#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#include "utils.h"

char* my_strcasestr(const char *haystack, const char *needle) {
    if (!haystack || !needle || *needle == '\0') return (char*)haystack;
    size_t needle_len = strlen(needle);
    while (*haystack) {
        if (strncasecmp(haystack, needle, needle_len) == 0) return (char*)haystack;
        haystack++;
    }
    return NULL;
}

void html_escape(const char *src, char *dst, size_t dst_size) {
    if (!src || !dst || dst_size == 0) return;
    char *p = dst;
    size_t i = 0;
    while (*src && i < dst_size - 6) {
        switch (*src) {
            case '<': strcpy(p, "&lt;"); p += 4; i += 4; break;
            case '>': strcpy(p, "&gt;"); p += 4; i += 4; break;
            case '"': strcpy(p, "&quot;"); p += 6; i += 6; break;
            case '&': strcpy(p, "&amp;"); p += 5; i += 5; break;
            default: *p++ = *src; i++; break;
        }
        src++;
    }
    *p = '\0';
}

void format_size(long long size, char* buffer) {
    if (size < 1024) snprintf(buffer, 32, "%lld B", size);
    else if (size < 1024 * 1024) snprintf(buffer, 32, "%.1f KB", size / 1024.0);
    else if (size < 1024 * 1024 * 1024) snprintf(buffer, 32, "%.1f MB", size / (1024.0 * 1024.0));
    else snprintf(buffer, 32, "%.1f GB", size / (1024.0 * 1024.0 * 1024.0));
}

void format_date(time_t mtime, char* buffer, size_t size) {
    struct tm *tm_info = localtime(&mtime);
    strftime(buffer, size, "%d.%m.%Y", tm_info);
}

void url_encode(const char *src, char *dst, size_t dst_size) {
    static const char *hex = "0123456789ABCDEF";
    char *p = dst;
    size_t i = 0;
    while (*src && i < dst_size - 3) {
        unsigned char c = (unsigned char)*src;
        if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') ||
            (c >= '0' && c <= '9') || strchr("-_.~", c)) {
            *p++ = c; i++;
        } else if (c == ' ') {
            *p++ = '%'; *p++ = '2'; *p++ = '0'; i += 3;
        } else {
            *p++ = '%'; *p++ = hex[(c >> 4) & 0xF]; *p++ = hex[c & 0xF]; i += 3;
        }
        src++;
    }
    *p = '\0';
}

void url_decode_enhanced(const char *src, char *dst, size_t dst_size) {
    char *p = dst;
    size_t decoded_len = 0;
    while (*src && decoded_len < dst_size - 1) {
        if (*src == '%') {
            if (src[1] && src[2] && isxdigit(src[1]) && isxdigit(src[2])) {
                char hex[3] = {src[1], src[2], '\0'};
                unsigned char c = (unsigned char)strtol(hex, NULL, 16);
                if (c >= 0x80 || c >= 0x20 || c == 0x0A || c == 0x0D) {
                    *p++ = c;
                    decoded_len++;
                } else {
                    *p++ = '_';
                    decoded_len++;
                }
                src += 3;
            } else {
                src++;
            }
        } else if (*src == '+') {
            *p++ = ' ';
            decoded_len++;
            src++;
        } else {
            *p++ = *src++;
            decoded_len++;
        }
    }
    *p = '\0';
}