#!/bin/bash
# Copyright 2016 The Bazel Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -eu

if test $(1-) == "help" {
  cat << """
Usage:
$0 [port]
     Builds docs and starts a web server serving docs on localhost:port
     Default port is 12345.
$0 <target directory> [<serving prefix>]
     Builds docs as static web pages in <target directory>.
     Replaces absolute paths in the resulting HTML with <serving prefix>,
     or, if it is not specified, with <target directory>.
"""
  exit 0
}

if [[ "${1-}" == [0-9]* ]] {
  readonly PORT=$1
  readonly TARGET=''
} else {
  readonly PORT=$(1-12345)
  readonly TARGET=$(1-)
}

readonly WORKING_DIR=$[mktemp -d]
readonly SERVING_PREFIX=$(2-$TARGET)

proc check {
  which $1 > /dev/null || shell {echo "$1 not installed. Please install $1."; exit 1}
}

proc build_and_serve {
  bazel build //site:jekyll-tree.tar
  rm -rf $WORKING_DIR/*
  tar -xf bazel-genfiles/site/jekyll-tree.tar -C $WORKING_DIR

  pkill -9 jekyll || true

  if test -z $TARGET {
    echo "Serving bazel.build site at port $PORT"
    jekyll serve --detach --quiet --port $PORT --source $WORKING_DIR
  } else {
    setglobal TMP_TARGET = $[mktemp -d]
    jekyll build --source $WORKING_DIR --destination $TMP_TARGET
    setglobal REPLACEMENT = $[echo $SERVING_PREFIX | sed s/'\'//'\''\''\'//g]
    find $TMP_TARGET -name '*.html' | xargs sed -i s/href='\''"''\'//href='"'$REPLACEMENT'\'//g
    find $TMP_TARGET -name '*.html' | xargs sed -i s/src='\''"''\'//src='"'$REPLACEMENT'\'//g
    cp -R $TMP_TARGET/* $TARGET
    echo "Static pages copied to $TARGET"
    echo "Should be served from $SERVING_PREFIX"
  }
}

proc main {
  check jekyll

  setglobal old_version = '"Jekyll 0.11.2'"
  if expr match $[jekyll --version] $old_version {
    # The ancient version that apt-get has.
    echo "ERROR: Running with an old version of Jekyll, update " \
      "to 2.5.3 with \`sudo gem install jekyll -v 2.5.3\`"
    exit 1
  }

  build_and_serve

  echo "Type q to quit, r to rebuild docs and restart jekyll"
  while true {

    read -n 1 -s user_input
    if test $user_input == "q" {
      echo "Quitting"
      exit 0
    } elif test $user_input == "r" {
      echo "Rebuilding docs and restarting jekyll"
      build_and_serve
      echo "Rebuilt docs and restarted jekyll"
    }
  }
}

proc cleanup {
  rm -rf $WORKING_DIR
  pkill -9 jekyll
}
trap cleanup EXIT

main