frontend/src/app/api/provider/route.ts

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

/**
 * API route to read/update the current provider.
 * GET: reads from .env (initial value)
 * POST: writes to .provider file for hot-swap (no restart needed)
 */

const ENV_PATH = path.join(process.cwd(), "..", ".env");
const PROVIDER_FILE = path.join(process.cwd(), "..", ".provider");

export async function GET() {
  try {
    // First check .provider file (hot-swap state)
    if (fs.existsSync(PROVIDER_FILE)) {
      const provider = fs.readFileSync(PROVIDER_FILE, "utf-8").trim().toLowerCase();
      if (provider === "openai" || provider === "gemini") {
        return NextResponse.json({ provider, available: ["openai", "gemini"] });
      }
    }
    
    // Fallback to .env file
    if (!fs.existsSync(ENV_PATH)) {
      return NextResponse.json({ provider: "openai", available: ["openai", "gemini"] });
    }
    
    const envContent = fs.readFileSync(ENV_PATH, "utf-8");
    const lines = envContent.split("\n");
    
    // Find REALTIME_PROVIDER line (not commented)
    for (const line of lines) {
      const trimmed = line.trim();
      if (trimmed.startsWith("#")) continue;
      if (trimmed.startsWith("REALTIME_PROVIDER=")) {
        const provider = trimmed.split("=")[1]?.trim().toLowerCase() || "openai";
        return NextResponse.json({ 
          provider, 
          available: ["openai", "gemini"] 
        });
      }
    }
    
    // Default to openai if not found
    return NextResponse.json({ provider: "openai", available: ["openai", "gemini"] });
  } catch (error) {
    console.error("Error reading provider:", error);
    return NextResponse.json({ provider: "openai", available: ["openai", "gemini"] });
  }
}

export async function POST(request: Request) {
  try {
    const body = await request.json();
    const newProvider = body.provider?.toLowerCase();
    
    if (newProvider !== "openai" && newProvider !== "gemini") {
      return NextResponse.json({ ok: false, error: "Invalid provider" }, { status: 400 });
    }
    
    // Write to .provider file for hot-swap (backend polls this)
    fs.writeFileSync(PROVIDER_FILE, newProvider);
    
    return NextResponse.json({ 
      ok: true, 
      provider: newProvider,
      message: "Provider switching... (hot-swap in progress)"
    });
  } catch (error) {
    console.error("Error updating provider:", error);
    return NextResponse.json({ ok: false, error: "Failed to update provider" }, { status: 500 });
  }
}