exchange.sh

APPNAME=exchange.sh

p () { printf '%s\n' "$@";}

: "${XDG_CACHE_HOME:=$HOME/.cache}"
cachedget () {
	URL=$1
	CACHEDIR="$XDG_CACHE_HOME/$APPNAME/curl/GET-$(base64 -w0 <<< "$URL")"
	mkdir --parents "$CACHEDIR"
	curl -sS \
		--etag-save    "$CACHEDIR/etag" \
		--etag-compare "$CACHEDIR/etag" \
		--output       "$CACHEDIR/data" \
		"$URL"
	p "$CACHEDIR/data"
}

DATAFILE=$(cachedget https://api.exchangerate.host/latest)


p 'unset _exchange_sh_SYMBOLS'
p 'declare -a _exchange_sh_SYMBOLS=('
	jq -r '.rates | keys[] | "\t\(.)"' "$DATAFILE"
p ')'

p 'unset _exchange_sh_RATES' 
p 'declare -A _exchange_sh_RATES=('
	jq -r '.rates | to_entries[] | "\t[\(.key)]=\(.value)"' "$DATAFILE"
p ')'

# add validation
p 'exchange () { set -eu; bc <<< "scale=2; $1 * ${_exchange_sh_RATES[$3]} / ${_exchange_sh_RATES[$2]}";}'