require "fileutils"
require "ostruct"

module Qemu 
  def self.qemu_bin_for(arch)
    {
        x86_64:      "qemu-system-x86_64",
        x86_32:      "qemu-system-i386",
        arm64:       "qemu-system-aarch64",
        armv7:       "qemu-system-arm",
        armv6:       "qemu-system-arm",
        armv5:       "qemu-system-arm",
        riscv64:     "qemu-system-riscv64",
        ppc64le:     "qemu-system-ppc64",
        ppc64:       "qemu-system-ppc64",
        ppc32:       "qemu-system-ppc",
        s390x:       "qemu-system-s390x",
        mips64el:    "qemu-system-mips64el",
        mips64:      "qemu-system-mips64",
        mipsel:      "qemu-system-mipsel",
        mips:        "qemu-system-mips",
        loongarch64: "qemu-system-loongarch64",
        sparc64:     "qemu-system-sparc64",
        alpha:       "qemu-system-alpha",
        hppa:        "qemu-system-hppa",
        ia64:        "qemu-system-ia64",
    }.fetch(arch) { raise "Unsupported arch: #{arch.inspect}" }
  end

  def self.accel_args
    host = RbConfig::CONFIG["host_os"]
    if host =~ /linux/i && File.exist?("/dev/kvm")
      ["-accel", "kvm"]
    elsif host =~ /darwin/i
      # hvf exists on Apple Silicon + Intel macOS; QEMU falls back if not available
      ["-accel", "hvf"]
    elsif host =~ /freebsd/i
      # if QEMU was built with it; otherwise it will ignore
      ["-accel", "bhyve"]
    else
      ["-accel", "tcg"]
    end
  end

  def self.machine_args_for(arch)
    case arch
    when :x86_64, :x86_32
      []
    when :arm64
      # -machine type=virt
      # -cpu cortex-a72
      ["-machine", "virt", "-cpu", "max"]
    when :armv7, :armv6, :armv5
      ["-machine", "virt", "-cpu", "cortex-a15"]
    when :riscv64
      ["-machine", "virt"]
    when :loongarch64
      ["-machine", "virt"]
    else
      []
    end
  end

  #def self.launch(arch, disk_path, cdrom = nil, detach = true)
  def self.launch(arch, disk_path, **options)
    defaults = {
      arch: System::ARCH,
      cdrom: nil,
      detach: true,
      ram: 2048,
      cpus: 1,
      fullscreen: true
    }
    opts = defaults.merge(options)
    
    puts opts

    qemu = qemu_bin_for(arch)
    args = []
    
    if System::OS == :macos && arch == :arm64
      # args += ["-bios", "/opt/homebrew/share/qemu/edk2-aarch64-code.fd"]
      args += ["-drive", "if=pflash,format=raw,unit=0,readonly=on,file=/opt/homebrew/share/qemu/edk2-aarch64-code.fd"]

      #args += ["-device", "virtio-gpu-device"]
      if opts[:fullscreen] 
        args += ["-display", "cocoa,full-screen=on"]
      else
        args += ["-display", "cocoa"]
      end

      args += ["-device", "qemu-xhci,id=xhci"]
      args += ["-device", "usb-kbd"]
      args += ["-device", "usb-tablet"]

      args += ["-device", "virtio-keyboard-device"]
      args += ["-device", "virtio-mouse-device"]
      args += ["-device", "virtio-gpu"]
      

      # copy to /Users/artur/.cache/dat/vm/debian/arm64/debian/vars.fd
      # /opt/homebrew/share/qemu/edk2-aarch64-vars.fd
      # args += ["-drive", "if=pflash,format=raw,unit=1,file=/Users/artur/.cache/dat/vm/debian/arm64/debian/vars.fd"]
    end

    args += accel_args
    args += machine_args_for(arch)
    args += ["-m", opts[:ram].to_s, "-smp", opts[:cpus].to_s]
    args += ["-name", "FirstVM", "-boot", "order=d"] # boot from CD first
    args += ["-drive", "file=#{disk_path},if=virtio,cache=writeback,format=raw"]
    if opts[:cdrom] != nil 
      args += ["-cdrom", opts[:cdrom]]
    end
    args += ["-device", "virtio-net,netdev=n0", "-netdev", "user,id=n0"] # user-mode NAT
    # optional: uncomment to run headless with VNC on :5901
    # args += ["-display", "none", "-vnc", "127.0.0.1:1"]

    cmd = [qemu, *args]

    puts "Launching: #{cmd.join(' ')}"
    pid = Process.spawn(*cmd, pgroup: true, out: $stdout, err: $stderr)
    
    if opts[:detach]
      Process.detach(pid)
      puts "QEMU pid=#{pid}"
    else 
      Process.wait(pid)
      status = $?
      puts "Exit status: #{status.exitstatus}"
    end
  end
end