emcomm-tools-os-community/overlay/opt/emcomm-tools/bin/et-common

#!/bin/bash
# Author  : Gaston Gonzalez
# Date    : 1 February 2025
# Updated : 20 August 2025
# Purpose : Common environment variables and functions

# Standardized device paths for supported hardware
export ET_DEVICE_AUDIO="/dev/et-audio"
export ET_DEVICE_CAT="/dev/et-cat"
export ET_DEVICE_GPS="/dev/et-gps"
export ET_DEVICE_SDR="/dev/et-sdr"

export ESC="\x1B"
export RED="${ESC}[1;31m"
export BLUE="${ESC}[1;34m"
export GREEN="${ESC}[1;32m"
export WHITE="${ESC}[97m"
export YELLOW="${ESC}[1;33m"
export NC="${ESC}[0m"

# Display an error message in the terminal
show-err-dialog() {
  local message="$1"
  dialog --title "Notification" --msgbox "$message" 8 60
}

# Display a notification message as a UI popup in the desktop
notify-user() {
  notify-send -t 5000 --app-name="EmComm Tools" "$1"
}

exit_if_no_sdr() {
  if [[ ! -e ${ET_DEVICE_SDR} ]]; then
    et-log "No ${ET_DEVICE_SDR} detected."
    exit 1
  fi
}

exit_on_service_failure() {
  local systemd_unit_name="$1"
  systemctl is-active --user --quiet "${systemd_unit_name}"
  if [ $? -ne 0 ]; then
    et-log "Can't start mode. ${systemd_unit_name} failed to start."
    exit 1
  fi
}

start_and_wait_for_service() {
  local timeout=15  # Total time to wait in seconds
  local interval=2  # Interval between checks in seconds
  local systemd_unit_name="$1"
  local elapsed=0

  et-log "Starting ${systemd_unit_name}..."
  systemctl --user start ${systemd_unit_name}

  et-log "Waiting for ${systemd_unit_name} to become active..."

  while ! systemctl is-active --user --quiet "${systemd_unit_name}"; do
      sleep "$interval"
      elapsed=$((elapsed + interval))
      if [ "$elapsed" -ge "$timeout" ]; then
          et-log "Timeout reached. ${systemd_unit_name} failed to start."
          exit 1
      fi
      et-log "Waiting for ${systemd_unit_name} to become active..."
  done

  # Some applications even when started still need a bit of extra time to be available.
  # Add a short think time of 2 seconds. The ARDOP modem requies extra time.
  sleep 2

  # Do one more check to ensure that we are running, otherwise exit.
  exit_on_service_failure ${systemd_unit_name}
}


# download_with_retries downloads a file from a URL with retry and checksum support.
#
# This function attempts to download a file up to a maximum number of retries.
# If a checksum is provided, the downloaded file will be verified against it.
# On checksum mismatch, the file is deleted and the download retried.
#
# Args:
#   url: The URL of the file to download. (required)
#   filename: The local filename to save the file as. (required)
#   checksum: Optional sha256 checksum string to validate the downloaded file.
#   max_retries: Optional max number of retries (default: 3).
#   wait_seconds: Optional wait time in seconds between retries (default: 2).
#
# Returns:
#   0 if the file was successfully downloaded (and checksum verified if given).
#   1 if arguments are missing, download fails after all retries,
#     or checksum verification fails.
#
# Example:
#   download_with_retries "https://example.com/file.tar.gz" "file.tar.gz"
#   download_with_retries "https://example.com/file.tar.gz" "file.tar.gz" "abc123..." 5 3
download_with_retries() {
  local url="$1"
  local filename="$2"
  local checksum="$3"          # expected checksum (sha256)
  local max_retries="${4:-3}"  # default = 3 retries
  local wait_seconds="${5:-2}" # default = 2s wait between retries

  # Require at least URL and filename
  if [[ -z "$url" || -z "$filename" ]]; then
    echo "Usage: download_with_retries <url> <filename> [checksum] [max_retries] [wait_seconds]"
    return 1
  fi

  for ((i=1; i<=max_retries; i++)); do
    echo "Attempt $i of $max_retries to download $url..."

    if curl -L -f -o "$filename" "$url"; then
      echo "Download successful: $filename"

      if [[ -n "$checksum" ]]; then
        echo "Verifying checksum..."
        local file_checksum
        file_checksum=$(sha256sum "$filename" | awk '{print $1}')

        if [[ "$file_checksum" == "$checksum" ]]; then
          echo "Checksum OK"
          return 0
        else
          echo "Checksum mismatch (expected $checksum, got $file_checksum)"
          rm -f "$filename"
        fi
      else
        # no checksum provided, just succeed
        return 0
      fi
    else
      echo "Download failed (attempt $i)."
    fi

    sleep "$wait_seconds"
  done

  echo "Download failed after $max_retries attempts."
  return 1
}