import { NextRequest, NextResponse } from "next/server";
import Anthropic from "@anthropic-ai/sdk";
import { tools, systemPrompt } from "@/lib/tools";
import { executeTool } from "@/lib/stacks-api";
// Type definitions for Claude API responses
interface TextBlock {
type: "text";
text: string;
}
interface ToolUseBlock {
type: "tool_use";
id: string;
name: string;
input: Record<string, unknown>;
}
type ContentBlock = TextBlock | ToolUseBlock;
interface Message {
role: "user" | "assistant";
content: string | ContentBlock[];
}
interface ToolResult {
type: "tool_result";
tool_use_id: string;
content: string;
}
/**
* POST /api/chat
* Handle chat messages with Claude API and tool execution
*/
export async function POST(request: NextRequest) {
try {
const body = await request.json();
const { message, history = [] } = body;
if (!message || typeof message !== "string") {
return NextResponse.json(
{ success: false, error: "Message is required" },
{ status: 400 }
);
}
// Check for API key
const apiKey = process.env.ANTHROPIC_API_KEY;
if (!apiKey) {
return NextResponse.json(
{
success: false,
error: "ANTHROPIC_API_KEY is not configured. Please add it to your .env file.",
},
{ status: 500 }
);
}
// Initialize Anthropic client
const anthropic = new Anthropic({ apiKey });
// Build conversation history
const messages: Message[] = [...history];
messages.push({ role: "user", content: message });
// Initial API call
let response = await anthropic.messages.create({
model: "claude-sonnet-4-20250514",
max_tokens: 4096,
system: systemPrompt,
tools: tools,
messages: messages as Anthropic.MessageParam[],
});
// Handle tool use loop
while (response.stop_reason === "tool_use") {
// Find all tool use blocks
const toolUseBlocks = response.content.filter(
(block): block is Anthropic.ToolUseBlock => block.type === "tool_use"
);
if (toolUseBlocks.length === 0) break;
// Execute all tool calls in parallel
const toolResults: ToolResult[] = await Promise.all(
toolUseBlocks.map(async (toolUse) => {
console.log(`[Tool] Executing: ${toolUse.name}`, toolUse.input);
const result = await executeTool(
toolUse.name,
toolUse.input as Record<string, unknown>
);
console.log(`[Tool] Result for ${toolUse.name}:`, result.substring(0, 200));
return {
type: "tool_result" as const,
tool_use_id: toolUse.id,
content: result,
};
})
);
// Add assistant response and tool results to history
messages.push({
role: "assistant",
content: response.content as ContentBlock[],
});
messages.push({
role: "user",
content: toolResults as unknown as ContentBlock[],
});
// Continue conversation with tool results
response = await anthropic.messages.create({
model: "claude-sonnet-4-20250514",
max_tokens: 4096,
system: systemPrompt,
tools: tools,
messages: messages as Anthropic.MessageParam[],
});
}
// Extract final text response
const textBlocks = response.content.filter(
(block): block is Anthropic.TextBlock => block.type === "text"
);
const assistantMessage = textBlocks.map((b) => b.text).join("\n") || "";
// Add final assistant response to history
messages.push({
role: "assistant",
content: response.content as ContentBlock[],
});
// Return response with simplified history for the client
const simplifiedHistory = messages.map((msg) => {
if (typeof msg.content === "string") {
return msg;
}
// For assistant messages with tool use, extract just the text
if (msg.role === "assistant") {
const textContent = (msg.content as ContentBlock[])
.filter((b): b is TextBlock => b.type === "text")
.map((b) => b.text)
.join("\n");
return { role: msg.role, content: textContent || "[Processing...]" };
}
// For user messages with tool results, skip them in UI history
return null;
}).filter((msg): msg is Message => msg !== null && msg.content !== "");
return NextResponse.json({
success: true,
message: assistantMessage,
history: simplifiedHistory,
});
} catch (error) {
console.error("[Chat API Error]", error);
// Handle specific Anthropic errors
if (error instanceof Anthropic.APIError) {
if (error.status === 401) {
return NextResponse.json(
{ success: false, error: "Invalid API key. Please check your ANTHROPIC_API_KEY." },
{ status: 401 }
);
}
if (error.status === 429) {
return NextResponse.json(
{ success: false, error: "Rate limited. Please wait a moment and try again." },
{ status: 429 }
);
}
}
return NextResponse.json(
{
success: false,
error: error instanceof Error ? error.message : "An unexpected error occurred",
},
{ status: 500 }
);
}
}
