#include "common/string.h"
#include "common/panic.h"
#include "common/result.h"
#include <stddef.h>
#include <stdlib.h>

HeapString stringbuilder_build(StringBuilder* builder)
{
	ASSERT(builder->length != 0, "builder cannot be empty");
	if (*stringbuilder_get(builder, builder->length - 1) != '\0')
		stringbuilder_append(builder, '\0');
	return heapstring_from(builder->data, builder->length);
}

RESULT_CTORS(
	HeapString, HeapString, UnescapeStringResult, unescaped_string_result
)

UnescapeStringResult common_unescape_string(StringView source)
{
	StringBuilder builder;
	stringbuilder_construct(&builder);
	size_t i = 0;
	while (i < source.length) {
		if (source.data[i] == '\\') {
			i++;
			if (i >= source.length) {
				stringbuilder_destroy(&builder);
				return unescaped_string_result_ok(
					heapstring_from_cstring("malformed escape sequence")
				);
			}
			switch (source.data[i]) {
				case '0':
					stringbuilder_append(&builder, '\0');
					break;
				case 't':
					stringbuilder_append(&builder, '\t');
					break;
				case 'r':
					stringbuilder_append(&builder, '\r');
					break;
				case 'n':
					stringbuilder_append(&builder, '\n');
					break;
				default:
					stringbuilder_append(&builder, source.data[i]);
					break;
			}
		} else {
			stringbuilder_append(&builder, source.data[i]);
		}
		i++;
	}
	HeapString string = stringbuilder_build(&builder);
	stringbuilder_destroy(&builder);
	return unescaped_string_result_ok(string);
}

HeapString common_escape_string(StringView source)
{
	StringBuilder builder;
	stringbuilder_construct(&builder);
	for (size_t i = 0; i < source.length; ++i) {
		switch (source.data[i]) {
			case '\0':
				stringbuilder_append(&builder, '\\');
				stringbuilder_append(&builder, '0');
				break;
			case '\t':
				stringbuilder_append(&builder, '\\');
				stringbuilder_append(&builder, 't');
				break;
			case '\r':
				stringbuilder_append(&builder, '\\');
				stringbuilder_append(&builder, 'r');
				break;
			case '\n':
				stringbuilder_append(&builder, '\\');
				stringbuilder_append(&builder, 'n');
				break;
			case '\\':
				stringbuilder_append(&builder, '\\');
				stringbuilder_append(&builder, '\\');
				break;
			case '\"':
				stringbuilder_append(&builder, '\\');
				stringbuilder_append(&builder, '\"');
				break;
			case '\'':
				stringbuilder_append(&builder, '\\');
				stringbuilder_append(&builder, '\'');
				break;
			default:
				stringbuilder_append(&builder, source.data[i]);
				break;
		}
	}
	HeapString string = stringbuilder_build(&builder);
	stringbuilder_destroy(&builder);
	return string;
}