#include "codegen.h"

#include <mie/block.h>
#include <mie/func.h>
#include <mie/module.h>

struct unit_codegen_state {
	struct code_generator_state s_base;
	/* function for top-level statements */
	struct mie_func *s_immediate;
};

static enum ivy_status switch_to_immediate_func(
	struct ivy_codegen *gen, struct unit_codegen_state *unit)
{
	if (!unit->s_immediate) {
		struct mie_type *ret_type
			= mie_ctx_get_type(gen->c_ctx, MIE_TYPE_VOID);
		unit->s_immediate = mie_func_create(
			"init", MIE_FUNC_STATIC, ret_type, NULL, 0);

		if (!unit->s_immediate) {
			return IVY_ERR_NO_MEMORY;
		}

		mie_module_add_function(gen->c_module, unit->s_immediate);
	}

	struct mie_block *block = mie_func_get_last_block(unit->s_immediate);
	if (!block || mie_block_is_terminated(block)) {
		block = mie_func_create_block(unit->s_immediate, NULL);
		mie_func_insert_block(unit->s_immediate, block, NULL);
	}

	mie_builder_set_insert_point(gen->c_builder, block);

	return IVY_OK;
}

static struct code_generator_result gen_expr(
	struct ivy_codegen *gen, struct code_generator_state *state,
	struct ivy_ast_node *node)
{
	struct unit_codegen_state *unit = (struct unit_codegen_state *)state;
	struct mie_builder *builder = gen->c_builder;
	struct mie_func *current = mie_builder_get_current_func(builder);

	enum ivy_status status = IVY_OK;
	if (!current || current != unit->s_immediate) {
		status = switch_to_immediate_func(gen, unit);
	}

	if (status != IVY_OK) {
		return CODEGEN_RESULT_ERR(status);
	}

	codegen_push_generator(gen, CODE_GENERATOR_EXPR, NULL);
	return CODEGEN_RESULT_OK(CODEGEN_REPEAT_NODE);
}

struct code_generator unit_generator = {
	.g_type = CODE_GENERATOR_UNIT,
	.g_state_size = sizeof(struct unit_codegen_state),
	.g_node_generators_pre = {
		[IVY_AST_INT] = gen_expr,
		[IVY_AST_OP] = gen_expr,
	},
};