#include <stdio.h>
#include <gb.h>
#include <r_io.h>
#include <r_util.h>

typedef struct gb_mbc1_data {
	RIO *io;
	ut32 *rombank_to_io_map;
	ut32 *rambank_to_io_map;
	ut64 seek;
	ut32 size;
	int file_fd;
	int mem_fd;
	ut8 n_rombanks;
	ut8 n_rambanks;
	ut8 rombank_mask;
	ut8 rombank;
	union {
		ut8 high_rombank;
		ut8 rambank;
	};
	bool ram_enable;
	bool small_ram;
} MBC1;

ut8 mbc1_mask[] = { 0x1, 0x3, 0x7, 0xf, 0x1f, 0x1f, 0x1f };

static RIODesc *__open(RIO *io, const char *pathname, int rw, int mode) {
	if (!r_str_startswith (pathname, "gb_mbc1://")) {
		return NULL;
	}
	if (!r_file_exists (&pathname[10]) || !r_file_is_regular (&pathname[10])) {
		return NULL;
	}
	RIODesc *desc = r_io_desc_open (io, &pathname[10], R_PERM_R, 0);
	if (!desc) {
		return NULL;
	}
	ut8 mbc_info[3] = {0xfb, 0xff, 0xff};
	r_io_desc_read_at (desc, 0x147, mbc_info, 3);
	r_io_desc_close (desc);
	if (R_UNLIKELY (!mbc_info[0] || (mbc_info[0] > 3) ||
		(mbc_info[1] > 6) || (mbc_info[2] > 2))) {
		//not a mbc1 game
		return NULL;
	}
	MBC1 *mbc = R_NEW0 (MBC1);
	if (!mbc) {
		return NULL;
	}
	mbc->n_rombanks = 0x1 << (mbc_info[1] + 1);
	mbc->rombank_to_io_map = R_NEWS0 (ut32, mbc->n_rombanks);
	if (!mbc->rombank_to_io_map) {
		free (mbc);
		return NULL;
	}
	mbc->rombank_mask = mbc1_mask[mbc_info[1]];
	if (mbc_info[0] != 1) {
		switch (mbc_info[2]) {
		case 0x1:
			mbc->small_ram = true;
		case 0x3:
			mbc->n_rambanks = 4;
			break;
		case 0x2:
			mbc->n_rambanks = 1;
			break;
		}
		mbc->rambank_to_io_map = R_NEWS0 (ut32, mbc->n_rambanks);
		if (!mbc->rambank_to_io_map) {
			free (mbc->rombank_to_io_map);
			free (mbc);
			return NULL;
		}
	}
	mbc->io = r_io_new ();
	if (!mbc->io) {
		free (mbc->rombank_to_io_map);
		free (mbc->rambank_to_io_map);
		free (mbc);
		return NULL;
	}
	mbc->file_fd = r_io_fd_open (mbc->io, &pathname[10], R_PERM_R, 0);
	{
		char *malloc_uri = r_str_newf ("malloc://0x%"PFMT64x, 
			mbc->small_ram? 0x800: (0x2000 * mbc->n_rambanks));
		mbc->mem_fd = r_io_fd_open (mbc->io, malloc_uri, R_PERM_RW, 0);
		free (malloc_uri);
	}
	if ((mbc->file_fd < 0) || (mbc->mem_fd < 0)) {
		goto fail;
	}
	RIOMap *map = r_io_map_add (mbc->io, mbc->file_fd, R_PERM_R, 0ULL, 0ULL, 0x4000);
	if (!map) {
		goto fail;
	}
	mbc->rombank_to_io_map[0] = map->id;
	ut32 i;
	for (i = 1; i < mbc->n_rombanks; i++) {
		map = r_io_map_add_bottom (mbc->io, mbc->file_fd, R_PERM_R,
			0x4000 * i, 0x4000, 0x4000);
		if (!map) {
			goto fail;
		}
		mbc->rombank_to_io_map[i] = map->id;
	}
	if (mbc->small_ram) {
		for (i = 0; i < 4; i++) {
			map = r_io_map_add (mbc->io, mbc->mem_fd, R_PERM_RW,
				0ULL, 0xa000 + 0x800 * i, 0x800);
			if (!map) {
				goto fail;
			}
			mbc->rambank_to_io_map[i] = map->id;
		}
	} else {
		for (i = 0; i < 4; i++) {
			map = r_io_map_add_bottom (mbc->io, mbc->mem_fd, R_PERM_RW,
				0x2000 * i, 0xa000, 0x2000);
			if (!map) {
				goto fail;
			}
			mbc->rambank_to_io_map[i] = map->id;
		}
	}
	mbc->rombank = 1;
	mbc->io->cache.mode = 0;
	desc = r_io_desc_new (io, &r_io_plugin_gb_mbc1, pathname,
		R_PERM_RWX, mode, mbc);
	return desc;
fail:
	r_io_free (mbc->io);
	free (mbc->rombank_to_io_map);
	free (mbc->rambank_to_io_map);
	free (mbc);
	return NULL;
}