#!/bin/sh
set -eu

SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
APP_DIR=$(CDPATH= cd -- "$SCRIPT_DIR/.." && pwd)
CONFIG_PATH=${1:-"$APP_DIR/router_local.conf"}

if [ ! -r "$CONFIG_PATH" ]; then
  echo "[router-http] config not found: $CONFIG_PATH" >&2
  exit 1
fi

# shellcheck disable=SC1090
. "$CONFIG_PATH"

RUNTIME_DIR=${RUNTIME_DIR:-"$APP_DIR/cfip_runtime"}
VALUE_TEXT_FILE=${VALUE_TEXT_FILE:-"current_ip.txt"}
VALUE_JSON_FILE=${VALUE_JSON_FILE:-"current_ip.json"}
STATE_FILE=${STATE_FILE:-"state.json"}
EXPORT_VARS_FILE=${EXPORT_VARS_FILE:-"substore_vars.json"}
HTTP_PORT=${HTTP_PORT:-8080}

TEXT_PATH="$RUNTIME_DIR/$VALUE_TEXT_FILE"
JSON_PATH="$RUNTIME_DIR/$VALUE_JSON_FILE"
STATE_PATH="$RUNTIME_DIR/$STATE_FILE"
EXPORT_PATH="$RUNTIME_DIR/$EXPORT_VARS_FILE"
TMP_BASE=${TMPDIR:-/tmp}

nc_listen() {
  if nc -h 2>&1 | grep -qi 'busybox'; then
    nc -l -p "$HTTP_PORT"
  else
    nc -l "$HTTP_PORT"
  fi
}

serve_once() {
  req_fifo="$TMP_BASE/router_http_req.$$"
  resp_fifo="$TMP_BASE/router_http_resp.$$"

  rm -f "$req_fifo" "$resp_fifo"
  mkfifo "$req_fifo" "$resp_fifo"

  cat "$resp_fifo" | nc_listen > "$req_fifo" 2>/dev/null &
  nc_pid=$!
  sleep 1
  if ! kill -0 "$nc_pid" 2>/dev/null; then
    rm -f "$req_fifo" "$resp_fifo"
    echo "[router-http] nc listen failed on port $HTTP_PORT" >&2
    return 1
  fi

  exec 3<"$req_fifo"
  exec 4>"$resp_fifo"

  if ! IFS= read -r request_line <&3; then
    exec 3<&-
    exec 4>&-
    wait "$nc_pid" 2>/dev/null || true
    rm -f "$req_fifo" "$resp_fifo"
    return 0
  fi

  while IFS= read -r header_line <&3; do
    [ "$header_line" = "$(printf '\r')" ] && break
    [ -z "$header_line" ] && break
  done

  request_path=$(printf '%s' "$request_line" | awk '{print $2}')
  status_line="HTTP/1.1 200 OK\r"
  content_type="text/plain; charset=utf-8"
  file_path="$TEXT_PATH"

  case "$request_path" in
    /|/current_ip.txt|"/$VALUE_TEXT_FILE")
      content_type="text/plain; charset=utf-8"
      file_path="$TEXT_PATH"
      ;;
    /current_ip.json|"/$VALUE_JSON_FILE")
      content_type="application/json; charset=utf-8"
      file_path="$JSON_PATH"
      ;;
    /state.json|"/$STATE_FILE")
      content_type="application/json; charset=utf-8"
      file_path="$STATE_PATH"
      ;;
    /substore_vars.json|"/$EXPORT_VARS_FILE")
      content_type="application/json; charset=utf-8"
      file_path="$EXPORT_PATH"
      ;;
    *)
      status_line="HTTP/1.1 404 Not Found\r"
      file_path=""
      ;;
  esac

  if [ -n "$file_path" ] && [ -f "$file_path" ]; then
    content_length=$(wc -c < "$file_path" | tr -d ' ')
    printf '%b\n' "$status_line" >&4
    printf 'Content-Type: %s\r\n' "$content_type" >&4
    printf 'Content-Length: %s\r\n' "$content_length" >&4
    printf 'Connection: close\r\n' >&4
    printf '\r\n' >&4
    cat "$file_path" >&4
  else
    body='not found'
    printf '%b\n' "$status_line" >&4
    printf 'Content-Type: text/plain; charset=utf-8\r\n' >&4
    printf 'Content-Length: %s\r\n' "$(printf '%s' "$body" | wc -c | tr -d ' ')" >&4
    printf 'Connection: close\r\n' >&4
    printf '\r\n' >&4
    printf '%s' "$body" >&4
  fi

  exec 3<&-
  exec 4>&-
  wait "$nc_pid" 2>/dev/null || true
  rm -f "$req_fifo" "$resp_fifo"
}

echo "[router-http] listening on 0.0.0.0:$HTTP_PORT"
while true; do
  if ! serve_once; then
    exit 1
  fi
done