u64 un_string_get_length(u8 *cstring) {
    u8* start = cstring;

    while (*start != '\0') {
        start++;
    }

    return start - cstring;
}

String un_string_from_cstring(u8* cstring) {
    String result;
    u64 length = un_string_get_length(cstring);
    assert(length < LLONG_MAX);
    result.size = length;
    result.data = cstring;
    return result;
}

u8* un_string_to_cstring(String string, Allocator alloc) {
    u8 *mem;

    assert(string.size > 0);

    mem = (u8*)un_memory_alloc(string.size + 1, alloc);
    un_memory_copy(mem, string.data, (u64)string.size);

    return mem;
}

String un_string_copy(String source, Allocator alloc) {
    u8 *mem;
    String result;

    mem = (u8*)un_memory_alloc(source.size, alloc);
    un_memory_copy(mem, source.data, (u64)source.size);

    result.size = source.size;
    result.data = mem;

    return result;
}

s32 un_string_compare(String left, String right) {
    s32 result;

    if (left.size == right.size && left.size == 0) return 0;
    if (left.size == 0) return -1;
    if (right.size == 0) return 1;

    result = un_memory_compare(left.data, right.data, left.size);

    if (result == 0) {
        if (left.size > right.size) return 1;
        if (left.size < right.size) return -1;
        return 0;
    } else {
        return result;
    }
}

String un_string_concat(String left, String right, Allocator alloc) {
    String result = { 0 };

    if (left.size == right.size && left.size == 0) {
        return result;
    }

    u8* data = (u8*)un_memory_alloc(left.size + right.size, alloc);

    if (left.size > 0) {
        assert(left.data != NULL);
        un_memory_copy(data, left.data, left.size);
    }

    if (right.size > 0) {
        assert(right.data != NULL);
        un_memory_copy((data + left.size), right.data, right.size);
    }

    result.size = left.size + right.size;
    result.data = data;

    return result;
}

String un_string_swap(String input, u8 from, u8 to, Allocator alloc) {
    u64 i;
    String output;

    output = un_string_copy(input, alloc);

    for (i = 0; i < input.size; i++) {
        if (output.data[i] != from)
            continue;

        output.data[i] = to;
    }

    return output;
}

List un_string_split(String input, String pattern, Allocator alloc) {
    List splits;
    String string;
    u64 i, start;
    u64 matches, size;
    u8 *buffer;

    UN_CLEAR(splits);

    if (input.size <= pattern.size) {
        return splits;
    }

    if (pattern.size == 0) {
        return splits;
    }

    for (i = 0, matches = 1; i < (input.size - (pattern.size - 1)); i++) {
        if (un_memory_compare(input.data + i, pattern.data, pattern.size) != 0) {
            continue;
        }

        matches++;
    }

    splits = un_list_create(matches, sizeof(String), alloc);

    start = 0;

    for (i = 0; i < (input.size - (pattern.size - 1)); i++) {
        if (un_memory_compare(input.data + i, pattern.data, pattern.size) != 0) {
            continue;
        }

        size = i - start; 

        if (size == 0) {
            start = i + pattern.size;
            continue;
        }

        buffer = (u8*)un_memory_alloc(size, alloc);
        un_memory_copy(buffer, input.data + start, size);
        string = CLITERAL(String) { .size = size, .data = buffer };
        un_list_append(&splits, &string);
        start = i + pattern.size;
    }

    if (start != input.size - pattern.size) {
        if (un_memory_compare(input.data + start, pattern.data, pattern.size) == 0) {
            return splits;
        }

        size = input.size - start; 
        if (size == 0) {
            return splits;
        }

        buffer = (u8*)un_memory_alloc(size, alloc);
        un_memory_copy(buffer, input.data + start, size);
        string = CLITERAL(String) { .size = size, .data = buffer };
        un_list_append(&splits, &string);
    }

    return splits;
}

String un_string_join(List string_list, String separator, Allocator alloc) {
    String cont, temp;
    u64 i;
    Allocator talloc;

    UN_CLEAR(cont);

    talloc = un_allocator_get_temporary();

    assert(string_list.element_size == sizeof(String));


    for (i = 0; i < string_list.count; i++) {
        temp = *(String *)un_list_get(&string_list, i);

        cont = un_string_concat(cont, temp, talloc);

        if (i != (string_list.count - 1)) {
            cont = un_string_concat(cont, separator, talloc);
        }
    }

    return un_string_copy(cont, alloc);
}

String un_string_substring(String input, u64 start, u64 max_size) {
    String slice;

    assert(max_size > 0);

    slice.size = UN_MIN(max_size, (input.size - (u64)max_size));
    slice.data = input.data + start;


    if (start > (input.size - max_size)) {
        slice.size = UN_MIN(max_size, (input.size - (u64)max_size));
    } else {
        slice.size = max_size;
    }

    slice.data = input.data + start;
    return slice;
}

s64 un_string_index_of(String input, u8 value, u64 skip_count) {
    u64 i;
    
    for (i = 0; i < input.size; i++) {
        if (input.data[i] != value) {
            continue;
        }

        if (skip_count) {
            skip_count--;
        } else {
            return i;
        }
    }

    return -1;
}
s64 un_string_index_of_last(String input, u8 value) {
    s64 i, index;

    index = -1;

    for (i = 0; i < (s64)input.size; i++) {
        if (input.data[i] == value) index = i;
    }

    return index;
}

static String format_u64(u64 value) {
    String output;
    u64 l, r, size;
    u8 t;
    u8 buffer[32];

    size = 0;

    if (value == 0) {
        return UN_STR("0");
    }
 
    while (value) {
        buffer[size++] = '0' + (value % 10);
        value /= 10;
    }

    assert(size <= 20);

    for (l = 0, r = size - 1; l < r; l++, r--) {
        t         = buffer[l];
        buffer[l] = buffer[r];
        buffer[r] = t;
    }

    output.size = size;
    output.data = buffer;
    return un_string_copy(output, un_allocator_get_temporary());
}

static String format_s64(s64 value) {
    String output;
    u64 l, r, size;
    b32 negative;
    u8 t;
    u8 buffer[32];

    size = 0;

    if (value == 0) {
        return UN_STR("0");
    }
 
    negative = false;

    if (value < 0) {
        value    = -value;
        negative = true;
    }

    while (value) {
        buffer[size++] = '0' + (value % 10);
        value /= 10;
    }

    if (negative) {
        buffer[size++] = '-';
    }

    assert(size <= 20);

    for (l = 0, r = size - 1; l < r; l++, r--) {
        t         = buffer[l];
        buffer[l] = buffer[r];
        buffer[r] = t;
    }

    output.size = size;
    output.data = buffer;
    return un_string_copy(output, un_allocator_get_temporary());
}

String un_string_format(Allocator alloc, String buffer, ...) {
    va_list args;
    String result;
    va_start(args, buffer);
    result = un_string_vformat(alloc, buffer, args);
    va_end(args);
    return result;
}

String un_string_vformat(Allocator alloc, String buffer, va_list args) {
    List output;
    String s;
    u64 i, j;
    u32 b;

    Allocator talloc = un_allocator_get_temporary();
    // @todo @bug: this would fail on realloc, because we need to realloc
    output = un_list_create(UN_KB(1), sizeof(u8), talloc);

    for (i = 0; i < buffer.size; i++) {
        if (buffer.data[i] != '%') {
            un_list_append(&output, buffer.data + i);
            continue;
        }

        switch (buffer.data[++i]) {
            case '%':
            {
                un_list_append(&output, buffer.data + i);
            } break;

            case 'c':
            {
                b = va_arg(args, u32);
                un_list_append(&output, &b);
            } break;

            case 'u':
            {
                s = format_u64(va_arg(args, u64));
                for (j = 0; j < s.size; j++) {
                    un_list_append(&output, s.data + j);
                }
            } break;

            case 'd': 
            {
                s = format_s64(va_arg(args, u64));
                for (j = 0; j < s.size; j++) {
                    un_list_append(&output, s.data + j);
                }
            } break;

            case 's':
            {
                s = va_arg(args, String);
                for (j = 0; j < s.size; j++) {
                    un_list_append(&output, s.data + j);
                }
            } break;
            default: break;
        }
    }

    s.size = (s64)output.count;
    s.data = output.data;

    return un_string_copy(s, alloc);
}