require 'digest'
require 'fileutils'

module ConfCtl
  class GitRepoMirror
    attr_reader :url, :name

    # @param url [String]
    # @param quiet [Boolean]
    def initialize(url, quiet: false)
      @url = url
      @quiet = quiet
      @name = Digest::SHA256.hexdigest(url)
      @cmd = SystemCommand.new
    end

    def setup(ref: nil)
      File.stat(mirror_path)
    rescue Errno::ENOENT
      FileUtils.mkdir_p(mirror_path)
      git('clone', args: ['--mirror', url, mirror_path])
    else
      git_repo('fetch', opts: ['--no-show-forced-updates'], args: (ref ? ['origin', ref] : []))
    end

    def revision_parse(str)
      git_repo('rev-parse', args: [str])
    end

    # @param from_ref [String]
    # @param to_ref [String]
    def log(from_ref, to_ref, opts: [])
      ret = "git log for #{from_ref}..#{to_ref}\n"
      ret << git_repo(
        'log',
        opts: ['--no-decorate', '--left-right', '--cherry-mark'] + opts,
        args: ["#{from_ref}..#{to_ref}"]
      )
      ret
    end

    # @param from_ref [String]
    # @param to_ref [String]
    def diff(from_ref, to_ref, opts: [])
      ret = "git diff for #{from_ref}..#{to_ref}\n"
      ret << git_repo(
        'diff',
        opts:,
        args: ["#{from_ref}..#{to_ref}"]
      )
      ret
    end

    protected

    attr_reader :cmd, :quiet

    def git_repo(git_cmd, *args, **kwargs)
      kwargs[:gopts] ||= []
      kwargs[:gopts] << '-C' << mirror_path
      git(git_cmd, *args, **kwargs)
    end

    def git(git_cmd, args: [], opts: [], gopts: [])
      opts << '--quiet' if quiet && %w[clone fetch].include?(git_cmd)

      out, = cmd.run('git', *gopts, git_cmd, *opts, *args)
      out.strip
    end

    def mirror_path
      File.join(mirror_dir, name)
    end

    def mirror_dir
      File.join(ConfCtl.cache_dir, 'git-mirrors')
    end
  end
end