#include <kernel.h>
#include <init/boot.h>
#include <ex/malloc.h>
#include <mm/mm.h>
#include <ke/idt.h>
#include <lib/buf.h>
#include <io/vga.h>

enum
{
    MF_PRESENT      = 1 << 0,
    MF_READWRITE    = 1 << 1,
    MF_USERMODE     = 1 << 2,
    MF_WRITETHR     = 1 << 3,
    MF_CACHEDIS     = 1 << 4,
    MF_ACCESSED     = 1 << 5,
    MF_DIRTY        = 1 << 6,
    MF_HUGE         = 1 << 7,
    MF_NX           = 1 << 31
};

#define RAM_MAX 32
#define NB_4K 150
                // * 2 MB

//-----------

volatile pdpe_t MmPML4[512] __attribute__((__aligned__(KPAGESIZE)));

volatile pde_t MmPDP[512] __attribute__((__aligned__(KPAGESIZE)));

volatile pde_t MmPD[512 * RAM_MAX] __attribute__((__aligned__(KPAGESIZE)));;

volatile pte_t MmPT[512 * NB_4K] __attribute__((__aligned__(KPAGESIZE)));;

extern ulong _text;
extern ulong _text_end;
extern ulong _rodata;
extern ulong _rodata_end;
extern ulong _data;
extern ulong _data_end;

ulong MmStackGuards[2] = { 0 };

//
// Creates our new page table structure and loads it
//
void MmInitPaging(void)
{
    extern MemoryMap_t memoryMap;
    ulong phRamSize = memoryMap.freeRamSize + memoryMap.nonfreeRamSize;

    memzero((void *)&MmPML4[0], sizeof(MmPML4));
    memzero((void *)&MmPDP[0], sizeof(MmPDP));
    memzero((void *)&MmPD[0], sizeof(MmPD));
    memzero((void *)&MmPT[0], sizeof(MmPT));

    for (volatile ulong i = 0; i < 512 *  NB_4K; i++) {
        // STACK GUARD PAGE
        if ((ulong)(i*KPAGESIZE) == (ulong)BtLoaderInfo.stackEndAddr) {
            MmPT[i] = ((ulong)(i*KPAGESIZE));
            MmStackGuards[0] = ((ulong)(i*KPAGESIZE ));
            continue;
        }

        // ENOMEM like
        if ((ulong)(i*KPAGESIZE) > (ulong)phRamSize) {
            break;
        }

        // STACK GARD PAGE
        if ((ulong)(i*KPAGESIZE) == (ulong)BtLoaderInfo.kernelEndAddr) {
            MmPT[i] = ((ulong)(i*KPAGESIZE));
            MmStackGuards[1] = ((ulong)(i*KPAGESIZE));
            continue;
        }

        // TEXT
        if ((ulong)(i*KPAGESIZE) >= (ulong)&_text && (ulong)(i*KPAGESIZE) <= (ulong)&_text_end) {
            MmPT[i] = ((ulong)(i*KPAGESIZE))| MF_PRESENT;
            continue;
        }

        // RODATA
        if ((ulong)(i*KPAGESIZE) >= (ulong)&_rodata && (ulong)(i*KPAGESIZE) <= (ulong)&_rodata_end) {
            MmPT[i] = ((ulong)(i*KPAGESIZE)) | MF_PRESENT | MF_WRITETHR;
            continue;
        }

        // DATA
        if ((ulong)(i*KPAGESIZE) >= (ulong)&_data && (ulong)(i*KPAGESIZE) <= (ulong)&_data_end) {
            MmPT[i] = ((ulong)(i*KPAGESIZE)) | MF_PRESENT | MF_WRITETHR | MF_READWRITE;
            continue;
        }

        MmPT[i] = ((ulong)(i*KPAGESIZE)) | MF_PRESENT | MF_WRITETHR | MF_READWRITE;
    }

    for (volatile ulong i = 0; i <  NB_4K; i++) {
        MmPD[i] = (ulong)(&MmPT[i*512])| MF_PRESENT | MF_READWRITE;
    }

    for (volatile ulong i =  NB_4K; i < 512 * RAM_MAX; i++) {
        // ENOMEM like
        if ((ulong)(i* UPAGESIZE) > (ulong)phRamSize) {
            break;
        }

        MmPD[i] = 0;
        MmPD[i] = ((ulong)(i* UPAGESIZE)) | MF_PRESENT | MF_READWRITE | MF_HUGE;
    }

    for (volatile int i = 0; i < RAM_MAX; i++) {
        MmPDP[i] = (ulong)(&MmPD[i*512])| MF_PRESENT | MF_READWRITE;
    }

    MmPML4[0] = (ulong)(&MmPDP[0])| MF_PRESENT | MF_READWRITE;

    MmLoadPML4((void *)MmPML4);
    MmEnableWriteProtect();
    DebugLog("\tPage RO from %p to %p\n", (ulong)&_text, (ulong)&_text_end);
    DebugLog("\tPage RO from %p to %p\n", (ulong)&_rodata, (ulong)&_rodata_end);
    //DebugLog("\tPaging tables initialized at %p, %p\n", &MmPD, &MmPT);
    //DebugLog("\tStack Guards at %p, %p\n", MmStackGuards[0], MmStackGuards[1]);
}

// Returns the rank of the Stack Guards
void *MmGetStackGuards(char rank)
{
    return (void *)MmStackGuards[(int)rank];
}

// Returns an address corresponding to the PT rank
void *MmTranslateKPageToAddr(void *rank)
{
    return (void *)MmPT[(ulong)rank];
}

//
// Page fault handler
//
static void PagingHandler(ISRFrame_t *regs)
{
    ulong StackGuardOne = (ulong)MmGetStackGuards(0);
    ulong StackGuardTwo = (ulong)MmGetStackGuards(1);
    if ((regs->cr2 >= StackGuardOne) && (regs->cr2 <= StackGuardOne + 4*KB) && (regs->rsp <= regs->cr2)) {
        bprintf(BStdOut,
            "\n\n%CPANIC\n[ISR 0x8] Irrecoverable Kernel Stack Underflow\n\n"
                     "  Double Fault Error code : %#x (%b)\n"
                     "  Stack Guard bypassed    : %#x",

                     VGA_COLOR_LIGHT_RED,
                     regs->ErrorCode,
                     regs->ErrorCode,
                     StackGuardOne
                 );
    } else if ((regs->cr2 >= StackGuardTwo) && (regs->cr2 <= StackGuardTwo + 4*KB) && (regs->rsp >= regs->cr2)) {
        bprintf(BStdOut,
            "\n\n%CPANIC\n[ISR 0x8] Irrecoverable Kernel Stack Overflow\n\n"
                     "  Double Fault Error code : %#x (%b)\n"
                     "  Stack Guard bypassed    : %#x",

                     VGA_COLOR_LIGHT_RED,
                     regs->ErrorCode,
                     regs->ErrorCode,
                     StackGuardTwo
                 );
    } else {
        //XXX page fault
        bprintf(BStdOut, "\n\n%CPANIC\n[ISR 0x%x] Irrecoverable Kernel Page Fault at %p\n\n"
                     "  Error code : 0x%x (%b)",

                     VGA_COLOR_LIGHT_RED,
                     regs->intNo,
                     regs->cr2,
                     regs->ErrorCode,
                     regs->ErrorCode
                 );
    }

    KeBrkDumpRegisters(regs);

    BStdOut->flusher(BStdOut);

    KeHaltCPU();
}

void MmActivatePageHandler(void)
{
    KeRegisterISR(PagingHandler, 0xe);
    DebugLog("\tPaging activated\n");
}