#include <lcrash/pci/pci.h>

#include <lcrash/mm/virt.h>
#include <lcrash/acpi/acpi.h>
#include <lcrash/debug/debug.h>
#include <lcrash/driver/sysbus.h>
#include <lcrash/mm/kmalloc.h>
#include <lcrash/driver/vga.h>
#include <lcrash/util.h>

#define PSD_MISC_() PciCreateMiscDevice(Parent, Bus, Device, DeviceHeader->Class, DeviceHeader->Subclass, DeviceHeader->ProgIF)

bool PciIsPresent   = false;
bool PciSupportsECM = false;

void* PciBusses[256] = {};

struct SysbusDeviceDescription* PciSBHostControllerDevice = 0;
struct SysbusDeviceDescription* PciSBMiscDevice = 0;

void PciCreateMiscDevice(struct SysbusDevice* Parent, u8 Bus, u8 Device, u8 Class, u8 Subclass, u8 ProgInterface) {
	struct SysbusDevice* Dev = SysbusCreateDevice(PciSBMiscDevice, Parent, NULL);
	struct PciSBMiscDevice* DeviceData = KernelHeapAlloc(sizeof(PciSBMiscDevice), 1, 0);

	DeviceData->Bus = Bus;
	DeviceData->Device = Device;
	DeviceData->Class = Class;
	DeviceData->Subclass = Subclass;
	DeviceData->ProgInterface = ProgInterface;

	Dev->DeviceName = "PCI Misc Device";
	Dev->DeviceData = DeviceData;
}

void PciScanDevice(u32 Bus, u32 Device, struct SysbusDevice* Parent) {
	struct PciConfigurationSpaceHeader* DeviceHeader = (struct PciConfigurationSpaceHeader*)(PciBusses[Bus] + Device * 0x8000);

	// Is a device connected here?
	if (DeviceHeader->VendorID != 0xFFFF) {
		if ((DeviceHeader->HeaderType & 3) == 0) {
			if (DeviceHeader->Class == 3) {
				if (DeviceHeader->Subclass == 0) {
					if (DeviceHeader->ProgIF == 0) {
						// It looks like theres something in the
						// VGA's BARs but i can't seem to find any
						// documentation on them, so we'll just use
						// legacy vga ports!
						
						// Get VGA drivers ready
						if (!VgaIsInitialized()) VgaInitialize();

						// QEMU oh so kindly provides us with a builtin version of the VESA BIOS Extensions!
						// They break our code. Disable them.
						if (DeviceHeader->VendorID == 0x1234 && DeviceHeader->DeviceID == 0x1111) {
							PortWrite16(0x01CE, 0x04); // VBE_DISPI_IOPORT_INDEX <= 0x04
							PortWrite16(0x01D0, 0x00); // [IDX:04] ENABLED <= FALSE
						}

						struct SysbusDevice* VgaDev = VgaCreateDevice(Parent);
						VgaDev->DeviceName = "VGA Device";
					} else PSD_MISC_();
				} else PSD_MISC_();
			} else if (DeviceHeader->Class == 6) {
				if (DeviceHeader->Subclass == 0) {
					if (DeviceHeader->HeaderType & 0x80) {
						Panic("No support for multiple host controller busses");
					} else {
						struct PciSBHostController_CreateArgs CreateArgs;
						CreateArgs.Bus = Bus;
						CreateArgs.Device = Device;
						CreateArgs.OwnedBusCount = 1;
						CreateArgs.OwnedBusses[0] = Bus;

						struct SysbusDevice* HostController = SysbusCreateDevice(
							PciSBHostControllerDevice,
							Parent, &CreateArgs
						);
						HostController->DeviceName = "PCI Host Controller";

						if (Device == 0) {
							for (int i = 1; i < 32; i++) PciScanDevice(Bus, i, HostController);
						} else Panic("Bus root inside bus");
					}
				} else PSD_MISC_();
			} else PSD_MISC_();
		} else PSD_MISC_();
	}
}

s32 PciSBHostControllerDevice_Create(struct SysbusDevice* Device, void* Data) {
	struct PciSBHostController_CreateArgs* CreateArgs = Data;
	struct PciSBHostController* DeviceData = KernelHeapAlloc(sizeof(struct PciSBHostController), 1, KHA_ZERO);

	// Copy parameters
	DeviceData->Bus = CreateArgs->Bus;
	DeviceData->Device = CreateArgs->Device;
	DeviceData->OwnedBusCount = CreateArgs->OwnedBusCount;
	for (int i = 0; i < DeviceData->OwnedBusCount; i++) DeviceData->OwnedBusses[i] = CreateArgs->OwnedBusses[i];

	// Save device data
	Device->DeviceData = (void*)DeviceData;

	return 0;
}

s32 PciSBHostControllerDevice_Delete(struct SysbusDevice* Device) {
	struct PciSBHostController* DeviceData = Device->DeviceData;

	// Free device data
	KernelHeapFree(DeviceData);

	return 0;
}

void PciInitialize() {	
	// Try to figure out if we have PCIe
	if (!AcpiPresent()) Panic("Failed to initialize PCI"); 

	// Define our devices
	PciSBHostControllerDevice = SysbusCreateDeviceDescription();
	PciSBHostControllerDevice->DeviceName = "PCI Host Controller";
	PciSBHostControllerDevice->CreateDevice = PciSBHostControllerDevice_Create;
	PciSBHostControllerDevice->DeleteDevice = PciSBHostControllerDevice_Delete;

	PciSBMiscDevice = SysbusCreateDeviceDescription();
	PciSBMiscDevice->DeviceName = "PCI Misc Device";

	// Acpi
	struct AcpiMCFG* BridgeTable = AcpiGetTable("MCFG");

	// Guess not
	if (BridgeTable == NULL) Panic("Failed to find PCI bridge table");

	// Take our pcie bridges
	s32 Length = (BridgeTable->Header.Length - 44) / 16;
	for (int i = 0; i < Length; i++) {
		// Identity map our busses because linux doesn't do it for us
		VmemMapMemory(
			BridgeTable->Bridges[i].Address, BridgeTable->Bridges[i].Address,
			(BridgeTable->Bridges[i].EndBus - BridgeTable->Bridges[i].StartBus + 1) * 0x100000
		);

		for (int Bus = BridgeTable->Bridges[i].StartBus; Bus < BridgeTable->Bridges[i].EndBus; Bus++) {
			PciBusses[Bus] = BridgeTable->Bridges[i].Address + (Bus - BridgeTable->Bridges[i].StartBus) * 0x100000;
		}
	}
	
	// Scan the root bus
	PciScanDevice(0, 0, SysbusGetRootDevice());

	return;
}

bool PciPresent()  { return PciIsPresent; }
bool PciePresent() { return PciSupportsECM; }