bin/tick

#! /bin/bash
#
# tick
# A program to get the price of a symbol from Binance
# Copyright (C) 2021 Vintage Salt <rehashedsalt@cock.li>
#
# Distributed under terms of the MIT license.
#
set -e

# Read-only set-once variables
declare -r _name="$(basename -- "$0")"
# Options
declare -i _opthelp
declare -i _optverbose
declare -i _optcolor
declare _optsymbol
# Working variables
declare -a _args
declare _return

# Helper functions
log() {
	# Print a line to the terminal if _optverbose is greater than $2
	# $2 defaults to 0
	# loglevel 0: Daily-use messages
	# loglevel 1: Detailed but not quite debugging
	# loglevel 2: Definitely debugging
	[ -z "$1" ] && return 1
	if (( _optverbose >= ${2:-0} )); then
		printf "%s\\n" "$1"
	fi
}
warn() {
	# Print a yellow line to the terminal, respecting _optverbose
	[ -z "$1" ] && return 1
	if (( _optverbose >= ${2:-0} )); then
		if [ -t 1 ]; then
			printf "\\e[33m%s\\e[0m\\n" "$1"
		else
			printf "WARN: %s\\n" "$1"
		fi
	fi
}
error() {
	# Print a red line to the terminal, exit if $2 is specified
	[ -z "$1" ] && return 1
	if [ -t 2 ]; then
		printf "\\e[31m%s\\e[0m\\n" "$1" 1>&2
	else
		printf "ERROR: %s\\n" "$1" 1>&2
	fi
	[ -z "$2" ] && return
	exit "${2:-1}"
}
has() {
	# Parse out all arguments and try to find them in path
	# If an argument cannot be found, set _return and fail
	for prog in "$@"; do
		if ! command -v "$prog" > /dev/null 2>&1; then
			_return="$prog"
			return 1
		fi
	done
	return 0
}

# Core program functions
printhelp() {
	cat << EOF
Usage: $_name [OPTION]... SYMBOL
Get the 24hr price change for a particular symbol from Binance

  -c			Add color to the output
  -d SYMBOL		Change the symbol displayed. Useful for comparisons against USDC
			and other stablecoins
  -h			Print this help text
  -v			Print more status messages. Stacks

Copyright (c) 2021 rehashedsalt@cock.li
Licensed under the MIT license
EOF
}
getprice() {
	# Get the price of a coin from Binance
	[ -z "$1" ] && return 1
	symbol="$1"
	result="$(curl -sL "https://api.binance.com/api/v3/ticker/24hr?symbol=$symbol")"
	# Test to see if we got an error
	if echo "$result" | jq '.code' -e > /dev/null 2>&1; then
		code="$(echo "$result" | jq -re '.code')"
		msg="$(echo "$result" | jq -re '.msg')"
		error "Error $code: $msg" 51
	fi
	# Parse out the data
	if [ -n "$_optsymbol" ]; then
		symbol="$_optsymbol"
	else
		symbol="$(echo "$result" | jq -re '.symbol')"
	fi
	price="$(echo "$result" | jq -re '.priceChangePercent')"
	if [ -n "$_optcolor" ]; then
		if [[ "$price" == -* ]]; then
			price="\e[31m$price\e[0m"
		else
			price="\e[32m$price\e[0m"
		fi
	fi
	printf "$symbol $price\n"
}

# Main
main() {
	# Parse out arguments
	while [ -n "$1" ]; do
		# Parse out flags
		while getopts ":cd:hv" opt; do
			case $opt in
				c)
					_optcolor=1
					;;
				d)
					_optsymbol="$OPTARG"
					;;
				h)
					_opthelp=1
					;;
				v)
					_optverbose+=1
					;;
				:)
					error "Option requires argument: -$OPTARG" 2
					;;
				*)
					error "Invalid option: -$OPTARG" 2
					;;
			esac
		done
		# Store arguments
		shift $((OPTIND - 1))
		if [ -n "$1" ]; then
			_args+=("$1")
			shift
		fi
		unset OPTIND
	done
	# Early hook for help
	[ -n "$_opthelp" ] && printhelp && exit 0
	# Validate critical options
	if [ -z "${_args[*]}" ]; then
		error "No symbol specified" 50
	fi
	# Validate core program dependencies
	log "Validating dependencies" 2
	if ! has basename curl jq; then
		error "Failed to find program: $_return" 1
	fi

	# Do the do
	getprice "${_args[0]}"
	exit 0
}

main "$@"