#!/bin/bash
#
# Based on a gist https://gist.github.com/sandeepraju/1f5fbdbdd89551ba7925abe2645f92b5
# by https://github.com/sandeepraju
#
# Modified by jay@gooby.org, @jaygooby
#
# Usage: ttfb [options] url [url...]
#   -d debug
#   -l <log file> (infers -d)
#   -n number of times to test
#
# Examples:
#
# ttfb example.com
# DNS lookup: 0.523402 TLS handshake: 0.000000 TTFB including connection: 0.692724 TTFB: .692724 Total time: 0.693508
#
# ttfb -n 5 example.com
# min .203970 max .181486 median .190033
#
# ttfb -n 5 bbc.co.uk news.bbc.co.uk
# bbc.co.uk       min .032791 max .039401 median .029214
# news.bbc.co.uk  min .032927 max .032237 median .037458
#
# ttfb bbc.co.uk news.bbc.co.uk
# bbc.co.uk        DNS lookup: 0.005291 TLS handshake: 0.089403 TTFB including connection: 0.119651 TTFB: .030248 Total time: 0.506010
# news.bbc.co.uk   DNS lookup: 0.004266 TLS handshake: 0.077179 TTFB including connection: 0.110649 TTFB: .033470 Total time: 0.598472
#
# Implicitly follows redirects using curl's -L
#
# Log all response headers (default log file is curl.log) by calling with -d
#
# Override the default log file by specifying -l /some/file
#
# Get min, max and median values by specifying the number of times to call
# the URL (-n2 etc)
#
# If you specify more than one url and have specified -d or -l the log file
# will be prefixed with the URL being requested.
#
# See https://blog.cloudflare.com/a-question-of-timing/
# and https://curl.haxx.se/docs/manpage.html for an explanation
# of how the curl variables relate to the various stages of
# the transfer.
#
# To get a better approximation of devtool's TTFB, consider
# the time without the connection overhead:
# %{time_starttransfer} - %{time_appconnect}
#
# Uses a dirty eval to do the ttfb arithmetic. Depends
# on bc and column commands.
set -eu

# Cribbed from https://stackoverflow.com/a/41762669/391826
median() {
  arr=($(printf '%s\n' "${@}" | sort -n))
  nel=${#arr[@]}
  if (( $nel % 2 == 1 )); then     # Odd number of elements
    val="${arr[ $(($nel/2)) ]}"
  else                            # Even number of elements
    (( j=nel/2 ))
    (( k=j-1 ))
    # (( val=(${arr[j]} + ${arr[k]})/2 ))
    val=$(echo "scale=6;(${arr[j]}" + "${arr[k]})"/2|bc -l)
  fi
  echo $val
}

DEBUG=""
LOG=""

while getopts ":n:dl:" OPTION
do
    case $OPTION in
        d) DEBUG=1 ;;
        l) LOG="$OPTARG" ;;
        n) NUM_REQUESTS=$OPTARG ;;
        \?) echo -e "tfb [options] url [url...]\n\t-d debug\n\t-l <log file> (infers -d)\n\t-n number of times to test the url" >&2
            exit 1
            ;;
    esac
done

shift $((OPTIND - 1))  # shifts away every option argument,
                       # leaving urls as $@

if [ -z "$1" ]; then
  echo "You didn't specify any urls to fetch"
  exit 1
else
  URLS="$@"
fi

# if we're given a custom log file, implicitly set DEBUG=1
[ -n "$LOG" ] && DEBUG=1

# default the log file to curl.log in pwd
LOG="${LOG:-curl.log}"
DEBUG=${DEBUG:-0}

options=()
options+=(-o /dev/null)
options+=(-s)
options+=(-L)
options+=(--http2)
options+=(-H 'Cache-Control: no-cache')
options+=(-w 'echo DNS lookup: %{time_namelookup} TLS handshake: %{time_appconnect} TTFB including connection: %{time_starttransfer} TTFB: $(echo %{time_starttransfer} - %{time_appconnect} | bc) Total time: %{time_total} \n')
if [ $DEBUG -eq 1 ]; then
  options+=(-D ${LOG})
fi

for URL in $URLS; do

  # if we're checking more than one url, and debug is set, then log
  # the headers to a per-url file
  if [[ ${#@} -gt 1 && $DEBUG -eq 1 ]]; then
    LOGFILE="${URL//[^[:alnum:]]/_}"
    options+=(-D "${LOGFILE}-${LOG}")
  fi

  # if we're checking more than one url
  # output it on the results line
  if [ ${#@} -gt 1 ]; then
    SHOW_URL="${URL}|"
  else
    SHOW_URL=""
  fi

  # if multiple requests have been specified, then show min, max & median values
  if [[ -n "$NUM_REQUESTS" && "$NUM_REQUESTS" -gt 1 ]]; then
    times=()
    for i in $(seq $NUM_REQUESTS); do
      printf "." >&2
      times+=($(eval $(curl "${options[@]}" "$URL") | grep -oE "TTFB: .{0,7}" | cut -d' ' -f2 | sort -n));
    done
    printf "\n" >&2
    # sort the times
    times=( $( printf "%s\n" "${times[@]}" | sort -n ) )
    # show quickest, slowest and median fftb
    printf "${SHOW_URL}\e[32mfastest \e[39m${times[0]} \e[91mslowest \e[39m${times[${#times[*]}-1]} \e[95mmedian \e[39m$(median ${times[*]})\e[39m\n";
  else
   echo -e $SHOW_URL $(eval $(curl "${options[@]}" "$URL"))
  fi
done | column -s'|' -t