api-client.c

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/*
 * Prompt Workbench Core - API Client Implementation
 * Copyright (c) 2025 nnlazaro
 * 
 * This file is part of Prompt Workbench Core, licensed under the
 * Educational and Non-Commercial Use License.
 * See LICENSE file for details.
 * 
 * FOR EDUCATIONAL USE ONLY - NOT FOR PRODUCTION OR COMMERCIAL USE
 */
 
#include "api-client.h"
#include <curl/curl.h>
#include <cjson/cJSON.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
 
struct MemoryChunk {
    char *memory;
    size_t size;
};
 
static size_t write_callback(void *contents, size_t size, size_t nmemb, void *userp) {
    size_t realsize = size * nmemb;
    struct MemoryChunk *mem = (struct MemoryChunk *)userp;
    
    char *ptr = realloc(mem->memory, mem->size + realsize + 1);
    if (!ptr) {
        return 0;
    }
    
    mem->memory = ptr;
    memcpy(&(mem->memory[mem->size]), contents, realsize);
    mem->size += realsize;
    mem->memory[mem->size] = 0;
    
    return realsize;
}
 
char* api_ask(const char* api_endpoint, 
              const char* api_key,
              const char* model,
              const char* system_prompt,
              const char* user_prompt) {
    
    if (!api_endpoint || !api_key || !model || !system_prompt || !user_prompt) {
        return NULL;
    }
    
    CURL *curl;
    CURLcode res;
    struct MemoryChunk chunk = {0};
    struct curl_slist *headers = NULL;
    char auth_header[512];
    char *json_payload = NULL;
    char *result = NULL;
    
    // Build JSON request payload
    cJSON *root = cJSON_CreateObject();
    cJSON *messages = cJSON_CreateArray();
    cJSON *system_msg = cJSON_CreateObject();
    cJSON *user_msg = cJSON_CreateObject();
    
    cJSON_AddStringToObject(root, "model", model);
    
    cJSON_AddStringToObject(system_msg, "role", "system");
    cJSON_AddStringToObject(system_msg, "content", system_prompt);
    cJSON_AddItemToArray(messages, system_msg);
    
    cJSON_AddStringToObject(user_msg, "role", "user");
    cJSON_AddStringToObject(user_msg, "content", user_prompt);
    cJSON_AddItemToArray(messages, user_msg);
    
    cJSON_AddItemToObject(root, "messages", messages);
    
    json_payload = cJSON_PrintUnformatted(root);
    cJSON_Delete(root);
    
    if (!json_payload) {
        return NULL;
    }
    
    // Initialize response buffer
    chunk.memory = malloc(1);
    chunk.size = 0;
    
    // Initialize curl
    curl_global_init(CURL_GLOBAL_DEFAULT);
    curl = curl_easy_init();
    
    if (!curl) {
        free(chunk.memory);
        free(json_payload);
        curl_global_cleanup();
        return NULL;
    }
    
    // Set headers
    headers = curl_slist_append(headers, "Content-Type: application/json");
    snprintf(auth_header, sizeof(auth_header), "Authorization: Bearer %s", api_key);
    headers = curl_slist_append(headers, auth_header);
    
    // Configure curl
    curl_easy_setopt(curl, CURLOPT_URL, api_endpoint);
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, json_payload);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&chunk);
    curl_easy_setopt(curl, CURLOPT_USERAGENT, "prompt-workbench-core/1.0");
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 2L);
    
    // Perform the request
    res = curl_easy_perform(curl);
    
    // Cleanup
    curl_slist_free_all(headers);
    curl_easy_cleanup(curl);
    curl_global_cleanup();
    free(json_payload);
    
    if (res != CURLE_OK) {
        free(chunk.memory);
        return NULL;
    }
    
    // Parse JSON response and extract choices[0].message.content
    cJSON *response_json = cJSON_Parse(chunk.memory);
    free(chunk.memory);
    
    if (!response_json) {
        return NULL;
    }
    
    cJSON *choices = cJSON_GetObjectItem(response_json, "choices");
    if (!choices || !cJSON_IsArray(choices) || cJSON_GetArraySize(choices) == 0) {
        cJSON_Delete(response_json);
        return NULL;
    }
    
    cJSON *first_choice = cJSON_GetArrayItem(choices, 0);
    if (!first_choice) {
        cJSON_Delete(response_json);
        return NULL;
    }
    
    cJSON *message = cJSON_GetObjectItem(first_choice, "message");
    if (!message) {
        cJSON_Delete(response_json);
        return NULL;
    }
    
    cJSON *content = cJSON_GetObjectItem(message, "content");
    if (!content || !cJSON_IsString(content)) {
        cJSON_Delete(response_json);
        return NULL;
    }
    
    // Duplicate the content string before deleting JSON
    result = strdup(content->valuestring);
    cJSON_Delete(response_json);
    
    return result;
}
 
void api_ask_free(char* response) {
    if (response) {
        free(response);
    }
}