#!/bin/sh

set -eu

echo 'Retrieving Flake information' >&2
flake_info=$(nix flake show --json 2>/dev/null)
packages=$(
	jq --raw-output '.packages."x86_64-linux" | select(. != null) | keys[]' <<-EOF
		$flake_info
	EOF
)
echo "Packages:" >&2
echo "$packages" >&2
configurations=$(
	jq --raw-output '.nixosConfigurations | select(. != null) | keys[]' <<-EOF
		$flake_info
	EOF
)
echo "NixOS Configurations:" >&2
echo "$configurations" >&2

pkgs_json() {
	for package in $packages; do
		echo "Building $package" >&2
		path=$(nix build --print-out-paths ".#$package" 2>/dev/null)
		echo "Calculating size of $package" >&2
		nix path-info --closure-size --json "$path" 2>/dev/null |
			jq --compact-output --arg pkg "$package" '.[] | {"name": $pkg, "size": .closureSize, "narSize": .narSize}'
	done
}

configs_json() {
	for config in $configurations; do
		echo "Building $config" >&2
		path=$(nix build --print-out-paths ".#nixosConfigurations.$config.config.system.build.toplevel" 2>/dev/null)
		echo "Calculating size of $config" >&2
		nix path-info --closure-size --json "$path" 2>/dev/null |
			jq --compact-output --arg pkg "$config" '.[] | {"name": $pkg, "size": .closureSize, "narSize": .narSize}'
	done
}

pkgs=$(pkgs_json | jq --slurp '.')
configs=$(configs_json | jq --slurp '.')

echo "{}" | jq \
	--argjson pkgs "$pkgs" \
	--argjson configs "$configs" \
	'{"packages": $pkgs, "nixosConfigurations": $configs}'