#!/usr/bin/env bash
set -euo pipefail

VM_DIR="$(cd "$(dirname "$0")/.." && pwd)/vm"
DISK_IMAGE="$VM_DIR/yino-vm.qcow2"
UEFI_VARS="$VM_DIR/yino-vm-vars.fd"

# --- OVMF firmware discovery ---

find_ovmf_code() {
    local paths=(
        /opt/homebrew/share/qemu/edk2-x86_64-code.fd
        /usr/local/share/qemu/edk2-x86_64-code.fd
    )
    for p in "${paths[@]}"; do
        [[ -f "$p" ]] && echo "$p" && return
    done
    # Cellar fallbacks
    local cellar_dirs=(/opt/homebrew/Cellar/qemu /usr/local/Cellar/qemu)
    for d in "${cellar_dirs[@]}"; do
        if [[ -d "$d" ]]; then
            local found
            found=$(find "$d" -name 'edk2-x86_64-code.fd' -print -quit 2>/dev/null)
            [[ -n "$found" ]] && echo "$found" && return
        fi
    done
    return 1
}

find_ovmf_vars_template() {
    local paths=(
        /opt/homebrew/share/qemu/edk2-i386-vars.fd
        /usr/local/share/qemu/edk2-i386-vars.fd
    )
    for p in "${paths[@]}"; do
        [[ -f "$p" ]] && echo "$p" && return
    done
    local cellar_dirs=(/opt/homebrew/Cellar/qemu /usr/local/Cellar/qemu)
    for d in "${cellar_dirs[@]}"; do
        if [[ -d "$d" ]]; then
            local found
            found=$(find "$d" -name 'edk2-i386-vars.fd' -print -quit 2>/dev/null)
            [[ -n "$found" ]] && echo "$found" && return
        fi
    done
    return 1
}

# --- CPU/accelerator auto-detection ---

detect_accel() {
    local arch
    arch=$(uname -m)
    if [[ "$arch" == "arm64" ]]; then
        echo "tcg"
    else
        echo "hvf"
    fi
}

detect_cpu() {
    local arch
    arch=$(uname -m)
    if [[ "$arch" == "arm64" ]]; then
        echo "qemu64"
    else
        echo "host"
    fi
}

# --- Subcommands ---

cmd_create() {
    if ! command -v qemu-system-x86_64 &>/dev/null; then
        echo "Error: qemu-system-x86_64 not found." >&2
        echo "Install it with: brew install qemu" >&2
        exit 1
    fi

    if [[ -f "$DISK_IMAGE" ]]; then
        echo "Error: Disk image already exists: $DISK_IMAGE" >&2
        echo "Run 'yino-vm delete' first to remove it." >&2
        exit 1
    fi

    local vars_template
    if ! vars_template=$(find_ovmf_vars_template); then
        echo "Error: OVMF vars template (edk2-i386-vars.fd) not found." >&2
        echo "Install it with: brew install qemu" >&2
        exit 1
    fi

    echo "Creating 30G sparse disk image..."
    qemu-img create -f qcow2 "$DISK_IMAGE" 30G

    echo "Copying UEFI vars template..."
    cp "$vars_template" "$UEFI_VARS"

    echo "VM created:"
    echo "  Disk:      $DISK_IMAGE"
    echo "  UEFI vars: $UEFI_VARS"
}

cmd_boot() {
    if ! command -v qemu-system-x86_64 &>/dev/null; then
        echo "Error: qemu-system-x86_64 not found." >&2
        echo "Install it with: brew install qemu" >&2
        exit 1
    fi

    if [[ ! -f "$DISK_IMAGE" ]]; then
        echo "Error: Disk image not found: $DISK_IMAGE" >&2
        echo "Run 'yino-vm create' first." >&2
        exit 1
    fi

    local ovmf_code
    if ! ovmf_code=$(find_ovmf_code); then
        echo "Error: OVMF firmware (edk2-x86_64-code.fd) not found." >&2
        echo "Install it with: brew install qemu" >&2
        exit 1
    fi

    if [[ ! -f "$UEFI_VARS" ]]; then
        echo "Error: UEFI vars not found: $UEFI_VARS" >&2
        echo "Run 'yino-vm create' first." >&2
        exit 1
    fi

    local accel cpu
    accel=$(detect_accel)
    cpu=$(detect_cpu)

    if [[ "$accel" == "tcg" ]]; then
        echo "Warning: Running x86_64 VM under TCG emulation (Apple Silicon host)."
        echo "This works but is significantly slower than hardware virtualization."
        echo ""
    fi

    local iso_args=()
    local serial=false
    while [[ $# -gt 0 ]]; do
        case "$1" in
            --serial)
                serial=true
                shift
                ;;
            --iso)
                if [[ -z "${2:-}" ]]; then
                    echo "Error: --iso requires a path argument." >&2
                    exit 1
                fi
                if [[ ! -f "$2" ]]; then
                    echo "Error: ISO file not found: $2" >&2
                    exit 1
                fi
                iso_args=(-drive "file=$2,media=cdrom,readonly=on" -boot d)
                shift 2
                ;;
            *)
                echo "Error: Unknown option: $1" >&2
                echo "Usage: yino-vm boot [--serial] [--iso PATH]" >&2
                exit 1
                ;;
        esac
    done

    local display_args
    if [[ "$serial" == true ]]; then
        display_args=(-serial mon:stdio -nographic -display none)
    else
        display_args=(-display cocoa -vga virtio)
    fi

    echo "Booting VM (accel=$accel, cpu=$cpu)..."
    if [[ "$serial" != true ]]; then
        echo "SSH available at: ssh -p 2222 localhost"
    fi
    echo ""

    qemu-system-x86_64 \
        -machine q35 \
        -accel "$accel" \
        -cpu "$cpu" \
        -m 4G \
        -smp 2 \
        -drive "file=$DISK_IMAGE,if=virtio,cache=writeback" \
        -drive "if=pflash,format=raw,readonly=on,file=$ovmf_code" \
        -drive "if=pflash,format=raw,file=$UEFI_VARS" \
        -device virtio-net-pci,netdev=net0 \
        -netdev user,id=net0,hostfwd=tcp::2222-:22 \
        "${display_args[@]}" \
        "${iso_args[@]}"
}

cmd_delete() {
    if [[ ! -f "$DISK_IMAGE" && ! -f "$UEFI_VARS" ]]; then
        echo "Nothing to delete — no VM files found."
        exit 0
    fi

    echo "This will delete:"
    [[ -f "$DISK_IMAGE" ]] && echo "  $DISK_IMAGE"
    [[ -f "$UEFI_VARS" ]] && echo "  $UEFI_VARS"
    echo ""
    read -rp "Are you sure? [y/N] " confirm
    if [[ "$confirm" != [yY] ]]; then
        echo "Cancelled."
        exit 0
    fi

    [[ -f "$DISK_IMAGE" ]] && rm "$DISK_IMAGE" && echo "Removed $DISK_IMAGE"
    [[ -f "$UEFI_VARS" ]] && rm "$UEFI_VARS" && echo "Removed $UEFI_VARS"
    echo "VM deleted."
}

cmd_status() {
    echo "VM directory: $VM_DIR"
    echo ""
    if [[ -f "$DISK_IMAGE" ]]; then
        local size
        size=$(qemu-img info --output=json "$DISK_IMAGE" 2>/dev/null \
            | python3 -c "import sys,json; d=json.load(sys.stdin); print(f\"virtual: {d['virtual-size']/(1<<30):.0f}G, actual: {d['actual-size']/(1<<20):.1f}M\")" 2>/dev/null \
            || echo "present")
        echo "Disk image: $size"
    else
        echo "Disk image: not created"
    fi
    if [[ -f "$UEFI_VARS" ]]; then
        echo "UEFI vars:  present"
    else
        echo "UEFI vars:  not created"
    fi
}

cmd_help() {
    cat <<'EOF'
Usage: yino-vm <command> [options]

Commands:
  create          Create VM disk image and UEFI vars
  boot [opts]     Boot the VM (--serial for console, --iso P for installer)
  delete          Delete VM disk image and UEFI vars
  status          Show VM status
  help            Show this help
EOF
}

# --- Main ---

case "${1:-help}" in
    create) cmd_create ;;
    boot)   shift; cmd_boot "$@" ;;
    delete) cmd_delete ;;
    status) cmd_status ;;
    help|--help|-h) cmd_help ;;
    *)
        echo "Error: Unknown command: $1" >&2
        cmd_help >&2
        exit 1
        ;;
esac