import type { Context } from "hono";
import { stream } from "hono/streaming";
import { runAgentTurn } from "../agent/runner";
import { agentOptions } from "../agent-options";

interface ChatMessage {
	role: string;
	content: string;
}

interface ChatCompletionRequest {
	messages?: ChatMessage[];
	stream?: boolean;
}

function extractLastUserMessage(messages: ChatMessage[]): string | null {
	for (let i = messages.length - 1; i >= 0; i--) {
		if (messages[i].role === "user" && messages[i].content) {
			return messages[i].content;
		}
	}
	return null;
}

export async function handleChatCompletions(c: Context) {
	const body = await c.req.json<ChatCompletionRequest>();

	if (
		!body.messages ||
		!Array.isArray(body.messages) ||
		body.messages.length === 0
	) {
		return c.json(
			{ error: "messages array is required and must not be empty" },
			400,
		);
	}

	const userMessage = extractLastUserMessage(body.messages);
	if (!userMessage) {
		return c.json({ error: "No user message found in messages array" }, 400);
	}

	const opts = await agentOptions();
	const result = await runAgentTurn("conversation", {
		...opts,
		customMessage: userMessage,
	});

	const runId = `run_${crypto.randomUUID()}`;
	const created = Math.floor(Date.now() / 1000);
	const content = result.success
		? result.summary || "Agent completed with no summary."
		: `Error: ${result.error || "Agent failed"}`;

	if (body.stream) {
		return stream(c, async (s) => {
			c.header("Content-Type", "text/event-stream");
			c.header("Cache-Control", "no-cache");
			c.header("Connection", "keep-alive");

			const chunk = JSON.stringify({
				id: runId,
				object: "chat.completion.chunk",
				created,
				model: "clarkling",
				choices: [
					{
						index: 0,
						delta: { role: "assistant", content },
						finish_reason: "stop",
					},
				],
			});

			await s.write(`data: ${chunk}\n\n`);
			await s.write("data: [DONE]\n\n");
		});
	}

	return c.json({
		id: runId,
		object: "chat.completion",
		created,
		model: "clarkling",
		choices: [
			{
				index: 0,
				message: { role: "assistant", content },
				finish_reason: "stop",
			},
		],
		usage: { prompt_tokens: 0, completion_tokens: 0, total_tokens: 0 },
	});
}