#include <openssl/evp.h>
#include <curl/curl.h>
#include <stdio.h>
#include <string.h>
#include "curl_utils.h"


struct curl_buffer {
    char *data;
    size_t size;
};



struct curl_slist *MakeHeaders(e6_auth_t auth) {
    struct curl_slist *headers = NULL;

    char auth_buf[256];
    char base64_buf[128];
    snprintf(auth_buf, sizeof(auth_buf), "%s:%s", auth.username, auth.api_key);
    EVP_EncodeBlock((unsigned char*)base64_buf, (unsigned char*)auth_buf, strlen(auth_buf));
    memset(auth_buf, 0, sizeof(auth_buf));
    snprintf(auth_buf, sizeof(base64_buf), "Authorization: Basic %s", base64_buf);
    headers = curl_slist_append(headers, auth_buf);

    char user_agent_buf[256];
    snprintf(user_agent_buf, sizeof(user_agent_buf), "User-Agent: %s/%f (by %s on e621)", auth.project_name, auth.project_ver, auth.username);
    headers = curl_slist_append(headers, user_agent_buf);
    
    return headers;
}


static size_t WriteCallback(void *contents, size_t size, size_t nmemb, void *userdata) {
    size_t total = size * nmemb;
    struct curl_buffer *mem = (struct curl_buffer *)userdata;

    char *ptr = realloc(mem->data, mem->size + total + 1);
    if (!ptr)
        return 0;

    mem->data = ptr;
    memcpy(&(mem->data[mem->size]), contents, total);
    mem->size += total;
    mem->data[mem->size] = '\0';

    return total;
}


char *MakeUrl(char *path, curl_url_peram_t *perams, int peram_count) {
    char *url = (char *)malloc(E621_URL_BUF_SIZE);
    strncpy(url, E621_HOST, E621_URL_BUF_SIZE);
    strncat(url, path, strlen(path));
    strcat(url, "?");

    for (int i=0; i < peram_count; i++){
        strncat(url, perams[i].key, strlen(perams[i].key));
        strcat(url, "=");

        for (int j = 0; j < perams[i].count; j++) {
            strncat(url, perams[i].value[j], strlen(perams[i].value[j]));
            if (j != perams[i].count - 1) {
                strcat(url, "+");
            }
        }

        if(i < peram_count-1){
            strcat(url, "&");
        }
    }
    return url;
}


char *CurlGet(char *path, curl_url_peram_t *perams, int peram_count, e6_auth_t auth) {
    CURL *curl = curl_easy_init();
    CURLcode result;

    struct curl_buffer buffer;
    buffer.data = malloc(1);
    buffer.size = 0;

    if(!curl){
        fprintf(stderr, "Failed to initialize CURL");
        exit(EXIT_FAILURE);
    }

    char *url = MakeUrl(path, perams, peram_count);

    struct curl_slist *headers = MakeHeaders(auth);
    curl_easy_setopt(curl, CURLOPT_URL, url);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&buffer);
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    result = curl_easy_perform(curl);

    if (result != CURLE_OK) {
        fprintf(stderr, "CURL error: %s", curl_easy_strerror(result));
        return NULL;
    }

    return buffer.data;
}