#!/usr/bin/env bash
# Launch or validate USB hub enumeration (P3-A state machine) in QEMU.
#
# Topology under test:
#   qemu-xhci root port 1 → usb-hub (USB 2.0, 8 ports)
#     └─ hub port 2 → usb-kbd
#   qemu-xhci root port 2 → usb-tablet (control case, direct attach)
#
# Validates: hub descriptor read, usbhubd spawn, EP1 change detection or
# polling fallback, power-on, debounce, reset-wait, attach delegation to
# xhcid, child enumeration behind the hub (usbhidd spawn), no panics.

set -euo pipefail

find_uefi_firmware() {
    local candidates=(
        "/usr/share/ovmf/x64/OVMF.4m.fd"
        "/usr/share/OVMF/x64/OVMF.4m.fd"
        "/usr/share/ovmf/x64/OVMF_CODE.4m.fd"
        "/usr/share/OVMF/x64/OVMF_CODE.4m.fd"
        "/usr/share/ovmf/OVMF.fd"
        "/usr/share/OVMF/OVMF_CODE.fd"
        "/usr/share/qemu/edk2-x86_64-code.fd"
    )
    local path
    for path in "${candidates[@]}"; do
        if [[ -f "$path" ]]; then
            printf '%s\n' "$path"
            return 0
        fi
    done
    return 1
}

usage() {
    cat <<'USAGE'
Usage: test-usb-hub-qemu.sh [--check] [config]

Boot or validate USB hub enumeration (usbhubd P3-A state machine) on a
Red Bear image in QEMU. Defaults to redbear-mini.
USAGE
}

check_mode=0
config="redbear-mini"
for arg in "$@"; do
    case "$arg" in
        --help|-h|help)
            usage
            exit 0
            ;;
        --check)
            check_mode=1
            ;;
        redbear-*)
            config="$arg"
            ;;
    esac
done

firmware="$(find_uefi_firmware)" || {
    echo "ERROR: no usable x86_64 UEFI firmware found" >&2
    exit 1
}

arch="${ARCH:-$(uname -m)}"
# Prefer the live ISO (canonical artifact of build-redbear.sh). harddrive.img
# is only produced by older `make all`-style flows and can go stale — booting
# it tests the wrong tree (this happened in practice: a stale Jul-17 image
# with a pre-version-sync bootloader masked the current build).
iso="build/$arch/$config.iso"
image="build/$arch/$config/harddrive.img"
extra="build/$arch/$config/extra.img"

boot_media=""
if [[ -f "$iso" ]]; then
    boot_media="iso"
elif [[ -f "$image" ]]; then
    boot_media="harddrive"
else
    echo "ERROR: no bootable image found" >&2
    echo "Build it first with: ./local/scripts/build-redbear.sh $config" >&2
    exit 1
fi

pkill -f "qemu-system-x86_64.*$config" 2>/dev/null || true
sleep 1

# Assemble the boot-media args once so check and interactive modes share it.
if [[ "$boot_media" == "iso" ]]; then
    media_args=(-cdrom "$iso")
else
    if [[ ! -f "$extra" ]]; then
        truncate -s 1g "$extra"
    fi
    media_args=(
        -drive "file=$image,format=raw,if=none,id=drv0,snapshot=on"
        -device nvme,drive=drv0,serial=NVME_SERIAL
        -drive "file=$extra,format=raw,if=none,id=drv1,snapshot=on"
        -device nvme,drive=drv1,serial=NVME_EXTRA
    )
fi

if [[ "$check_mode" -eq 1 ]]; then
    log_file="build/$arch/$config/usb-hub-check.log"
    rm -f "$log_file"
    set +e
    # Timeout budget: hub enumeration itself is quick, but a hub-child's
    # class driver then performs its own descriptor/control transfers on the
    # (slow, emulated) TT path, and the guest clock runs several times
    # slower than wall time under load. 180s was not enough for a hub-child
    # HID driver to finish registering after being spawned.
    timeout 360s qemu-system-x86_64 \
      -name "Red Bear OS x86_64" \
      -device qemu-xhci,id=xhci \
      -device usb-hub,bus=xhci.0,port=1 \
      -device usb-kbd,bus=xhci.0,port=1.2 \
      -device usb-tablet,bus=xhci.0,port=2 \
      -smp 4 \
      -m 2048 \
      -bios "$firmware" \
      -chardev stdio,id=debug,signal=off,mux=on \
      -serial chardev:debug \
      -mon chardev=debug \
      -machine q35 \
      -device ich9-intel-hda -device hda-output \
      -device virtio-net,netdev=net0 \
      -netdev user,id=net0 \
      -nographic -vga none \
      "${media_args[@]}" \
      -enable-kvm -cpu host \
      > "$log_file" 2>&1
    status=$?
    set -e

    fail=0

    # 1. xhcid detected the controller.
    if ! grep -q "^.*XHCI " "$log_file"; then
        echo "ERROR: xHCI controller not detected in boot log; see $log_file" >&2
        exit 1
    fi

    # 2. usbhubd spawned for the hub device. The "USB HUB driver spawned"
    #    log line is emitted before setup_logging and never reaches the
    #    serial console, so the reliable spawn proof is the hub-descriptor
    #    read. Serial output from many daemons interleaves mid-line, so
    #    match a short fragment rather than the full sentence.
    if ! grep -q "port(s) detected" "$log_file"; then
        echo "ERROR: usbhubd did not spawn or hub descriptor read failed" >&2
        echo "       Expected fragment: 'port(s) detected'" >&2
        grep -i "usbhubd" "$log_file" | tail -10 >&2 || true
        echo "       See $log_file" >&2
        exit 1
    fi

    # 4. Change detection is active (interrupt EP or polling fallback).
    if ! grep -Eq "change detection|using polling|falling back to polling" "$log_file"; then
        echo "ERROR: usbhubd did not report a change-detection mode" >&2
        echo "       See $log_file" >&2
        exit 1
    fi

    # 5. Hub-child enumeration: the usb-kbd sits BEHIND the hub (QEMU port
    #    1.2, a dotted PortId). Requiring the hub-child subdriver line proves
    #    the full chain (power-on → debounce → reset-wait → enable → attach →
    #    xhcid enumerate → class match). A root-port HID (the tablet on port 2)
    #    must NOT satisfy this — the match is on the hub-child "5.2" form.
    if ! grep -Eq 'Loading subdriver "USB HID" for port [0-9]+\.[0-9]+' "$log_file"; then
        echo "ERROR: hub-child (usb-kbd behind hub) did not enumerate to a HID driver" >&2
        echo "       Expected: 'Loading subdriver \"USB HID\" for port <root>.<child>'" >&2
        echo "       See $log_file" >&2
        exit 1
    fi

    # 6. No panics anywhere in the boot.
    if grep -qiE "panic|RUST_BACKTRACE" "$log_file"; then
        echo "ERROR: panic detected in boot log" >&2
        grep -iE "panic|RUST_BACKTRACE" "$log_file" | head -5 >&2
        echo "       See $log_file" >&2
        exit 1
    fi

    echo "HUB_ENUMERATION=ok"
    echo "HUB_LOG=$log_file"
    echo "USB hub enumeration confirmed in $log_file"
    exit 0
fi

exec qemu-system-x86_64 \
  -name "Red Bear OS x86_64" \
  -device qemu-xhci,id=xhci \
  -device usb-hub,bus=xhci.0,port=1 \
  -device usb-kbd,bus=xhci.0,port=1.2 \
  -device usb-tablet,bus=xhci.0,port=2 \
  -smp 4 \
  -m 2048 \
  -bios "$firmware" \
  -chardev stdio,id=debug,signal=off,mux=on \
  -serial chardev:debug \
  -mon chardev=debug \
  -machine q35 \
  -device ich9-intel-hda -device hda-output \
  -device virtio-net,netdev=net0 \
  -netdev user,id=net0 \
  -vga std \
  "${media_args[@]}" \
  -enable-kvm -cpu host