#include "dis.h"

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>

static void print_const(Chunk *ch, uint8_t ix) {
	Val k = ch->consts.d[ix];
	printf("%-4s : ", typename_str(k));
	println_val(k);
}

static void disasm_chunk_h(Chunk *ch, int depth);
void disasm_chunk(Chunk *ch) {
	disasm_chunk_h(ch, 0);
}

static size_t disasm_instr_h(Chunk *ch, size_t ip, int depth);
size_t disasm_instr(Chunk *ch, size_t ip) {
	return disasm_instr_h(ch, ip, 0);
}


static size_t disasm_instr_h(Chunk *ch, size_t ip, int depth) {
	size_t orig_ip = ip;
	uint8_t instr = ch->bc.d[ip];
	printf("%*s%04zd\t",depth,"",ip);
	ip ++;
	switch (instr) {
	case OP_LOADK: {
		uint8_t ix = ch->bc.d[ip++];
		printf("loadk #%d\t; ",ix);
		print_const(ch, ix);
		break;
	}
	case OP_GETGLOBAL: {
		uint8_t ix = ch->bc.d[ip++];
		printf("getglobal #%d\t; ",ix);
		print_const(ch, ix);
		break;
	}
	case OP_SETGLOBAL: {
		uint8_t ix = ch->bc.d[ip++];
		printf("setglobal #%d\t; ",ix);
		print_const(ch, ix);
		break;
	}
	case OP_CALL: {
		uint8_t nargs = ch->bc.d[ip++];
		printf("call #%hhu\n",nargs);
		break;
	}
	#define RSHORT() (uint16_t)( ch->bc.d[ip-2] | ch->bc.d[ip-1] << 8 )
	case OP_SKIP: {
		ip += 2;
		uint16_t offset = RSHORT();
		printf("skip +%5hu\t; -> %04zd\n", offset, ip + offset);
		break;
	}
	case OP_0BRANCH: {
		ip += 2;
		uint16_t offset = RSHORT();
		printf("0branch +%5hu\t; -> %04zd\n", offset, ip + offset);
		break;
	}
	case OP_REDO: {
		ip += 2;
		uint16_t offset = RSHORT();
		printf("redo -%5hu\t; -> %04zd\n", offset, ip - offset);
		break;
	}
	#undef RSHORT

	#define SIMPLE_INSTR(opcode, str) \
		case opcode: puts(str); break;
	SIMPLE_INSTR(OP_RET, "ret")
	SIMPLE_INSTR(OP_PUTS, "puts")
	SIMPLE_INSTR(OP_PRINT, "print")
	SIMPLE_INSTR(OP_DROP, "drop")
	SIMPLE_INSTR(OP_ADD, "add")
	SIMPLE_INSTR(OP_SUB, "sub")
	SIMPLE_INSTR(OP_MUL, "mul")
	SIMPLE_INSTR(OP_DIV, "div")
	SIMPLE_INSTR(OP_MOD, "mod")
	SIMPLE_INSTR(OP_NIL, "nil")
	SIMPLE_INSTR(OP_TRUE, "true")
	SIMPLE_INSTR(OP_FALSE, "false")
	SIMPLE_INSTR(OP_CMP, "cmp")
	SIMPLE_INSTR(OP_EQU, "equ")
	SIMPLE_INSTR(OP_HALT, "halt")
	#undef SIMPLE_INSTR

	default:
		printf("unknown opcode %d\n", instr);
		exit(2);

	}

	return ip - orig_ip;

}

static void disasm_chunk_h(Chunk *ch, int depth) {
	#define P(msg) printf("%*s%s\n",depth,"",msg);
	P("constants:");
	for (uint8_t cix = 0; cix < ch->consts.len; cix++) {
		printf("%*s%hd\t",depth,"",cix);
		print_const(ch, cix);
	}

	P("bytecode:");
	#undef P
	for (size_t ip = 0; ip < ch->bc.len; ) {
		ip += disasm_instr_h(ch, ip, depth);
	}
	printf("\n");

	for (uint8_t cix = 0; cix < ch->consts.len; cix++) {
		Val c = ch->consts.d[cix];
		if (IS_FUNC(c)) {
			printf("%*sconst %d is function:\n",depth,"", cix);
			disasm_chunk_h(&AS_FUNC(c)->ch,depth+4);
		}
	}


}