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

#include "val.h"
#include "vm.h"
#include "mem.h"
#include "dis.h"


Chunk chunk_new(State *S) {
	return (Chunk){ 0 };
}

size_t chunk_wbc(State *S, Chunk *ch, uint8_t byte) {
	if (ch->bc.len == ch->bc.cap) {
		size_t newsz = (ch->bc.cap == 0 ? 8 : ch->bc.cap * 2);
		ch->bc.d = RENEW_ARR(S, ch->bc.d, uint8_t, ch->bc.cap, newsz);
		ch->bc.cap = newsz;
	}
	size_t ix = ch->bc.len;
	ch->bc.d[ix] = byte;
	ch->bc.len ++;
	return ix;
}
size_t chunk_wconst(State *S, Chunk *ch, Val v) {
	if (ch->consts.len == ch->consts.cap) {
		size_t newsz = (ch->consts.cap == 0 ? 8 : ch->consts.cap *2);
		ch->consts.d = RENEW_ARR(S, ch->consts.d, Val, ch->consts.cap, newsz);
		ch->consts.cap = newsz;
	}
	size_t ix = ch->consts.len;
	ch->consts.d[ix] = v;
	ch->consts.len ++;
	return ix;
}

Thread thread_new(State *S) {
	Thread th = (Thread){ 0 };
	for (int i = 0; i < STACKSIZE; i++) {
		th.stack[i] = VAL_NIL;
	}
	return th;
}


void runvm(State *S) {
	Thread *th = S->th;
	Chunk *ch = th->ch;

	disasm_chunk(ch);

#define RBYTE() (ch->bc.d[th->ip++])

#define PUSH(v) th->stack[th->sp++] = v;
#define POP()   (th->stack[--th->sp])

	puts("---");
	while (1) {
		uint8_t instr = RBYTE();
		switch (instr) {
		case OP_RET:
			printf("done!\n");
			goto done;
			break;
		case OP_LOADK:;
			uint8_t cix = RBYTE();
			Val v = ch->consts.d[cix];
			PUSH(v);
			// printf("   (pushing ");
			// print_val(v);
			// printf(")\n");
			break;
		case OP_PRINT:
			println_val(POP());
			break;

#define ARITH_OP(opcode, OP) \
		case opcode: { \
			Val b = POP(); \
			Val a = POP(); \
			if (!IS_NUM(a) || !IS_NUM(b)) { \
				printf("can't do arithmetic on %s and %s\n", \
					typename_str(a), typename_str(b)); \
				goto done; \
			} \
			PUSH(VAL_NUM(AS_NUM(a) OP AS_NUM(b))); \
			} \
			break;

			ARITH_OP(OP_ADD, +)
			ARITH_OP(OP_SUB, -)
			ARITH_OP(OP_MUL, *)
			ARITH_OP(OP_DIV, /)
#undef ARITH_OP


		}
	}
	done:;
}