#!/usr/bin/env bash

# exit if a command fails
set -o errexit

# exit if required variables are not set
set -o nounset

# return the exit status of the final command before a failure
set -o pipefail

# make sure the correct number of arguments are passed; if not, output syntax and exit
if [ "$#" -ne 4 ]; then
  echo -e "\nUsage: $0 <file name> <panel> <start timestamp> <end timestamp>\n"
  exit 1
fi

# commands required for script execution
required_commands="curl"
missing_counter=0
for command in ${required_commands}; do
  if ! hash "${command}" >/dev/null 2>&1; then
    printf "Command not found in PATH: %s\n" "${command}" >&2
    ((missing_counter++))
  fi
done
if ((missing_counter > 0)); then
  printf "%d or more commands are missing from PATH. Exiting.\n" "${missing_counter}" >&2
  exit 1
fi

# host-specific configs
if [ "$(hostname)" == "crimson" ]; then
  api_token="$(cat "${HOME}/bin/.grafana_api_token.crimson.file")"
  server_url="https://grafana.seedno.de"
  dashboard_url="8008K41Wk/countries-and-networks"
elif [ "$(hostname)" == "casa" ]; then
  api_token="$(cat "${HOME}/bin/.grafana_api_token.casa.file")"
  server_url="https://grafana.home.seedno.de"
  dashboard_url="8008K41Wk/countries-and-networks"
else
  echo "Unknown grafana host."
  exit 1
fi

# grafana org
org_id="1"

# filename for output image
file_name="${1}"

# panel to render
panel_id="${2}"

# start and end timestamps
start_timestamp="${3}"
end_timestamp="${4}"

# resolution to render the image
image_height="720"
image_width="1280"

# timezone
timezone="America%2FChicago"

function main() {
  local url
  url="${server_url}"
  url+="/render/d-solo"
  url+="/${dashboard_url}"
  url+="?orgId=${org_id}"
  url+="&refresh=5s"
  url+="&from=${start_timestamp}"
  url+="&to=${end_timestamp}"
  url+="&panelId=${panel_id}"
  url+="&width=${image_width}"
  url+="&height=${image_height}"
  url+="&tz=${timezone}"

  curl -s -H "Authorization: Bearer ${api_token}" "${url}" > "${file_name}"
}

# generate images
main