import { NextResponse } from "next/server";
import { promises as fs } from "fs";
import path from "path";

const MESSAGES_FILE = path.join(process.cwd(), ".messages.json");

type Msg = { id: string; from: string; text: string; ts: number; channel?: string };

async function getMessages(): Promise<Msg[]> {
  try {
    const data = await fs.readFile(MESSAGES_FILE, "utf-8");
    return JSON.parse(data) as Msg[];
  } catch {
    return [];
  }
}

async function saveMessages(msgs: Msg[]) {
  const toSave = msgs.slice(-500);
  await fs.writeFile(MESSAGES_FILE, JSON.stringify(toSave, null, 2), "utf-8");
}

export async function GET(req: Request) {
  const url = new URL(req.url);
  const channel = url.searchParams.get("channel") || "global";
  const msgs = await getMessages();
  const channelMsgs = msgs.filter((m) => m.channel === channel || channel === "all");
  return NextResponse.json({ ok: true, messages: channelMsgs });
}

export async function POST(req: Request) {
  try {
    const body = await req.json();
    const { from, text, channel = "global" } = body;
    
    if (!from || !text) {
      return NextResponse.json({ ok: false, error: "Missing fields" }, { status: 400 });
    }

    const newMsg: Msg = {
      id: Math.random().toString(36).slice(2, 10),
      from: from.trim(),
      text: text.trim().slice(0, 500),
      ts: Date.now(),
      channel,
    };

    const msgs = await getMessages();
    msgs.push(newMsg);
    await saveMessages(msgs);

    return NextResponse.json({ ok: true, message: newMsg });
  } catch (err) {
    return NextResponse.json({ ok: false, error: "Failed to save message" }, { status: 500 });
  }
}

export async function DELETE(req: Request) {
  try {
    const url = new URL(req.url);
    const id = url.searchParams.get("id");
    const clearAll = url.searchParams.get("all") === "true";

    let msgs = await getMessages();

    if (clearAll) {
      msgs = [];
    } else if (id) {
      msgs = msgs.filter((m) => m.id !== id);
    } else {
      return NextResponse.json({ ok: false, error: "Provide id or all=true" }, { status: 400 });
    }

    await saveMessages(msgs);
    return NextResponse.json({ ok: true });
  } catch (err) {
    return NextResponse.json({ ok: false, error: "Failed to delete" }, { status: 500 });
  }
}