#include <stdio.h>
#include <string.h>
#include <assert.h>

unsigned int len(char* str)
{
    int i = 0;

    while (str[i] != '\0')
    {
        i++;
    }
       
    return i;
}

char* ft_strcat(char* dest, char* src)
{
    unsigned int dest_i;
    unsigned int src_i;
    unsigned int src_size;
    
    dest_i = 0;
    src_i = 0;
    src_size = len(src);
    while (dest[dest_i] != '\0')
    {
        dest_i++;
    }

    while (src_i < src_size)
    {
        dest[dest_i] = src[src_i];
        src_i++;
        dest_i++;
    }

    dest[dest_i] = '\0';

    return dest;
}

int main(void)
{
    // Test Case 1: Basic concatenation
    char buffer1_1[100] = "Hello, ";
    char buffer2_1[50] = "World!";

    assert(strcmp(ft_strcat(buffer1_1, buffer2_1), "Hello, World!") == 0);

    // Test Case 2: Concatenating empty string
    char buffer1_2[100] = "Hello, ";
    char buffer2_2[50] = "";

    assert(strcmp(ft_strcat(buffer1_2, buffer2_2), "Hello, ") == 0);

    // Test Case 3: Concatenating to empty string
    char buffer1_3[100] = "";
    char buffer2_3[50] = "World!";

    assert(strcmp(ft_strcat(buffer1_3, buffer2_3), "World!") == 0);

    // Test Case 4: Both strings are empty
    char buffer1_4[100] = "";
    char buffer2_4[50] = "";

    assert(strcmp(ft_strcat(buffer1_4, buffer2_4), "") == 0);

    // Test Case 5: Long strings
    char buffer1_5[100] = "This is a long string. ";
    char buffer2_5[50] = "This is another long string.";

    assert(strcmp(ft_strcat(buffer1_5, buffer2_5), "This is a long string. This is another long string.") == 0);

    // Test Case 6: Overlapping strings
    char overlapping[100] = "Overlapping";

    assert(strcmp(ft_strcat(overlapping, overlapping + 4), "Overlappinglapping") == 0);

    printf("All tests passed.\n");
}