test
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "str.h"
#include "util.h"

#define INIT_SZ 20

void _str_ensure(str *s, int newsz) {
    int tmp;
    newsz += 1;
    if (newsz < s->capacity) return;

    tmp = s->capacity * 2;
    if (tmp > newsz) newsz = tmp;
    s->ptr = xrealloc(s->ptr, newsz);
    s->capacity = newsz;
}

void str_init(str *s) {
    assert(s);
    s->len = 0;
    s->capacity = INIT_SZ;
    s->ptr = xmalloc(s->capacity);
    s->ptr[0] = '\0';
    printf("str_init: len=%d, capacity=%d\n", s->len, s->capacity);
}

void str_deinit(str *s) {
    if (s->ptr) free(s->ptr);
    s->ptr = NULL;
    s->len = 0;
    s->capacity = 0;
    printf("str_deinit: memory freed\n");
}

void str_init_data(str *s, const char *initial) {
    assert(s && initial);
    int len = strlen(initial);
    s->len = len;
    s->capacity = len + 1;
    if (s->capacity < INIT_SZ) s->capacity = INIT_SZ;
    s->ptr = xmalloc(s->capacity);
    strcpy(s->ptr, initial);
    printf("str_init_data: '%s' (%d)\n", s->ptr, s->len);
}

char * str_data(str *s) {
    assert(s);
    return s->ptr;
}

void str_set(str *s, char *cstr) {
    assert(s && cstr);
    int len = strlen(cstr);
    _str_ensure(s, len);
    strcpy(s->ptr, cstr);
    s->len = len;
    printf("str_set: '%s' (%d)\n", s->ptr, s->len);
}

str str_copy(str *s) {
    assert(s);
    str new_str;
    str_init(&new_str);
    _str_ensure(&new_str, s->len);
    strcpy(new_str.ptr, s->ptr);
    new_str.len = s->len;
    printf("str_copy: '%s' -> '%s'\n", s->ptr, new_str.ptr);
    return new_str;
}

int str_count(str *s, char ch) {
    assert(s);
    int count = 0;
    for (int i = 0; i < s->len; i++) {
        if (s->ptr[i] == ch) count++;
    }
    printf("str_count: '%c' = %d in '%s'\n", ch, count, s->ptr);
    return count;
}

void str_append(str *s, char *cstr) {
    assert(s && cstr);
    str_append_n(s, cstr, strlen(cstr));
}

void str_append_n(str *s, char *cstr, int len) {
    assert(s && cstr);
    _str_ensure(s, s->len + len);
    memcpy(s->ptr + s->len, cstr, len);
    s->len += len;
    s->ptr[s->len] = '\0';
    printf("str_append_n: '%s' (%d)\n", s->ptr, s->len);
}

void str_shrink(str *s, int len) {
    assert(s && len >= 0);
    if (len > s->len) len = s->len;
    s->len = len;
    s->ptr[s->len] = '\0';
    printf("str_shrink: '%s' (%d)\n", s->ptr, s->len);
}

int str_find(str *s, char *substr) {
    assert(s && substr);
    char *p = strstr(s->ptr, substr);
    int result = (p == NULL) ? -1 : p - s->ptr;
    printf("str_find: '%s' in '%s' = %d\n", substr, s->ptr, result);
    return result;
}

str str_sub(str *s, int start_idx, int length) {
    assert(s && start_idx >= 0 && length >= 0);

    str s2;
    str_init(&s2);
    
    if (start_idx >= s->len) return s2;
    
    if (start_idx + length > s->len) length = s->len - start_idx;
    
    _str_ensure(&s2, length);
    memcpy(s2.ptr, s->ptr + start_idx, length);
    s2.ptr[length] = '\0';
    s2.len = length;
    
    printf("str_sub: '%s'[%d:%d] = '%s'\n", s->ptr, start_idx, start_idx+length, s2.ptr);
    return s2;
}

int str_replace(str *s, char *substr, char *replacement) {
    assert(s && substr && replacement);
    
    int count = 0;
    str result;
    str_init(&result);
    
    int substr_len = strlen(substr);
    int replacement_len = strlen(replacement);
    
    char *current = s->ptr;
    char *found;
    
    while ((found = strstr(current, substr)) != NULL) {
        int prefix_len = found - current;
        if (prefix_len > 0) str_append_n(&result, current, prefix_len);
        str_append_n(&result, replacement, replacement_len);
        current = found + substr_len;
        count++;
    }
    
    if (*current != '\0') str_append(&result, current);
    
    free(s->ptr);
    s->ptr = result.ptr;
    s->len = result.len;
    s->capacity = result.capacity;
    
    printf("str_replace: '%s' (%d)\n", s->ptr, count);
    return count;
}