# typed: strict
# frozen_string_literal: true

require "abstract_command"
require "fileutils"
require "utils/github"
require "utils/github/artifacts"
require "tmpdir"
require "formula"

module Homebrew
  module DevCmd
    class PrPull < AbstractCommand
      include FileUtils

      cmd_args do
        description <<~EOS
          Download and publish bottles and apply the bottle commit from a
          pull request with artifacts generated by GitHub Actions.
          Requires write access to the repository.
        EOS
        switch "--no-upload",
               description: "Download the bottles but don't upload them."
        switch "--no-commit",
               description: "Do not generate a new commit before uploading."
        switch "--no-cherry-pick",
               description: "Do not cherry-pick commits from the pull request branch."
        switch "-n", "--dry-run",
               description: "Print what would be done rather than doing it."
        switch "--clean",
               description: "Do not amend the commits from pull requests."
        switch "--keep-old",
               description: "If the formula specifies a rebuild version, " \
                            "attempt to preserve its value in the generated DSL."
        switch "--autosquash",
               description: "Automatically reformat and reword commits in the pull request to our " \
                            "preferred format."
        switch "--branch-okay",
               description: "Do not warn if pulling to a branch besides the repository default (useful for testing)."
        switch "--resolve",
               description: "When a patch fails to apply, leave in progress and allow user to resolve, " \
                            "instead of aborting."
        switch "--warn-on-upload-failure",
               description: "Warn instead of raising an error if the bottle upload fails. " \
                            "Useful for repairing bottle uploads that previously failed."
        switch "--retain-bottle-dir",
               description: "Does not clean up the tmp directory for the bottle so it can be used later."
        flag   "--committer=",
               description: "Specify a committer name and email in `git`'s standard author format."
        flag   "--message=",
               depends_on:  "--autosquash",
               description: "Message to include when autosquashing revision bumps, deletions and rebuilds."
        flag   "--artifact-pattern=", "--artifact=",
               description: "Download artifacts with the specified pattern (default: `bottles{,_*}`)."
        flag   "--tap=",
               description: "Target tap repository (default: `homebrew/core`)."
        flag   "--root-url=",
               description: "Use the specified <URL> as the root of the bottle's URL instead of Homebrew's default."
        flag   "--root-url-using=",
               description: "Use the specified download strategy class for downloading the bottle's URL instead of " \
                            "Homebrew's default."
        comma_array "--workflows",
                    description: "Retrieve artifacts from the specified workflow (default: `tests.yml`). " \
                                 "Can be a comma-separated list to include multiple workflows."
        comma_array "--ignore-missing-artifacts",
                    description: "Comma-separated list of workflows which can be ignored if they have not been run."

        conflicts "--clean", "--autosquash"

        named_args :pull_request, min: 1
      end

      sig { override.void }
      def run
        # Needed when extracting the CI artifact.
        ensure_executable!("unzip", reason: "extracting CI artifacts")

        workflows = args.workflows.presence || ["tests.yml"]
        artifact_pattern = args.artifact_pattern || "bottles{,_*}"
        tap = Tap.fetch(args.tap || CoreTap.instance.name)
        raise TapUnavailableError, tap.name unless tap.installed?

        Utils::Git.set_name_email!(committer: args.committer.blank?)
        Utils::Git.setup_gpg!

        if (committer = args.committer)
          committer = Utils.parse_author!(committer)
          ENV["GIT_COMMITTER_NAME"] = committer[:name]
          ENV["GIT_COMMITTER_EMAIL"] = committer[:email]
        end

        args.named.uniq.each do |arg|
          arg = "#{tap.default_remote}/pull/#{arg}" if arg.to_i.positive?
          url_match = arg.match HOMEBREW_PULL_OR_COMMIT_URL_REGEX
          _, user, repo, pr = *url_match
          odie "Not a GitHub pull request: #{arg}" unless pr

          git_repo = tap.git_repository
          if !git_repo.default_origin_branch? && !args.branch_okay? && !args.no_commit? && !args.no_cherry_pick?
            origin_branch_name = git_repo.origin_branch_name
            opoo "Current branch is #{git_repo.branch_name}: do you need to pull inside #{origin_branch_name}?"
          end

          pr_labels = GitHub.pull_request_labels(user, repo, pr)
          if pr_labels.include?("autosquash") && !args.autosquash?
            opoo "Pull request is labelled `autosquash`: do you need to pass `--autosquash`?"
          end

          pr_check_conflicts("#{user}/#{repo}", pr)

          ohai "Fetching #{tap} pull request ##{pr}"
          dir = Dir.mktmpdir("pr-pull-#{pr}-", HOMEBREW_TEMP)
          begin
            cd dir do
              current_branch_head = ENV["GITHUB_SHA"] || tap.git_head
              original_commit = if args.no_cherry_pick?
                # TODO: Handle the case where `merge-base` returns multiple commits.
                Utils.safe_popen_read("git", "-C", tap.path, "merge-base", "origin/HEAD",
                                      current_branch_head).strip
              else
                current_branch_head
              end
              odebug "Pull request merge-base: #{original_commit}"

              unless args.no_commit?
                cherry_pick_pr!(user, repo, pr, path: tap.path) unless args.no_cherry_pick?
                if args.autosquash? && !args.dry_run?
                  autosquash!(original_commit, tap:, cherry_picked: !args.no_cherry_pick?,
                              verbose: args.verbose?, resolve: args.resolve?, reason: args.message)
                end
                signoff!(git_repo, pull_request: pr, dry_run: args.dry_run?) unless args.clean?
              end

              unless formulae_need_bottles?(tap, original_commit, pr_labels)
                ohai "Skipping artifacts for ##{pr} as the formulae don't need bottles"
                next
              end

              workflows.each do |workflow|
                workflow_run = GitHub.get_workflow_run(
                  user, repo, pr, workflow_id: workflow, artifact_pattern:
                )
                if args.ignore_missing_artifacts.present? &&
                   args.ignore_missing_artifacts&.include?(workflow) &&
                   workflow_run.first.blank?
                  # Ignore that workflow as it was not executed and we specified
                  # that we could skip it.
                  ohai "Ignoring workflow #{workflow} as requested by `--ignore-missing-artifacts`"
                  next
                end

                ohai "Downloading bottles for workflow: #{workflow}"

                urls = GitHub.get_artifact_urls(workflow_run)
                urls.each { |url| GitHub.download_artifact(url, pr) }
              end

              next if args.no_upload?

              upload_args = ["pr-upload"]
              upload_args << "--debug" if args.debug?
              upload_args << "--verbose" if args.verbose?
              upload_args << "--no-commit" if args.no_commit?
              upload_args << "--dry-run" if args.dry_run?
              upload_args << "--keep-old" if args.keep_old?
              upload_args << "--warn-on-upload-failure" if args.warn_on_upload_failure?
              upload_args << "--committer=#{args.committer}" if args.committer
              upload_args << "--root-url=#{args.root_url}" if args.root_url
              upload_args << "--root-url-using=#{args.root_url_using}" if args.root_url_using
              safe_system HOMEBREW_BREW_FILE, *upload_args
            end
          ensure
            if args.retain_bottle_dir? && GitHub::Actions.env_set?
              ohai "Bottle files retained at:", dir
              File.open(ENV.fetch("GITHUB_OUTPUT"), "a") do |f|
                f.puts "bottle_path=#{dir}"
              end
            else
              FileUtils.remove_entry dir
            end
          end
        end
      end

      # Separates a commit message into subject, body and trailers.
      sig { params(message: String).returns([String, String, String]) }
      def separate_commit_message(message)
        first_line = message.lines.first
        return ["", "", ""] unless first_line

        # Skip the subject and separate lines that look like trailers (e.g. "Co-authored-by")
        # from lines that look like regular body text.
        trailers, body = message.lines.drop(1).partition { |s| s.match?(/^[a-z-]+-by:/i) }

        trailers = trailers.uniq.join.strip
        body = body.join.strip.gsub(/\n{3,}/, "\n\n")

        [first_line.strip, body, trailers]
      end

      sig { params(git_repo: GitRepository, pull_request: T.nilable(String), dry_run: T::Boolean).void }
      def signoff!(git_repo, pull_request: nil, dry_run: false)
        msg = git_repo.commit_message
        return if msg.blank?

        subject, body, trailers = separate_commit_message(msg)

        if pull_request
          # This is a tap pull request and approving reviewers should also sign-off.
          tap = Tap.from_path(git_repo.pathname)
          review_trailers = GitHub.approved_reviews(tap.user, tap.full_name.split("/").last,
                                                    pull_request).map do |r|
            "Signed-off-by: #{r["name"]} <#{r["email"]}>"
          end
          trailers = trailers.lines.concat(review_trailers).map(&:strip).uniq.join("\n")

          # Append the close message as well, unless the commit body already includes it.
          close_message = "Closes ##{pull_request}."
          body.concat("\n\n#{close_message}") unless body.include?(close_message)
        end

        git_args = Utils::Git.git, "-C", git_repo.pathname, "commit", "--amend", "--signoff", "--allow-empty",
                   "--quiet", "--message", subject, "--message", body, "--message", trailers

        if dry_run
          puts(*git_args)
        else
          safe_system(*git_args)
        end
      end

      sig { params(tap: Tap, subject_name: String, subject_path: Pathname, content: String).returns(T.untyped) }
      def get_package(tap, subject_name, subject_path, content)
        if subject_path.to_s.start_with?("#{tap.cask_dir}/")
          cask = begin
            Cask::CaskLoader.load(content.dup)
          rescue Cask::CaskUnavailableError
            nil
          end
          return cask
        end

        begin
          Formulary.from_contents(subject_name, subject_path, content, :stable)
        rescue FormulaUnavailableError
          nil
        end
      end

      sig {
        params(old_contents: String, new_contents: String, subject_path: T.any(String, Pathname),
               reason: T.nilable(String)).returns(String)
      }
      def determine_bump_subject(old_contents, new_contents, subject_path, reason: nil)
        subject_path = Pathname(subject_path)
        tap          = Tap.from_path(subject_path)
        subject_name = subject_path.basename.to_s.chomp(".rb")
        is_cask      = subject_path.to_s.start_with?("#{tap.cask_dir}/")
        name         = is_cask ? "cask" : "formula"

        new_package = get_package(tap, subject_name, subject_path, new_contents)

        return "#{subject_name}: delete #{reason}".strip if new_package.blank?

        old_package = get_package(tap, subject_name, subject_path, old_contents)

        if old_package.blank?
          "#{subject_name} #{new_package.version} (new #{name})"
        elsif old_package.version != new_package.version
          "#{subject_name} #{new_package.version}"
        elsif !is_cask && old_package.revision != new_package.revision
          "#{subject_name}: revision #{reason}".strip
        elsif is_cask && old_package.sha256 != new_package.sha256
          "#{subject_name}: checksum update #{reason}".strip
        else
          "#{subject_name}: #{reason || "rebuild"}".strip
        end
      end

      # Cherry picks a single commit that modifies a single file.
      # Potentially rewords this commit using {determine_bump_subject}.
      sig {
        params(commit: String, file: String, git_repo: GitRepository, reason: T.nilable(String), verbose: T::Boolean,
               resolve: T::Boolean).void
      }
      def reword_package_commit(commit, file, git_repo:, reason: "", verbose: false, resolve: false)
        package_file = git_repo.pathname / file
        package_name = package_file.basename.to_s.chomp(".rb")

        odebug "Cherry-picking #{package_file}: #{commit}"
        Utils::Git.cherry_pick!(git_repo.to_s, commit, verbose:, resolve:)

        old_package = Utils::Git.file_at_commit(git_repo.to_s, file, "HEAD^")
        new_package = Utils::Git.file_at_commit(git_repo.to_s, file, "HEAD")

        bump_subject = determine_bump_subject(old_package, new_package, package_file, reason:).strip
        msg = git_repo.commit_message
        return if msg.blank?

        subject, body, trailers = separate_commit_message(msg)

        if subject != bump_subject && !subject.start_with?("#{package_name}:")
          safe_system("git", "-C", git_repo.pathname, "commit", "--amend", "-q",
                      "-m", bump_subject, "-m", subject, "-m", body, "-m", trailers)
          ohai bump_subject
        else
          ohai subject
        end
      end

      # Cherry picks multiple commits that each modify a single file.
      # Words the commit according to {determine_bump_subject} with the body
      # corresponding to all the original commit messages combined.
      sig {
        params(commits: T::Array[String], file: String, git_repo: GitRepository, reason: T.nilable(String),
               verbose: T::Boolean, resolve: T::Boolean).void
      }
      def squash_package_commits(commits, file, git_repo:, reason: "", verbose: false, resolve: false)
        odebug "Squashing #{file}: #{commits.join " "}"

        # Format commit messages into something similar to `git fmt-merge-message`.
        # * subject 1
        # * subject 2
        #   optional body
        # * subject 3
        messages = []
        trailers = []
        commits.each do |commit|
          msg = git_repo.commit_message(commit)
          next if msg.blank?

          subject, body, trailer = separate_commit_message(msg)
          body = body.lines.map { |line| "  #{line.strip}" }.join("\n")
          messages << "* #{subject}\n#{body}".strip
          trailers << trailer
        end

        # Get the set of authors in this series.
        authors = Utils.safe_popen_read("git", "-C", git_repo.pathname, "show",
                                        "--no-patch", "--pretty=%an <%ae>", *commits).lines.map(&:strip).uniq.compact

        # Get the author and date of the first commit of this series, which we use for the squashed commit.
        original_author = authors.shift
        original_date = Utils.safe_popen_read "git", "-C", git_repo.pathname, "show", "--no-patch", "--pretty=%ad",
                                              commits.first

        # Generate trailers for coauthors and combine them with the existing trailers.
        co_author_trailers = authors.map { |au| "Co-authored-by: #{au}" }
        trailers = [trailers + co_author_trailers].flatten.uniq.compact

        # Apply the patch series but don't commit anything yet.
        Utils::Git.cherry_pick!(git_repo.pathname, "--no-commit", *commits, verbose:, resolve:)

        # Determine the bump subject by comparing the original state of the tree to its current state.
        package_file = git_repo.pathname / file
        old_package = Utils::Git.file_at_commit(git_repo.pathname, file, "#{commits.first}^")
        new_package = package_file.read
        bump_subject = determine_bump_subject(old_package, new_package, package_file, reason:)

        # Commit with the new subject, body and trailers.
        safe_system("git", "-C", git_repo.pathname, "commit", "--quiet",
                    "-m", bump_subject, "-m", messages.join("\n"), "-m", trailers.join("\n"),
                    "--author", original_author, "--date", original_date, "--", file)
        ohai bump_subject
      end

      # TODO: fix test in `test/dev-cmd/pr-pull_spec.rb` and assume `cherry_picked: false`.
      sig {
        params(original_commit: String, tap: Tap, reason: T.nilable(String), verbose: T::Boolean, resolve: T::Boolean,
               cherry_picked: T::Boolean).void
      }
      def autosquash!(original_commit, tap:, reason: "", verbose: false, resolve: false, cherry_picked: true)
        git_repo = tap.git_repository

        commits = Utils.safe_popen_read("git", "-C", tap.path, "rev-list",
                                        "--reverse", "#{original_commit}..HEAD").lines.map(&:strip)

        # Generate a bidirectional mapping of commits <=> formula/cask files.
        files_to_commits = {}
        commits_to_files = commits.to_h do |commit|
          files = Utils.safe_popen_read("git", "-C", tap.path, "diff-tree", "--diff-filter=AMD",
                                        "-r", "--name-only", "#{commit}^", commit).lines.map(&:strip)
          files.each do |file|
            files_to_commits[file] ||= []
            files_to_commits[file] << commit
            tap_file = (tap.path/file).to_s
            if (tap_file.start_with?("#{tap.formula_dir}/") || tap_file.start_with?("#{tap.cask_dir}/")) &&
               File.extname(file) == ".rb"
              next
            end

            odie <<~EOS
              Autosquash can only squash commits that modify formula or cask files.
                File:   #{file}
                Commit: #{commit}
            EOS
          end
          [commit, files]
        end

        # Reset to state before cherry-picking.
        safe_system "git", "-C", tap.path, "reset", "--hard", original_commit

        # Iterate over every commit in the pull request series, but if we have to squash
        # multiple commits into one, ensure that we skip over commits we've already squashed.
        processed_commits = T.let([], T::Array[String])
        commits.each do |commit|
          next if processed_commits.include? commit

          files = commits_to_files[commit]
          if files.length == 1 && files_to_commits[files.first].length == 1
            # If there's a 1:1 mapping of commits to files, just cherry pick and (maybe) reword.
            reword_package_commit(
              commit, files.first, git_repo:, reason:, verbose:, resolve:
            )
            processed_commits << commit
          elsif files.length == 1 && files_to_commits[files.first].length > 1
            # If multiple commits modify a single file, squash them down into a single commit.
            file = files.first
            commits = files_to_commits[file]
            squash_package_commits(commits, file, git_repo:, reason:, verbose:, resolve:)
            processed_commits += commits
          else
            # We can't split commits (yet) so just raise an error.
            odie <<~EOS
              Autosquash can't split commits that modify multiple files.
                Commit: #{commit}
                Files:  #{files.join " "}
            EOS
          end
        end
      rescue
        original_head = git_repo&.head_ref
        return if original_head.nil?

        opoo "Autosquash encountered an error; resetting to original state at #{original_head}"
        system "git", "-C", tap.path.to_s, "reset", "--hard", original_head
        system "git", "-C", tap.path.to_s, "cherry-pick", "--abort" if cherry_picked
        raise
      end

      private

      sig { params(user: String, repo: String, pull_request: String, path: T.any(String, Pathname)).void }
      def cherry_pick_pr!(user, repo, pull_request, path: ".")
        if args.dry_run?
          puts <<~EOS
            git fetch --force origin +refs/pull/#{pull_request}/head
            git merge-base HEAD FETCH_HEAD
            git cherry-pick --ff --allow-empty $merge_base..FETCH_HEAD
          EOS
          return
        end

        commits = GitHub.pull_request_commits(user, repo, pull_request)
        safe_system "git", "-C", path, "fetch", "--quiet", "--force", "origin", commits.last
        ohai "Using #{commits.count} commit#{"s" if commits.count != 1} from ##{pull_request}"
        Utils::Git.cherry_pick!(path, "--ff", "--allow-empty", *commits, verbose: args.verbose?,
                                                                         resolve: args.resolve?)
      end

      sig { params(tap: Tap, original_commit: String, labels: T::Array[String]).returns(T::Boolean) }
      def formulae_need_bottles?(tap, original_commit, labels)
        return false if args.dry_run?

        return false if labels.include?("CI-syntax-only") || labels.include?("CI-no-bottles")

        changed_packages(tap, original_commit).any? do |f|
          !f.instance_of?(Cask::Cask)
        end
      end

      sig { params(tap: Tap, original_commit: String).returns(T::Array[String]) }
      def changed_packages(tap, original_commit)
        formulae = Utils.popen_read("git", "-C", tap.path, "diff-tree",
                                    "-r", "--name-only", "--diff-filter=AM",
                                    original_commit, "HEAD", "--", tap.formula_dir)
                        .lines
                        .filter_map do |line|
          next unless line.end_with? ".rb\n"

          name = "#{tap.name}/#{File.basename(line.chomp, ".rb")}"
          if Homebrew::EnvConfig.disable_load_formula?
            opoo "Can't check if updated bottles are necessary as HOMEBREW_DISABLE_LOAD_FORMULA is set!"
            break
          end
          begin
            Formulary.resolve(name)
          rescue FormulaUnavailableError
            nil
          end
        end
        casks = Utils.popen_read("git", "-C", tap.path, "diff-tree",
                                 "-r", "--name-only", "--diff-filter=AM",
                                 original_commit, "HEAD", "--", tap.cask_dir)
                     .lines
                     .filter_map do |line|
          next unless line.end_with? ".rb\n"

          name = "#{tap.name}/#{File.basename(line.chomp, ".rb")}"
          begin
            Cask::CaskLoader.load(name)
          rescue Cask::CaskUnavailableError
            nil
          end
        end
        formulae + casks
      end

      sig { params(repo: String, pull_request: String).void }
      def pr_check_conflicts(repo, pull_request)
        long_build_pr_files = GitHub.issues(
          repo:, state: "open", labels: "no long build conflict",
        ).each_with_object({}) do |long_build_pr, hash|
          next unless long_build_pr.key?("pull_request")

          number = long_build_pr["number"]
          next if number == pull_request.to_i

          GitHub.get_pull_request_changed_files(repo, number).each do |file|
            key = file["filename"]
            hash[key] ||= []
            hash[key] << number
          end
        end

        return if long_build_pr_files.blank?

        this_pr_files = GitHub.get_pull_request_changed_files(repo, pull_request)

        conflicts = this_pr_files.each_with_object({}) do |file, hash|
          filename = file["filename"]
          next unless long_build_pr_files.key?(filename)

          long_build_pr_files[filename].each do |pr_number|
            key = "#{repo}/pull/#{pr_number}"
            hash[key] ||= []
            hash[key] << filename
          end
        end

        return if conflicts.blank?

        # Raise an error, display the conflicting PR. For example:
        # Error: You are trying to merge a pull request that conflicts with a long running build in:
        # {
        #   "homebrew-core/pull/98809": [
        #    "Formula/icu4c.rb",
        #    "Formula/node@10.rb"
        #   ]
        # }
        odie <<~EOS
          You are trying to merge a pull request that conflicts with a long running build in:
          #{JSON.pretty_generate(conflicts)}
        EOS
      end
    end
  end
end
