#include "ctx.h"
#include "interface.h"
#include "lex.h"
#include "msg.h"

#include <stdio.h>

#define report_error(...) fprintf(stderr, __VA_ARGS__)

static bool peek_keyword(struct lex *lex, enum token_keyword kw)
{
	struct token *tok = lex_peek(lex);
	return (tok && tok->tok_type == TOK_KEYWORD && tok->tok_kw == kw);
}

static bool parse_keyword(struct lex *lex, enum token_keyword kw)
{
	struct token *tok = lex_peek(lex);
	if (!tok || tok->tok_type != TOK_KEYWORD || tok->tok_kw != kw) {
		return false;
	}

	lex_advance(lex);
	return true;
}

static bool parse_symbol(struct lex *lex, enum token_symbol sym)
{
	struct token *tok = lex_peek(lex);
	if (!tok || tok->tok_type != TOK_SYMBOL || tok->tok_sym != sym) {
		return false;
	}

	lex_advance(lex);
	return true;
}

static bool parse_word(struct lex *lex, char **out)
{
	struct token *tok = lex_peek(lex);
	if (!tok || tok->tok_type != TOK_WORD) {
		return false;
	}

	*out = tok->tok_str;
	tok->tok_str = NULL;
	lex_advance(lex);
	return true;
}

struct msg_definition *parse_msg_definition(struct ctx *ctx, struct lex *lex)
{
	struct msg_definition *msg = NULL;

	if (!parse_keyword(lex, KW_MSG)) {
		report_error("expected `msg` keyword\n");
		goto fail;
	}

	char *msg_name = NULL;
	if (!parse_word(lex, &msg_name)) {
		report_error("expected message identifier\n");
		goto fail;
	}

	msg = msg_definition_create(msg_name);
	free(msg_name);

	if (!parse_symbol(lex, SYM_LEFT_PAREN)) {
		report_error("expected `(` after message identifier\n");
		goto fail;
	}

	size_t i = 0;
	bool ok = true;
	while (ok) {
		if (parse_symbol(lex, SYM_RIGHT_PAREN)) {
			break;
		}

		if (i > 0 && !parse_symbol(lex, SYM_COMMA)) {
			report_error("expected `,` after message parameter\n");
			ok = false;
			break;
		}

		char *type_name;
		if (!parse_word(lex, &type_name)) {
			report_error("expected message parameter type\n");
			ok = false;
			break;
		}

		const struct type *type = ctx_get_type(ctx, type_name);
		if (!type) {
			report_error(
				"message parameter has unknown type "
				"'%s'\n",
				type_name);
			free(type_name);
			ok = false;
			break;
		}

		free(type_name);

		char *param_name;
		if (!parse_word(lex, &param_name)) {
			report_error("expected message parameter name\n");
			ok = false;
			break;
		}

		bool duplicate = msg_definition_has_param(msg, param_name)
		              || msg_definition_has_result(msg, param_name);
		if (duplicate) {
			free(param_name);
			report_error(
				"message has multiple parameters/results with "
				"name '%s'\n",
				param_name);
			ok = false;
			break;
		}

		msg_definition_add_param(msg, type, param_name);
		free(param_name);
		i++;
	}

	if (!ok) {
		goto fail;
	}

	if (!parse_symbol(lex, SYM_HYPHEN_RIGHT_ANGLE)) {
		report_error("expected `->` after message parameter list\n");
		goto fail;
	}

	if (!parse_symbol(lex, SYM_LEFT_PAREN)) {
		report_error("expected `(` for message results list\n");
		goto fail;
	}

	i = 0;
	while (ok) {
		if (parse_symbol(lex, SYM_RIGHT_PAREN)) {
			break;
		}

		if (i > 0 && !parse_symbol(lex, SYM_COMMA)) {
			report_error(
				"expected `,` or `)` after message result\n");
			ok = false;
			break;
		}

		char *type_name;
		if (!parse_word(lex, &type_name)) {
			report_error("expected message result type\n");
			ok = false;
			break;
		}

		const struct type *type = ctx_get_type(ctx, type_name);
		if (!type) {
			report_error(
				"message result has unknown type "
				"'%s'\n",
				type_name);
			free(type_name);
			ok = false;
			break;
		}
		free(type_name);

		char *result_name;
		if (!parse_word(lex, &result_name)) {
			report_error("expected message parameter name\n");
			ok = false;
			break;
		}

		bool duplicate = msg_definition_has_param(msg, result_name)
		              || msg_definition_has_result(msg, result_name);
		if (duplicate) {
			report_error(
				"message has multiple parameters/results with "
				"name '%s'\n",
				result_name);
			free(result_name);
			ok = false;
			break;
		}

		msg_definition_add_result(msg, type, result_name);
		free(result_name);
	}

	if (!parse_symbol(lex, SYM_SEMICOLON)) {
		report_error("expected `;` after message definition\n");
		goto fail;
	}

	return msg;

fail:
	if (msg) {
		msg_definition_destroy(msg);
	}

	return NULL;
}

struct interface_definition *parse_interface_definition(
	struct ctx *ctx,
	struct lex *lex)
{
	struct interface_definition *iface = NULL;

	if (!parse_keyword(lex, KW_INTERFACE)) {
		report_error("expected `interface` keyword");
		goto fail;
	}

	char *if_name = NULL;
	if (!parse_word(lex, &if_name)) {
		report_error("expected interface identifier");
		goto fail;
	}

	iface = interface_definition_create(if_name);
	free(if_name);
	if (!iface) {
		goto fail;
	}

	if (!parse_symbol(lex, SYM_LEFT_BRACE)) {
		report_error("expected `{` after interface identifier");
		goto fail;
	}

	bool ok = true;

	while (ok) {
		if (parse_symbol(lex, SYM_RIGHT_BRACE)) {
			break;
		}

		if (peek_keyword(lex, KW_MSG)) {
			struct msg_definition *msg
				= parse_msg_definition(ctx, lex);
			if (!msg) {
				ok = false;
				break;
			}

			if (interface_definition_has_msg(
				    iface,
				    msg->msg_name)) {
				msg_definition_destroy(msg);
				ok = false;
				break;
			}

			interface_definition_add_msg(iface, msg);
			continue;
		}

		report_error("expected `}` or message definition\n");
		ok = false;
		break;
	}

	if (!ok) {
		goto fail;
	}

	return iface;

fail:
	if (iface) {
		interface_definition_destroy(iface);
	}

	return NULL;
}