# frozen_string_literal: true

require 'json'
require 'digest/sha1'

# Public: Keeps track of watched files and triggers builds as needed.
class ViteRuby::Builder
  def initialize(vite_ruby)
    @vite_ruby = vite_ruby
  end

  # Public: Checks if the watched files have changed since the last compilation,
  # and triggers a Vite build if any files have changed.
  def build(*args)
    last_build = last_build_metadata
    if args.delete('--force') || last_build.stale?
      build_with_vite(*args).tap { |success| record_build_metadata(success, last_build) }
    elsif last_build.success
      logger.debug "Skipping vite build. Watched files have not changed since the last build at #{ last_build.timestamp }"
      true
    else
      logger.error "Skipping vite build. Watched files have not changed since the build failed at #{ last_build.timestamp } ❌"
      false
    end
  end

  # Internal: Reads the result of the last compilation from disk.
  def last_build_metadata
    ViteRuby::Build.from_previous(last_build_attrs, watched_files_digest)
  end

private

  extend Forwardable

  def_delegators :@vite_ruby, :config, :logger, :run

  # Internal: Reads metadata recorded on the last build, if it exists.
  def last_build_attrs
    last_build_path.exist? ? JSON.parse(last_build_path.read.to_s) : {}
  rescue JSON::JSONError, Errno::ENOENT, Errno::ENOTDIR
    {}
  end

  # Internal: Writes a digest of the watched files to disk for future checks.
  def record_build_metadata(success, build)
    config.build_cache_dir.mkpath
    last_build_path.write build.with_result(success).to_json
  end

  # Internal: The file path where metadata of the last build is stored.
  def last_build_path
    config.build_cache_dir.join("last-build-#{ config.mode }.json")
  end

  # Internal: Returns a digest of all the watched files, allowing to detect
  # changes, and skip Vite builds if no files have changed.
  def watched_files_digest
    Dir.chdir File.expand_path(config.root) do
      files = Dir[*config.watched_paths].reject { |f| File.directory?(f) }
      file_ids = files.sort.map { |f| "#{ File.basename(f) }/#{ Digest::SHA1.file(f).hexdigest }" }
      Digest::SHA1.hexdigest(file_ids.join('/'))
    end
  end

  # Public: Initiates a Vite build command to generate assets.
  #
  # Returns true if the build is successful, or false if it failed.
  def build_with_vite(*args)
    logger.info 'Building with Vite ⚡️'

    stdout, stderr, status = run(['build', *args])
    log_build_result(stdout, stderr.to_s, status)

    status.success?
  end

  # Internal: Outputs the build results.
  #
  # NOTE: By default it also outputs the manifest entries.
  def log_build_result(_stdout, stderr, status)
    if status.success?
      logger.info "Build with Vite complete: #{ config.build_output_dir }"
      logger.error stderr.to_s unless stderr.empty?
    else
      logger.error stderr
      logger.error 'Build with Vite failed! ❌'
      logger.error '❌ Check that vite and vite-plugin-ruby are in devDependencies and have been installed. ' if stderr.include?('ERR! canceled')
    end
  end
end