#include "codegen.h"

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include "ast.h"

static void gencondjmp(FILE *f, cond_t *c, bool neg)
{
	uint8_t cmp = neg ? c->cmp^0x80 : c->cmp;
	fprintf(f, "cmp %s %s\n", c->a, c->b);
	switch (cmp) {
		case CEQ:
			fprintf(f, "je ");
			break;
		case CNEQ:
			fprintf(f, "jne ");
			break;
		case CGT:
			fprintf(f, "jg ");
			break;
		case CLT:
			fprintf(f, "jl ");
			break;
		case CLEQ:
			fprintf(f, "jle ");
			break;
		case CGEQ:
			fprintf(f, "jge ");
			break;
		default:
			fprintf(stderr, "Invalid cmp type %x", cmp);
			fprintf(f, "jmp ");
	}
}

static void genif(FILE *f, struct genctx *ctx, ast_node_t *n)
{
	bool doElse = n->flowctrl.iffalse;
	// Create conditional jump
	gencondjmp(f, n->flowctrl.condition, true);
	if ( doElse ) {
		fprintf(f, "else_%d\n", ctx->nested);
	} else {
		fprintf(f, "end_%d\n", ctx->nested);
	}

	struct genctx octx = { ctx->nested+1 };
	// Paste code
	gentree(f, &octx, n->flowctrl.iftrue);
	
	// Do else
	if ( doElse ) {
		fprintf(f, "jmp end_%d\n", ctx->nested);
		fprintf(f, "else_%d:\n", ctx->nested);
		gentree(f, &octx, n->flowctrl.iffalse);
	}

	// End block
	fprintf(f, "end_%d:\n", ctx->nested);
}

static void genwhile(FILE *f, struct genctx *ctx, ast_node_t *n)
{
	// Create loop label
	fprintf(f, "loop_%d:\n", ctx->nested);

	// Create conditional jump
	gencondjmp(f, n->flowctrl.condition, true);
	fprintf(f, "end_%d\n", ctx->nested);

	struct genctx octx = { ctx->nested+1 };
	// Paste code
	gentree(f, &octx, n->flowctrl.iftrue);

	// Jump to start
	fprintf(f, "jmp loop_%d\n", ctx->nested);
	
	// End block
	fprintf(f, "end_%d:\n", ctx->nested);
}

static void genfor(FILE *f, struct genctx *ctx, ast_node_t *n)
{
	// Do pre stuff
	fprintf(f, "%s\n", n->forloop.pre);

	// Create loop label
	fprintf(f, "loop_%d:\n", ctx->nested);

	// Create conditional jump
	gencondjmp(f, n->flowctrl.condition, true);
	fprintf(f, "end_%d\n", ctx->nested);

	struct genctx octx = { ctx->nested+1 };
	// Paste code
	gentree(f, &octx, n->forloop.stuff);

	// Do inc stuff
	fprintf(f, "%s\n", n->forloop.inc);
	// Jump to start
	fprintf(f, "jmp loop_%d\n", ctx->nested);
	
	// End block
	fprintf(f, "end_%d:\n", ctx->nested);
}

void gentree(FILE *f, struct genctx *ctx, ast_node_t *n)
{
	if ( !n ) {
		return;
	}
	if ( ctx == NULL ) {
		ctx = malloc(sizeof(struct genctx));
		ctx->nested = 0;
	}
	switch (n->t) {
		case TSTM_LIST: 
			gentree(f, ctx, n->list.children[0]);
			gentree(f, ctx, n->list.children[1]);
			break;
		case TIF:
			genif(f, ctx, n);
			break;
		case TIDENT:
			fprintf(f, "%s\n", n->ident);
			break;
		case TFOR:
			genfor(f, ctx, n);
			break;
		case TWHILE:
			genwhile(f, ctx, n);
			break;
		default:
			return;
	}
}