#include "ctx.h"

#include <ivy/lang/ast.h>

bool parse_match(struct ivy_parser *parser, struct ivy_ast_node **out)
{
	if (!parse_keyword(parser, IVY_KW_MATCH)) {
		parse_trace(parser, "expected `match` keyword");
		return false;
	}

	struct ivy_ast_match_node *match = create_node(IVY_AST_MATCH);

	if (!parse_expr(parser, EXPR_PARSE_STOP_LEFT_BRACKET, &match->n_cond)) {
		parse_trace(parser, "invalid match predicate");
		return false;
	}

	if (!parse_symbol(parser, IVY_SYM_LEFT_BRACKET)) {
		parse_trace(parser, "expected `[` after match predicate");
		return false;
	}

	bool ok = true;
	while (1) {
		if (parse_symbol(parser, IVY_SYM_RIGHT_BRACKET)) {
			break;
		}

		if (!fx_queue_empty(&match->n_branches)
		    && !parse_symbol(parser, IVY_SYM_COMMA)) {
			parse_trace(
				parser,
				"expected `,` or `]` after match branch value");
			ok = false;
			break;
		}

		struct ivy_ast_node *branch_pred = NULL;
		struct ivy_ast_node *branch_value = NULL;
		if (!parse_expr(parser, EXPR_PARSE_NORMAL, &branch_pred)) {
			parse_trace(parser, "invalid match branch predicate");
			ok = false;
			break;
		}

		if (!parse_symbol(parser, IVY_SYM_EQUAL_RIGHT_ANGLE)) {
			parse_trace(
				parser,
				"expected `=>` after match branch predicate");
			ok = false;
			break;
		}

		if (peek_symbol(parser, IVY_SYM_LEFT_BRACKET)) {
			ok = parse_block(parser, &branch_value);
		} else {
			ok = parse_expr(
				parser, EXPR_PARSE_STOP_COMMA, &branch_value);
		}

		if (!ok) {
			parse_trace(parser, "invalid match branch value");
			break;
		}

		struct ivy_ast_cond_node *cond = create_node(IVY_AST_COND);
		cond->n_cond = branch_pred;
		cond->n_body = branch_value;
		fx_queue_push_back(&match->n_branches, &cond->n_base.n_entry);
	}

	*out = generic_node(match);
	return true;
}