#include "../debug.h"
#include "codegen.h"

#include <stdio.h>

struct expr_codegen_state {
	struct code_generator_state s_base;
	struct ivy_ast_node *s_expr_root;
};

static struct code_generator_result check_expr_root(
	struct ivy_codegen *gen, struct code_generator_state *state,
	struct ivy_ast_node *node)
{
	struct expr_codegen_state *expr = (struct expr_codegen_state *)state;
	if (!expr->s_expr_root) {
		expr->s_expr_root = node;
	}

	return CODEGEN_RESULT_OK(0);
}

static struct code_generator_result gen_int(
	struct ivy_codegen *gen, struct code_generator_state *state,
	struct ivy_ast_node *node)
{
	struct expr_codegen_state *expr = (struct expr_codegen_state *)state;

	debug_printf("codegen: got int\n");

	struct ivy_ast_int_node *int_node = (struct ivy_ast_int_node *)node;
	struct mie_value *value
		= mie_ctx_get_int(gen->c_ctx, int_node->n_value->t_int, 32);

	codegen_push_value(gen, value);

	if (node == expr->s_expr_root) {
		codegen_pop_generator(gen);
	}

	return CODEGEN_RESULT_OK(0);
}

static struct code_generator_result gen_op(
	struct ivy_codegen *gen, struct code_generator_state *state,
	struct ivy_ast_node *node)
{
	struct expr_codegen_state *expr = (struct expr_codegen_state *)state;

	debug_printf("codegen: got operator\n");

	struct mie_value *left = codegen_pop_value(gen);
	struct mie_value *right = codegen_pop_value(gen);

	if (!left || !right) {
		return CODEGEN_RESULT_ERR(IVY_ERR_INVALID_VALUE);
	}

	struct ivy_ast_op_node *op_node = (struct ivy_ast_op_node *)node;
	const struct ivy_operator *op = op_node->n_op;
	struct mie_value *op_instr = NULL;

	switch (op->op_id) {
	case IVY_OP_ADD:
		op_instr
			= mie_builder_add(gen->c_builder, left, right, "addtmp");
		break;
	case IVY_OP_SUBTRACT:
		op_instr
			= mie_builder_sub(gen->c_builder, left, right, "subtmp");
		break;
	case IVY_OP_MULTIPLY:
		op_instr
			= mie_builder_mul(gen->c_builder, left, right, "multmp");
		break;
	case IVY_OP_DIVIDE:
		op_instr
			= mie_builder_div(gen->c_builder, left, right, "divtmp");
		break;
	default:
		mie_value_destroy(left);
		mie_value_destroy(right);
		return CODEGEN_RESULT_ERR(IVY_ERR_NOT_SUPPORTED);
	}

	if (!op_instr) {
		mie_value_destroy(left);
		mie_value_destroy(right);
		return CODEGEN_RESULT_ERR(IVY_ERR_NO_MEMORY);
	}

	codegen_push_value(gen, op_instr);

	if (node == expr->s_expr_root) {
		codegen_pop_generator(gen);
	}

	return CODEGEN_RESULT_OK(0);
}

static enum ivy_status state_init(
	struct ivy_codegen *gen, struct code_generator_state *state)
{
	debug_printf("codegen: start of expression\n");
	return IVY_OK;
}

static enum ivy_status state_fini(
	struct ivy_codegen *gen, struct code_generator_state *state)
{
	debug_printf("codegen: end of expression\n");
	return IVY_OK;
}

struct code_generator expr_generator = {
	.g_type = CODE_GENERATOR_UNIT,
	.g_state_size = sizeof(struct expr_codegen_state),
	.g_state_init = state_init,
	.g_state_fini = state_fini,
	.g_node_generators_pre = {
		[IVY_AST_INT] = check_expr_root,
		[IVY_AST_OP] = check_expr_root,
	},
	.g_node_generators_post = {
		[IVY_AST_INT] = gen_int,
		[IVY_AST_OP] = gen_op,
	},
};