#!/usr/bin/env bash
# streamdeck-go watchdog — runs every 30s via systemd timer (Linux) or launchd
# StartInterval (macOS).
#
# Why this exists: when the Stream Deck is unplugged and replugged, the daemon's
# in-process reconnect logic does not always notice. On Linux, hidraw can keep
# returning read timeouts on the now-stale fd instead of surfacing an error, so
# the "3 consecutive errors → reconnect" path never triggers, and the service
# manager still reports the service as active even though the device is
# unreachable.
#
# Strategy: track the device's transient USB address (Linux: bus:device,
# macOS: Location ID). When it changes (unplug/replug) or the service is
# inactive while a device is present, restart the service.
set -euo pipefail

# Stream Deck product IDs we support (see internal/device/streamdeck.go).
PIDS_RE="00ba|006c|006d"

OS="$(uname -s)"

case "$OS" in
    Linux)
        STATE_DIR="${XDG_RUNTIME_DIR:-/tmp}"
        ;;
    Darwin)
        # No XDG_RUNTIME_DIR on macOS; use the user-private temp dir.
        STATE_DIR="${TMPDIR:-/tmp}"
        ;;
    *)
        echo "watchdog: unsupported OS: $OS" >&2
        exit 1
        ;;
esac

STATE_FILE="$STATE_DIR/streamdeck-go-watchdog.state"

# Print a transient identifier for the first matching Stream Deck on the USB
# bus, or empty if none is present. The identifier must change across
# unplug/replug so we can detect it.
current_addr() {
    case "$OS" in
        Linux)
            # "Bus 003 Device 052: ID 0fd9:00ba ..." → "003:052"
            lsusb 2>/dev/null | awk -v pids="$PIDS_RE" '
                $0 ~ ("ID 0fd9:(" pids ")") {
                    gsub(":", "", $4)
                    print $2 ":" $4
                    exit
                }
            '
            ;;
        Darwin)
            # system_profiler entry per device:
            #     Stream Deck XL:
            #       Product ID: 0x00ba
            #       Vendor ID: 0x0fd9 (Elgato ...)
            #       ...
            #       Location ID: 0x14140000 / 5
            # The trailing "/ N" is the bus address — it changes on replug.
            system_profiler SPUSBDataType 2>/dev/null | awk -v pids="$PIDS_RE" '
                /^[[:space:]]*Product ID:/  { pid = $3 }
                /^[[:space:]]*Vendor ID:/   { vid = $3 }
                /^[[:space:]]*Location ID:/ {
                    sub(/^[[:space:]]*Location ID:[[:space:]]*/, "")
                    if (vid == "0x0fd9" && pid ~ ("^0x(" pids ")$")) {
                        print
                        exit
                    }
                }
            '
            ;;
    esac
}

# Is the streamdeck-go service currently active?
service_active() {
    case "$OS" in
        Linux)
            systemctl --user is-active --quiet streamdeck-go.service
            ;;
        Darwin)
            # launchctl list prints "PID Status Label". A PID of "-" means
            # the agent is loaded but not running.
            local line
            line="$(launchctl list 2>/dev/null | awk '$3 == "com.woodarddigital.streamdeck-go" { print $1 }')"
            [[ -n "$line" && "$line" != "-" ]]
            ;;
    esac
}

restart_service() {
    case "$OS" in
        Linux)
            systemctl --user restart streamdeck-go.service
            ;;
        Darwin)
            # kickstart -k stops and restarts; works whether or not it's running.
            launchctl kickstart -k "gui/$(id -u)/com.woodarddigital.streamdeck-go"
            ;;
    esac
}

prev=""
[[ -f "$STATE_FILE" ]] && prev="$(cat "$STATE_FILE" 2>/dev/null || true)"

curr="$(current_addr)"

# Always update the state file so the next run sees a fresh baseline.
printf '%s' "$curr" > "$STATE_FILE"

# No device present — nothing to do. Don't touch the service.
if [[ -z "$curr" ]]; then
    exit 0
fi

reason=""

if [[ -z "$prev" ]]; then
    # First observation (or state file was wiped). Only restart if the service
    # is also down — if it's already running, assume it's healthy and just
    # record the baseline.
    if ! service_active; then
        reason="device present at $curr but service is not active"
    fi
elif [[ "$curr" != "$prev" ]]; then
    reason="device address changed: $prev → $curr (likely unplug/replug)"
elif ! service_active; then
    reason="device present at $curr but service is not active"
fi

if [[ -n "$reason" ]]; then
    echo "watchdog: $reason — restarting streamdeck-go"
    restart_service
fi