{ lib, config, pkgs, modulesPath, ... }:

let
  cfg = config.cspark-single-gpu-passthru;
in
{
  options.cspark-single-gpu-passthru = {
    enable 
      = lib.mkEnableOption "Enable Single GPU Passthrough Setup";

    vmName = lib.mkOption {
      default = "win11";
      description = ''
        Name of the virtual machine
      '';
    };

    gpuPCI = lib.mkOption {
      default = "0000:08:00.0";
      description = ''
        PCI ID of GPU VGA
      '';
    };

    gpuAudioPCI = lib.mkOption {
      default = "0000:08:00.1";
      description = ''
        PCI ID of GPU Audio
      '';
    };
  };

  config = lib.mkIf cfg.enable {
    # Virtualisation, Virt Manager and Waydroid
    virtualisation.libvirtd = {
      enable = true;
      qemu = {
        package = pkgs.qemu_kvm;
        runAsRoot = true;
        swtpm.enable = true;
        ovmf = {
          enable = true;
          packages = [(pkgs.OVMF.override {
            secureBoot = true;
            tpmSupport = true;
          }).fd];
        };
      };
    };
    programs.virt-manager.enable = true;
    systemd.services.libvirtd = {
      # Add binaries to path so that hooks can use it
      path = let
               env = pkgs.buildEnv {
                 name = "qemu-hook-env";
                 paths = with pkgs; [
                   bash
                   libvirt
                   kmod
                   systemd
                   ripgrep
                   sd
                   procps
                   gawk
                 ];
               };
             in
             [ env ];
  
      preStart = let
		   qemuscript_source = builtins.readFile ./resources/libvirt/hooks/qemu;
		   startscript_source = builtins.readFile ./resources/libvirt/hooks/qemu.d/vm/prepare/begin/start.sh;
		   revertscript_source = builtins.readFile ./resources/libvirt/hooks/qemu.d/vm/release/end/revert.sh;
		   qemuscript = pkgs.writeShellScript "cspark-single-gpu-passthru-qemu" qemuscript_source;
		   startscript = pkgs.writeShellScript "cspark-single-gpu-passthru-start.sh" startscript_source;
		   revertscript = pkgs.writeShellScript "cspark-single-gpu-passthru-revert.sh" revertscript_source;
		   gpuvbios = ./resources/libvirt/vgabios/gpuvbios.rom;
                 in
      ''
        mkdir -p /var/lib/libvirt/hooks
        mkdir -p /var/lib/libvirt/hooks/qemu.d/${cfg.vmName}/prepare/begin
        mkdir -p /var/lib/libvirt/hooks/qemu.d/${cfg.vmName}/release/end
        mkdir -p /var/lib/libvirt/vgabios
        
        ln -sf ${qemuscript} /var/lib/libvirt/hooks/qemu
        ln -sf ${startscript} /var/lib/libvirt/hooks/qemu.d/${cfg.vmName}/prepare/begin/start.sh
        ln -sf ${revertscript} /var/lib/libvirt/hooks/qemu.d/${cfg.vmName}/release/end/revert.sh
        ln -sf ${gpuvbios} /var/lib/libvirt/vgabios/gpuvbios.rom
        
#        chmod +x /var/lib/libvirt/hooks/qemu
#        chmod +x /var/lib/libvirt/hooks/qemu.d/${cfg.vmName}/prepare/begin/start.sh
#        chmod +x /var/lib/libvirt/hooks/qemu.d/${cfg.vmName}/release/end/revert.sh
      '';
    };
    # Vendor Reset Patches for Single GPU Passthrough - https://github.com/gnif/vendor-reset
    boot.extraModulePackages = with config.boot.kernelPackages; [ vendor-reset ];
    # Ensures GPU is configured to use vendor reset module
    systemd.services.vendor-reset-config = {
      description = "Ensures GPU is configured to use vendor reset module";
      wantedBy = [ "multi-user.target" ];
      path = [ pkgs.coreutils ];
      enable = true;
      serviceConfig = {
        User = "root";
        Group = "root";
      };
      script = ''echo device_specific > "/sys/bus/pci/devices/${cfg.gpuPCI}/reset_method"'';
    };
    hardware.opengl.enable = true;
    virtualisation.spiceUSBRedirection.enable = true;
  };
}