#!/usr/bin/env bash

RELEASE=25.05

update_channel() {
	local channel_name="$1"     # Hydra channel name (e.g., nixos-24.11)
	local flake_input_name="$2" # Flake input name (e.g., nixpkgs)
	local new old

	# Get latest revision from Hydra
	new=$(curl -sL "https://monitoring.nixos.org/prometheus/api/v1/query?query=channel_revision" |
		jq -r ".data.result[] | select(.metric.channel==\"${channel_name}\") | .metric.revision")

	# Get current revision from flake.lock using input name
	old=$(jq -r ".nodes as \$nodes | 
                .nodes.root.inputs.[\"${flake_input_name}\"] as \$target_input |
                \$nodes | to_entries[] | 
                select(.key == \$target_input) | 
                .value.locked.rev" flake.lock)

	if [ "${old}" == "${new}" ]; then
		return
	fi

	replace_hash "${flake_input_name}" "${new}"

	echo "${new}"
}

replace_hash() {
	local name="$1" hash="$2"

  sed -i "s|\(${name}\.url = \"github:NixOS/nixpkgs/\)[^\"]*|\1${hash}|" flake.nix
	# sed -i "s|${name}/${old}|${name}/${new}|" flake.nix
}

update_stable() {
	echo "Checking NixOS ${RELEASE}..."

	new_hash=$(update_channel "nixos-${RELEASE}" "nixpkgs")

	if [ -z "$new_hash" ]; then
		return
	fi

	echo "Updated stable to: ${new_hash}"
}

update_unstable() {
	echo "Checking unstable..."

	new_hash=$(update_channel "nixos-unstable" "nixos-unstable")

	if [ -z "$new_hash" ]; then
		return
	fi

	echo "Updated unstable to: ${new_hash}"
}

update_stable
update_unstable