#!/bin/bash
# detect-i2s-device.sh — Probe for available I2S audio devices
# and create /run/i2s-audio-dev containing the best candidate.
# Called by detect-i2s-device.service before pd-synth-i2s starts.

set -euo pipefail

DEVICE_FILE="/run/i2s-audio-dev"
write_dev() { echo "$1" > "$DEVICE_FILE"; echo "[DETECT] I2S device: $1"; exit 0; }

# Try named I2S devices first (most reliable)
for dev in "hw:I2S,0" "hw:MI2S,0" "hw:i2s,0" "hw:mi2s,0"; do
    if aplay -l 2>/dev/null | grep -qi "${dev%,*}"; then
        write_dev "$dev"
    fi
done

# Try probing ALSA device list for anything that looks like I2S
while read -r card; do
    id=$(echo "$card" | awk '{print $2}' | tr -d ':')
    name=$(echo "$card" | cut -d: -f2- | xargs)
    if echo "$name" | grep -qi -E "(i2s|mi2s|quat|tert|dac|audio)"; then
        write_dev "hw:$id,0"
    fi
done < <(cat /proc/asound/cards 2>/dev/null || true)

# Fallback to hw:0,0 (first audio device, may be HDMI or analog)
if aplay -l 2>/dev/null | grep -q "^card 0"; then
    write_dev "hw:0,0"
fi

# Nothing found
echo "[DETECT] No I2S audio device found" >&2
echo "" > "$DEVICE_FILE"
exit 1