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

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

void *M(void *p, size_t sz) {
	if (sz == 0) {
		free(p);
		return NULL;
	} else {
		return realloc(p, sz);
	}
}


Chunk chunk_new() {
	return (Chunk){
		.blen = 0, .bcap = 0, .b = NULL,
		.clen = 0, .ccap = 0, .c = NULL,
	};
}
size_t chunk_wbc(Chunk *ch, uint8_t byte) {
	if (ch->blen == ch->bcap) {
		size_t newsz = (ch->bcap == 0 ? 8 : ch->bcap * 2);
		ch->b = M(ch->b, newsz * sizeof(uint8_t));
		ch->bcap = newsz;
	}
	size_t ix = ch->blen;
	ch->b[ix] = byte;
	ch->blen ++;
	return ix;
}
size_t chunk_wconst(Chunk *ch, Val v) {
	if (ch->clen == ch->ccap) {
		size_t newsz = (ch->ccap == 0 ? 8 : ch->ccap *2);
		ch->c = M(ch->c, newsz * sizeof(Val));
		ch->ccap = newsz;
	}
	size_t ix = ch->clen;
	ch->c[ix] = v;
	ch->clen ++;
	return ix;
}

Vm vm_new(Chunk *ch) {
	Vm vm = (Vm){ 
		.ch = ch,
		.ip = 0,
		.sp = 0
	};
	for (int i = 0; i < STACKSIZE; i++) {
		vm.stack[i] = VAL_NIL;
	}
	return vm;
}


static void runvm() {
	Chunk ch = chunk_new();

	chunk_wbc(&ch, OP_LOADK);
	chunk_wbc(&ch, chunk_wconst(&ch, VAL_NUM(10.0)));
	chunk_wbc(&ch, OP_LOADK);
	chunk_wbc(&ch, chunk_wconst(&ch, VAL_NUM(3.0)));
	chunk_wbc(&ch, OP_DIV);
	chunk_wbc(&ch, OP_PRINT);

	chunk_wbc(&ch, OP_RET);


	disasm_chunk(&ch);

	Vm vm = vm_new(&ch);
#define RBYTE() (vm.ch->b[vm.ip++])

#define PUSH(v) vm.stack[vm.sp++] = v;
#define POP()   (vm.stack[--vm.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 = vm.ch->c[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", \
					valty_str(a.ty), valty_str(b.ty)); \
				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:;
}

int main() { runvm(); }