Update C chat samples with using ChatHistory class

samples/c/text_generation/benchmark_genai_c.c

@@ -188,4 +188,4 @@ int main(int argc, char* argv[]) {
     if (results)
         ov_genai_decoded_results_free(results);
     return EXIT_SUCCESS;
-}
+}

samples/c/text_generation/chat_sample_c.c

@@ -6,14 +6,68 @@
 #include <string.h>
 
 #include "openvino/genai/c/llm_pipeline.h"
+#include "openvino/genai/c/chat_history.h"
 
-#define MAX_PROMPT_LENGTH 64
+#define MAX_PROMPT_LENGTH 1024
+#define MAX_JSON_LENGTH 4096
 
 #define CHECK_STATUS(return_status)                                                      \
     if (return_status != OK) {                                                           \
         fprintf(stderr, "[ERROR] return status %d, line %d\n", return_status, __LINE__); \
         goto err;                                                                        \
     }
+
+#define CHECK_CHAT_HISTORY_STATUS(return_status)                                                      \
+    if (return_status != OV_GENAI_CHAT_HISTORY_OK) {                                                           \
+        fprintf(stderr, "[ERROR] chat history status %d, line %d\n", return_status, __LINE__); \
+        goto err;                                                                        \
+    }
+
+// Simple JSON escape function for strings
+static void json_escape_string(const char* input, char* output, size_t output_size) {
+    size_t i = 0;
+    size_t j = 0;
+    while (input[i] != '\0' && j < output_size - 1) {
+        switch (input[i]) {
+            case '"':
+                if (j < output_size - 2) {
+                    output[j++] = '\\';
+                    output[j++] = '"';
+                }
+                break;
+            case '\\':
+                if (j < output_size - 2) {
+                    output[j++] = '\\';
+                    output[j++] = '\\';
+                }
+                break;
+            case '\n':
+                if (j < output_size - 2) {
+                    output[j++] = '\\';
+                    output[j++] = 'n';
+                }
+                break;
+            case '\r':
+                if (j < output_size - 2) {
+                    output[j++] = '\\';
+                    output[j++] = 'r';
+                }
+                break;
+            case '\t':
+                if (j < output_size - 2) {
+                    output[j++] = '\\';
+                    output[j++] = 't';
+                }
+                break;
+            default:
+                output[j++] = input[i];
+                break;
+        }
+        i++;
+    }
+    output[j] = '\0';
+}
+
 ov_genai_streaming_status_e print_callback(const char* str, void* args) {
     if (str) {
         // If args is not null, it needs to be cast to its actual type.
@@ -27,37 +81,80 @@ ov_genai_streaming_status_e print_callback(const char* str, void* args) {
 }
 
 int main(int argc, char* argv[]) {
-    if (argc != 2) {
-        fprintf(stderr, "Usage: %s <MODEL_DIR>\n", argv[0]);
+    if (argc < 2 || argc > 3) {
+        fprintf(stderr, "Usage: %s <MODEL_DIR> [DEVICE]\n", argv[0]);
         return EXIT_FAILURE;
     }
     const char* models_path = argv[1];
-    const char* device = "CPU";  // GPU, NPU can be used as well
+    const char* device = (argc == 3) ? argv[2] : "CPU";  // GPU, NPU can be used as well
 
     ov_genai_generation_config* config = NULL;
     ov_genai_llm_pipeline* pipeline = NULL;
+    ov_genai_chat_history* chat_history = NULL;
+    ov_genai_decoded_results* results = NULL;
     streamer_callback streamer;
     streamer.callback_func = print_callback;
+    streamer.args = NULL;
     char prompt[MAX_PROMPT_LENGTH];
+    char message_json[MAX_JSON_LENGTH];
+    char output_buffer[MAX_JSON_LENGTH];
+    size_t output_size = 0;
+    char assistant_message_json[MAX_JSON_LENGTH];
+    char escaped_prompt[MAX_PROMPT_LENGTH * 2];  // Escaped string may be longer
+    char escaped_output[MAX_JSON_LENGTH * 2];    // Escaped string may be longer
 
     CHECK_STATUS(ov_genai_llm_pipeline_create(models_path, device, 0, &pipeline));
     CHECK_STATUS(ov_genai_generation_config_create(&config));
     CHECK_STATUS(ov_genai_generation_config_set_max_new_tokens(config, 100));
 
-    CHECK_STATUS(ov_genai_llm_pipeline_start_chat(pipeline));
+    CHECK_CHAT_HISTORY_STATUS(ov_genai_chat_history_create(&chat_history));
+
     printf("question:\n");
     while (fgets(prompt, MAX_PROMPT_LENGTH, stdin)) {
+        // Remove newline character
         prompt[strcspn(prompt, "\n")] = 0;
-        CHECK_STATUS(ov_genai_llm_pipeline_generate(pipeline,
-                                                    prompt,
-                                                    config,
-                                                    &streamer,
-                                                    NULL));  // Only the streamer functionality is used here.
+
+        // Skip empty lines
+        if (strlen(prompt) == 0) {
+            continue;
+        }
+
+        json_escape_string(prompt, escaped_prompt, sizeof(escaped_prompt));
+
+        snprintf(message_json, sizeof(message_json), 
+                 "{\"role\": \"user\", \"content\": \"%s\"}", escaped_prompt);
+
+        CHECK_CHAT_HISTORY_STATUS(ov_genai_chat_history_push_back(chat_history, message_json));
+
+        results = NULL;
+        CHECK_STATUS(ov_genai_llm_pipeline_generate_with_history(pipeline,
+                                                                  chat_history,
+                                                                  config,
+                                                                  &streamer,
+                                                                  &results));
+
+        if (results) {
+            output_size = sizeof(output_buffer);
+            CHECK_STATUS(ov_genai_decoded_results_get_string(results, output_buffer, &output_size));
+
+            json_escape_string(output_buffer, escaped_output, sizeof(escaped_output));
+
+            snprintf(assistant_message_json, sizeof(assistant_message_json),
+                     "{\"role\": \"assistant\", \"content\": \"%s\"}", escaped_output);
+            CHECK_CHAT_HISTORY_STATUS(ov_genai_chat_history_push_back(chat_history, assistant_message_json));
+
+            ov_genai_decoded_results_free(results);
+            results = NULL;
+        }
+
         printf("\n----------\nquestion:\n");
     }
-    CHECK_STATUS(ov_genai_llm_pipeline_finish_chat(pipeline));
 
 err:
+    if (results)
+        ov_genai_decoded_results_free(results);
+    if (chat_history)
+        ov_genai_chat_history_free(chat_history);
     if (pipeline)
         ov_genai_llm_pipeline_free(pipeline);
     if (config)

samples/c/text_generation/greedy_causal_lm_c.c

@@ -53,4 +53,4 @@ int main(int argc, char* argv[]) {
         free(output);
 
     return EXIT_SUCCESS;
-}
+}

src/c/include/openvino/genai/c/chat_history.h

@@ -0,0 +1,213 @@
+// Copyright (C) 2025 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+//
+// This is a C wrapper for ov::genai::ChatHistory class.
+
+#pragma once
+
+#include "visibility.h"
+#include <stddef.h>
+
+/**
+ * @struct ov_genai_chat_history
+ * @brief Opaque type for ChatHistory
+ */
+typedef struct ov_genai_chat_history_opaque ov_genai_chat_history;
+
+/**
+ * @brief Status codes for chat history operations
+ */
+typedef enum {
+    OV_GENAI_CHAT_HISTORY_OK = 0,
+    OV_GENAI_CHAT_HISTORY_INVALID_PARAM = -1,
+    OV_GENAI_CHAT_HISTORY_OUT_OF_BOUNDS = -2,
+    OV_GENAI_CHAT_HISTORY_EMPTY = -3,
+    OV_GENAI_CHAT_HISTORY_INVALID_JSON = -4,
+    OV_GENAI_CHAT_HISTORY_ERROR = -5
+} ov_genai_chat_history_status_e;
+
+/**
+ * @brief Create a new empty ChatHistory instance.
+ * @param history A pointer to the newly created ov_genai_chat_history.
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_create(ov_genai_chat_history** history);
+
+/**
+ * @brief Create a ChatHistory instance from a JSON array string.
+ * @param messages_json A JSON string containing an array of message objects.
+ * @param history A pointer to the newly created ov_genai_chat_history.
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_create_from_json(
+    const char* messages_json,
+    ov_genai_chat_history** history);
+
+/**
+ * @brief Release the memory allocated by ov_genai_chat_history.
+ * @param history A pointer to the ov_genai_chat_history to free memory.
+ */
+OPENVINO_GENAI_C_EXPORTS void ov_genai_chat_history_free(ov_genai_chat_history* history);
+
+/**
+ * @brief Add a message to the chat history from a JSON object string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param message_json A JSON string containing a message object (e.g., {"role": "user", "content": "Hello"}).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_push_back(
+    ov_genai_chat_history* history,
+    const char* message_json);
+
+/**
+ * @brief Remove the last message from the chat history.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_pop_back(ov_genai_chat_history* history);
+
+/**
+ * @brief Get all messages as a JSON array string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param output A pointer to the pre-allocated output string buffer. It can be set to NULL, in which case the
+ * *output_size will provide the needed buffer size. The user should then allocate the required buffer size and call
+ * this function again to obtain the entire output.
+ * @param output_size A pointer to the size of the output string, including the null terminator. If output is not NULL,
+ * *output_size should be greater than or equal to the result string size; otherwise, the function will return
+ * OUT_OF_BOUNDS(-2).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_get_messages(
+    const ov_genai_chat_history* history,
+    char* output,
+    size_t* output_size);
+
+/**
+ * @brief Get a message at a specific index as a JSON object string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param index The index of the message to retrieve.
+ * @param output A pointer to the pre-allocated output string buffer. It can be set to NULL, in which case the
+ * *output_size will provide the needed buffer size. The user should then allocate the required buffer size and call
+ * this function again to obtain the entire output.
+ * @param output_size A pointer to the size of the output string, including the null terminator. If output is not NULL,
+ * *output_size should be greater than or equal to the result string size; otherwise, the function will return
+ * OUT_OF_BOUNDS(-2).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_get_message(
+    const ov_genai_chat_history* history,
+    size_t index,
+    char* output,
+    size_t* output_size);
+
+/**
+ * @brief Get the first message as a JSON object string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param output A pointer to the pre-allocated output string buffer. It can be set to NULL, in which case the
+ * *output_size will provide the needed buffer size. The user should then allocate the required buffer size and call
+ * this function again to obtain the entire output.
+ * @param output_size A pointer to the size of the output string, including the null terminator. If output is not NULL,
+ * *output_size should be greater than or equal to the result string size; otherwise, the function will return
+ * OUT_OF_BOUNDS(-2).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_get_first(
+    const ov_genai_chat_history* history,
+    char* output,
+    size_t* output_size);
+
+/**
+ * @brief Get the last message as a JSON object string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param output A pointer to the pre-allocated output string buffer. It can be set to NULL, in which case the
+ * *output_size will provide the needed buffer size. The user should then allocate the required buffer size and call
+ * this function again to obtain the entire output.
+ * @param output_size A pointer to the size of the output string, including the null terminator. If output is not NULL,
+ * *output_size should be greater than or equal to the result string size; otherwise, the function will return
+ * OUT_OF_BOUNDS(-2).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_get_last(
+    const ov_genai_chat_history* history,
+    char* output,
+    size_t* output_size);
+
+/**
+ * @brief Clear all messages from the chat history.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_clear(ov_genai_chat_history* history);
+
+/**
+ * @brief Get the number of messages in the chat history.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param size A pointer to store the size (number of messages).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_size(
+    const ov_genai_chat_history* history,
+    size_t* size);
+
+/**
+ * @brief Check if the chat history is empty.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param empty A pointer to store the boolean result (1 for empty, 0 for not empty).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_empty(
+    const ov_genai_chat_history* history,
+    int* empty);
+
+/**
+ * @brief Set tools definitions (for function calling) as a JSON array string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param tools_json A JSON string containing an array of tool definitions.
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_set_tools(
+    ov_genai_chat_history* history,
+    const char* tools_json);
+
+/**
+ * @brief Get tools definitions as a JSON array string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param output A pointer to the pre-allocated output string buffer. It can be set to NULL, in which case the
+ * *output_size will provide the needed buffer size. The user should then allocate the required buffer size and call
+ * this function again to obtain the entire output.
+ * @param output_size A pointer to the size of the output string, including the null terminator. If output is not NULL,
+ * *output_size should be greater than or equal to the result string size; otherwise, the function will return
+ * OUT_OF_BOUNDS(-2).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_get_tools(
+    const ov_genai_chat_history* history,
+    char* output,
+    size_t* output_size);
+
+/**
+ * @brief Set extra context (for custom template variables) as a JSON object string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param extra_context_json A JSON string containing an object with extra context.
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_set_extra_context(
+    ov_genai_chat_history* history,
+    const char* extra_context_json);
+
+/**
+ * @brief Get extra context as a JSON object string.
+ * @param history A pointer to the ov_genai_chat_history instance.
+ * @param output A pointer to the pre-allocated output string buffer. It can be set to NULL, in which case the
+ * *output_size will provide the needed buffer size. The user should then allocate the required buffer size and call
+ * this function again to obtain the entire output.
+ * @param output_size A pointer to the size of the output string, including the null terminator. If output is not NULL,
+ * *output_size should be greater than or equal to the result string size; otherwise, the function will return
+ * OUT_OF_BOUNDS(-2).
+ * @return ov_genai_chat_history_status_e A status code, return OK(0) if successful.
+ */
+OPENVINO_GENAI_C_EXPORTS ov_genai_chat_history_status_e ov_genai_chat_history_get_extra_context(
+    const ov_genai_chat_history* history,
+    char* output,
+    size_t* output_size);
+