cache

#!/bin/sh

URL=

case $1 in
	"stations") URL="https://www.edsm.net/dump/stations.json.gz" ;;
	"systems" | "systems-nofilter" | "systems-filteronly") URL="https://www.edsm.net/dump/systemsPopulated.json.gz" ;;
	*)
		echo "usage: cache <stations | systems | systems-nofilter | systems-filteronly>" 1>&2
		echo "(The systems cache is normally filtered to discard extraneous data; systems-nofilter and systems-filteronly provide more control over this.)" 1>&2
		exit 1
		;;
esac

if [ "$1" = "systems-nofilter" ]; then
	NOFILTER=1
fi
if [ "$1" = "systems-filteronly" ]; then
	FILTERONLY=1
fi

GZ=${URL##*/}
FILE=${GZ%.gz}

if [ -z "$FILTERONLY" ]; then
	echo "Downloading $URL"
	curl -C - -O $URL && gunzip $GZ || exit 1
fi

if [ -z "$NOFILTER" -a "$1" = "systems" -o -n "$FILTERONLY" ]; then
	echo "Stripping extraneous system data"
node <<END
	const fs = require("fs")
	let inputJSON = fs.readFileSync("$FILE")
	console.log("Parsing the JSON")
	let systems = JSON.parse(inputJSON)
	console.log(systems.length + " systems")
	
	console.log("Filtering attributes")
	systems = systems.map((system) => {
		let newSystem = {}
		newSystem.name = system.name
		newSystem.id = system.id
		newSystem.coords = system.coords
		return newSystem
	})
	
	console.log("Reserializing")
	let outputJSON = JSON.stringify(systems)
	console.log("Saving")
	fs.writeFileSync("$FILE", outputJSON)
END
fi