#include "zero.h"

#include "alloc.h"
#include "errno.h"
#include "kernel.h"
#include "klibc.h"
#include "mem.h"
#include "list.h"
#include "paging.h"
#include "types.h"

struct zeroMappedPage {
    uaddr_t mappedAddr;
    paddr_t phyAddr;

    struct zeroMappedPage *prev, *next;
};

struct zeroMappedEntry {
    int refCnt;

    struct zeroMappedPage *listMapped;
};

static int insertMappedPage(struct zeroMappedEntry *entry, uaddr_t vAddr, paddr_t pAddr){
    struct zeroMappedPage *info = (struct zeroMappedPage *)zalloc(sizeof(struct zeroMappedPage));

    if(!info)
        return -ENOMEM;

    info->mappedAddr = vAddr;
    info->phyAddr = pAddr;

    list_add_tail(entry->listMapped, info);
    return 0;
}


static int zeroOpen(struct uAddrVirtualReg *vreg)
{
    struct zeroMappedEntry *ent = (struct zeroMappedEntry *)vreg->res->customData;
    ent->refCnt++;
    return 0;
}

static int zeroClose(struct uAddrVirtualReg *vreg)
{
    struct zeroMappedEntry *ent = (struct zeroMappedEntry *)vreg->res->customData;
    ent->refCnt--;
    if (ent->refCnt == 0) {
        struct zeroMappedPage *pageInfo;
        list_collapse(ent->listMapped, pageInfo){
            pageUnmap(pageInfo->mappedAddr);
            free(pageInfo);
        }
        free(vreg->res->customData);
        free(vreg->res);
    }
    return 0;
}

static int zeroNoPage(struct uAddrVirtualReg *vreg, uaddr_t addr, int right)
{
    int ret            = 0;
    paddr_t ppage      = allocPhyPage(1);
    uaddr_t mappedAddr = ALIGN_DOWN(addr, PAGE_SIZE);
    ret                = pageMap(mappedAddr, ppage, right | PAGING_MEM_USER);

    struct zeroMappedEntry *ent = (struct zeroMappedEntry *)vreg->res->customData;

    unrefPhyPage(ppage);
    if (ret) {
        return ret;
    }

    ret = insertMappedPage(ent, mappedAddr, ppage);
    if (ret) {
        pageUnmap(mappedAddr);
        return ret;
    }

    memset((void *)mappedAddr, 0, PAGE_SIZE);

    return ret;
}

static struct mappedRessourceOps zeroOps = {
    .open   = zeroOpen,
    .close  = zeroClose,
    .unmap  = NULL,
    .nopage = zeroNoPage,
};

int zeroOnMapped(struct uAddrVirtualReg *vreg)
{
    (void)vreg;
    return 0;
}

int zeroMmap(struct uAddrSpace *as, uaddr_t *uaddr, size_t size, uint32_t rights,
             uint32_t flags)
{
    int ret = 0;
    struct mappedRessource *res =
        (struct mappedRessource *)zalloc(sizeof(struct mappedRessource));
    struct zeroMappedEntry *cust =
        (struct zeroMappedEntry *)zalloc(sizeof(struct zeroMappedEntry));

    list_init(cust->listMapped);

    res->allowedRight = PAGING_MEM_READ | PAGING_MEM_WRITE | PAGING_MEM_EXEC | PAGING_MEM_USER;
    res->ops          = &zeroOps;
    res->customData   = cust;
    res->onResMapped = zeroOnMapped;

    ret = uAddrSpaceMmap(as, uaddr, size, rights, flags, res, 0);

    if (ret) {
        free(res);
        free(cust);
    }

    return ret;
}