#include <posix/unistd.h>
#include <posix/fcntl.h>
#include <kjarna/interface.h>
#include <libc/string.h>
#include <libc/stdio.h>
#include <libc/stdlib.h>
#include <lib/elf.h>
#include <posix/unistd.h>
#include <posix/sys/mman.h>

#include "kjarna_efi.h"

#include "config.h"

#include <efi/error.h>

static int create_image_buffer(int fd, struct image_buffer *buffer)
{
	if ((buffer->length = elf64_size_fd(fd)) == 0)
	{
		return -1;
	}

	printf("creating image buffer, %d bytes\n", buffer->length);

	if((buffer->base = mmap(nullptr, buffer->length, 0, 0, -1, 0)) == MAP_FAILED)
	{
		buffer->length = 0;
		buffer->base = nullptr;
		
		return -1;
	}

	printf("image buffer base %p\n", buffer->base);

	return 0;
}

static struct image_buffer load_image(void)
{
	const char *image_entry_path = SERVICE_FILE_PATH;

	int image_fd;

	struct image_buffer buffer = { nullptr, 0 };

	if ((image_fd = open(image_entry_path, O_RDONLY, 0)) == -1)
	{
		return buffer;
	}

	if (!elf64_validate_fd(image_fd, ET_DYN, EM_X86_64))
	{
		return buffer;
	}

	if (create_image_buffer(image_fd, &buffer) < 0)
	{
		return buffer;
	}

	if (buffer.base != nullptr && elf64_load_segments(image_fd, buffer.length, buffer.base) < 0)
	{
		printf("error detected: buffer {base: %p, length: %zu}\n", buffer.base, buffer.length);
		munmap(buffer.base, buffer.length);
		buffer.base = nullptr;
	}

	close(image_fd);

	return buffer;
}

kjarna_image_entry_func *image_entry_addr(struct image_buffer *buffer)
{
	if (buffer->base == nullptr)
	{
		return nullptr;
	}

	Elf64_Ehdr *ehdr = (Elf64_Ehdr *)buffer->base;

	return (kjarna_image_entry_func *)(buffer->base + ehdr->e_entry);
}

struct kjarna_interface get_boot_interface(void)
{
	struct kjarna_interface result =
	{
		efi_open,
		efi_close,
		efi_lseek,
		efi_read,
		efi_write,
		efi_mmap,
		efi_munmap
	};

	return result;
}

struct kjarna_boot_image get_boot_image(void)
{
	struct kjarna_boot_image image = 
	{
		{ nullptr, 0 },
		nullptr
	};

	image.buffer = load_image();

	if (image.buffer.base != nullptr)
	{
		image.entry = image_entry_addr(&image.buffer);
	}

	return image;
}

int image_start(void)
{
	struct kjarna_interface interface = get_boot_interface();
	struct kjarna_entry_params params =
	{
		&interface,
		0,
		nullptr,
		nullptr
	};

	struct kjarna_boot_image image = get_boot_image();

	if (image.buffer.base != nullptr)
	{
		image.entry = image_entry_addr(&image.buffer);
	}

	if (image.entry != nullptr)
	{
		image.entry(&params);
	}

	if (munmap(image.buffer.base, image.buffer.length) == -1)
	{
		write(STDOUT_FILENO, "failed unmap\r\n", -1);

		if (efi_errno == EFI_NOT_FOUND)
		{
			write(STDOUT_FILENO, "not found\r\n", -1);
		}
		else
		{
			write(STDOUT_FILENO, "bad alignment?\r\n", -1);
		}
	}

	return -1;
}