#!/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

package_size_table() {
	table='| Installable | NAR Size | Closure Size |
|-------------|---------:|-------------:|
'
	for package in $packages; do
		echo "Building $package" >&2
		path=$(nix build --print-out-paths ".#$package" 2>/dev/null)
		echo "Calculating size of $package" >&2
		row=$(nix path-info --size --closure-size --human-readable "$path" 2>/dev/null |
			sed "s/^\(\S\+\)\(\s\+\)\(\S\+\)\(\s\+\)\(\S\+\)$/| \`$package\` | \3 | \5 |/")
		table="$table$row
"
	done

	printf '%s' "$table"
}

configuration_size_table() {
	table='| NixOS Configuration | NAR Size | Closure Size |
|-------------|---------:|-------------:|
'
	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 $config" >&2
		row=$(nix path-info --size --closure-size --human-readable "$path" 2>/dev/null |
			sed "s/^\(\S\+\)\(\s\+\)\(\S\+\)\(\s\+\)\(\S\+\)$/| \`$config\` | \3 | \5 |/")
		table="$table$row
"
	done

	printf '%s' "$table"
}

markdown() {
	cat <<-EOF
		## Outputs' size

		### NixOS Configurations sizes

		$(configuration_size_table)

		### Package sizes

		$(package_size_table)
	EOF
}

markdown >size-report.md