gcw() {
  # Filter specific workflows.
  local ADD_STATUS=$(git diff --staged --diff-filter=A --name-only)
  local DELETE_STATUS=$(git diff --staged --diff-filter=D --name-only)
  local RENAME_STATUS=$(git diff --staged --diff-filter=R --name-only)
  # Update status includes everything else.
  local UPDATE_STATUS=$(git diff --staged --diff-filter=MCTUXB --name-only)

  # Make sure we're using one workflow by counting up workflow changes.
  local STATUS_CHANGE_COUNT=0
  if [ ! -z "$ADD_STATUS" ]; then
    STATUS_CHANGE_COUNT=$((STATUS_CHANGE_COUNT+1))
  fi
  if [ ! -z "$DELETE_STATUS" ]; then
    STATUS_CHANGE_COUNT=$((STATUS_CHANGE_COUNT+1))
  fi
  if [ ! -z "$RENAME_STATUS" ]; then
    STATUS_CHANGE_COUNT=$((STATUS_CHANGE_COUNT+1))
  fi
  if [ ! -z "$UPDATE_STATUS" ]; then
    STATUS_CHANGE_COUNT=$((STATUS_CHANGE_COUNT+1))
  fi
  if [ $STATUS_CHANGE_COUNT -gt 1 ]; then
    echo "Too many changes. Use 'git commit' directly instead."
    return
  elif [ $STATUS_CHANGE_COUNT -eq 0 ]; then
    echo "No changes found."
    return
  fi

  # Find the correct context for these changes.
  # Select parts of the selected source.
  # Example:
  #   Selected: src/modules/nvim/nvim.sh
  #   > [src, modules, nvim, nvim.sh]
  #   Select option "modules"
  #   > [nvim, nvim.sh]
  #   Continue until exhausted or "DONE"
  local SELECTED_UPDATE=$(echo "$ADD_STATUS$DELETE_STATUS$RENAME_STATUS$UPDATE_STATUS" | fzf)
  local SELECTED_UPDATE_PARTS=($(echo $SELECTED_UPDATE | sed -e 's/\//\n/g'))
  __gcm_select_source_part() {
    local SELECTED_UPDATE_PART_OPTIONS=("${SELECTED_UPDATE_PARTS[@]}" "DONE")
    local SELECTED_UPDATE_PART=$(printf "%s\n" "${SELECTED_UPDATE_PART_OPTIONS[@]}" | fzf | sed 's/^src\///g')

    # Return "DONE".
    if [[ "$SELECTED_UPDATE_PART" == "DONE" ]]; then
      echo -1
      return
    fi

    # Return selected part index.
    local PART_INDEX=0; for PART in "${SELECTED_UPDATE_PARTS[@]}"; do
        [[ $PART == "$SELECTED_UPDATE_PART" ]] && break
        PART_INDEX=$((PART_INDEX+1))
    done
    echo $((PART_INDEX))
  }
  __gcm_inside_out_select() {
    local NEXT_INDEX=0; while [ ! $NEXT_INDEX -eq -1 ]; do
      SELECTED_UPDATE_PARTS=("${SELECTED_UPDATE_PARTS[@]:$NEXT_INDEX}")
      if [ "${#SELECTED_UPDATE_PARTS[@]}" -le "0" ]; then
        break
      fi

      local SELECTED_INDEX=$(__gcm_select_source_part $NEXT_INDEX)
      if [ "$SELECTED_INDEX" -le "-1" ]; then
        # User manually exited.
        break
      fi
      echo "${SELECTED_UPDATE_PARTS[$SELECTED_INDEX+1]}"
      NEXT_INDEX=$((SELECTED_INDEX+1))
    done
  }

  # Common message format.
  local MESSAGE_CONTEXT=$(__gcm_inside_out_select | tr '\n' '/' | sed 's/.$//')

  # Get additional context if any.
  git diff --staged
  echo "\n"
  local MESSAGE_CONTEXT_ADDITION
  MESSAGE_CONTEXT_ADDITION=$(bash -c 'read -e -p "Additional Context: " tmp; echo $tmp')
  if [ ! -z $MESSAGE_CONTEXT_ADDITION ]; then
    MESSAGE_CONTEXT_ADDITION=" $MESSAGE_CONTEXT_ADDITION"
  fi

  # Execute workflow.
  if [ ! -z "$ADD_STATUS" ]; then
    # Add.
    git commit -m "Add '$MESSAGE_CONTEXT'$MESSAGE_CONTEXT_ADDITION"
  elif [ ! -z "$DELETE_STATUS" ]; then
    # Delete.
    git commit -m "Delete '$MESSAGE_CONTEXT'$MESSAGE_CONTEXT_ADDITION"
  elif [ ! -z "$RENAME_STATUS" ]; then
    # Rename.
    git commit -m "Rename '$MESSAGE_CONTEXT'$MESSAGE_CONTEXT_ADDITION"
  elif [ ! -z "$UPDATE_STATUS" ]; then
    # Update.
    git commit -m "Update '$MESSAGE_CONTEXT'$MESSAGE_CONTEXT_ADDITION"
  fi
}