#include "allocArea.h"
#include "alloc.h"
#include "assert.h"
#include "kernel.h"
#include "list.h"
#include "mem.h"
#include "stdarg.h"

struct memArea {
    vaddr_t startAddr;
    uint nbPages;
    struct memArea *next;
    struct memArea *prev;
};

static struct memArea *freeArea;
static struct memArea *usedArea;

static int areaMergeFreeArea(struct memArea *prev, struct memArea *next);

void areaInit(void)
{
    list_init(freeArea);
    list_init(usedArea);

    vaddr_t areaAddr, descAddr, entryAddr;
    allocSetup(sizeof(struct memArea), &areaAddr, &descAddr, &entryAddr);
    areaAdd(descAddr, PAGE_SIZE, FALSE);
    if (entryAddr != descAddr)
        areaAdd(entryAddr, PAGE_SIZE, FALSE);
    if (areaAddr != descAddr && areaAddr != entryAddr)
        areaAdd(areaAddr, PAGE_SIZE, FALSE);
    allocPopulate();
}

struct memArea *areaFindFit(unsigned int nbPages)
{
    struct memArea *area;
    int count;

    list_foreach(freeArea, area, count)
    {
        if (area->nbPages >= nbPages)
            return area;
    }
    return NULL;
}

static void insertSorted(struct memArea *list, struct memArea *item)
{
    struct memArea *prev, *cur;
    int count;
    prev = NULL;

    list_foreach(list, cur, count)
    {
        if (cur->startAddr > item->startAddr)
            break;
        prev = cur;
    }
    if (prev)
        list_insert_after(list, prev, item);
    else
        list_add_tail(list, item);
}

vaddr_t areaAlloc(unsigned int nbPages)
{
    struct memArea *area, *allocated;

    area = areaFindFit(nbPages);
    if (!area)
        return (vaddr_t)NULL;

    if (area->nbPages == nbPages) {
        list_delete(freeArea, area);
        insertSorted(usedArea, area);
        allocated = area;
    }

    struct memArea *newArea = (struct memArea *)malloc(sizeof(struct memArea));
    if (!newArea)
        return (vaddr_t)NULL;

    // Avoid insertSorted(freeArea, newArea) call by modifying area

    newArea->nbPages   = nbPages;
    newArea->startAddr = area->startAddr;

    area->nbPages -= nbPages;
    area->startAddr += nbPages * PAGE_SIZE;

    insertSorted(usedArea, newArea);

    allocated = newArea;

    for (uint i = 0; i < nbPages; i++) {
        paddr_t page = allocPhyPage(1);
        if (page) {
            pageMap(area->startAddr + i * PAGE_SIZE, page, PAGING_MEM_WRITE);
        } else {
            // TODO
            assert(1);
        }
    }

    return allocated->startAddr;
}

int areaAdd(vaddr_t addr, uint nbPages, int isFree)
{
    struct memArea *area;

    struct memArea *newArea = (struct memArea *)malloc(sizeof(struct memArea));
    if (!newArea)
        return (vaddr_t)NULL;

    newArea->nbPages   = nbPages;
    newArea->startAddr = addr;

    if (isFree) {
        area = freeArea;
    } else {
        area = usedArea;
    }

    insertSorted(area, newArea);

    if (isFree) {
        if (newArea->prev)
            areaMergeFreeArea(newArea->prev, area);

        if (newArea->next)
            areaMergeFreeArea(area, newArea->next);
    }

    return 0;
}

static int areaMergeFreeArea(struct memArea *prev, struct memArea *next)
{
    if (prev->startAddr + prev->nbPages * PAGE_SIZE != next->startAddr) {
        return -1;
    }

    prev->nbPages += next->nbPages;
    list_delete(freeArea, next);
    free(next);

    next = prev;

    return 0;
}

static struct memArea *areaFindMemArea(struct memArea *list, vaddr_t addr)
{
    struct memArea *area;
    int count;
    list_foreach(list, area, count)
    {
        if (area->startAddr <= addr && addr <= area->startAddr + area->nbPages * PAGE_SIZE)
            return area;
    }

    return NULL;
}

int areaFree(vaddr_t addr)
{
    struct memArea *area;

    area = areaFindMemArea(usedArea, addr);
    if (!area) {
        pr_info("Cannot find memArea associated to %p\n", addr);
        return -1;
    }
    list_delete(usedArea, area);
    insertSorted(freeArea, area);

    if (area->prev)
        areaMergeFreeArea(area->prev, area);

    if (area->next)
        areaMergeFreeArea(area, area->next);

    return 0;
}