package notify

import (
	"context"
	"io"
	"time"
)

const defaultRecordCloseTimeout = 5 * time.Second

type recordCloseMode uint8

const (
	recordCloseNone recordCloseMode = iota
	recordCloseWrite
	recordCloseFull
)

func (r *recordStream) CloseWrite() error {
	if r == nil {
		return errRecordStreamNil
	}
	return r.closeRecord(recordCloseWrite)
}

func (r *recordStream) Close() error {
	if r == nil {
		return nil
	}
	return r.closeRecord(recordCloseFull)
}

func (r *recordStream) closeRecord(mode recordCloseMode) error {
	r.closeMu.Lock()
	defer r.closeMu.Unlock()
	if r.closeDone {
		return r.closeErr
	}
	if mode == recordCloseWrite && r.halfClosed {
		return nil
	}
	r.mu.Lock()
	r.outboundClosed = true
	target := r.enqueuedOutboundSeq
	err := r.streamErrorLocked()
	r.signalStateLocked()
	r.mu.Unlock()
	if err != nil {
		r.abortUnderlyingStream(err)
		r.closeDone, r.closeErr = true, err
		return err
	}
	timeout := r.cfg.CloseTimeout
	if timeout <= 0 {
		timeout = defaultRecordCloseTimeout
	}
	// A successful underlying Close can itself cancel the stream context.
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()
	err = r.flushAndClose(ctx, target, mode)
	if err != nil {
		r.setTerminalError(err)
		r.abortUnderlyingStream(err)
		r.closeDone, r.closeErr = true, err
		return err
	}
	if mode == recordCloseFull {
		r.setTerminalError(io.ErrClosedPipe)
		r.closeDone = true
	} else {
		r.halfClosed = true
	}
	return nil
}

func (r *recordStream) flushAndClose(ctx context.Context, target uint64, mode recordCloseMode) error {
	req := recordFlushRequest{
		ctx: ctx, targetSeq: target, forceAck: true, closeMode: mode,
		done: make(chan error, 1),
	}
	select {
	case <-r.ctx.Done():
		return r.streamError()
	case <-ctx.Done():
		return ctx.Err()
	case r.flushCh <- req:
	}
	select {
	case err := <-req.done:
		return err
	case <-r.writerCh:
		select {
		case err := <-req.done:
			return err
		default:
			return r.streamError()
		}
	case <-ctx.Done():
		select {
		case err := <-req.done:
			return err
		default:
			return ctx.Err()
		}
	}
}

// The writer serializes the last data, final ACK and close control message.
func (r *recordStream) closeUnderlyingFromWriter(req recordFlushRequest) error {
	if err := req.ctx.Err(); err != nil {
		return err
	}
	if req.closeMode == recordCloseWrite && r.useHalfClose {
		return r.writePayloadFrame(encodeRecordFINFrame(req.targetSeq))
	}
	deadline, _ := req.ctx.Deadline()
	if err := r.stream.SetWriteDeadline(deadline); err != nil {
		return err
	}
	if req.closeMode == recordCloseFull {
		return r.stream.Close()
	}
	return r.stream.CloseWrite()
}

func (r *recordStream) abortUnderlyingStream(err error) {
	if stream, ok := r.stream.(*streamHandle); ok {
		stream.mu.Lock()
		resetFn := stream.resetFn
		stream.mu.Unlock()
		// Local teardown must not wait for a reset reply from a stalled peer.
		if !stream.applyResetState(err) {
			return
		}
		if resetFn != nil {
			go func() {
				ctx, cancel := context.WithTimeout(context.Background(), defaultRecordCloseTimeout)
				defer cancel()
				_ = resetFn(ctx, stream, streamResetMessage(err))
			}()
		}
		return
	}
	_ = r.stream.SetDeadline(time.Now())
	_ = r.stream.Reset(err)
}

func (r *recordStream) abortRecord(err error) {
	r.setTerminalError(err)
	r.abortUnderlyingStream(err)
}

func (r *recordStream) abortProtocol(err error) {
	r.setTerminalError(err)
	_ = r.notifyFailureAndAbort(RecordFailure{
		FailedSeq: r.nextInboundFailureSeq(),
		Code:      RecordErrorCodeProtocol,
		Message:   err.Error(),
	})
}

func (r *recordStream) abortTimeout() time.Duration {
	if r.cfg.CloseTimeout > 0 && r.cfg.CloseTimeout < defaultRecordCloseTimeout {
		return r.cfg.CloseTimeout
	}
	return defaultRecordCloseTimeout
}

func (r *recordStream) closeReceive() {
	r.recvCloseOnce.Do(func() { close(r.recvCh) })
}

func (r *recordStream) receiveFIN(finalSeq uint64) error {
	r.mu.Lock()
	if !r.useHalfClose || r.inboundClosed || finalSeq != r.inboundReceivedSeq {
		r.mu.Unlock()
		return errRecordSeqInvalid
	}
	r.inboundClosed = true
	r.mu.Unlock()
	// The reader owns recvCh; it keeps consuming control frames after data EOF.
	r.closeReceive()
	return nil
}