#include <stdbool.h>
#include <stdint.h>

#include <sys/kconfig.h>
#include <sys/kassert.h>
#include <sys/kdebug.h>
#include <sys/kmem.h>

#include <machine/amd64.h>
#include <machine/amd64op.h>
#include <machine/mp.h>
#include <machine/pmap.h>

typedef struct AS
{
    PageTable	*root;
    uint64_t	tables;
    uint64_t	mappings;
} AS;

AS systemAS;
AS *currentAS[MAX_CPUS];

void
PMap_Init()
{
    int i, j;

    kprintf("Initializing PMAP ... ");

    // Setup global state
    for (i = 0; i < MAX_CPUS; i++) {
	currentAS[i] = 0;
    }

    // Allocate system page table
    systemAS.root = PAlloc_AllocPage();
    systemAS.tables = PAGETABLE_ENTRIES / 2 + 1;
    systemAS.mappings = 0;
    if (!systemAS.root)
	PANIC("Cannot allocate system page table");

    for (i = 0; i < PAGETABLE_ENTRIES / 2; i++)
	systemAS.root->entries[i] = 0;

    for (i = PAGETABLE_ENTRIES / 2; i < PAGETABLE_ENTRIES; i++) {
	PageTable *pgtbl = PAlloc_AllocPage();
	PageEntry pte = DMVA2PA((uint64_t)pgtbl) | PTE_W | PTE_P;
	if (!pgtbl)
	    PANIC("Not enough memory!");

	systemAS.root->entries[i] = pte;

	for (j = 0; j < PAGETABLE_ENTRIES; j++) {
	    pgtbl->entries[j] = 0;
	}
    }

    // Setup system mappings
    PMap_SystemLMap(0x0, MEM_DIRECTMAP_BASE + 0x0,
		    3*512, 0); // 3GB RWX
    PMap_SystemLMap(0xC0000000, MEM_DIRECTMAP_BASE + 0xC0000000,
		    512, PTE_NX|PTE_PCD); // 1GB RW + PCD
    PMap_SystemLMap(0x100000000, MEM_DIRECTMAP_BASE + 0x100000000,
		    60*512, 0); // 60GB RWX

    write_cr3(DMVA2PA((uint64_t)systemAS.root));

    kprintf("Done!\n");
}

AS*
PMap_NewAS()
{
    int i;
    AS *as = PAlloc_AllocPage();

    if (!as)
	return 0;

    as->root = PAlloc_AllocPage();
    as->tables = 1;
    as->mappings = 0;

    if (!as->root) {
	PAlloc_FreePage(as);
	return 0;
    }

    for (i = 0; i < PAGETABLE_ENTRIES / 2; i++)
    {
	as->root->entries[i] = 0;
    }
    for (i = PAGETABLE_ENTRIES / 2; i < PAGETABLE_ENTRIES; i++) {
	as->root->entries[i] = systemAS.root->entries[i];
    }

    return as;
}

void
PMap_DestroyAS(AS *space)
{
    int i;

    for (i = 0; i < PAGETABLE_ENTRIES / 2; i++)
    {
	if (space->root->entries[i] != 0) {
	    // Remove subpages
	    PAlloc_FreePage((void *)DMPA2VA(space->root->entries[i]));
	}
    }
}

void
PMap_LoadAS(AS *space)
{
    write_cr3(DMVA2PA((uint64_t)space->root));
    currentAS[THISCPU()] = space;
}

PageTable *
PMapAllocPageTable()
{
    int i;
    PageTable *pgtbl = PAlloc_AllocPage();

    if (!pgtbl)
	return 0;

    for (i = 0; i < PAGETABLE_ENTRIES; i++) {
	pgtbl->entries[i] = 0;
    }

    return pgtbl;
}

void
PMapLookupEntry(AS *space, uint64_t va, PageEntry **entry, int size)
{
    int i,j,k,l;
    PageTable *table = space->root;
    PageEntry pte;

    i = (va >> (HUGE_PGSHIFT + PGIDXSHIFT)) & PGIDXMASK;
    j = (va >> HUGE_PGSHIFT) & PGIDXMASK;
    k = (va >> LARGE_PGSHIFT) & PGIDXMASK;
    l = (va >> PGSHIFT) & PGIDXMASK;

    *entry = NULL;

    pte = table->entries[i];
    if (pte == 0) {
	PageTable *newtable = PMapAllocPageTable();
	if (!newtable)
	    return;

	pte = DMVA2PA((uint64_t)newtable) | PTE_P | PTE_W | PTE_U;
	table->entries[i] = pte;
    }
    table = (PageTable *)DMPA2VA(pte & 0xFFFFFFFFFFFFF000);

    pte = table->entries[j];
    if (size == HUGE_PGSIZE) {
	// Handle 1GB pages
	*entry = &table->entries[j];
	return;
    }
    if (pte == 0) {
	PageTable *newtable = PMapAllocPageTable();
	if (!newtable)
	    return;

	pte = DMVA2PA((uint64_t)newtable) | PTE_P | PTE_W | PTE_U;
	table->entries[j] = pte;
    }
    table = (PageTable *)DMPA2VA(pte & 0xFFFFFFFFFFFFF000);

    pte = table->entries[k];
    if (size == LARGE_PGSIZE) {
	// Handle 2MB pages
	*entry = &table->entries[k];
	return;
    }
    if (pte == 0) {
	PageTable *newtable = PMapAllocPageTable();
	if (!newtable)
	    return;

	pte = DMVA2PA((uint64_t)newtable) | PTE_P | PTE_W | PTE_U;
	table->entries[k] = pte;
    }
    table = (PageTable *)DMPA2VA(pte & 0xFFFFFFFFFFFFF000);

    // Handle 4KB pages
    ASSERT(size == PGSIZE);
    *entry = &table->entries[l];
    return;
}

bool
PMap_Map(AS *as, uint64_t phys, uint64_t virt, uint64_t pages, uint64_t flags)
{
    int i;
    PageEntry *entry;

    for (i = 0; i < pages; i++) {
	uint64_t va = virt + PGSIZE * i;
	PMapLookupEntry(as, va, &entry, PGSIZE);
	if (!entry) {
	    kprintf("Map failed to allocate memory!\n");
	    return false;
	}

	*entry = (phys + PGSIZE * i) | PTE_P | PTE_W | PTE_U | flags;
    }

    return true;
}

bool
PMap_Unmap(AS *as, uint64_t va, uint64_t pages)
{
    int i;
    PageEntry *entry;

    for (i = 0; i < pages; i++) {
	uint64_t vai = va + PGSIZE * i;
	PMapLookupEntry(as, vai, &entry, PGSIZE);
	if (!entry) {
	    kprintf("Unmap tried to allocate memory!\n");
	    return false;
	}

	*entry = 0;
    }

    return true;
}

bool
PMap_AllocMap(AS *as, uint64_t virt, uint64_t len, uint64_t flags)
{
    int i;
    uint64_t pages = (len + PGSIZE - 1) / PGSIZE;
    PageEntry *entry;

    ASSERT((virt & PGMASK) == 0);

    for (i = 0; i < pages; i++) {
	uint64_t va = virt + PGSIZE * i;
	PMapLookupEntry(as, va, &entry, PGSIZE);
	if (!entry) {
	    kprintf("Map failed to allocate memory!\n");
	    return false;
	}

	if ((*entry & PTE_P) != PTE_P) {
	    void *pg = PAlloc_AllocPage();
	    *entry = (uint64_t)DMVA2PA(pg) | PTE_P | PTE_U | flags;
	}
    }

    return true;
}

void
PMap_SystemLookup(uint64_t va, PageEntry **entry, int size)
{
    PMapLookupEntry(&systemAS, va, entry, size);
}

bool
PMap_SystemLMap(uint64_t phys, uint64_t virt, uint64_t lpages, uint64_t flags)
{
    int i;
    PageEntry *entry;

    for (i = 0; i < lpages; i++) {
	uint64_t va = virt + LARGE_PGSIZE * i;
	PMapLookupEntry(&systemAS, va, &entry, LARGE_PGSIZE);
	if (!entry) {
	    kprintf("SystemLMap failed to allocate memory!\n");
	    return false;
	}

	*entry = (phys + LARGE_PGSIZE * i) | PTE_P | PTE_W | PTE_PS | flags;
    }

    return true;
}

bool
PMap_SystemMap(uint64_t phys, uint64_t virt, uint64_t pages, uint64_t flags)
{
    int i;
    PageEntry *entry;

    for (i = 0; i < pages; i++) {
	uint64_t va = virt + PGSIZE * i;
	PMapLookupEntry(&systemAS, va, &entry, PGSIZE);
	if (!entry) {
	    kprintf("SystemMap failed to allocate memory!\n");
	    return false;
	}

	*entry = (phys + PGSIZE * i) | PTE_P | PTE_W | flags;
    }

    return true;
}

bool
PMap_SystemUnmap(uint64_t virt, uint64_t pages)
{
    NOT_IMPLEMENTED();
    return false;
}

uint64_t
AddrFromIJKL(uint64_t i, uint64_t j, uint64_t k, uint64_t l)
{
    return (i << 39) | (j << HUGE_PGSHIFT) | (k << LARGE_PGSHIFT) | (l << PGSHIFT);
}

void
PMap_Dump(AS *space)
{
    int i = 0;
    int j = 0;
    int k = 0;
    int l = 0;
    PageTable *root = space->root;

    kprintf("Root: %016llx\n", (uint64_t)space->root);

    for (i = 0; i < PAGETABLE_ENTRIES; i++) {
	PageEntry pte = root->entries[i];
	PageTable *l1 = (PageTable *)DMPA2VA(pte & 0xFFFFFFFFFFFFF000);

	if (!(pte & PTE_P))
	    continue;

	kprintf("Level 1: %016llx\n", (uint64_t)pte);

	for (j = 0; j < PAGETABLE_ENTRIES; j++) {
	    PageEntry pte2 = l1->entries[j];
	    PageTable *l2 = (PageTable *)DMPA2VA(pte2 & 0xFFFFFFFFFFFFF000);

	    if (!(pte2 & PTE_P))
		continue;

	    kprintf("Level 2: %016llx\n", (uint64_t)pte2);

	    for (k = 0; k < PAGETABLE_ENTRIES; k++) {
		PageEntry pte3 = l2->entries[k];
		PageTable *l3 = (PageTable *)DMPA2VA(pte3 & 0xFFFFFFFFFFFFF000);

		if (!(pte3 & PTE_P))
		    continue;

		kprintf("Level 3: %016llx:%016llx\n",
			AddrFromIJKL(i, j, k, l),
			(uint64_t)pte3);

		if ((pte3 & PTE_PS) == 0) {
		    for (l = 0; l < PAGETABLE_ENTRIES; l++) {
			PageEntry pte4 = l3->entries[l];

			kprintf("Level 4: %016llx:%016llx\n",
				AddrFromIJKL(i, j, k, l),
				(uint64_t)pte4);
		    }
		    l = 0;
		}
	    }
	    k = 0;
	}
	j = 0;
    }

    return;
}

void
Debug_PMapDump(int argc, const char *argv[])
{
    PMap_Dump(currentAS[THISCPU()]);
}

REGISTER_DBGCMD(pmapdump, "Dump memory mappings", Debug_PMapDump);