#include "std.h"

char* _strcat_malloc(size_t n, cstr str0, ...){
    va_list argv;
    va_start(argv, str0);
    char* heap_ptr = _vstrcat_malloc(n, str0, argv);
    va_end(argv);
    return heap_ptr;
}

char* _vstrcat_malloc(size_t n, cstr str0, va_list argv){
    size_t str0_len = strlen(str0);
    size_t total_len = str0_len;
    cstr* const parts = malloc(sizeof(cstr) * n);
    size_t* const part_lengths = malloc(sizeof(size_t) * n);
    for(size_t i = 0; i < n; i++){
        cstr part = va_arg(argv, cstr);
        size_t length = strlen(part);
        parts[i] = part;
        part_lengths[i] = length;
        total_len += length;
    }
    char* const buf = malloc(total_len + 1);
    memcpy(buf, str0, str0_len);
    char* walking_ptr = buf + str0_len;
    for(size_t i = 0; i < n; i++){
        memcpy(walking_ptr, parts[i], part_lengths[i]);
        walking_ptr += part_lengths[i];
    }
    buf[total_len] = '\0';
    free(parts);
    free(part_lengths);
    return buf;
}

char* NULLABLE(sprintf_malloc)(size_t buffer_size, cstr format, ...){
    va_list argv;
    va_start(argv, format);
    char* NULLABLE(heap_ptr) = vsprintf_malloc(buffer_size, format, argv);
    va_end(argv);
    return heap_ptr;
}

char* NULLABLE(vsprintf_malloc)(size_t buffer_size, cstr format, va_list argv){
    char* buf = malloc(buffer_size);
    int r = vsprintf_s(buf, buffer_size, format, argv);
    if(r < 0){
        free(buf);
        return NULL;
    }
    return buf;
}