# frozen_string_literal: true

require "open3"

module Utils
  # Helper functions for querying Git information.
  #
  # @api private
  module Git
    module_function

    def available?
      version.present?
    end

    def version
      return @version if defined?(@version)

      stdout, _, status = system_command(HOMEBREW_SHIMS_PATH/"scm/git", args: ["--version"], print_stderr: false)
      @version = status.success? ? stdout.chomp[/git version (\d+(?:\.\d+)*)/, 1] : nil
    end

    def path
      return unless available?
      return @path if defined?(@path)

      @path = Utils.popen_read(HOMEBREW_SHIMS_PATH/"scm/git", "--homebrew=print-path").chomp.presence
    end

    def remote_exists?(url)
      return true unless available?

      quiet_system "git", "ls-remote", url
    end

    def clear_available_cache
      remove_instance_variable(:@version) if defined?(@version)
      remove_instance_variable(:@path) if defined?(@path)
    end

    def last_revision_commit_of_file(repo, file, before_commit: nil)
      args = if before_commit.nil?
        ["--skip=1"]
      else
        [before_commit.split("..").first]
      end

      out, = Open3.capture3(
        HOMEBREW_SHIMS_PATH/"scm/git", "-C", repo,
        "log", "--format=%h", "--abbrev=7", "--max-count=1",
        *args, "--", file
      )
      out.chomp
    end

    def last_revision_commit_of_files(repo, files, before_commit: nil)
      args = if before_commit.nil?
        ["--skip=1"]
      else
        [before_commit.split("..").first]
      end

      # git log output format:
      #   <commit_hash>
      #   <file_path1>
      #   <file_path2>
      #   ...
      # return [<commit_hash>, [file_path1, file_path2, ...]]
      out, = Open3.capture3(
        HOMEBREW_SHIMS_PATH/"scm/git", "-C", repo, "log",
        "--pretty=format:%h", "--abbrev=7", "--max-count=1",
        "--diff-filter=d", "--name-only", *args, "--", *files
      )
      rev, *paths = out.chomp.split(/\n/).reject(&:empty?)
      [rev, paths]
    end

    def last_revision_of_file(repo, file, before_commit: nil)
      relative_file = Pathname(file).relative_path_from(repo)

      commit_hash = last_revision_commit_of_file(repo, relative_file, before_commit: before_commit)
      out, = Open3.capture3(
        HOMEBREW_SHIMS_PATH/"scm/git", "-C", repo,
        "show", "#{commit_hash}:#{relative_file}"
      )
      out
    end

    def ensure_installed!
      return if available?

      # we cannot install brewed git if homebrew/core is unavailable.
      if CoreTap.instance.installed?
        begin
          oh1 "Installing #{Formatter.identifier("git")}"

          # We need to unset `HOMEBREW_TEST_GENERIC_OS`, otherwise `git` will be
          # installed from source in tests that need it. This is slow and will
          # also likely fail due to `OS::Linux` and `OS::Mac` being undefined.
          with_env "HOMEBREW_TEST_GENERIC_OS" => nil do
            safe_system HOMEBREW_BREW_FILE, "install", "git"
            clear_available_cache
          end
        rescue
          raise "Git is unavailable"
        end
      end

      raise "Git is unavailable" unless available?
    end

    def set_name_email!(author: true, committer: true)
      if Homebrew::EnvConfig.git_name
        ENV["GIT_AUTHOR_NAME"] = Homebrew::EnvConfig.git_name if author
        ENV["GIT_COMMITTER_NAME"] = Homebrew::EnvConfig.git_name if committer
      end

      return unless Homebrew::EnvConfig.git_email

      ENV["GIT_AUTHOR_EMAIL"] = Homebrew::EnvConfig.git_email if author
      ENV["GIT_COMMITTER_EMAIL"] = Homebrew::EnvConfig.git_email if committer
    end
  end
end