import { sql } from "@/lib/db";
import { requireRideParticipant, rideIsActive } from "@/lib/ride-participants";

// In-app WebRTC audio call signaling, carried over the same DB-backed polling
// pattern as chat (no WebSocket). Non-trickle ICE: each side gathers all
// candidates locally and bundles them into a single SDP offer/answer stored as
// text, so the whole handshake is a few polled round-trips.
//
//   POST   { sdp_offer }            -> caller starts a call (status=ringing)
//   GET                           -> poll: callee reads the offer, both read
//                                    the answer + status; lazily sweeps stale
//                                    ringing calls to 'missed'.
//   PATCH  { action, sdp_answer? }  -> answer / decline / end

// A ringing call older than this with no answer is treated as missed. Swept
// lazily inside GET, the way the broadcast advances on the ride-status poll.
const RINGING_TTL_SECONDS = 30;

type CallRow = {
  id: number;
  ride_id: number;
  caller_type: "rider" | "driver";
  status: "ringing" | "answered" | "ended" | "declined" | "missed";
  sdp_offer: string | null;
  sdp_answer: string | null;
  started_at: string | null;
  ended_at: string | null;
  created_at: string;
};

// POST — initiate a call. Rejects if the ride isn't active or a call is already
// in flight for it, so two calls can't stack on one ride.
export async function POST(req: Request, { id }: { id: string }) {
  const rideId = Number(id);
  if (!Number.isInteger(rideId)) {
    return Response.json({ error: "Invalid ride id." }, { status: 400 });
  }

  const participant = await requireRideParticipant(req, rideId);
  if ("error" in participant) return participant.error;

  let body: { sdp_offer?: string };
  try {
    body = await req.json();
  } catch {
    return Response.json({ error: "Invalid JSON body." }, { status: 400 });
  }

  const sdpOffer = body.sdp_offer;
  if (!sdpOffer || typeof sdpOffer !== "string") {
    return Response.json({ error: "Missing sdp_offer." }, { status: 400 });
  }

  try {
    if (!(await rideIsActive(rideId))) {
      return Response.json(
        { error: "This ride is no longer active." },
        { status: 409 },
      );
    }

    // Snapshot both parties onto the call row so authorization is one
    // equality check on poll and the call survives a driver reassignment.
    const ride = await sql<{ user_id: string; driver_id: number }>`
      SELECT user_id, driver_id FROM rides
      WHERE ride_id = ${rideId} AND driver_id IS NOT NULL
    `;
    if (!ride[0]) {
      return Response.json(
        { error: "This ride has no driver assigned." },
        { status: 409 },
      );
    }

    // Only one non-terminal call per ride at a time.
    const inFlight = await sql<{ n: number }>`
      SELECT COUNT(*)::int AS n FROM calls
      WHERE ride_id = ${rideId} AND status IN ('ringing','answered')
    `;
    if ((inFlight[0]?.n ?? 0) > 0) {
      return Response.json(
        { error: "A call is already in progress for this ride." },
        { status: 409 },
      );
    }

    const inserted = await sql<{ id: number }>`
      INSERT INTO calls (ride_id, user_id, driver_id, caller_type, status, sdp_offer)
      VALUES (
        ${rideId},
        ${ride[0].user_id},
        ${ride[0].driver_id},
        ${participant.role},
        'ringing',
        ${sdpOffer}
      )
      RETURNING id
    `;

    return Response.json({ data: { callId: inserted[0].id } }, { status: 201 });
  } catch (error) {
    console.error("[POST_CALL]: ", error);
    return Response.json({ error: "Internal Server Error." }, { status: 500 });
  }
}

// GET — poll the call for this ride. Returns the latest non-terminal call (or
// the most recent terminal one so the caller sees ended/declined/missed), with
// `is_caller` so each side knows whether it placed the call.
export async function GET(req: Request, { id }: { id: string }) {
  const rideId = Number(id);
  if (!Number.isInteger(rideId)) {
    return Response.json({ error: "Invalid ride id." }, { status: 400 });
  }

  const participant = await requireRideParticipant(req, rideId);
  if ("error" in participant) return participant.error;

  try {
    // Lazy missed-call sweep: a ringing call nobody answered in time is
    // marked missed so the caller's screen can stop ringing.
    await sql`
      UPDATE calls
      SET status = 'missed', ended_at = CURRENT_TIMESTAMP
      WHERE ride_id = ${rideId}
        AND status = 'ringing'
        AND created_at < CURRENT_TIMESTAMP - make_interval(secs => ${RINGING_TTL_SECONDS})
    `;

    const rows = await sql<CallRow>`
      SELECT id, ride_id, caller_type, status, sdp_offer, sdp_answer,
             started_at, ended_at, created_at
      FROM calls
      WHERE ride_id = ${rideId}
      ORDER BY created_at DESC
      LIMIT 1
    `;

    const call = rows[0] ?? null;
    return Response.json({
      data: call
        ? { ...call, is_caller: call.caller_type === participant.role }
        : null,
    });
  } catch (error) {
    console.error("[GET_CALL]: ", error);
    return Response.json({ error: "Internal Server Error." }, { status: 500 });
  }
}

// PATCH — answer (callee only), decline (callee only), or end (either).
export async function PATCH(req: Request, { id }: { id: string }) {
  const rideId = Number(id);
  if (!Number.isInteger(rideId)) {
    return Response.json({ error: "Invalid ride id." }, { status: 400 });
  }

  const participant = await requireRideParticipant(req, rideId);
  if ("error" in participant) return participant.error;

  let body: { action?: string; sdp_answer?: string };
  try {
    body = await req.json();
  } catch {
    return Response.json({ error: "Invalid JSON body." }, { status: 400 });
  }

  const action = body.action;
  if (action !== "answer" && action !== "decline" && action !== "end") {
    return Response.json(
      { error: "action must be 'answer', 'decline', or 'end'." },
      { status: 400 },
    );
  }

  try {
    // Answer/decline are the callee's moves; end is either party's.
    const isCaller = (callerType: string) => callerType === participant.role;
    const rows = await sql<{ caller_type: string; status: string }>`
      SELECT caller_type, status FROM calls
      WHERE ride_id = ${rideId} AND status IN ('ringing','answered')
      ORDER BY created_at DESC LIMIT 1
    `;
    const call = rows[0];
    if (!call) {
      return Response.json(
        { error: "No active call for this ride." },
        { status: 409 },
      );
    }

    if (action === "answer") {
      if (isCaller(call.caller_type)) {
        return Response.json(
          { error: "Caller cannot answer their own call." },
          { status: 403 },
        );
      }
      if (call.status !== "ringing") {
        return Response.json(
          { error: "Call is no longer ringing." },
          { status: 409 },
        );
      }
      const sdpAnswer = body.sdp_answer;
      if (!sdpAnswer || typeof sdpAnswer !== "string") {
        return Response.json({ error: "Missing sdp_answer." }, { status: 400 });
      }
      await sql`
        UPDATE calls
        SET status = 'answered', sdp_answer = ${sdpAnswer}, started_at = CURRENT_TIMESTAMP
        WHERE ride_id = ${rideId} AND status = 'ringing'
      `;
      return Response.json({ data: { action: "answered" } });
    }

    if (action === "decline") {
      if (isCaller(call.caller_type)) {
        return Response.json(
          { error: "Caller cannot decline their own call." },
          { status: 403 },
        );
      }
      await sql`
        UPDATE calls
        SET status = 'declined', ended_at = CURRENT_TIMESTAMP
        WHERE ride_id = ${rideId} AND status = 'ringing'
      `;
      return Response.json({ data: { action: "declined" } });
    }

    // end — either party, while ringing or answered.
    await sql`
      UPDATE calls
      SET status = 'ended', ended_at = CURRENT_TIMESTAMP
      WHERE ride_id = ${rideId} AND status IN ('ringing','answered')
    `;
    return Response.json({ data: { action: "ended" } });
  } catch (error) {
    console.error("[PATCH_CALL]: ", error);
    return Response.json({ error: "Internal Server Error." }, { status: 500 });
  }
}