#!/usr/bin/env bash
# lesavka‑core.sh - one‑shot USB‑gadget bring‑up (Pi‑5 / Arch‑ARM)
# Presents:  • Boot‑protocol keyboard (hidg0)
#            • Boot‑protocol mouse    (hidg1)
#            • Stereo UAC2 speaker + microphone
set -euo pipefail

log() { printf '[lesavka-core] %s\n' "$*"; }

#──────────────────────────────────────────────────
# 1.  Ensure overlay + kernel modules
#──────────────────────────────────────────────────
CFG=/boot/config.txt
grep -q 'dtoverlay=dwc2,dr_mode=peripheral' "$CFG" || echo 'dtoverlay=dwc2,dr_mode=peripheral' >> "$CFG"

modprobe dwc2 || { echo "dwc2 not in kernel; abort" >&2; exit 1; }
modprobe libcomposite || { echo "libcomposite not in kernel; abort" >&2; exit 1; }

modprobe -r uvcvideo 2>/dev/null || true
modprobe uvcvideo || { echo "uvcvideo not in kernel; abort" >&2; exit 1; }

udevadm control --reload
udevadm trigger --subsystem-match=video4linux
udevadm settle

#──────────────────────────────────────────────────
# 2.  Wait for UDC device to appear (max 10 s)
#──────────────────────────────────────────────────
log "⏳ waiting for UDC to register ..."
UDC=""
for _ in {1..100}; do                       # 100 × 100ms = 10s
    UDC=$(ls /sys/class/udc 2>/dev/null | head -n1) && [[ -n $UDC ]] && break
    sleep 0.1
done

if [[ -z $UDC ]]; then
    log "⚠️  UDC still absent - trying manual bind"
    for drv in dwc2 dwc3; do
        drv_root="/sys/bus/platform/drivers/$drv"
        [[ -d $drv_root ]] || continue
        for node in /sys/bus/platform/devices/*usb*; do
            node=${node##*/}               # strip path
            echo "$node" >"$drv_root/bind" 2>/dev/null || continue
        done
    done
    # re-check for another 5 s
    for i in {1..50}; do
        UDC=$(ls /sys/class/udc 2>/dev/null | head -n1) && [[ -n $UDC ]] && break
        sleep 0.1
    done
fi

[[ -n $UDC ]] || { log "❌ UDC not present after manual bind"; exit 1; }
log "✅ UDC detected: $UDC"

#──────────────────────────────────────────────────
# 3.  (Re‑)create gadget
#──────────────────────────────────────────────────
mountpoint -q /sys/kernel/config || mount -t configfs none /sys/kernel/config
G=/sys/kernel/config/usb_gadget/lesavka

if [[ -d $G ]]; then
  echo '' >"$G/UDC" 2>/dev/null || true
  sleep 0.2
  find "$G/configs" -type l -delete 2>/dev/null || true
  rm -rf "$G" 2>/dev/null || true
fi

mkdir -p "$G"
echo 0x1d6b >"$G/idVendor"       # Linux Foundation
echo 0x0104 >"$G/idProduct"      # Multifunction Composite Gadget
echo 0x0200 >"$G/bcdUSB"

mkdir -p "$G/strings/0x409"
echo "$(cat /proc/sys/kernel/random/uuid)" >"$G/strings/0x409/serialnumber"
echo "Lesavka"                               >"$G/strings/0x409/manufacturer"
echo "Lesavka Composite"                     >"$G/strings/0x409/product"

# ----------------------- HID keyboard (usb0) -----------------------
mkdir -p "$G/functions/hid.usb0"
echo 1  >"$G/functions/hid.usb0/protocol"
echo 1  >"$G/functions/hid.usb0/subclass"
echo 8  >"$G/functions/hid.usb0/report_length"
printf '\x05\x01\x09\x06\xa1\x01\x05\x07\x19\xe0\x29\xe7\x15\x00\x25\x01'\
'\x75\x01\x95\x08\x81\x02\x95\x01\x75\x08\x81\x01\x95\x05\x75\x01\x05'\
'\x08\x19\x01\x29\x05\x91\x02\x95\x01\x75\x03\x91\x01\x95\x06\x75\x08'\
'\x15\x00\x25\x65\x05\x07\x19\x00\x29\x65\x81\x00\xc0' \
  >"$G/functions/hid.usb0/report_desc"

# ----------------------- HID mouse (usb1) --------------------------
mkdir -p "$G/functions/hid.usb1"
echo 2 > "$G/functions/hid.usb1/protocol"   # Boot mouse
echo 1 > "$G/functions/hid.usb1/subclass"
echo 4 > "$G/functions/hid.usb1/report_length"
printf '\x05\x01\x09\x02\xa1\x01\x09\x01\xa1\x00'\
'\x05\x09\x19\x01\x29\x03\x15\x00\x25\x01\x95\x03\x75\x01\x81\x02'\
'\x95\x01\x75\x05\x81\x03'\
'\x05\x01\x09\x30\x09\x31\x09\x38\x15\x81\x25\x7f\x75\x08\x95\x03\x81\x06'\
'\xc0\xc0' >"$G/functions/hid.usb1/report_desc"

# ---------- UAC2 function - speaker + mic, 2×48 kHz stereo ---------
mkdir -p "$G/functions/uac2.usb0"
U="$G/functions/uac2.usb0"
# Playback (speaker)
echo 0x3     >"$U/p_chmask"   # L+R
echo 48000   >"$U/p_srate"
echo 2       >"$U/p_ssize"    # 16 bit
# Capture (microphone)
echo 0x3     >"$U/c_chmask"
echo 48000   >"$U/c_srate"
echo 2       >"$U/c_ssize"
# Optional: allocate a few extra request buffers
echo 32      >"$U/req_number" 2>/dev/null || true

# ----------------------- UVC function (usb‑video) ------------------
mkdir -p "$G/functions/uvc.usb0"
F="$G/functions/uvc.usb0"

# ── 1.  FORMAT DESCRIPTOR (uncompressed YUY2, 16 bpp) ──────────────
mkdir -p "$F/streaming/uncompressed/u"
# GUID = {59555932-0000-0010-8000-00aa00389b71} (“YUY2”) little‑endian
printf '\x59\x55\x59\x32\x00\x00\x10\x00\x80\x00\x00\xaa\x00\x38\x9b\x71' \
      >"$F/streaming/uncompressed/u/guidFormat"
echo 16  >"$F/streaming/uncompressed/u/bBitsPerPixel"

# ── 2.  FRAME DESCRIPTOR (index 1 @ 30 fps) ────────────────────────
mkdir -p "$F/streaming/uncompressed/u/f1"
echo 1280    >"$F/streaming/uncompressed/u/f1/wWidth"
echo 720     >"$F/streaming/uncompressed/u/f1/wHeight"
echo 1843200 >"$F/streaming/uncompressed/u/f1/dwMaxVideoFrameBufferSize"
echo 333333  >"$F/streaming/uncompressed/u/f1/dwDefaultFrameInterval"  # 30 fps
echo 333333  >"$F/streaming/uncompressed/u/f1/dwFrameInterval"

# ── 3.  REQUIRED HEADER LINKS  (absolute‑paths, no “1”)  ──────────────
header_h="$F/streaming/header/h"          # convenience variables
fmt_dir="$F/streaming/uncompressed/u"

mkdir -p "$header_h"

# wait until the kernel has rebuilt the directory and added its attribute
# files (bmInfo is always created by the driver)
for _ in {1..50}; do
    [ -e "$header_h/bmInfo" ] && break
    sleep 0.010          # max 0.5 s total
done

# ABSOLUTE symlink → no relative elements, name is “fmt” (not “1”)
ln -sf "$fmt_dir"  "$header_h/fmt"
# echo 1 >"$header_h/bNumFormats"
# echo 0 >"$header_h/bmInfo"

# per‑speed class directories (absolute links)
for s in fs hs ss; do
    mkdir -p "$F/streaming/class/$s"
    ln -sf "$header_h"  "$F/streaming/class/$s/h"
done

# control‑interface header – share the very same directory
mkdir -p "$F/control/header"
ln -sf "$header_h"  "$F/control/header/h"
for s in fs hs ss; do
    mkdir -p "$F/control/class/$s"
    ln -sf "$header_h"  "$F/control/class/$s/h"
done

# friendly label
mkdir -p "$F/control/header/strings/0x409"
echo "Lesavka UVC" >"$F/control/header/strings/0x409/label"

# ----------------------- configuration -----------------------------
mkdir -p "$G/configs/c.1/strings/0x409"
echo 500 > "$G/configs/c.1/MaxPower"
# echo "Config 1" > "$G/configs/c.1/strings/0x409/configuration"
echo "Config 1: HID + UAC2" >"$G/configs/c.1/strings/0x409/configuration"

ln -s  $G/functions/hid.usb0  $G/configs/c.1/
ln -s  $G/functions/hid.usb1  $G/configs/c.1/
ln -s  $U                     $G/configs/c.1/
ln -s  $G/functions/uvc.usb0  $G/configs/c.1/

# mkdir -p $G/functions/hid.usb0/os_desc
# mkdir -p $G/functions/hid.usb1/os_desc
# mkdir -p $U/os_desc

# ---------- optional Microsoft OS descriptors ----------------------
# if [ -e "$G/os_desc/use" ]; then
#     echo 1        >"$G/os_desc/use"
#     echo 0xcd     >"$G/os_desc/b_vendor_code"
#     echo "MSFT100" >"$G/os_desc/qw_sign"

#     ln -s "$G/configs/c.1" "$G/os_desc"          # creates $G/os_desc/conf

#     echo "Lesavka Keyboard" >"$G/functions/hid.usb0/os_desc/interface"
#     echo "Lesavka Mouse"    >"$G/functions/hid.usb1/os_desc/interface"
#     echo "Lesavka Mic+Spkr" >"$U/os_desc/interface"
# fi

#──────────────────────────────────────────────────
# 4.  Bind gadget
#──────────────────────────────────────────────────
echo "$UDC" >"$G/UDC"
log "🎉 gadget bound on $UDC (hidg0, hidg1, UAC2 L+R, UVC)"

exit 0