//----------------------------------------------------------------------------//
//                           GNU GPL OS/K                                     //
//                                                                            //
//  Desc:         Page allocator related functions                            //
//                                                                            //
//                                                                            //
//  Copyright © 2018-2019 The OS/K Team                                       //
//                                                                            //
//  This file is part of OS/K.                                                //
//                                                                            //
//  OS/K is free software: you can redistribute it and/or modify              //
//  it under the terms of the GNU General Public License as published by      //
//  the Free Software Foundation, either version 3 of the License, or         //
//  any later version.                                                        //
//                                                                            //
//  OS/K is distributed in the hope that it will be useful,                   //
//  but WITHOUT ANY WARRANTY//without even the implied warranty of            //
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
//  GNU General Public License for more details.                              //
//                                                                            //
//  You should have received a copy of the GNU General Public License         //
//  along with OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
//----------------------------------------------------------------------------//

#include <kernel.h>
#include <init/boot.h>
#include <ex/malloc.h>
#include <mm/paging.h>
#include <mm/palloc.h>
#include <mm/map.h>
#include <io/vga.h>
#include <lib/buf.h>
#include <ke/time.h>

//---------

enum
{
    Whatever           = 1UL << 52,
    Whatever2          = 1UL << 62
};

static AllocatedPage_t busyPagesList = { (void*)0, (void*)0, 0, (AllocatedPage_t*)0 };
extern MemoryMap_t memoryMap;
extern ulong MmPhysLastKernAddress;

static ulong NSuccessfulAlloc = 0;
static ulong NSuccessfulFree = 0;

//---------

// Returns 0 if page is not busy, its last address if yes
static ulong isPageBusy(void *phyPageAddr)
{
    AllocatedPage_t *busyPage = &busyPagesList;
    ulong isBusy = 0;

    // In case of NVS, ACPI or BADRAM zone, considered busy
    if (!MmGetAvailZoneSize(phyPageAddr))
        return true;

    // Search in the busylist if the phy addr is here
    while(busyPage->next) {
        busyPage = busyPage->next;
        if (phyPageAddr >= busyPage->phyAddressBegin
            && phyPageAddr <= busyPage->phyAddressEnd
            ) {
            isBusy = (ulong)busyPage->phyAddressEnd;
            break;
        }
    }
    return isBusy;
}

static void printBusyPages(void)
{
    AllocatedPage_t *busyPage = &busyPagesList;

    if (!busyPage->next) {
        KernLog("No busy page\n");
    } else {
        while(busyPage->next) {
            busyPage = busyPage->next;
            KernLog("Busy page at %p-%p\n", busyPage->phyAddressBegin,
                    busyPage->phyAddressEnd);
        }
    }
}

ulong MmGetBusyPageSize(void)
{
    ulong c = 0;
    AllocatedPage_t *busyPage = &busyPagesList;

    if (!busyPage->next) {
        return 0;
    } else {
        while(busyPage->next) {
            busyPage = busyPage->next;
            c += 4096 + (busyPage->phyAddressEnd - busyPage->phyAddressBegin);
        }
    }
    return c;
}

ulong MmGetTotalPageSize(void)
{
    // Maximum PHYSICAL address in memory
    ulong phRamSize = memoryMap.freeRamSize + memoryMap.nonfreeRamSize;
    return (phRamSize - (MmPhysLastKernAddress + KPAGESIZE));
}

static void addPageToBusyList(void *phyPageAddrBegin, void *phyPageAddrEnd, ulong id)
{
    AllocatedPage_t *busyPage = &busyPagesList;
    AllocatedPage_t *prevBusyPage = NULL;

    while(busyPage->next) {
        prevBusyPage = busyPage;
        busyPage = busyPage->next;

        if (busyPage->phyAddressBegin > phyPageAddrEnd) {
            busyPage = prevBusyPage;
            break;
        }
    }

    AllocatedPage_t *newBusyPage =
        (AllocatedPage_t*)malloc(sizeof(AllocatedPage_t));
    newBusyPage->phyAddressBegin = phyPageAddrBegin;
    newBusyPage->phyAddressEnd = phyPageAddrEnd;
    newBusyPage->id = id;
    newBusyPage->next = busyPage->next;
    busyPage->next = newBusyPage;
}

static void removePageFromBusyList(void *phyPageAddrBegin)
{
    AllocatedPage_t *busyPage = &busyPagesList;
    AllocatedPage_t *prevBusyPage = NULL;

    while(busyPage->next) {
        prevBusyPage = busyPage;
        busyPage = busyPage->next;

        if (phyPageAddrBegin == busyPage->phyAddressBegin) {
            prevBusyPage->next = busyPage->next;
            free(busyPage);
            break;
        }
    }
}

//
// Returns an id to identify a page frame allocated (kernel)
//
ulong MmAllocPageFrame(size_t size, bool contiguous)
{
    static ulong id = 0;
    ulong pageNumber = (((ulong)size - 1) / KPAGESIZE) + 1;

    size_t curNumber = 0;

    void *futureBegin = 0;
    void *futureEnd = 0;

    ulong busyLastAddr = 0;

    // Incrementing id
    id++;

    // Maximum PHYSICAL address in memory
    ulong phRamSize = memoryMap.freeRamSize + memoryMap.nonfreeRamSize;

    DebugLog("Allocating %d pages...\n", pageNumber);
    for (void *curPage = (void*)(MmPhysLastKernAddress + KPAGESIZE);
         curPage < (void*)phRamSize; curPage += KPAGESIZE) {
         busyLastAddr = isPageBusy(curPage);

         if (!busyLastAddr) {

            if (!futureBegin) {
                futureBegin = curPage;
                //DebugLog("Select begin : %p\n", curPage);
            }

            futureEnd = curPage;
            //DebugLog("Select page : %p\n", curPage);
            if (++curNumber >= pageNumber) {
                break;
            }

        } else {
            if (!contiguous) {
                if (futureBegin && futureEnd)
                    addPageToBusyList(futureBegin, futureEnd, id);
                futureBegin = 0;
            } else {
                curNumber = 0;
                futureBegin = 0;
            }
        }
    }

    if (curNumber != pageNumber) {
        KeStartPanic("MmAllocPageFrame() : No more free pages to allocate");
    }

    if (futureBegin && futureEnd)
                    addPageToBusyList(futureBegin, futureEnd, id);

    NSuccessfulAlloc++;

    return id;
}

//
// Frees a page frame by its id
//
void MmFreePageFrame(ulong id)
{
    AllocatedPage_t *busyPage = &busyPagesList;
    bool success = false;

    while(busyPage->next) {
        busyPage = busyPage->next;

        if (id == busyPage->id) {
            removePageFromBusyList(busyPage->phyAddressBegin);
            success = true;
        }
    }

    if (success)
        NSuccessfulFree++;
}

//
// Maps an allocated page frame to the given address
//
error_t MmMapPageFrame(ulong id, void *virtAddr, ulong flags)
{
    AllocatedPage_t *busyPage = &busyPagesList;

    while(busyPage->next) {
        busyPage = busyPage->next;

        if (id == busyPage->id) {
            for (void *addr = busyPage->phyAddressBegin; addr <= busyPage->phyAddressEnd; addr += KPAGESIZE) {
                if (MmTransPhyToVirtAddr(addr)) {
                    return EADDRINUSE;
                }
                //DebugLog("Map %p at %p\n", addr, virtAddr);
                MmMapPage((void*)((ulong)virtAddr), (void*)addr, flags);
                virtAddr += KPAGESIZE;
            }
        }
    }

    return EOK;
}

error_t MmUnmapPageFrame(ulong id)
{
    AllocatedPage_t *busyPage = &busyPagesList;
    void *actualPhys = 0;

    while(busyPage->next) {
        busyPage = busyPage->next;

        if (id == busyPage->id) {
            for (void *addr = busyPage->phyAddressBegin; addr <= busyPage->phyAddressEnd; addr += KPAGESIZE) {
                actualPhys = MmTransPhyToVirtAddr(addr);
                //DebugLog("Map %p at %p\n", addr, virtAddr);
                if (actualPhys && id == busyPage->id) {
                    MmUnmapPage(MmTransPhyToVirtAddr(addr));
                }
            }
        }
    }

    return EOK;
}