livereload.sh

#!/usr/bin/env bash

set -euo pipefail

: "${HTTP_LISTEN_PORT:=8080}"  # miniserve listenport
: "${WS_LISTEN_PORT:=34729}"   # websocat listenport
: "${INDEX_HTML:=index.html}"  # miniserve index
: "${LIVERELOAD:=true}"        # livereload on file modification
: "${SPA:=true}"               # Single Page Application mode
: "${QRCODE:=true}"            # Enable QR code display

: "${WATCH_EXCLUDE_RE:=.kate-swp}"

# Path options
: "${WWW_PATH:=./www}"                     # Directory contains web source
: "${LIVERELOADJS_PATH:=./livereload.js}"  # Path to livereload.js

: "${INTERNAL_SERVE_PATH:=./blivereloadserv}" # Tmp dir include livereload.js on *.html


# Websocket server func
ws_server() {
    set -euo pipefail

    cmd_reload() {
      # Build json reload command
      jq -crn \
        --arg command 'reload' \
        --arg path "${1:-"/"}" \
        --arg liveCSS "${2:-true}" \
        --arg reloadMissingCSS "${3:-true}" \
        --arg liveIMG "${4:-true}" \
          '. | .["command"]=$command | .["path"]=$path | .["liveCSS"]=$liveCSS | .["reloadMissingCSS"]=$reloadMissingCSS | .["liveIMG"]=$liveIMG'
    }
    cmd_hello() {
      # Build json hello command
      jq -crn \
        --arg command 'hello' \
        --arg serverName "${1:-"dwl-reloader"}" \
        --arg protocols "${2:-"http://livereload.com/protocols/official-7"}" \
          '. | .["command"]=$command | .["serverName"]=$serverName | .["protocols"]=[$protocols]'
    }

    # SIGUSR1 => reload event
    trap cmd_reload SIGUSR1;

    # https://www.gnu.org/software/bash/manual/html_node/Signals.html#Signals
    jq --unbuffered -cr '.command' | while read -r cmd; do
      if [ "$cmd" = "hello" ]; then
        cmd_hello "$@"
      elif [ "$cmd" = "info" ]; then
        true
      else
        printf "%s\n" "docker web reload Unknown command ${cmd}"
      fi
    done &
    wait || true
}
export -f ws_server

main() {
  check::cmd jq find sed miniserve websocat cp socat inotifywait mkdir pkill

  local should_livereload=${LIVERELOAD}
  local miniserve_args=()
  "${SPA:-false}"    && miniserve_args+=("--spa")
  "${QRCODE:-false}" && miniserve_args+=("--qrcode")

  patch_livereload() {
      cp "${LIVERELOADJS_PATH}" "${INTERNAL_SERVE_PATH}"
      # find all html file and add livereload.js
      find "${INTERNAL_SERVE_PATH}" -type f -name "*.html" -exec sed -i "s#</body>#</body>\\n<script src=\"livereload.js?port=${WS_LISTEN_PORT}\"></script>#" '{}' ";"
  }

  bootstrap() {
      mkdir -p "${INTERNAL_SERVE_PATH}"
      # Copy file into serve directory
      cp  -rT "${WWW_PATH}" "${INTERNAL_SERVE_PATH}"
      if [ "${should_livereload}" = "true" ]; then
          # Patch livereload
          patch_livereload
      fi
  }

  signal_websockets() {
    # Send signal to websocket servers
    pkill -USR1 -fx '/bin/bash -c ws_server' || true
  }

  # Run http server
  bootstrap
  miniserve "${miniserve_args[@]}" --port "${HTTP_LISTEN_PORT}" --index "${INDEX_HTML}" "${INTERNAL_SERVE_PATH}" &
  if [ "${should_livereload:-false}" = "true" ]; then
      # Start websocat to spawn ws_server func on each new client
      (socat TCP-LISTEN:11111,reuseaddr,fork,crlf exec:"/bin/bash -c ws_server") &
      (websocat --exit-on-eof --text "ws-listen:0.0.0.0:${WS_LISTEN_PORT}" tcp:127.0.0.1:11111) &

      printf '%b%s%b' "\e[34m" "Waiting for file changes" "\e[0m\n"

      local now_ms last_upload_ms=0
      inotifywait -q -m --format '%w%f' -e modify -r "${WWW_PATH}" \
        | while read -r file; do
            if [[ "${file}" =~ ${WATCH_EXCLUDE_RE} ]]; then
                continue
            fi
            # echo "$file" >&2
            now_ms="$(date +%s)"
            # Only reload every second
            if [ $(( now_ms - last_upload_ms )) -gt 1 ]; then
                printf "%b%s%b" "\e[34m" "File ${file} modified reloading" "\e[0m\n" >&2
                bootstrap
                signal_websockets
                last_upload_ms=${now_ms}
            fi
        done
  fi
  wait || true
}

check::cmd() {
    # check if a shell command is available
    local cmd
    for cmd; do
        # else test command
        command -v "${cmd}" &> /dev/null \
        || { printf >&2 "%s\n" "${cmd} is required but it's not installed."; exit 1; }
    done
}

main "$@"