#!/bin/bash
# Copyright 2024 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

set -euE -o pipefail

# If true, `./multifuchsia enter` will create a new namespace and mount the
# checkout with the $MOUNTPOINT path. This has the advantage of making all
# checkouts have the same path, but may prevent the ability to use tools like
# RBE that will error out if run in a sub-namespace.
ENTER_ISOLATED_NAMESPACE="false"

function swap() {
  local -r file1=$1
  local -r file2=$2
  python3 -c 'import sys; import ctypes; syscall=ctypes.CDLL(None).syscall; syscall.restype=ctypes.c_int; syscall.argtypes=(ctypes.c_long, ctypes.c_int, ctypes.c_char_p, ctypes.c_int, ctypes.c_char_p, ctypes.c_uint); sys.exit(syscall(316, -100, sys.argv[1].encode("utf-8"), -100, sys.argv[2].encode("utf-8"), 2))' "$file1" "$file2" || (
    echo "failed to exchange snapshots: $?"
    return 1
  )
}

readonly WORKDIR="$(dirname "${BASH_SOURCE[0]}")"

function lookup_checkout() {
  local -r name="$1"
  if [[ "$name" == *"/"* ]]; then
    echo "$name"
  else
    echo "$WORKDIR/checkouts/$name"
  fi
}

function cmd_sync_and_build() {
  local -r multifuchsia_workdir="$(realpath $(dirname "${BASH_SOURCE[0]}"))"
  local -r multifuchsia_srcdir="$(dirname $(realpath "${BASH_SOURCE[0]}"))"
  if [ "${multifuchsia_workdir}" == "${multifuchsia_srcdir}" ]; then
    echo "error: multifuchsia should be run from a symlink located in the root of the multifuchsia workspace, not a copy or run directly." >&2
    return 1
  fi

  local args=(
    "${multifuchsia_srcdir}/update_and_build_inner.sh"
    --workspace "${multifuchsia_workdir}"
  )

  if [ ${ENTER_ISOLATED_NAMESPACE} == "true" ]; then
    unshare \
      --user \
      --mount \
      --map-current-user \
      --keep-caps \
      "${args[@]}" \
      --mount "${MOUNTPOINT}"
  else
    bash -- \
      "${args[@]}"
  fi
}

# For calling from systemd units/anywhere where it's easier to manipulate the
# working directory than the executable path.
function cmd_sync_and_build_here() {
  local -r multifuchsia_current="$(realpath "${BASH_SOURCE[0]}")"
  local -r multifuchsia_local="$(realpath ./multifuchsia)"
  if [ "${multifuchsia_current}" != "${multifuchsia_local}" ]; then
    echo "error: $(pwd) doesn't look like a multifuchsia workspace. \$(realpath ./multifuchsia) = \"${multifuchsia_local}\"" >&2
    return 1
  fi

  ./multifuchsia sync_and_build "$@"
}

function cmd_checkout() {
  local -r branch="$1"
  local mode="$DEFAULT_CHECKOUT_MODE"
  if [ $# -eq 2 ]; then
    mode="$2"
  elif [ $# -gt 2 ]; then
    echo "error: too many arguments" >&2
  fi

  cd "$WORKDIR"

  destdir="checkouts/$branch"
  if [ -d "$destdir" ]; then
    echo "error: $destdir already exists" >&2
    return 1
  else
    case "$mode" in
      worktree)
        echo "Creating subvolume $destdir.new" >&2
        btrfs subvolume snapshot snapshots/update.success "$destdir.new"
        readonly git_commit="$(git -C "$destdir.new" rev-parse HEAD)"

        echo "Creating worktree $destdir" >&2
        git -C clean worktree add ../"$destdir" --detach --no-checkout "$git_commit"
        git -C "$destdir" reset --quiet
        readonly gitdir="$(git -C "$destdir" rev-parse --git-dir)"

        echo "Joining subvolume $destdir.new with worktree $destdir" >&2
        mv "$destdir.new"/.git/index "$gitdir"/index
        mv "$destdir.new"/.git/modules "$gitdir"/
        # fixup submodule .git links
        sed -i 's|gitdir: \(../\)\+.git|'"$(cat "$destdir"/.git)"'|' $(find "$destdir.new" -path "$destdir.new/out" -prune -o -type f -name .git -print | grep -v "^$destdir.new/.git" | grep -v "^$destdir.new/out/")
        rm -rf "$destdir.new"/.git
        mv "$destdir"/.git "$destdir.new"/
        rmdir "$destdir"
        mv "$destdir.new" "$destdir"

        # fixup core.worktree in submodule gitdirs
        git -C "$destdir" submodule foreach --recursive --quiet 'sed -i "/^\tworktree/d" "$(cat .git|sed "s/^gitdir: //")"/config'
        git -C "$destdir" submodule foreach --recursive --quiet 'git config core.worktree "$(pwd)"'

        git -C "$destdir" status

        echo "Restoring JIRI_HEAD to ${git_commit}" >&2
        echo "create JIRI_HEAD ${git_commit}" | git -C "$destdir" update-ref --stdin -m 'copy JIRI_HEAD from snapshot'
        ;;
      snapshot)
        echo "Creating subvolume $destdir" >&2
        btrfs subvolume snapshot snapshots/update.success "$destdir"
        ;;
      *)
        echo "unknown mode '$mode'" >&2
        return 1
        ;;
    esac
  fi
}

function cmd_mount() {
  local -r branch="$1"

  unmount_repo

  cd "$WORKDIR"

  destdir="checkouts/$branch"
  if [ -d "$destdir" ]; then
    echo "Reusing existing $destdir" >&2
    while [[ "$(git -C "$destdir" show -s --format='%s' HEAD)" == "wip!"* ]]; do git -C "$destdir" reset HEAD^; done
  else
    cmd_checkout "$branch"
  fi

  echo "Bind mounting $destdir as fuchsia" >&2
  sudo mount --bind "$destdir" "$MOUNTPOINT"
}

function cmd_umount() {
  unmount_repo
}

function unmount_repo() {
  if findmnt --raw --noheadings --output 'SOURCE' --mountpoint "$MOUNTPOINT" >/dev/null; then
    echo "Trying to unmount $MOUNTPOINT" >&2
    if ! sudo umount "$MOUNTPOINT" ; then
      echo "Stopping goma" >&2
      (cd ~/src/fuchsia && ./scripts/fx goma_ctl ensure_stop)
      echo "Stopping ffx daemon" >&2
      (cd "$MOUNTPOINT" && ./scripts/fx ffx emu stop --all)
      (cd "$MOUNTPOINT" && ./scripts/fx ffx daemon stop)
      echo "Stopping bazel" >&2
      (cd "$MOUNTPOINT" && ./scripts/fx bazel shutdown)
      echo "Unmounting $MOUNTPOINT" >&2
      sudo umount "$MOUNTPOINT"
    fi
  fi
}

## rebase

function cmd_rebase() {
  local -r checkout_name="$1"
  local checkout
  checkout="$(dirname "$(lookup_checkout "$checkout_name")"/fakefile)"

  if [ ! -d "$checkout" ]; then
    echo "$checkout/: not found" >&2
    return 1
  fi

  if [ -d "$checkout.new" ]; then
    btrfs subvolume delete -c "$checkout.new"
  fi
  btrfs subvolume snapshot "$WORKDIR"/snapshots/update.success "$checkout.new"
  base_hash=$(git -C "$checkout.new" rev-parse HEAD)

  local using_branchless
  if [ -d "$checkout/.git/branchless" ]; then
    echo "Detected git-branchless, will advance JIRI_HEAD and try to use "'`git branchless sync`' >&2
    # Start by detaching so we don't move branch pointers around
    git -C "$checkout" switch --detach
    using_branchless="true"
  else
    using_branchless="false"
  fi

  local -r git_status="$(git -C "$checkout" status -s)"
  local workdir_dirty
  if [ -z "$git_status" ]; then
    # clean
    workdir_dirty="false"
  else
    workdir_dirty="true"
    git -C "$checkout" add -A .
    git -C "$checkout" commit -m "wip! changes from `date --iso`"
  fi
  git -C "$checkout" fetch --recurse-submodules=no "$(realpath $checkout.new)" "$base_hash"
  echo "Updating JIRI_HEAD to ${base_hash}"
  echo "update JIRI_HEAD ${base_hash}" | git -C "$checkout" update-ref --stdin -m 'copy JIRI_HEAD from snapshot'
  if [ "$using_branchless" == "true" ]; then
    # for branchless, we just leave all the commits where they are (including
    # the wip! one), checkout the new JIRI_HEAD, and then use `git branchless
    # sync`
    git -C "$checkout" switch --detach "${base_hash}"
    local -r branchless_main_branch="$(git -C "$checkout" config branchless.core.mainBranch)"
    echo "Updating branchless main branch '${branchless_main_branch}' to ${base_hash}"
    echo "update refs/heads/${branchless_main_branch} ${base_hash}" | git -C "$checkout" update-ref --stdin -m 'update git-branchless main branch with new JIRI_HEAD'
    git -C "$checkout" branchless sync -m
  else
    git -C "$checkout" rebase "$base_hash"
    new_hash=$(git -C "$checkout" rev-parse HEAD)
    if [ "$workdir_dirty" == "true" ]; then
      # undo the wip! commit we made earlier
      git -C "$checkout" reset HEAD^
    fi
    git -C "$checkout.new" fetch --recurse-submodules=no "$(realpath $checkout)" "$new_hash"
    git -C "$checkout.new" checkout "$new_hash"
  fi
  echo "restoring submodules to match snapshot" >&2
  local gitmodules_dir
  gitmodules_dir="$(git -C "$checkout" rev-parse --absolute-git-dir)/modules"
  rm -rf "$gitmodules_dir"
  mv "$checkout.new/.git/modules" "$gitmodules_dir"
  rm -rf "$checkout.new/.git"
  cp -a --reflink=auto "$checkout/.git" "$checkout.new/.git"
  if ! cmp --quiet "$checkout/out/default/args.gn" "$checkout.new/out/default/args.gn"; then
    cp "$checkout/out/default/args.gn" "$checkout.new/out/default/args.gn"
  fi

  # Update the checkout's remotes/origin/main.
  echo "updating remotes/origin/main"
  git -C "$checkout.new" fetch "$WORKDIR/snapshots/update.success" "remotes/origin/main:remotes/origin/main"

  swap "$checkout" "$checkout.new"
  btrfs subvolume delete -c "$checkout.new"

  if [ -f "$checkout/.git" ]; then
    echo "fixing gitmodule links for worktree" >&2
    # fixup submodule .git links
    sed -i 's|gitdir: \(../\)\+.git|'"$(cat "$checkout"/.git)"'|' $(find "$checkout" -path "$checkout/out" -prune -o -type f -name .git -print | grep -v "^$checkout/.git" | grep -v "^$checkout/out/")
    # fixup core.worktree in submodule gitdirs
    git -C "$checkout" submodule foreach --recursive --quiet 'sed -i "/^\tworktree/d" "$(cat .git|sed "s/^gitdir: //")"/config'
    git -C "$checkout" submodule foreach --recursive --quiet 'git config core.worktree "$(pwd)"'
  fi
}

function detect_non_fuchsia_git_changes() {
  local checkout="$1"
  local base_path="$(realpath "$checkout")"
  readarray -d $'\0' -t git_dirs < <(find "$base_path" -path "$base_path/out" -prune -o -path "$base_path/.git" -prune -o -name '.git' -print0)
  local result=0
  for git_dir in ${git_dirs[@]}; do
    local repo_path="${git_dir%/.git}"
    if ! cleanup_repo "$checkout" "$repo_path"; then
      result=1
    fi
  done
  return $result
}

function cmd_pack() {
  readonly gitdir="$(dirname "$1"/fakefile)"

  echo "Checking for changes in other repos (which cannot currently be packed)" >&2
  if ! detect_non_fuchsia_git_changes "$gitdir" ; then
    echo "clean up or back up the changes in other repos, and then retry" >&2
    return 1
  fi

  if ! git -C "$gitdir" symbolic-ref -q HEAD >/dev/null; then
    echo "detected detached HEAD, creating branch" >&2
    if ! git -C "$gitdir" switch -c "$(basename "$gitdir")"; then
      return 1
    fi
  fi
  local branchname
  branchname="$(git -C "$gitdir" symbolic-ref HEAD)"

  git -C "$gitdir" add -A .
  git -C "$gitdir" add -f out/*/args.gn
  git -C "$gitdir" commit -m "wip! changes from `date --iso`" --allow-empty

  if [ ! -f "$gitdir"/.git ]; then
    echo "pushing branch '$branchname' to clean" >&2
    git -C "$gitdir" push "$(realpath "$WORKDIR/clean")" "$branchname":"$branchname"
  fi

  btrfs subvolume delete -c "$gitdir"
}

## update

function cmd_update() {
  local -r repository="$(realpath "$WORKDIR")/repository/fuchsia.com"
  if [ -d "$WORKDIR/snapshots/update.new" ] ; then
    btrfs property set "$WORKDIR/snapshots/update.new" ro false
    btrfs subvolume delete -c "$WORKDIR/snapshots/update.new"
  fi
  btrfs subvolume snapshot -r "$WORKDIR/snapshots/build.success" "$WORKDIR/snapshots/update.new"
  (
    cd "$WORKDIR/snapshots/update.new"
    (
      cd out/default
      if [ -d "$repository" ]; then
        ../../scripts/fx host-tool --no-build package-tool repository publish --package-list all_package_manifests.list "$repository"
      else
        cp -a --reflink=always amber-files "$repository"
      fi
    )
  )

  "$WORKDIR"/multifuchsia enter "$WORKDIR/snapshots/update.new" "$(realpath "$WORKDIR")"/multifuchsia update_helper

  if [ -d "$WORKDIR"/snapshots/update.success ] ; then
    swap "$WORKDIR"/snapshots/update.new "$WORKDIR"/snapshots/update.success
    btrfs property set -ts "$WORKDIR"/snapshots/update.new ro false
    btrfs subvolume delete -c "$WORKDIR"/snapshots/update.new
  else
    mv "$WORKDIR"/snapshots/update.new "$WORKDIR"/snapshots/update.success
  fi
}

function cmd_update_helper() {
  local fuchsia_build_dir
  fuchsia_build_dir="$(./scripts/fx get-build-dir)"
  local expected_system_image_merkle
  expected_system_image_merkle=$(cat "${fuchsia_build_dir}"/obj/build/images/fuchsia/fuchsia/base/package_manifest.json | scripts/fx jq -r '.blobs[] | select(.path == "meta/") | .merkle' )

  local -r socket_dir="$WORKDIR/.update-ffx-daemon"
  mkdir -p "$socket_dir"
  mount --bind "$socket_dir" "$fuchsia_build_dir/.ffx-daemon"
  ./scripts/fx --dir=out/default shell update check-now --monitor || true
  ./scripts/fx --dir=out/default wait
  ./scripts/fx --dir=out/default shell update wait-for-commit
  if [[ $(./scripts/fx --dir=out/default shell 'read ver < /system/meta;echo $ver') != "${expected_system_image_merkle}" ]] ; then
    echo "After update, system appears still out of date. OTA may have failed. Run 'fx log' for details." >&2
    return 1
  fi
}

function cleanup_repo() {
  local -r checkout="$1"
  local base_path
  base_path="$(realpath "$checkout")"
  local -r repo_path="$2"
  local repo_relpath="${repo_path#$base_path}"
  local expected_revision
  expected_revision="$(git -C "$repo_path" rev-parse JIRI_HEAD)" || {
    echo "error in '$repo_path'" >&2
    return 1
  }
  local git_status
  git_status="$(git -C "$repo_path" status -s)" || {
    echo "error in '$repo_path'" >&2
    return 1
  }
  local workdir_dirty
  if [ -z "$git_status" ]; then
    # clean
    workdir_dirty="false"
    true
  else
    # git -C "$repo_path" status
    workdir_dirty="true"
    result=1
  fi
  local repo_revision
  repo_revision="$(git -C "$repo_path" rev-parse HEAD)" || return
  local raw_missing_commits
  raw_missing_commits="$(git -C "$repo_path" log "$expected_revision".. --format=format:%H)" || return
  local missing_commits=( $raw_missing_commits )
  if [ ${#missing_commits[*]} -gt 0 ] || [ "${workdir_dirty}" == "true" ] ; then
    echo "${checkout}${repo_relpath}:" >&2
  fi
  if [ "${workdir_dirty}" == "true" ]; then
    echo "  [dirty] working directory" >&2
  fi
  if [ ${#missing_commits[*]} -gt 20 ]; then
    echo "  too many missing commits ${#missing_commits[*]}" >&2
    result=1
  else
    for missing_commit in ${missing_commits[@]}; do
      local commit_status
      local change_id_trailer="$(
          git -C "$repo_path" cat-file -p "$missing_commit" \
          | git interpret-trailers --parse \
          | (grep '^Change-Id: ' || true)
      )"
      if [ -z "$change_id_trailer" ]; then
        commit_status="missing Change-Id"
        result=1
      else
        local submitted_revision="$(git -C clean/$repo_relpath log "$expected_revision"..origin/main --format=format:%H --grep '^'"$change_id_trailer"'$')"
        if [ -z "$submitted_revision" ]; then
          commit_status="not submitted"
          result=1
        else
          commit_status="submitted"
          # already have this commit
          true
        fi
      fi
      echo "  [$commit_status] $(git -C "$repo_path" show --oneline --quiet "$missing_commit" --color=always)" >&2
    done
  fi
  return $result
}

function cleanup_checkout() {
  local checkout="$1"
  local base_path="$(realpath "$checkout")"
  readarray -d $'\0' -t git_dirs < <(find "$base_path" -path "$base_path/out" -prune -o -name '.git' -print0)
  local result=0
  for git_dir in ${git_dirs[@]}; do
    local repo_path="${git_dir%/.git}"
    if ! cleanup_repo "$checkout" "$repo_path"; then
      result=1
    fi
  done
  return $result
}
function cmd_cleanup() {
  local to_clean=( )
  (
    cd "$WORKDIR"
    if [ $# -eq 1 ] ; then
      if cleanup_checkout "$1"; then
        return 0
      else
        return $?
      fi
    elif [ $# -gt 1 ]; then
      echo "Too many arguments" >&2
      return 1
    fi
    for checkout in checkouts/* ; do
      # echo "Considering $checkout for cleanup" >&2
      if cleanup_checkout "$checkout"; then
        to_clean+=( $checkout )
      fi
    done
    if [ ${#to_clean[*]} -gt 0 ]; then
      echo "To clean: ${to_clean[*]}"
      echo "btrfs subvolume delete -c ${to_clean[*]} && git -C clean worktree prune"
    fi
  )
}

function cmd_enter() {
  local -r checkout_name="$1"
  shift
  local checkout
  checkout=$(lookup_checkout "$checkout_name")
  # copy multifuchsia to a tempfile and run it out of there
  # `./multifuchsia enter` tends to be a long-running script and this helpfully
  # avoids us shooting ourselves in the foot if we edit it while running it.
  local -r tmp_multifuchsia=$(mktemp "$WORKDIR/.multifuchsia_enter_helper.XXXXXX")
  cp -p --reflink=auto "$WORKDIR/multifuchsia" "$tmp_multifuchsia"
  local -r multifuchsia_src="$(dirname "$(realpath "$WORKDIR/multifuchsia")")"

  local args=()

  if [ ${ENTER_ISOLATED_NAMESPACE} == "true" ]; then
    args+=( exec unshare --user --mount --map-current-user --keep-caps )
  fi

  args+=( "$tmp_multifuchsia" enter_helper "$multifuchsia_src" "$checkout" "$@" )

  "${args[@]}"
}

function bind_mount() {
  local -r source="$1"

  if mount --bind "$source" "$MOUNTPOINT" ; then
    # all good
    true
  else
    if findmnt --raw --noheadings --output 'SOURCE' --mountpoint "$MOUNTPOINT" >/dev/null; then
      echo "Working around mounted but broken $MOUNTPOINT" >&2
      local -r mountpoint_parent="$(dirname $MOUNTPOINT)"
      mount -t tmpfs fake_src "$mountpoint_parent"
      mkdir -p "$MOUNTPOINT"
      mount --bind "$source" "$MOUNTPOINT"
    else
      echo "Mount failed but nothing seems to be mounted on $MOUNTPOINT" >&2
      return 1
    fi
  fi
}

function cmd_enter_helper() {
  # we're running out of a tempfile, so unlink it as soon as possible.
  rm "${BASH_SOURCE[0]}"

  local -r multifuchsia_src="$1"
  shift
  local -r checkout="$1"
  shift

  if [ ! -e "$checkout" ]; then
    echo "error: '$checkout' not found" >&2
    return 1
  fi

  # Optionally set up an isolated namespace.
  if [ $ENTER_ISOLATED_NAMESPACE == "true" ]; then
    bind_mount "$checkout"
    cd "$MOUNTPOINT"
    export PATH="$MOUNTPOINT/.jiri_root/bin:$PATH"

    readonly goma_tmp_dir="$(./prebuilt/third_party/goma/linux-x64/gomacc tmp_dir)"
    mount -t tmpfs isolated_goma "$goma_tmp_dir"
    # goma complains about excessive permissions on this dir
    chmod go-rwx "$goma_tmp_dir"
  else
    cd "$checkout"
    export PATH="$checkout/.jiri_root/bin:$PATH"
    export FUCHSIA_DIR="$checkout"
  fi

  export MULTIFUCHSIA_ENTER_ENV="$(basename "$checkout")"
  # pick alternate ports so we don't interfere with the outside goma
  # default ports: 8089 19080
  # cron job ports: 8088 19081
  export GOMA_COMPILER_PROXY_PORT=8087
  export GOMACTL_PROXY_PORT=19082
  # only start goma if it looks like the build wants it
  # grep command courtesy of https://cs.opensource.google/fuchsia/fuchsia/+/main:tools/devshell/build;l=177;drc=84563a2c5e3f92d8d1a29e78bab504ea1fe93324
  if grep -q "^ *use_goma = true" "$(./scripts/fx get-build-dir)/args.gn"; then
    ./scripts/fx goma_ctl start
  fi
  local retcode=0
  if [ "$#" -gt 0 ]; then
    if "$@" ; then
      # success
      retcode=0
    else
      retcode="$?"
      echo "Failed, but still running cleanup" >&2
    fi
  else
    local -r shell="${SHELL:-bash}"
    case "$EDIT_SHELL_PROMPT" in
      true)
        case "$(basename "$shell")" in
          bash)
            "$shell" --rcfile "${multifuchsia_src}/enter.bashrc" -i || true
            ;;
          zsh)
            ZDOTDIR="${multifuchsia_src}/enter.zsh" "$shell" -i || true
            ;;
          *)
            # EDIT_SHELL_PROMPT doesn't support this shell yet.
            "$shell" -i || true
            ;;
        esac
        ;;
      false)
        "$shell" -i || true
        ;;
      *)
        echo 'error: $EDIT_SHELL_PROMPT should be true or false' >&2
        return 1
        ;;
    esac
  fi

  if grep -q "^ *use_goma = true" "$(./scripts/fx get-build-dir)/args.gn"; then
    ./scripts/fx goma_ctl ensure_stop
  fi

  return "$retcode"
}

function cmd_config_get_multifuchsia_root() {
  (cd "$WORKDIR" && pwd)
}

function cmd_config_get_mountpoint() {
  echo "$MOUNTPOINT"
}

function cmd_env_bash() {
  local -r multifuchsia_src="$(dirname "$(realpath "$WORKDIR/multifuchsia")")"
  cat "$multifuchsia_src/env/bash.template.sh" | sed 's|local -r MULTIFUCHSIA_ROOT={{placeholder}}$|local -r MULTIFUCHSIA_ROOT="'"$(cmd_config_get_multifuchsia_root)"'"|'
}

function cmd_env() {
  local -r subcommand="$1"
  shift

  case "$subcommand" in
    bash)
      cmd_env_bash "$@"
      ;;
    zsh)
      # Apparently zsh supports bash completions just fine lol
      cmd_env_bash "$@"
      ;;
    *)
      echo "error: unsupported shell '$subcommand' (contributions welcome)" >&2
      return 1
  esac
}

function find_service_unit() {
  for candidate in $((systemctl --user list-units --type service --all --quiet fuchsia_update_and_build.service && systemctl --user list-units --type service --all --quiet fuchsia_update_and_build@'*') | sed 's/^..//' | cut -f1 -d" " ); do
    if [ "$(systemctl --user show -P WorkingDirectory "$candidate")" == "$(realpath "$WORKDIR")" ]; then
      echo "$candidate"
      return
    fi
  done
  return 1
}

function cmd_status() {
  git -C "$WORKDIR/snapshots/build.success/integration" log HEAD^..HEAD --abbrev-commit --color=always --pretty="tformat:snapshots/build.success/integration: %C(auto)%h %ar %s"
  if [ ! -L "$WORKDIR/snapshots/update.success" ]; then
    git -C "$WORKDIR/snapshots/update.success/integration" log HEAD^..HEAD --abbrev-commit --color=always --pretty="tformat:snapshots/update.success/integration: %C(auto)%h %ar %s"
  fi
  systemctl --user status "$(find_service_unit)"
}

function main() {
  local -r subcommand="$1"
  shift


  if [ "$subcommand" != "sync_and_build_here" ]; then
    # note: cmd_sync_and_build_here isn't called from the workdir (and therefore
    # wouldn't find the config). It'll pick up the config when it later
    # re-enters the script by calling sync_and_build from the workdir.
    if [ ! -f "$WORKDIR/multifuchsia.rc" ]; then
      echo "error '$WORKDIR/multifuchsia.rc' does not exist. See $(dirname $(realpath "${BASH_SOURCE[0]}"))/multifuchsia.rc.example" >&2
      exit 1
    fi
    source "$WORKDIR/multifuchsia.rc"
    if [ -z "${MOUNTPOINT+x}" ]; then
      echo "error: '$WORKDIR/multifuchsia.rc' does not set MOUNTPOINT." >&2
      exit 1
    fi
    if [ -z "${DEFAULT_CHECKOUT_MODE+x}" ]; then
      echo "error: '$WORKDIR/multifuchsia.rc' does not set DEFAULT_CHECKOUT_MODE." >&2
      exit 1
    fi
    if [ -z "${EDIT_SHELL_PROMPT+x}" ]; then
      echo "error: '$WORKDIR/multifuchsia.rc' does not set EDIT_SHELL_PROMPT." >&2
      exit 1
    fi
  fi

  case "$subcommand" in
    sync_and_build)
      cmd_sync_and_build "$@"
      ;;
    sync_and_build_here)
      cmd_sync_and_build_here "$@"
      ;;
    checkout|co)
      cmd_checkout "$@"
      ;;
    mount)
      cmd_mount "$@"
      ;;
    umount)
      cmd_umount "$@"
      ;;
    update)
      cmd_update "$@"
      ;;
    update_helper)
      cmd_update_helper "$@"
      ;;
    rebase)
      cmd_rebase "$@"
      ;;
    cleanup)
      cmd_cleanup "$@"
      ;;
    enter)
      cmd_enter "$@"
      ;;
    enter_helper)
      cmd_enter_helper "$@"
      ;;
    pack)
      cmd_pack "$@"
      ;;
    config_get_multifuchsia_root)
      cmd_config_get_multifuchsia_root "$@"
      ;;
    config_get_mountpoint)
      cmd_config_get_mountpoint "$@"
      ;;
    env)
      cmd_env "$@"
      ;;
    status)
      cmd_status "$@"
      ;;
    *)
      echo "unknown subcommand '$subcommand'" >&2
      return 1
  esac
}

main "$@"