#include "../include/memorymanager.h"
#include "../include/system.h"
#include "../include/scrn.h"

static struct MemoryChunk* First;

struct MemoryManager* ActiveMemoryManager = {0};

void MemoryManager(size_t start, size_t size)
{
	if(size < sizeof(struct MemoryChunk))
	{
		First = 0;
		puts("First memory block is null\n");
		return;
	}
	
	First = (struct MemoryChunk*) start;
	
	First->Allocated = false;
	First->Prev = 0;
	First->Next = 0;
	First->Size = size - sizeof(struct MemoryChunk);
	puts("First block size ");
	puts(int_to_string(First->Size, 10));
	puts(" bytes.\n");
}

void* Malloc(size_t size)
{
	struct MemoryChunk *freeChunk = 0;

	for(struct MemoryChunk* chunk = First; chunk != 0 && freeChunk == 0; chunk = chunk->Next)
	{
		if(chunk->Size > size && !chunk->Allocated)
		{
			freeChunk = chunk;
		}
	}

	if(freeChunk == 0)
		return 0;
	
	if(freeChunk->Size >= size + sizeof(struct MemoryChunk))
	{
		struct MemoryChunk* temp = (struct MemoryChunk*)((size_t)freeChunk + sizeof(struct MemoryChunk) + size);
		
		temp->Allocated = false;
		temp->Size = freeChunk->Size - size - sizeof(struct MemoryChunk);
		temp->Prev = freeChunk;
		temp->Next = freeChunk->Next;

		if(temp->Next != 0)
			temp->Next->Prev = temp;

		freeChunk->Size = size;
		freeChunk->Next = temp;
	}

	freeChunk->Allocated = true;
	puts("Address of new chunk: 0x");
	puts(int_to_string((size_t)freeChunk + sizeof(struct MemoryChunk), 16));
	puts("\n");
	return (void*)(((size_t) freeChunk) + sizeof(struct MemoryChunk));
}

void Free(void* ptr)
{
	struct MemoryChunk* chunk = (struct MemoryChunk*)((size_t) ptr - sizeof(struct MemoryChunk));

	chunk->Allocated = false;

	if(chunk->Prev != 0 && !chunk->Prev->Allocated)
	{
		chunk->Prev->Next = chunk->Next;

		
	}
}

void ListBlocks()
{
	struct MemoryChunk *freeChunk = 0;
	int count = 0;
	
	for(struct MemoryChunk* chunk = First; chunk != 0 && freeChunk == 0; chunk = chunk->Next)
	{
		puts("\nChunk ");
		puts(int_to_string(count, 10));
		puts(" is ");
		puts(int_to_string(chunk->Size, 10));
		puts(" bytes. Allocated? ");
		if(chunk->Allocated)
			puts("True");
		else
			puts("False");
		count++;
	}
}