#include "../../backend.h"

#include "../../interface.h"
#include "../../msg.h"
#include "../../type.h"

#include <blue/core/hash.h>
#include <blue/io/file.h>
#include <blue/io/path.h>
#include <stdarg.h>
#include <stddef.h>

struct emit_ctx {
	b_stream *ctx_out;
};

static void emit(struct emit_ctx *ctx, const char *format, ...)
{
	va_list arg;
	va_start(arg, format);
	b_stream_write_vfmt(ctx->ctx_out, NULL, format, arg);
	va_end(arg);
}

static void emit_indent(struct emit_ctx *ctx)
{
	b_stream_push_indent(ctx->ctx_out, 4);
}

static void emit_indent_zero(struct emit_ctx *ctx)
{
	b_stream_push_indent(ctx->ctx_out, -100);
}

static void emit_unindent(struct emit_ctx *ctx)
{
	b_stream_pop_indent(ctx->ctx_out);
}

static int emit_include(struct emit_ctx *ctx, const char *path, bool system)
{
	if (system) {
		emit(ctx, "#include <%s>\n", path);
	} else {
		emit(ctx, "#include \"%s\"\n", path);
	}

	return 0;
}

static int emit_header_guard_start(
	struct emit_ctx *ctx,
	const struct interface_definition *iface)
{
	b_string *header_guard = b_string_create();
	b_string_append_cstrf(header_guard, "%s_H_", iface->if_name);
	b_string_toupper(header_guard);

	emit(ctx,
	     "#ifndef %s\n#define %s\n\n",
	     b_string_ptr(header_guard),
	     b_string_ptr(header_guard));
	b_string_unref(header_guard);
	return 0;
}

static int emit_header_guard_end(
	struct emit_ctx *ctx,
	const struct interface_definition *iface)
{
	emit(ctx, "\n#endif");
	return 0;
}

static int emit_header_lib_impl(struct emit_ctx *ctx)
{
	emit(ctx, "kern_status_t msg_recv_generic(\n");
	emit_indent(ctx);
	emit(ctx,
	     "kern_handle_t channel,\nmsgid_t *out_id,\nstruct msg_header "
	     "*out_hdr)\n");
	emit_unindent(ctx);
	emit(ctx, "{\n");
	emit_indent(ctx);

	/* clang-format off */
	emit(ctx,
		"struct iovec iov = IOVEC(out_hdr, sizeof *out_hdr);\n"
		"kern_status_t status = msg_recv(channel, out_id, &iov, 1);\n"
		"if (status != KERN_OK) return status;\n"
		"if (out_hdr->hdr_magic != MSG_MAGIC) return KERN_INVALID_ARGUMENT;\n"
		"return KERN_OK;\n");
	/* clang-format on */
	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	emit(ctx, "kern_status_t msg_read_generic(\n");
	emit_indent(ctx);
	emit(ctx,
	     "kern_handle_t channel,\nmsgid_t id,\nstruct msg_header "
	     "*out_hdr)\n");
	emit_unindent(ctx);
	emit(ctx, "{\n");
	emit_indent(ctx);

	/* clang-format off */
	emit(ctx,
		"struct iovec iov = IOVEC(out_hdr, sizeof *out_hdr);\n"
		"size_t r = 0;\n"
		"kern_status_t status = msg_read(channel, id, 0, &iov, 1, &r);\n"
		"if (status != KERN_OK) return status;\n"
		"if (r != sizeof *out_hdr) return KERN_INVALID_ARGUMENT;\n"
		"if (out_hdr->hdr_magic != MSG_MAGIC) return KERN_INVALID_ARGUMENT;\n"
		"return KERN_OK;\n");
	/* clang-format on */

	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	emit(ctx, "kern_status_t msg_reply_generic(\n");
	emit_indent(ctx);
	emit(ctx,
	     "kern_handle_t channel,\nmsgid_t id,\nconst struct msg_header "
	     "*msg, uint16_t status)\n");
	emit_unindent(ctx);
	emit(ctx, "{\n");
	emit_indent(ctx);

	/* clang-format off */
	emit(ctx,
		"struct msg_header resp_data = {\n");
	emit_indent(ctx);
	emit(ctx,
		".hdr_magic = MSG_MAGIC,\n.hdr_status = status,\n");
	emit_unindent(ctx);
	emit(ctx, "};\n");
	emit(ctx,
		"if (msg) {\n");
	emit_indent(ctx);
	emit(ctx,
		"resp_data.hdr_protocol = msg->hdr_protocol;\n"
		"resp_data.hdr_func = msg->hdr_func;\n");
	emit_unindent(ctx);
	emit(ctx, "}\n");

	emit(ctx,
		"struct iovec iov = IOVEC(&resp_data, sizeof resp_data);\n"
		"return msg_reply(channel, id, &iov, 1);\n");
	/* clang-format on */

	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	return 0;
}

static int emit_header_lib_definitions(struct emit_ctx *ctx)
{
	emit(ctx, "#if !defined(MSG_STRINGBUF_SIZE)\n");
	emit(ctx, "#define MSG_STRINGBUF_SIZE 256\n");
	emit(ctx, "#endif\n\n");

	emit(ctx, "#if !defined(MSG_LIB_DEFINED)\n");
	emit(ctx, "#define MSG_LIB_DEFINED\n\n");

	emit(ctx, "#define MSG_MAGIC 0x9AB07D10U\n\n");

	emit(ctx, "struct msg_header {\n");
	emit_indent(ctx);

	emit(ctx, "uint32_t hdr_magic;\n");
	emit(ctx, "uint32_t hdr_protocol;\n");
	emit(ctx, "uint16_t hdr_func;\n");
	emit(ctx, "uint16_t hdr_status;\n");

	emit_unindent(ctx);
	emit(ctx, "};\n\n");

	emit(ctx, "struct msg_string {\n");
	emit_indent(ctx);

	emit(ctx, "char *str_buf;\n");
	emit(ctx, "size_t str_len;\n");
	emit(ctx, "size_t str_max;\n");

	emit_unindent(ctx);
	emit(ctx, "};\n\n");

	emit(ctx, "extern kern_status_t msg_recv_generic(\n");
	emit_indent(ctx);
	emit(ctx,
	     "kern_handle_t channel,\nmsgid_t *out_id,\nstruct msg_header "
	     "*out_hdr);\n",
	     NULL);
	emit_unindent(ctx);

	emit(ctx, "extern kern_status_t msg_read_generic(\n");
	emit_indent(ctx);
	emit(ctx,
	     "kern_handle_t channel,\nmsgid_t id,\nstruct msg_header "
	     "*out_hdr);\n",
	     NULL);
	emit_unindent(ctx);

	emit(ctx, "extern kern_status_t msg_reply_generic(\n");
	emit_indent(ctx);
	emit(ctx,
	     "kern_handle_t channel,\nmsgid_t id,\nconst struct msg_header "
	     "*msg, uint16_t status);\n",
	     NULL);
	emit_unindent(ctx);

	emit(ctx, "#if defined(MSG_IMPLEMENTATION)\n\n");
	emit_header_lib_impl(ctx);
	emit(ctx, "#endif\n\n");

	emit(ctx, "#endif\n\n");
	return 0;
}

static int emit_interface_id_macros(
	struct emit_ctx *ctx,
	const struct interface_definition *iface)
{
	b_string *iface_define_name = b_string_create();
	b_string_append_cstr(iface_define_name, iface->if_name);
	b_string_toupper(iface_define_name);

	uint32_t protocol_id = b_hash_cstr(iface->if_name) & 0xFFFFFFFF;

	emit(ctx,
	     "/* %s protocol ID */\n#define PROTOCOL_%s 0x%08xU\n\n",
	     iface->if_name,
	     b_string_ptr(iface_define_name),
	     protocol_id);
	b_string_unref(iface_define_name);

	b_string *msg_name = b_string_create();
	b_queue_entry *entry = b_queue_first(&iface->if_msg);
	while (entry) {
		const struct msg_definition *msg
			= b_unbox(struct msg_definition, entry, msg_entry);
		b_string_clear(msg_name);
		b_string_append_cstrf(
			msg_name,
			"%s.%s",
			iface->if_name,
			msg->msg_name);

		emit(ctx, "/* %s message ID */\n", b_string_ptr(msg_name));
		uint16_t msg_id = b_hash_cstr(b_string_ptr(msg_name)) & 0xFFFF;

		b_string_clear(msg_name);
		b_string_append_cstrf(
			msg_name,
			"%s_%s",
			iface->if_name,
			msg->msg_name);
		b_string_toupper(msg_name);
		emit(ctx,
		     "#define MSG_%s 0x%04xU\n",
		     b_string_ptr(msg_name),
		     msg_id);

		entry = b_queue_next(entry);
	}

	emit(ctx, "\n");
	b_string_unref(msg_name);

	return 0;
}

static int emit_msg_struct_member(
	struct emit_ctx *ctx,
	const struct msg_parameter *param)
{
	switch (param->p_type->ty_id) {
	case TYPE_INT:
		emit(ctx, "uint32_t %s;\n", param->p_name);
		break;
	case TYPE_STRING:
		emit(ctx, "uint16_t %s_offset;\n", param->p_name);
		emit(ctx, "uint16_t %s_len;\n", param->p_name);
		break;
	default:
		break;
	}

	return 0;
}

static int emit_msg_struct_params(
	struct emit_ctx *ctx,
	const struct msg_definition *msg)
{
	b_queue_entry *entry = b_queue_first(&msg->msg_params);
	while (entry) {
		const struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit_msg_struct_member(ctx, param);
		entry = b_queue_next(entry);
	}

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		const struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		if (param->p_type->ty_id != TYPE_STRING) {
			entry = b_queue_next(entry);
			continue;
		}

		emit(ctx, "uint16_t %s_max;\n", param->p_name);

		entry = b_queue_next(entry);
	}

	return 0;
}

static int emit_msg_struct_results(
	struct emit_ctx *ctx,
	const struct msg_definition *msg)
{
	b_queue_entry *entry = b_queue_first(&msg->msg_results);
	while (entry) {
		const struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit_msg_struct_member(ctx, param);
		entry = b_queue_next(entry);
	}

	return 0;
}

static int emit_interface_msg_struct(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg)
{
	b_string *tmp = b_string_create();

	emit(ctx, "struct msg_%s_%s {\n", iface->if_name, msg->msg_name);
	emit_indent(ctx);

	emit(ctx, "struct msg_header msg_header;\n");
	emit(ctx, "union {\n");
	emit_indent(ctx);

	/* msg_request inner struct */
	emit(ctx, "struct {\n");
	emit_indent(ctx);

	emit_msg_struct_params(ctx, msg);

	emit_unindent(ctx);
	emit(ctx, "} msg_request;\n");

	/* msg_response inner struct */
	emit(ctx, "struct {\n");
	emit_indent(ctx);

	emit_msg_struct_results(ctx, msg);

	emit_unindent(ctx);
	emit(ctx, "} msg_response;\n");

	emit_unindent(ctx);
	emit(ctx, "};\n");

	emit_unindent(ctx);
	emit(ctx, "};\n");

	b_string_unref(tmp);
	return 0;
}

static int emit_interface_msg_structs(
	struct emit_ctx *ctx,
	const struct interface_definition *iface)
{
	b_queue_entry *entry = b_queue_first(&iface->if_msg);
	while (entry) {
		const struct msg_definition *msg
			= b_unbox(struct msg_definition, entry, msg_entry);

		emit_interface_msg_struct(ctx, iface, msg);

		entry = b_queue_next(entry);
	}

	emit(ctx, "\n");
	return 0;
}

static int emit_interface_msg_function_send_impl(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg)
{
	b_string *iface_ucase = b_string_create_from_cstr(iface->if_name);
	b_string_toupper(iface_ucase);
	b_string *msg_ucase = b_string_create_from_cstr(msg->msg_name);
	b_string_toupper(msg_ucase);

	emit(ctx,
	     "struct msg_%s_%s msg = {0};\n",
	     iface->if_name,
	     msg->msg_name);
	emit(ctx, "msg.msg_header.hdr_magic = MSG_MAGIC;\n");
	emit(ctx,
	     "msg.msg_header.hdr_protocol = PROTOCOL_%s;\n",
	     b_string_ptr(iface_ucase));
	emit(ctx,
	     "msg.msg_header.hdr_func = MSG_%s_%s;\n\n",
	     b_string_ptr(iface_ucase),
	     b_string_ptr(msg_ucase));

	b_string_unref(iface_ucase);
	b_string_unref(msg_ucase);

	emit(ctx, "uint16_t offset = sizeof msg;\n\n");

	b_queue_entry *entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx,
			     "msg.msg_request.%s = %s;\n\n",
			     param->p_name,
			     param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx,
			     "msg.msg_request.%s_offset = offset;\n",
			     param->p_name);
			emit(ctx,
			     "msg.msg_request.%s_len = strlen(%s);\n",
			     param->p_name,
			     param->p_name);
			emit(ctx,
			     "offset += msg.msg_request.%s_len;\n",
			     param->p_name);
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_STRING:
			emit(ctx,
			     "msg.msg_request.%s_max = out_%s->str_max;\n",
			     param->p_name,
			     param->p_name);
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	emit(ctx, "struct iovec req_iov[] = {\n");
	emit_indent(ctx);
	emit(ctx, "IOVEC(&msg, sizeof msg),\n");
	size_t nr_req_iov = 1;

	entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		if (param->p_type->ty_id != TYPE_STRING) {
			entry = b_queue_next(entry);
			continue;
		}

		emit(ctx,
		     "IOVEC(%s, msg.msg_request.%s_len),\n",
		     param->p_name,
		     param->p_name);

		nr_req_iov++;
		entry = b_queue_next(entry);
	}

	emit_unindent(ctx);
	emit(ctx, "};\n\n");

	emit(ctx, "struct iovec resp_iov[] = {\n");
	emit_indent(ctx);
	emit(ctx, "IOVEC(&msg, sizeof msg),\n");
	size_t nr_resp_iov = 1;

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		if (param->p_type->ty_id != TYPE_STRING) {
			entry = b_queue_next(entry);
			continue;
		}

		emit(ctx,
		     "IOVEC(out_%s->str_buf, out_%s->str_max),\n",
		     param->p_name,
		     param->p_name);

		nr_resp_iov++;
		entry = b_queue_next(entry);
	}

	emit_unindent(ctx);
	emit(ctx, "};\n\n");

	emit(ctx, "kern_status_t status = msg_send(port, req_iov, %zu, resp_iov, %zu);\n", nr_req_iov, nr_resp_iov);
	emit(ctx, "if (status != KERN_OK) return status;\n\n");

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_STRING:
			emit(ctx,
			     "out_%s->str_len = msg.msg_response.%s_len;\n",
			     param->p_name,
			     param->p_name);
			emit(ctx,
			     "out_%s->str_buf[out_%s->str_len < "
			     "out_%s->str_max ? out_%s->str_len : "
			     "(out_%s->str_max - 1)] = '\\0';\n",
			     param->p_name,
			     param->p_name,
			     param->p_name,
			     param->p_name,
			     param->p_name);
			break;
		default:
			emit(ctx,
			     "*out_%s = msg.msg_response.%s;\n",
			     param->p_name,
			     param->p_name);

			break;
		}

		entry = b_queue_next(entry);
	}

	emit(ctx, "return status;\n");
	return 0;
}

static int emit_interface_msg_function_recv_impl(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg)
{
	emit(ctx, "struct msg_%s_%s msg;\n", iface->if_name, msg->msg_name);
	emit(ctx, "struct iovec iov = IOVEC(&msg, sizeof msg);\n");
	emit(ctx, "size_t r = 0;\n\n");

	emit(ctx,
	     "kern_status_t status = msg_read(channel, id, 0, &iov, 1, "
	     "&r);\n");

	emit(ctx, "if (status != KERN_OK) return status;\n");
	emit(ctx, "if (r != sizeof msg) return KERN_INVALID_ARGUMENT;\n\n");

	b_queue_entry *entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx,
			     "*out_%s = msg.msg_request.%s;\n",
			     param->p_name,
			     param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx,
			     "out_%s->str_len = msg.msg_request.%s_len;\n",
			     param->p_name,
			     param->p_name);

			emit(ctx,
			     "if (out_%s->str_max > 1) {\n",
			     param->p_name);
			emit_indent(ctx);

			emit(ctx,
			     "iov.io_base = (virt_addr_t)out_%s->str_buf;\n",
			     param->p_name);
			emit(ctx,
			     "iov.io_len = out_%s->str_max - 1;\n",
			     param->p_name);
			emit(ctx,
			     "if (iov.io_len > out_%s->str_len) iov.io_len "
			     "= out_%s->str_len;\n",
			     param->p_name,
			     param->p_name);

			emit(ctx, "status = msg_read(\n");
			emit_indent(ctx);
			emit(ctx, "channel,\n");
			emit(ctx, "id,\n");
			emit(ctx,
			     "msg.msg_request.%s_offset,\n",
			     param->p_name);
			emit(ctx, "&iov,\n");
			emit(ctx, "1,\n");
			emit(ctx, "&r);\n");
			emit_unindent(ctx);

			emit(ctx, "if (status != KERN_OK) return status;\n\n");
			emit(ctx,
			     "if (r != iov.io_len) return "
			     "KERN_INVALID_ARGUMENT;\n\n");
			emit(ctx,
			     "out_%s->str_buf[iov.io_len] = '\\0';\n",
			     param->p_name);

			emit_unindent(ctx);
			emit(ctx, "} else if (out_%s->str_max > 0) {\n");
			emit_indent(ctx);
			emit(ctx,
			     "out_%s->str_buf[0] = '\\0';\n",
			     param->p_name);
			emit_unindent(ctx);
			emit(ctx, "}\n\n");
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	emit(ctx, "return status;\n");
	return 0;
}

static int emit_interface_msg_function_reply_impl(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg)
{
	b_string *iface_ucase = b_string_create_from_cstr(iface->if_name);
	b_string_toupper(iface_ucase);
	b_string *msg_ucase = b_string_create_from_cstr(msg->msg_name);
	b_string_toupper(msg_ucase);

	emit(ctx,
	     "struct msg_%s_%s msg = {0};\n",
	     iface->if_name,
	     msg->msg_name);
	emit(ctx, "msg.msg_header.hdr_magic = MSG_MAGIC;\n");
	emit(ctx,
	     "msg.msg_header.hdr_protocol = PROTOCOL_%s;\n",
	     b_string_ptr(iface_ucase));
	emit(ctx,
	     "msg.msg_header.hdr_func = MSG_%s_%s;\n\n",
	     b_string_ptr(iface_ucase),
	     b_string_ptr(msg_ucase));

	b_string_unref(iface_ucase);
	b_string_unref(msg_ucase);

	b_queue_entry *entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx,
			     "msg.msg_response.%s = %s;\n\n",
			     param->p_name,
			     param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx,
			     "msg.msg_response.%s_len = strlen(%s);\n",
			     param->p_name,
			     param->p_name);
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	emit(ctx, "\nstruct iovec iov[] = {\n");
	emit_indent(ctx);
	emit(ctx, "IOVEC(&msg, sizeof msg),\n");
	size_t nr_iov = 1;

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_STRING:
			emit(ctx,
			     "IOVEC(%s, msg.msg_response.%s_len),\n",
			     param->p_name,
			     param->p_name);
			nr_iov++;
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	emit_unindent(ctx);
	emit(ctx, "};\n\n");

	emit(ctx, "return msg_reply(channel, id, iov, %zu);\n", nr_iov);

	return 0;
}

static int emit_interface_msg_function_send(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg,
	bool prototype_only)
{
	if (prototype_only) {
		emit(ctx, "extern ");
	}

	emit(ctx, "kern_status_t %s_%s(\n", iface->if_name, msg->msg_name);

	emit_indent(ctx);

	emit(ctx, "kern_handle_t port");

	b_queue_entry *entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit(ctx, ",\n");
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int %s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, "const char *%s", param->p_name);
			break;
		default:
			break;
		}
		entry = b_queue_next(entry);
	}

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit(ctx, ",\n");
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int *out_%s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, "struct msg_string *out_%s", param->p_name);
			break;
		default:
			break;
		}
		entry = b_queue_next(entry);
	}

	emit(ctx, ")");
	emit_unindent(ctx);

	if (prototype_only) {
		emit(ctx, ";\n");
		return 0;
	}

	emit(ctx, "\n{\n");
	emit_indent(ctx);

	emit_interface_msg_function_send_impl(ctx, iface, msg);

	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	return 0;
}

static int emit_interface_msg_function_recv(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg,
	bool prototype_only)
{
	if (prototype_only) {
		emit(ctx, "extern ");
	}

	emit(ctx, "kern_status_t %s_%s_recv(\n", iface->if_name, msg->msg_name);

	emit_indent(ctx);

	emit(ctx, "kern_handle_t channel,\nmsgid_t id");

	b_queue_entry *entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit(ctx, ",\n");
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int *out_%s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, "struct msg_string *out_%s", param->p_name);
			break;
		default:
			break;
		}
		entry = b_queue_next(entry);
	}

	emit(ctx, ")");
	emit_unindent(ctx);

	if (prototype_only) {
		emit(ctx, ";\n");
		return 0;
	}

	emit(ctx, "\n{\n");
	emit_indent(ctx);

	emit_interface_msg_function_recv_impl(ctx, iface, msg);

	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	return 0;
}

static int emit_interface_msg_function_reply(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg,
	bool prototype_only)
{
	if (prototype_only) {
		emit(ctx, "extern ");
	}

	emit(ctx,
	     "kern_status_t %s_%s_reply(\n",
	     iface->if_name,
	     msg->msg_name);

	emit_indent(ctx);

	emit(ctx, "kern_handle_t channel,\nmsgid_t id");

	b_queue_entry *entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit(ctx, ",\n");
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int %s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, "const char *%s", param->p_name);
			break;
		default:
			break;
		}
		entry = b_queue_next(entry);
	}

	emit(ctx, ")");
	emit_unindent(ctx);

	if (prototype_only) {
		emit(ctx, ";\n");
		return 0;
	}

	emit(ctx, "\n{\n");
	emit_indent(ctx);

	emit_interface_msg_function_reply_impl(ctx, iface, msg);

	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	return 0;
}

static int emit_interface_msg_functions(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg,
	bool prototype_only)
{
	emit_interface_msg_function_send(ctx, iface, msg, prototype_only);
	emit_interface_msg_function_recv(ctx, iface, msg, prototype_only);
	emit_interface_msg_function_reply(ctx, iface, msg, prototype_only);
	return 0;
}

static int emit_string_destructor_list(
	struct emit_ctx *ctx,
	b_queue_entry *param_entry)
{
	while (param_entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, param_entry, p_entry);

		if (param->p_type->ty_id == TYPE_STRING) {
			emit(ctx, "free(%s.str_buf);\n", param->p_name);
		}

		param_entry = b_queue_prev(param_entry);
	}

	return 0;
}

static int emit_interface_dispatcher_impl_msg(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg)
{
	emit(ctx,
	     "if (!vtable->%s) return msg_reply_generic(channel, id, msg, "
	     "KERN_UNIMPLEMENTED);\n",
	     msg->msg_name);
	b_queue_entry *entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int %s;\n", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx,
			     "struct msg_string %s = {0};\n",
			     param->p_name);
			emit_indent_zero(ctx);
			emit(ctx, "#if defined(MSG_NO_MALLOC)\n");
			emit_unindent(ctx);
			emit(ctx,
			     "char %s_buf[MSG_STRINGBUF_SIZE];\n",
			     param->p_name);
			emit(ctx,
			     "%s.str_buf = %s_buf;\n",
			     param->p_name,
			     param->p_name);
			emit(ctx,
			     "%s.str_max = MSG_STRINGBUF_SIZE;\n",
			     param->p_name);

			emit_indent_zero(ctx);
			emit(ctx, "#endif\n");
			emit_unindent(ctx);
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int %s;\n", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx,
			     "struct msg_string %s = {0};\n",
			     param->p_name);
			emit_indent_zero(ctx);
			emit(ctx, "#if defined(MSG_NO_MALLOC)\n");
			emit_unindent(ctx);
			emit(ctx,
			     "char %s_buf[MSG_STRINGBUF_SIZE];\n",
			     param->p_name);
			emit(ctx,
			     "%s.str_buf = %s_buf;\n",
			     param->p_name,
			     param->p_name);
			emit(ctx,
			     "%s.str_max = MSG_STRINGBUF_SIZE;\n",
			     param->p_name);

			emit_indent_zero(ctx);
			emit(ctx, "#endif\n");
			emit_unindent(ctx);
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	emit(ctx, "status = %s_%s_recv(\n", iface->if_name, msg->msg_name);
	emit_indent(ctx);
	emit(ctx, "channel,\nid");
	entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit(ctx, ",\n&%s", param->p_name);

		entry = b_queue_next(entry);
	}

	emit(ctx, ");\n");
	emit_unindent(ctx);

	emit(ctx, "if (status != KERN_OK) {\n");
	emit_indent(ctx);
	emit(ctx, "msg_reply_generic(channel, id, msg, status);\n");
	emit(ctx, "return status;\n");
	emit_unindent(ctx);
	emit(ctx, "}\n");

	emit_indent_zero(ctx);
	emit(ctx, "#if !defined(MSG_NO_MALLOC)\n");
	emit_unindent(ctx);

	entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		switch (param->p_type->ty_id) {
		case TYPE_STRING:
			emit(ctx,
			     "%s.str_max = %s.str_len + 1;\n",
			     param->p_name,
			     param->p_name);
			emit(ctx,
			     "%s.str_buf = malloc(%s.str_max);\n",
			     param->p_name,
			     param->p_name);

			emit(ctx, "if (!%s.str_buf) {\n", param->p_name);
			emit_indent(ctx);
			emit_string_destructor_list(ctx, b_queue_prev(entry));
			emit(ctx, "return KERN_NO_MEMORY;\n");
			emit_unindent(ctx);
			emit(ctx, "}\n", param->p_name);
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	emit(ctx, "status = %s_%s_recv(\n", iface->if_name, msg->msg_name);
	emit_indent(ctx);
	emit(ctx, "channel,\nid");
	entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		emit(ctx, ",\n&%s", param->p_name);

		entry = b_queue_next(entry);
	}
	emit(ctx, ");\n");
	emit_unindent(ctx);

	emit(ctx, "if (status != KERN_OK) {\n");
	emit_indent(ctx);
	emit_string_destructor_list(ctx, b_queue_last(&msg->msg_params));
	emit(ctx, "msg_reply_generic(channel, id, msg, status);\n");
	emit(ctx, "return status;\n");
	emit_unindent(ctx);
	emit(ctx, "}\n");

	emit_indent_zero(ctx);
	emit(ctx, "#endif\n");
	emit_unindent(ctx);

	emit(ctx, "status = vtable->%s(\n", msg->msg_name);
	emit_indent(ctx);

	size_t i = 0;
	entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		if (i > 0) {
			emit(ctx, ",\n");
		}

		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "%s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, "%s.str_buf", param->p_name);
			break;
		default:
			break;
		}

		i++;
		entry = b_queue_next(entry);
	}

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		if (i > 0) {
			emit(ctx, ",\n");
		}

		emit(ctx, "&%s", param->p_name);

		i++;
		entry = b_queue_next(entry);
	}

	emit(ctx, ");\n");
	emit_unindent(ctx);

	emit_indent_zero(ctx);
	emit(ctx, "#if !defined(MSG_NO_MALLOC)\n");
	emit_unindent(ctx);
	emit_string_destructor_list(ctx, b_queue_last(&msg->msg_params));
	emit_indent_zero(ctx);
	emit(ctx, "#endif\n");
	emit_unindent(ctx);

	emit(ctx, "if (status != KERN_OK) {\n");
	emit_indent(ctx);
	emit(ctx, "msg_reply_generic(channel, id, msg, status);\n");
	emit(ctx, "return status;\n");
	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	emit(ctx, "status = %s_%s_reply(\n", iface->if_name, msg->msg_name);
	emit_indent(ctx);
	emit(ctx, "channel,\nid");
	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);

		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, ",\n%s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, ",\n%s.str_buf", param->p_name);
			break;
		default:
			break;
		}

		entry = b_queue_next(entry);
	}

	emit(ctx, ");\n");
	emit_unindent(ctx);

	emit(ctx, "if (status != KERN_OK) return status;\n");

	return 0;
}

static int emit_interface_dispatcher_impl(
	struct emit_ctx *ctx,
	const struct interface_definition *iface)
{
	b_string *iface_ucase = b_string_create_from_cstr(iface->if_name);
	b_string_toupper(iface_ucase);
	b_string *msg_ucase = b_string_create();

	emit(ctx,
	     "if (msg->hdr_protocol != PROTOCOL_%s) return "
	     "KERN_INVALID_ARGUMENT;\n\n",
	     b_string_ptr(iface_ucase));

	emit(ctx, "kern_status_t status = KERN_OK;\n");
	emit(ctx, "switch (msg->hdr_func) {\n");

	b_queue_entry *entry = b_queue_first(&iface->if_msg);
	while (entry) {
		const struct msg_definition *msg
			= b_unbox(struct msg_definition, entry, msg_entry);

		b_string_clear(msg_ucase);
		b_string_append_cstr(msg_ucase, msg->msg_name);
		b_string_toupper(msg_ucase);

		emit(ctx,
		     "case MSG_%s_%s: {\n",
		     b_string_ptr(iface_ucase),
		     b_string_ptr(msg_ucase));
		emit_indent(ctx);
		emit_interface_dispatcher_impl_msg(ctx, iface, msg);
		emit(ctx, "break;\n");
		emit_unindent(ctx);
		emit(ctx, "}\n");

		entry = b_queue_next(entry);
	}

	b_string_unref(iface_ucase);

	emit(ctx, "default:\n");
	emit_indent(ctx);
	emit(ctx, "status = KERN_INVALID_ARGUMENT;\nbreak;\n");
	emit_unindent(ctx);
	emit(ctx, "}\n\nreturn status;\n");

	return 0;
}

static int emit_interface_dispatcher(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	bool prototype_only)
{
	if (prototype_only) {
		emit(ctx, "extern ");
	}

	emit(ctx, "kern_status_t %s_dispatch(\n", iface->if_name);
	emit_indent(ctx);
	emit(ctx, "kern_handle_t channel,\n");
	emit(ctx, "const struct %s_vtable *vtable,\n", iface->if_name);
	emit(ctx, "msgid_t id,\n");
	emit(ctx, "const struct msg_header *msg)", iface->if_name);
	emit_unindent(ctx);

	if (prototype_only) {
		emit(ctx, ";\n");
		return 0;
	}

	emit(ctx, "\n{\n");
	emit_indent(ctx);

	emit_interface_dispatcher_impl(ctx, iface);

	emit_unindent(ctx);
	emit(ctx, "}\n\n");

	return 0;
}

static int emit_interface_functions(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	bool prototype_only)
{
	b_queue_entry *entry = b_queue_first(&iface->if_msg);
	while (entry) {
		const struct msg_definition *msg
			= b_unbox(struct msg_definition, entry, msg_entry);

		emit_interface_msg_functions(ctx, iface, msg, prototype_only);

		entry = b_queue_next(entry);
	}

	emit_interface_dispatcher(ctx, iface, prototype_only);

	return 0;
}

static int emit_interface_vtable_entry(
	struct emit_ctx *ctx,
	const struct interface_definition *iface,
	const struct msg_definition *msg)
{
	emit(ctx, "kern_status_t(*%s)(\n", msg->msg_name);
	emit_indent(ctx);

	size_t i = 0;
	b_queue_entry *entry = b_queue_first(&msg->msg_params);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		if (i > 0) {
			emit(ctx, ",\n");
		}

		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int %s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, "const char *%s", param->p_name);
			break;
		default:
			break;
		}

		i++;
		entry = b_queue_next(entry);
	}

	entry = b_queue_first(&msg->msg_results);
	while (entry) {
		struct msg_parameter *param
			= b_unbox(struct msg_parameter, entry, p_entry);
		if (i > 0) {
			emit(ctx, ",\n");
		}

		switch (param->p_type->ty_id) {
		case TYPE_INT:
			emit(ctx, "int *out_%s", param->p_name);
			break;
		case TYPE_STRING:
			emit(ctx, "struct msg_string *out_%s", param->p_name);
			break;
		default:
			break;
		}

		i++;
		entry = b_queue_next(entry);
	}

	emit(ctx, ");\n", msg->msg_name);
	emit_unindent(ctx);

	return 0;
}

static int emit_interface_vtable(
	struct emit_ctx *ctx,
	const struct interface_definition *iface)
{
	emit(ctx, "struct %s_vtable {\n", iface->if_name);
	emit_indent(ctx);

	b_queue_entry *entry = b_queue_first(&iface->if_msg);
	while (entry) {
		const struct msg_definition *msg
			= b_unbox(struct msg_definition, entry, msg_entry);

		emit_interface_vtable_entry(ctx, iface, msg);

		entry = b_queue_next(entry);
	}

	emit_unindent(ctx);
	emit(ctx, "};\n\n");
	return 0;
}

static int emit_header(
	struct emit_ctx *ctx,
	const struct interface_definition *iface)
{
	emit_header_guard_start(ctx, iface);
	emit_include(ctx, "stdint.h", true);
	emit_include(ctx, "stddef.h", true);
	emit_include(ctx, "string.h", true);
	emit(ctx, "#if !defined(MSG_NO_MALLOC)\n");
	emit_include(ctx, "stdlib.h", true);
	emit(ctx, "#endif\n");
	emit_include(ctx, "mango/msg.h", true);
	emit(ctx, "\n");

	emit_header_lib_definitions(ctx);
	emit_interface_id_macros(ctx, iface);
	emit_interface_vtable(ctx, iface);
	emit_interface_msg_structs(ctx, iface);
	emit_interface_functions(ctx, iface, true);

	emit(ctx, "\n#if defined(MSG_IMPLEMENTATION)\n");

	emit_interface_functions(ctx, iface, false);

	emit(ctx, "#endif\n");

	emit_header_guard_end(ctx, iface);
	return 0;
}

static int emit_interface(const struct interface_definition *iface)
{
	char path[4096];
	b_file *file = NULL;

	snprintf(path, sizeof path, "%s.h", iface->if_name);
	b_result result = b_file_open(
		NULL,
		B_RV_PATH(path),
		B_FILE_WRITE_ONLY | B_FILE_CREATE,
		&file);
	if (b_result_is_error(result)) {
		b_throw(result);
		fprintf(stderr, "cannot create C header file %s\n", path);
		return -1;
	}

	struct emit_ctx ctx = {
		.ctx_out = file,
	};

	int err = emit_header(&ctx, iface);
	b_file_unref(file);

	return err;
}

static struct backend backend = {
	.b_name = "c-mpc",
	.b_emit = emit_interface,
};

const struct backend *c_mpc_backend(void)
{
	return &backend;
}