frontend/src/utils/api.ts

/**
 * API Client for communicating with the backend.
 * Handles streaming responses from the A2UI protocol.
 */

import { A2UIMessage } from "../types/a2ui";

const API_BASE_URL = import.meta.env.VITE_API_URL || "";

/**
 * Send a message to the chat endpoint and stream A2UI events.
 *
 * @param message - User message to send
 * @param onMessage - Callback function for each received message
 * @param onError - Callback function for errors
 */
export async function streamChat(
  message: string,
  onMessage: (msg: A2UIMessage) => void,
  onError: (error: Error) => void
): Promise<void> {
  try {
    const response = await fetch(`${API_BASE_URL}/chat`, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ message }),
    });

    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }

    if (!response.body) {
      throw new Error("Response body is empty");
    }

    const reader = response.body.getReader();
    const decoder = new TextDecoder();

    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      const chunk = decoder.decode(value, { stream: true });
      const lines = chunk.split("\n");

      for (const line of lines) {
        if (line.startsWith("data: ")) {
          try {
            const jsonStr = line.slice(6);
            const message: A2UIMessage = JSON.parse(jsonStr);
            onMessage(message);
          } catch (e) {
            console.error("Failed to parse message:", e);
          }
        }
      }
    }
  } catch (error) {
    onError(error instanceof Error ? error : new Error(String(error)));
  }
}

/**
 * Check API health status.
 */
export async function checkHealth(): Promise<boolean> {
  try {
    const response = await fetch(`${API_BASE_URL}/health`);
    return response.ok;
  } catch {
    return false;
  }
}

/**
 * Get available tools from the backend.
 */
export async function getTools(): Promise<any[]> {
  try {
    const response = await fetch(`${API_BASE_URL}/tools`);
    if (!response.ok) {
      throw new Error(`HTTP ${response.status}`);
    }
    const data = await response.json();
    return data.tools || [];
  } catch (error) {
    console.error("Failed to fetch tools:", error);
    return [];
  }
}

/**
 * Clear chat history on the backend.
 */
export async function clearHistory(): Promise<boolean> {
  try {
    const response = await fetch(`${API_BASE_URL}/chat/history`, {
      method: "DELETE",
    });
    return response.ok;
  } catch (error) {
    console.error("Failed to clear history:", error);
    return false;
  }
}