import type { Event } from "@ace/ui";

import type { Item, Tool } from "./transcript";

const AGENT = "ace:agent";
const MENTION = /(?<=^|\s)@([a-zA-Z0-9_-]+)/g;

function text(value: string): Event.Message.Content.Text {
	const parts = [...value.matchAll(MENTION)].map((match) => ({
		type: "mention" as const,
		value: match[1]!,
		index: match.index,
	}));
	return parts.length ? { type: "text", text: value, parts } : { type: "text", text: value };
}

function tool(tool: Tool, busy: boolean): Event.Message.Content.Tool {
	const status = tool.result ? (tool.result.error ? "error" : "success") : busy ? "start" : "error";
	return {
		type: "tool",
		id: tool.call,
		name: tool.name,
		arguments: (tool.args ?? {}) as Record<string, unknown>,
		status,
		...(tool.result ? { result: { content: tool.result.text } } : {}),
	};
}

/** Channel transcript items in the shape the original timeline renders. */
export function toEvents(items: Item[], topic: string, busy: boolean): Event[] {
	return items.map((item) => {
		const base = {
			id: `${topic}::${item.key}`,
			uid: item.key,
			type: "message",
			topic,
			created_at: Math.floor(item.at / 1000),
		} as const;
		if (item.kind === "message") {
			return {
				...base,
				// Authors are Tailscale logins; the name before the domain reads as a handle.
				sender: { kind: "user", value: item.author, display: item.author.split("@")[0]! },
				content: [
					text(item.invoked && !/(^|\s)@ace\b/i.test(item.text) ? `@ace ${item.text}` : item.text),
				],
			} as Event;
		}
		const content: Event.Message.Agent["content"] = item.tools.map((call) => tool(call, busy));
		if (item.text) content.push(text(item.text));
		if (item.error) content.push(text(`Run failed: ${item.error}`));
		if (item.stopped) content.push(text("Stopped."));
		return {
			...base,
			sender: { kind: "agent", value: AGENT, display: item.model || "Agent" },
			content,
		} as Event;
	});
}