// SPDX-FileCopyrightText: 2012-2020 condret <condr3t@protonmail.com>
// SPDX-FileCopyrightText: 2012-2020 pancake <pancake@nopcode.org>
// SPDX-License-Identifier: LGPL-3.0-only

#include <rz_util.h>
#include <rz_types.h>
#include <rz_asm.h>
#include <string.h>

static void str_op(char *c) {
	if ((c[0] <= 'Z') && (c[0] >= 'A')) {
		c[0] += 0x20;
	}
}

static int gb_reg_idx(char r) {
	const char *rstr = "bcdehl a";
	const char *ptr = strchr(rstr, r);
	return ptr ? (int)(size_t)(ptr - rstr) : -1;
}

static bool gb_parse_cb1(ut8 *buf, const int minlen, char *buf_asm, ut8 base) {
	// minlen varries between 4 and 6
	int i;
	size_t j;
	if (strlen(buf_asm) < minlen || minlen < 1) {
		return false;
	}
	buf[0] = base;
	char *ptr_asm = buf_asm + minlen - 1;
	j = strlen(ptr_asm);
	rz_str_replace_in(ptr_asm, (ut32)j, "[ ", "[", true);
	rz_str_replace_in(ptr_asm, (ut32)j, " ]", "]", true);
	rz_str_do_until_token(str_op, buf_asm, ' ');
	i = gb_reg_idx(buf_asm[minlen - 1]);
	if (i != (-1)) {
		buf[0] |= (ut8)i;
		return true;
	}
	if (!strncmp(&buf_asm[minlen - 1], "[hl]", 4)) {
		buf[0] |= 6;
		return true;
	}
	return false;
}

static bool gb_parse_cb2(ut8 *buf, const int minlen, char *buf_asm, ut8 base) {
	ut64 num;
	int i;
	char *p, *q;
	if ((i = strlen(buf_asm)) < minlen) {
		return false;
	}
	rz_str_replace_in(buf_asm, (ut32)i, "[ ", "[", true);
	rz_str_replace_in(buf_asm, (ut32)i, " ]", "]", true);
	rz_str_replace_in(buf_asm, (ut32)i, ", ", ",", true);
	p = strchr(buf_asm, (int)' ');
	if (!p) {
		return false;
	}
	q = strchr(p, (int)',');
	if (!q) {
		return false;
	}
	q[0] = '\0';
	if (p[1] == '\0' || q[1] == '\0') {
		q[0] = ',';
		return false;
	}
	num = rz_num_get(NULL, &p[1]);
	q[0] = ',';
	if (num > 7) {
		return false;
	}
	buf[0] = base + (ut8)num * 8;
	i = gb_reg_idx(q[1]);
	if (i != -1) {
		buf[0] |= (ut8)i;
		return true;
	}
	if (strlen(q + 1) < 4) {
		return false;
	}
	if (!strncmp(q + 1, "[hl]", 4)) {
		buf[0] |= 6;
		return true;
	}
	return false;
}

static int gb_parse_arith1(ut8 *buf, const int minlen, char *buf_asm, ut8 base, ut8 alt) {
	int i;
	ut64 num;
	if (strlen(buf_asm) < minlen) {
		return 0;
	}
	buf[0] = base;
	char *ptr_asm = buf_asm + minlen - 1;
	i = strlen(ptr_asm);
	rz_str_replace_in(ptr_asm, (ut32)i, "[ ", "[", true);
	rz_str_replace_in(ptr_asm, (ut32)i, " ]", "]", true);
	rz_str_do_until_token(str_op, buf_asm, ' ');
	i = gb_reg_idx(buf_asm[minlen - 1]);
	if (i != -1) {
		buf[0] |= (ut8)i;
	} else if (!strncmp(buf_asm + minlen - 1, "[hl]", 4)) {
		buf[0] |= 6;
	} else {
		buf[0] = alt;
		num = rz_num_get(NULL, buf_asm + minlen - 1);
		buf[1] = (ut8)(num & 0xff);
		return 2;
	}
	return 1;
}

static bool gb_parse_ld1(ut8 *buf, const int minlen, char *buf_asm) {
	int i;
	rz_str_replace_in(buf_asm, strlen(buf_asm), ", ", ",", true);
	if (strlen(buf_asm) < minlen) {
		return false;
	}
	rz_str_do_until_token(str_op, buf_asm, '\0');
	if (buf_asm[4] == ',') {
		i = gb_reg_idx(buf_asm[3]);
		if (i == (-1)) {
			return false;
		}
		buf[0] = (ut8)(0x40 + (i * 8));
		i = gb_reg_idx(buf_asm[5]);
		if (i == -1) {
			if (strncmp(buf_asm + 5, "[hl]", 4)) {
				return false;
			}
			i = 6;
		}
		buf[0] |= (ut8)i;
		return true;
	}
	if (!strncmp(buf_asm + 3, "[hl],", 5)) {
		if ((i = gb_reg_idx(buf_asm[8])) == (-1)) {
			//'ld [hl], [hl]' does not exist
			return false;
		}
		buf[0] = 0x70 | (ut8)i;
		return true;
	}
	return false;
}

static bool gb_parse_ld2(ut8 *buf, char *buf_asm) {
	int i;
	ut64 num;
	if (strlen(buf_asm) < 6) {
		return false;
	}
	if (buf_asm[4] == ',') {
		if ((i = gb_reg_idx(buf_asm[3])) == -1) {
			return false;
		}
		buf[0] = 0x6 + (ut8)(i * 8);
		num = rz_num_get(NULL, buf_asm + 5);
		buf[1] = (ut8)(num & 0xff);
		return true;
	} else if (!strncmp(buf_asm + 3, "[hl],", 5)) {
		buf[0] = 0x36;
		num = rz_num_get(NULL, buf_asm + 8);
		buf[1] = (ut8)(num & 0xff);
		return true;
	}
	return false;
}

static bool gb_parse_ld3(ut8 *buf, char *buf_asm) {
	if (strlen(buf_asm) < 7) {
		return false;
	}
	if (buf_asm[5] != ',') {
		return false;
	}

	const ut16 reg = (buf_asm[3] << 8) | buf_asm[4];
	switch (reg) {
	case 0x6263: // bc
		buf[0] = 0x01;
		break;
	case 0x6465: // de
		buf[0] = 0x11;
		break;
	case 0x686c: // hl
		buf[0] = 0x21;
		break;
	case 0x7370: // sp
		buf[0] = 0x31;
		break;
	default:
		return false;
	}

	const ut64 num = rz_num_get(NULL, buf_asm + 6);
	buf[1] = num & 0xff;
	buf[2] = (num & 0xff00) >> 8;
	return true;
}

int gbAsm(RzAsm *a, RzAsmOp *op, const char *buf) {
	int mn_len, j, len = 1;
	ut32 mn = 0;
	ut64 num;
	size_t i;
	if (!a || !op || !buf) {
		return 0;
	}
	ut8 opbuf[4] = { 0 };
	rz_strbuf_set(&op->buf_asm, buf);
	char *buf_asm = rz_strbuf_get(&op->buf_asm);
	ut32 buf_len = strlen(buf);
	while (strstr(buf_asm, "  ")) {
		rz_str_replace_in(buf_asm, buf_len, "  ", " ", true);
	}
	rz_str_replace_in(buf_asm, buf_len, " ,", ",", true);
	mn_len = rz_str_do_until_token(str_op, buf_asm, ' ');
	if (mn_len < 2 || mn_len > 4) {
		return 0;
	}
	for (j = 0; j < mn_len; j++) {
		mn = (mn << 8) | buf_asm[j];
	}
	switch (mn) {
	case 0x6e6f70: // nop
		opbuf[0] = 0x00;
		break;
	case 0x696e63: // inc
		if ((i = strlen(buf_asm)) < 5) {
			return op->size = 0;
		}
		rz_str_replace_in(buf_asm, (ut32)i, "[ ", "[", true);
		rz_str_replace_in(buf_asm, (ut32)i, " ]", "]", true);
		rz_str_do_until_token(str_op, buf_asm + 4, '\0');
		if (buf_asm[4] == 'b') {
			opbuf[0] = (buf_asm[5] == 'c') ? 3 : 4;
		} else if (buf_asm[4] == 'c') {
			opbuf[0] = 0x0c;
		} else if (buf_asm[4] == 'd') {
			opbuf[0] = (buf_asm[5] == 'e') ? 0x13 : 0x14;
		} else if (buf_asm[4] == 'e') {
			opbuf[0] = 0x1c;
		} else if (buf_asm[4] == 'h') {
			opbuf[0] = (buf_asm[5] == 'l') ? 0x23 : 0x24;
		} else if (buf_asm[4] == 'l') {
			opbuf[0] = 0x2c;
		} else if (buf_asm[4] == 'a') {
			opbuf[0] = 0x3c;
		} else if (buf_asm[4] == 's' && buf_asm[5] == 'p') {
			opbuf[0] = 0x33;
		} else if (!strncmp(buf_asm + 4, "[hl]", 4)) {
			opbuf[0] = 0x34;
		} else {
			len = 0;
		}
		break;
	case 0x646563: // dec
		if ((i = strlen(buf_asm)) < 5) {
			return op->size = 0;
		}
		rz_str_replace_in(buf_asm, (ut32)i, "[ ", "[", true);
		rz_str_replace_in(buf_asm, (ut32)i, " ]", "]", true);
		rz_str_do_until_token(str_op, &buf_asm[4], '\0');
		switch (buf_asm[4]) {
		case 'b':
			opbuf[0] = (buf_asm[5] == 'c') ? 0x0b : 0x05;
			break;
		case 'c':
			opbuf[0] = 0x0d;
			break;
		case 'd':
			opbuf[0] = (buf_asm[5] == 'e') ? 0x1b : 0x15;
			break;
		case 'e':
			opbuf[0] = 0x1d;
			break;
		case 'h':
			opbuf[0] = (buf_asm[5] == 'l') ? 0x2b : 0x25;
			break;
		case 'l':
			opbuf[0] = 0x2d;
			break;
		case 'a':
			opbuf[0] = 0x3d;
			break;
		default:
			if (!strncmp(buf_asm + 4, "sp", 2)) {
				opbuf[0] = 0x3b;
			} else if (!strncmp(buf_asm, "[hl]", 4)) {
				opbuf[0] = 0x35;
			} else {
				len = 0;
			}
			break;
		}
		break;
	case 0x726c6361: // rlca
		opbuf[0] = 0x07;
		break;
	case 0x72726361: // rrca
		opbuf[0] = 0xf0;
		break;
	case 0x73746f70: // stop
		opbuf[0] = 0x10;
		break;
	case 0x726c61: // rla
		opbuf[0] = 0x17;
		break;
	case 0x727261: // rra
		opbuf[0] = 0x1f;
		break;
	case 0x646161: // daa
		opbuf[0] = 0x27;
		break;
	case 0x63706c: // cpl
		opbuf[0] = 0x2f;
		break;
	case 0x616464: // add
		rz_str_replace_in(buf_asm, strlen(buf_asm), ", ", ",", true);
		if (strlen(buf_asm) < 5)
			return op->size = 0;
		if (buf_asm[4] == 's' && buf_asm[5] == 'p' && buf_asm[6] == ',' && buf_asm[7] != '\0') {
			opbuf[0] = 0xe8;
			num = rz_num_get(NULL, buf_asm + 7);
			opbuf[1] = (ut8)(num & 0xff);
			len = 2;
		} else if (!strcmp(buf_asm, "hl,bc")) {
			opbuf[0] = 0x09;
		} else if (!strcmp(buf_asm + 4, "hl,de")) {
			opbuf[0] = 0x19;
		} else if (!strcmp(buf_asm + 4, "hl,hl")) {
			opbuf[0] = 0x29;
		} else if (!strcmp(buf_asm + 4, "hl,sp")) {
			opbuf[0] = 0x39;
		} else {
			len = gb_parse_arith1(opbuf, 5, buf_asm, 0x80, 0xc6);
		}
		break;
	case 0x616463: // adc
		len = gb_parse_arith1(opbuf, 5, buf_asm, 0x88, 0xce);
		break;
	case 0x737562: // sub
		len = gb_parse_arith1(opbuf, 5, buf_asm, 0x90, 0xd6);
		break;
	case 0x736263: // sbc
		len = gb_parse_arith1(opbuf, 5, buf_asm, 0x98, 0xde);
		break;
	case 0x616e64: // and
		len = gb_parse_arith1(opbuf, 5, buf_asm, 0xa0, 0xe6);
		break;
	case 0x786f72: // xor
		len = gb_parse_arith1(opbuf, 5, buf_asm, 0xa8, 0xee);
		break;
	case 0x6f72: // or
		len = gb_parse_arith1(opbuf, 4, buf_asm, 0xb0, 0xf6);
		break;
	case 0x6370: // cp
		len = gb_parse_arith1(opbuf, 4, buf_asm, 0xb8, 0xfe);
		break;
	case 0x736366: // scf
		opbuf[0] = 0x37;
		break;
	case 0x636366: // ccf
		opbuf[0] = 0x3f;
		break;
	case 0x68616c74: // halt
		opbuf[0] = 0x76;
		break;
	case 0x726574: // ret
		if (strlen(buf_asm) < 5) {
			opbuf[0] = 0xc9;
		} else if (strlen(buf_asm) < 6) {
			// there is no way that there can be "  " - we did rz_str_replace_in
			str_op(buf_asm + 4);
			if (buf_asm[4] == 'z') { // ret Z
				opbuf[0] = 0xc8;
			} else if (buf_asm[4] == 'c') { // ret C
				opbuf[0] = 0xd8;
			} else {
				return op->size = 0;
			}
		} else {
			str_op(&buf_asm[4]);
			if (buf_asm[4] != 'n') {
				return op->size = 0;
			}
			str_op(&buf_asm[5]); // if (!(strlen(buf_asm) < 6)) => must be 6 or greater
			if (buf_asm[5] == 'z') { // ret nZ
				opbuf[0] = 0xc0;
			} else if (buf_asm[5] == 'c') { // ret nC
				opbuf[0] = 0xd0;
			} else {
				return op->size = 0;
			}
		}
		break;
	case 0x72657469: // reti
		opbuf[0] = 0xd9;
		break;
	case 0x6469: // di
		opbuf[0] = 0xf3;
		break;
	case 0x6569: // ei
		opbuf[0] = 0xfb;
		break;
	case 0x6c64: // ld
		i = strlen(buf_asm);
		rz_str_replace_in(buf_asm, (ut32)i, "[ ", "[", true);
		rz_str_replace_in(buf_asm, (ut32)i, " ]", "]", true);
		if (!gb_parse_ld1(opbuf, 6, buf_asm)) {
			len++;
			if (!gb_parse_ld2(opbuf, buf_asm)) {
				len++;
				if (!gb_parse_ld3(opbuf, buf_asm)) {
					len = 0;
				}
			}
		}
		break;
	case 0x727374: // rst
		if (strlen(buf_asm) < 5) {
			return op->size = 0;
		}
		num = rz_num_get(NULL, &buf_asm[4]);
		if ((num & 7) || ((num / 8) > 7)) {
			return op->size = 0;
		}
		opbuf[0] = (ut8)((num & 0xff) + 0xc7);
		break;
	case 0x70757368: // push
		if (strlen(buf_asm) < 7) {
			return op->size = 0;
		}
		str_op(buf_asm + 5);
		str_op(buf_asm + 6);
		if (buf_asm[5] == 'b' && buf_asm[6] == 'c') {
			opbuf[0] = 0xc5;
		} else if (buf_asm[5] == 'd' && buf_asm[6] == 'e') {
			opbuf[0] = 0xd5;
		} else if (buf_asm[5] == 'h' && buf_asm[6] == 'l') {
			opbuf[0] = 0xe5;
		} else if (buf_asm[5] == 'a' && buf_asm[6] == 'f') {
			opbuf[0] = 0xf5;
		} else {
			len = 0;
		}
		break;
	case 0x706f70: // pop
		if (strlen(buf_asm) < 6)
			return op->size = 0;
		str_op(&buf_asm[4]);
		str_op(&buf_asm[5]);
		if (buf_asm[4] == 'b' && buf_asm[5] == 'c') {
			opbuf[0] = 0xc1;
		} else if (buf_asm[4] == 'd' && buf_asm[5] == 'e') {
			opbuf[0] = 0xd1;
		} else if (buf_asm[4] == 'h' && buf_asm[5] == 'l') {
			opbuf[0] = 0xe1;
		} else if (buf_asm[4] == 'a' && buf_asm[5] == 'f') {
			opbuf[0] = 0xf1;
		} else {
			len = 0;
		}
		break;
	case 0x6a70: // jp
		if (strlen(buf_asm) < 4) {
			return op->size = 0;
		}
		{
			char *p = strchr(buf_asm, (int)',');
			if (!p) {
				str_op(&buf_asm[3]);
				str_op(&buf_asm[4]);
				if (buf_asm[3] == 'h' && buf_asm[4] == 'l')
					opbuf[0] = 0xe9;
				else {
					num = rz_num_get(NULL, &buf_asm[3]);
					len = 3;
					opbuf[0] = 0xc3;
					opbuf[1] = (ut8)(num & 0xff);
					opbuf[2] = (ut8)((num & 0xff00) >> 8);
				}
			} else {
				str_op(p - 2);
				str_op(p - 1);
				if (*(p - 2) == 'n') {
					if (*(p - 1) == 'z') {
						opbuf[0] = 0xc2;
					} else if (*(p - 1) == 'c') {
						opbuf[0] = 0xd2;
					} else {
						return op->size = 0;
					}
				} else if (*(p - 2) == ' ') {
					if (*(p - 1) == 'z') {
						opbuf[0] = 0xca;
					} else if (*(p - 1) == 'c') {
						opbuf[0] = 0xda;
					} else {
						return op->size = 0;
					}
				} else {
					return op->size = 0;
				}
				rz_str_replace_in(p, strlen(p), ", ", ",", true);
				if (!p[0] || !p[1]) {
					return op->size = 0;
				}
				num = rz_num_get(NULL, p + 1);
				opbuf[1] = (ut8)(num & 0xff);
				opbuf[2] = (ut8)((num & 0xff00) >> 8);
				len = 3;
			}
		}
		break;
	case 0x6a72: // jr
		if (strlen(buf_asm) < 4)
			return op->size = 0;
		{
			char *p = strchr(buf_asm, (int)',');
			if (!p) {
				num = rz_num_get(NULL, &buf_asm[3]);
				len = 2;
				opbuf[0] = 0x18;
				opbuf[1] = (ut8)(num & 0xff);
			} else {
				str_op(p - 2);
				str_op(p - 1);
				if (*(p - 2) == 'n') {
					if (*(p - 1) == 'z')
						opbuf[0] = 0x20;
					else if (*(p - 1) == 'c')
						opbuf[0] = 0x30;
					else
						return op->size = 0;
				} else if (*(p - 2) == ' ') {
					if (*(p - 1) == 'z')
						opbuf[0] = 0x28;
					else if (*(p - 1) == 'c')
						opbuf[0] = 0x38;
					else
						return op->size = 0;
				} else {
					return op->size = 0;
				}
				rz_str_replace_in(p, strlen(p), ", ", ",", true);
				if (!p[1]) {
					return op->size = 0;
				}
				num = rz_num_get(NULL, p + 1);
				opbuf[1] = (ut8)(num & 0xff);
				len = 2;
			}
		}
		break;
	case 0x63616c6c: // call
		if (strlen(buf_asm) < 6) {
			return op->size = 0;
		}
		{
			char *p = strchr(buf_asm, (int)',');
			if (!p) {
				num = rz_num_get(NULL, buf_asm + 4);
				len = 3;
				opbuf[0] = 0xcd;
				opbuf[1] = (ut8)(num & 0xff);
				opbuf[2] = (ut8)((num & 0xff00) >> 8);
			} else {
				str_op(p - 2);
				str_op(p - 1);
				if (*(p - 2) == 'n') {
					if (*(p - 1) == 'z') {
						opbuf[0] = 0xc4;
					} else if (*(p - 1) == 'c') {
						opbuf[0] = 0xd4;
					} else {
						return op->size = 0;
					}
				} else if (*(p - 2) == ' ') {
					if (*(p - 1) == 'z') {
						opbuf[0] = 0xcc;
					} else if (*(p - 1) == 'c') {
						opbuf[0] = 0xdc;
					} else {
						return op->size = 0;
					}
				} else {
					return op->size = 0;
				}
				rz_str_replace_in(p, strlen(p), ", ", ",", true);
				if (!*p || !p[1]) {
					return op->size = 0;
				}
				num = rz_num_get(NULL, p + 1);
				opbuf[1] = (ut8)(num & 0xff);
				opbuf[2] = (ut8)((num & 0xff00) >> 8);
				len = 3;
			}
		}
		break;
	case 0x726c63:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 5, buf_asm, 0x00) ? 2 : 0;
		break;
	case 0x727263:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 5, buf_asm, 0x08) ? 2 : 0;
		break;
	case 0x726c:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 4, buf_asm, 0x10) ? 2 : 0;
		break;
	case 0x7272:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 4, buf_asm, 0x18) ? 2 : 0;
		break;
	case 0x736c61:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 5, buf_asm, 0x20) ? 2 : 0;
		break;
	case 0x737261:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 5, buf_asm, 0x28) ? 2 : 0;
		break;
	case 0x73776170:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 6, buf_asm, 0x30) ? 2 : 0;
		break;
	case 0x73726c:
		opbuf[0] = 0xcb;
		len = gb_parse_cb1(opbuf + 1, 6, buf_asm, 0x38) ? 2 : 0;
		break;
	case 0x626974:
		opbuf[0] = 0xcb;
		len = gb_parse_cb2(opbuf + 1, 6, buf_asm, 0x40) ? 2 : 0;
		break;
	case 0x726573:
		opbuf[0] = 0xcb;
		len = gb_parse_cb2(opbuf + 1, 6, buf_asm, 0x80) ? 2 : 0;
		break;
	case 0x736574:
		opbuf[0] = 0xcb;
		len = gb_parse_cb2(opbuf + 1, 6, buf_asm, 0xc0) ? 2 : 0;
		break;
	default:
		len = 0;
		break;
	}
	memcpy(rz_strbuf_get(&op->buf), opbuf, sizeof(ut8) * len);
	return op->size = len;
}
