews].each do |name|
    current = ROOT.join(name)
    FileUtils.mv(current, backup.join(name)) if current.exist?
  end
  begin
    FileUtils.mv(exports, ROOT.join("exports"))
    FileUtils.mv(previews, ROOT.join("previews"))
    FileUtils.rm_rf(backup)
  rescue StandardError
    FileUtils.rm_rf(ROOT.join("exports"))
    FileUtils.rm_rf(ROOT.join("previews"))
    %w[exports previews].each do |name|
      saved = backup.join(name)
      FileUtils.mv(saved, ROOT.join(name)) if saved.exist?
    end
    raise
  end
  puts "Rebuilt #{ROOT}"
ensure
  FileUtils.rm_rf(stage)
end