#include <gb.h>
#include <r_io.h>
#include <r_util.h>
#include <r_esil.h>
#include <r_anal.h>
#include <r_reg.h>

RIOPlugin r_io_plugin_gb_interrupts;

static ut64 __lseek(RIO* io, RIODesc *desc, ut64 offset, int whence) {
	GBInterrupts *ints = desc->data;
	ut64 seek = (ints->flags >> GB_INTERRUPT_SEEK) & 0x3;
	switch (whence) {
	case R_IO_SEEK_SET:
		seek = R_MIN (2, offset);
		break;
	case R_IO_SEEK_CUR:
		seek = R_MIN (2, seek + offset);
		break;
	case R_IO_SEEK_END:
		seek = 2;
		break;
	}
	ints->flags &= ~(0x3 << GB_INTERRUPT_SEEK);
	ints->flags |= seek << GB_INTERRUPT_SEEK;
	return seek;
}

static int __read(RIO *io, RIODesc *desc, ut8 *buf, int len) {
	GBInterrupts *ints = desc->data;
	ut64 seek = (ints->flags >> GB_INTERRUPT_SEEK) & 0x3;
	if (seek > 1 || len < 1) {
		return 0;
	}
	len = R_MIN (len, 2 - seek);
	ut32 i;
	for (i = 0; i < len; i++) {
		buf[i] = (ints->flags & (0x1f << (GB_INTERRUPT_N * seek))) >>
			(GB_INTERRUPT_N * seek);
		seek++;
	}
	ints->flags &= ~(0x3 << GB_INTERRUPT_SEEK);
	ints->flags |= seek << GB_INTERRUPT_SEEK;
	return len;
}

static int __write(RIO *io, RIODesc *desc, const ut8 *buf, int len) {
	GBInterrupts *ints = desc->data;
	ut64 seek = (ints->flags >> GB_INTERRUPT_SEEK) & 0x3;
	if (seek > 1 || len < 1) {
		return 0;
	}
	len = R_MIN (len, 2 - seek);
	ut32 i;
	for (i = 0; i < len; i++) {
		ints->flags &= ~(0x1f << (GB_INTERRUPT_N * seek));
		ints->flags |= (buf[i] & 0x1f) << (GB_INTERRUPT_N * seek);
		seek++;
	}
	ints->flags &= ~(0x3 << GB_INTERRUPT_SEEK);
	ints->flags |= seek << GB_INTERRUPT_SEEK;
	return len;
}

static bool __check(RIO *io, const char *pathname, bool many) {
	return r_str_startswith (pathname, "gb_interrupts://");
}

static RIODesc *__open(RIO *io, const char *pathname, int rw, int mode) {
	if (!r_str_startswith (pathname, "gb_interrupts://")) {
		return NULL;
	}
	GBInterrupts *ints = NULL;
	sscanf (pathname, "gb_interrupts://%p", &ints);
	RIODesc *desc = r_io_desc_new (io, &r_io_plugin_gb_interrupts, pathname,
		R_PERM_RWX, mode, ints);
	return desc;
}

static bool __close(RIODesc *desc) {
	return true;
}

RIOPlugin r_io_plugin_gb_interrupts = {
	.meta = {
		.name = "gb_interrupts",
		.desc = "gb_interrupts",
		.license = "LGPL",
	},
	.uris = "gb_interrupts://",
	.open = __open,
	.close = __close,
	.read = __read,
	.check = __check,
	.seek = __lseek,
	.write = __write,
};

bool gb_interrupts_init(GBInterrupts *ints, RIO *io, RReg *reg) {
	ints[0] = (const GBInterrupts) {0};
	ints->ime = r_reg_get (reg, "ime", R_REG_TYPE_GPR);
	char uri[64];
	memset (uri, 0x00, sizeof (char) * 64);
	sprintf (uri, "gb_interrupts://%p", ints);
	RIODesc *desc = r_io_desc_open_plugin (io, &r_io_plugin_gb_interrupts,
		uri, R_PERM_RWX, 0);
	if (!desc) {
		return false;
	}
	//map IF register
	if (!r_io_map_add (io, desc->fd, R_PERM_RWX, 0, 0xff0f, 1)) {
		r_io_desc_close (desc);
		return false;
	}
	//map IE register
	if (!r_io_map_add (io, desc->fd, R_PERM_RWX, 1, 0xffff, 1)) {
		r_io_desc_close (desc);
		//r_io will automatically remove the map for IF register
		return false;
	}
	ints->fd = desc->fd;
	return true;
}

void gb_interrupts_fini(GBInterrupts *ints, RIO *io) {
	r_unref (ints->ime);
	r_io_fd_close (io, ints->fd);
}

void gb_interrupts_continue(GB *gb) {
	const bool ime = !!r_reg_get_value (gb->anal->reg, gb->interrupts.ime);
	bool dec_pc = false;
	if (gb->interrupts.flags & (0x1 << GB_INTERRUPT_ENABLE_WAIT)) {
		gb->interrupts.flags ^= (0x1 << GB_INTERRUPT_ENABLE_WAIT);
		if (!ime) {
			return;
		}
		gb->interrupts.flags |= (0x1 << GB_INTERRUPT_ENABLED);
		if (gb->mode == GB_MODE_HALT_ENTER) {
			dec_pc = true;
		}
	} else if (ime && !(gb->interrupts.flags & (0x1 << GB_INTERRUPT_ENABLED))) {
		//wait 1 instruction
		gb->interrupts.flags |= (0x1 << GB_INTERRUPT_ENABLE_WAIT);
		return;
	} else if (!ime) {
		gb->interrupts.flags &= ~((0x1 << GB_INTERRUPT_ENABLED) |
			(0x1 << GB_INTERRUPT_ENABLE_WAIT) |
			(0x1 << GB_INTERRUPT_PENDING) |
			(0x1 << (GB_INTERRUPT_PENDING + 1)) |
			(0x1 << (GB_INTERRUPT_PENDING + 2)));
		return;
	}
	if (!(gb->interrupts.flags & (0x1 << GB_INTERRUPT_WAIT_TRIGGER))) {
		ut32 i;
		for (i = 0; i < GB_INTERRUPT_N; i++) {
			const ut16 imask = (0x1 << i) | (0x1 << (i + GB_INTERRUPT_N));
			if ((gb->interrupts.flags & imask) == imask) {
				gb->interrupts.flags |= (0x1 << GB_INTERRUPT_WAIT_TRIGGER);
				//stop exection of instructions for 20 cycles
				//gb_pause_exec (gb, 20);
				gb->pause_cycles += 20;
				//save pending interrupt index
				gb->interrupts.flags &= ~(0x7 << GB_INTERRUPT_PENDING);
				gb->interrupts.flags |= (i << GB_INTERRUPT_PENDING);
				if (R_UNLIKELY (dec_pc)) {
					gb->interrupts.flags |= (0x1 << GB_INTERRUPT_DEC_RET);
				}
				return;
			}
		}
		return;
	}
	dec_pc = !!(gb->interrupts.flags & (0x1 << GB_INTERRUPT_DEC_RET));
	gb->interrupts.flags &= ~(0x1 << GB_INTERRUPT_DEC_RET);
	gb->interrupts.flags ^= 0x1 << GB_INTERRUPT_WAIT_TRIGGER;
	const ut32 interrupt = (gb->interrupts.flags & (0x7 << GB_INTERRUPT_PENDING)) >> GB_INTERRUPT_PENDING;
	gb->interrupts.flags &= ~(0x1 << interrupt);
	const ut64 interrupt_vector = 0x40 + (interrupt << 3);
	//maybe make this a static buffer?
	char *interrupt_expr = r_str_newf (dec_pc ?
		"0,ime,:=,2,sp,-=,1,pc,-,sp,=[2],0x%"PFMT64x",pc,;="
		:"0,ime,:=,2,sp,-=,pc,sp,=[2],0x%"PFMT64x",pc,:=", interrupt_vector);
	r_esil_parse (gb->esil, interrupt_expr);
	free (interrupt_expr);
}

void gb_interrupts_request (GB *gb, int interrupt) {
	switch (interrupt) {
	case GB_INTERRUPT_VBLANK:
	case GB_INTERRUPT_STAT:
	case GB_INTERRUPT_TIMER:
	case GB_INTERRUPT_SERIAL:
	case GB_INTERRUPT_JOYPAD:
		gb->interrupts.flags |= (0x1 << interrupt);
		break;
	default:
		break;
	}
}