#!/bin/bash
# i3blocks ethernet indicator with one external helper at most.

set -euo pipefail

SCRIPT_DIR=${BASH_SOURCE[0]%/*}
[[ $SCRIPT_DIR == "${BASH_SOURCE[0]}" ]] && SCRIPT_DIR='.'
# shellcheck source=persist_common.sh
source "$SCRIPT_DIR/persist_common.sh"

# Picks a real physical ethernet interface. Virtual interfaces (docker/podman
# bridges, veth pairs, wireguard, tailscale, bonds) must be skipped: they sort
# alphabetically BEFORE enp*/eth*, so taking the first match reported "down"
# forever on a machine with docker installed, even with a live wired link.
# Physical NICs are the ones with a real device symlink under /sys/class/net.
find_ethernet_interface() {
	local iface_path iface state fallback=''
	for iface_path in /sys/class/net/*; do
		iface=${iface_path##*/}
		[[ $iface == lo ]] && continue
		[[ -d ${iface_path}/wireless ]] && continue
		[[ -e ${iface_path}/device ]] || continue
		[[ -r ${iface_path}/operstate ]] || continue
		read -r state <"${iface_path}/operstate"
		# Prefer an interface that is actually up; remember the first physical
		# one so an all-down machine still reports a real NIC rather than none.
		if [[ $state == up ]]; then
			printf '%s\n' "$iface"
			return 0
		fi
		[[ -z $fallback ]] && fallback=$iface
	done
	[[ -n $fallback ]] || return 1
	printf '%s\n' "$fallback"
	return 0
}

emit() {
	local iface state addr_output output_line
	iface=$(find_ethernet_interface) || {
		output_line='🌐 down'
		if i3blocks_update_if_changed_key "ethernet_output" "$output_line"; then
			printf '%s\n' "$output_line"
		fi
		return 0
	}

	read -r state <"/sys/class/net/${iface}/operstate"
	if [[ $state != up ]]; then
		output_line='🌐 down'
		if i3blocks_update_if_changed_key "ethernet_output" "$output_line"; then
			printf '%s\n' "$output_line"
		fi
		return 0
	fi

	addr_output=$(ip -o -4 addr show dev "$iface" scope global 2>/dev/null) || addr_output=''
	if [[ $addr_output =~ ([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/[0-9]+) ]]; then
		output_line="🌐 ${BASH_REMATCH[1]}"
	else
		output_line='🌐 down'
	fi

	if i3blocks_update_if_changed_key "ethernet_output" "$output_line"; then
		printf '%s\n' "$output_line"
	fi
}

is_persist_mode() {
	[[ ${BLOCK_INTERVAL:-} == "persist" ]]
}

emit_throttled() {
	if ! i3blocks_should_emit_by_interval_key "ethernet_emit" "$EMIT_MIN_INTERVAL_S"; then
		return 0
	fi
	emit
}

EMIT_MIN_INTERVAL_S=2

emit

if is_persist_mode; then
	ip monitor link address route 2>/dev/null |
		while read -r line; do
			[[ $line == *"eth"* || $line == *"en"* || $line == *"inet "* ]] || continue
			emit_throttled
		done
fi