package notify

import (
	"context"
	"net"
	"sync"
)

type bulkDedicatedSidecar struct {
	laneID    uint32
	conn      net.Conn
	closeOnce sync.Once

	senderMu sync.Mutex
	sender   *bulkDedicatedLaneSender
}

type bulkDedicatedLane struct {
	id           uint32
	activeBulks  int
	sidecar      *bulkDedicatedSidecar
	attachFlight *bulkDedicatedAttachFlight
}

type bulkDedicatedAttachFlight struct {
	done chan struct{}
	once sync.Once
	err  error
}

func normalizeBulkDedicatedLaneID(laneID uint32) uint32 {
	if laneID == 0 {
		return 1
	}
	return laneID
}

func newBulkDedicatedSidecar(conn net.Conn, laneID uint32) *bulkDedicatedSidecar {
	if conn == nil {
		return nil
	}
	return &bulkDedicatedSidecar{
		laneID: normalizeBulkDedicatedLaneID(laneID),
		conn:   conn,
	}
}

func newBulkDedicatedAttachFlight() *bulkDedicatedAttachFlight {
	return &bulkDedicatedAttachFlight{
		done: make(chan struct{}),
	}
}

func (f *bulkDedicatedAttachFlight) finish(err error) {
	if f == nil {
		return
	}
	f.once.Do(func() {
		f.err = err
		close(f.done)
	})
}

func (f *bulkDedicatedAttachFlight) wait(ctx context.Context) error {
	if f == nil {
		return nil
	}
	if ctx == nil {
		ctx = context.Background()
	}
	select {
	case <-ctx.Done():
		return ctx.Err()
	case <-f.done:
		return f.err
	}
}

func (s *bulkDedicatedSidecar) close() {
	if s == nil {
		return
	}
	s.closeOnce.Do(func() {
		if sender := s.laneSenderSnapshot(); sender != nil {
			sender.stop()
		}
		if s.conn != nil {
			_ = s.conn.Close()
		}
	})
}

func (s *bulkDedicatedSidecar) laneSenderSnapshot() *bulkDedicatedLaneSender {
	if s == nil {
		return nil
	}
	s.senderMu.Lock()
	defer s.senderMu.Unlock()
	return s.sender
}

func (s *bulkDedicatedSidecar) laneSenderWithFactory(factory func(net.Conn) *bulkDedicatedLaneSender) *bulkDedicatedLaneSender {
	if s == nil || factory == nil {
		return nil
	}
	s.senderMu.Lock()
	defer s.senderMu.Unlock()
	if s.sender != nil {
		return s.sender
	}
	if s.conn == nil {
		return nil
	}
	s.sender = factory(s.conn)
	return s.sender
}

func (c *ClientCommon) clientDedicatedSidecarSnapshot() *bulkDedicatedSidecar {
	if c == nil {
		return nil
	}
	c.bulkDedicatedSidecarMu.Lock()
	defer c.bulkDedicatedSidecarMu.Unlock()
	return firstClientDedicatedSidecarLocked(c.bulkDedicatedLanes)
}

func firstClientDedicatedSidecarLocked(lanes map[uint32]*bulkDedicatedLane) *bulkDedicatedSidecar {
	var (
		selected *bulkDedicatedSidecar
		bestID   uint32
	)
	for laneID, lane := range lanes {
		if lane == nil || lane.sidecar == nil {
			continue
		}
		if selected == nil || laneID < bestID {
			selected = lane.sidecar
			bestID = laneID
		}
	}
	return selected
}

func (c *ClientCommon) reserveBulkDedicatedLane() uint32 {
	if c == nil {
		return normalizeBulkDedicatedLaneID(0)
	}
	c.bulkDedicatedSidecarMu.Lock()
	defer c.bulkDedicatedSidecarMu.Unlock()
	if c.bulkDedicatedLanes == nil {
		c.bulkDedicatedLanes = make(map[uint32]*bulkDedicatedLane)
	}
	limit := c.bulkDedicatedLaneLimitSnapshot()
	var best *bulkDedicatedLane
	for _, lane := range c.bulkDedicatedLanes {
		if lane == nil {
			continue
		}
		if best == nil || lane.activeBulks < best.activeBulks || (lane.activeBulks == best.activeBulks && lane.id < best.id) {
			best = lane
		}
	}
	if best == nil || ((limit <= 0 || len(c.bulkDedicatedLanes) < limit) && best.activeBulks > 0) {
		c.bulkDedicatedNextLaneID++
		laneID := normalizeBulkDedicatedLaneID(c.bulkDedicatedNextLaneID)
		best = &bulkDedicatedLane{id: laneID}
		c.bulkDedicatedLanes[laneID] = best
	}
	best.activeBulks++
	return best.id
}

func (c *ClientCommon) releaseBulkDedicatedLane(laneID uint32) {
	if c == nil {
		return
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	c.bulkDedicatedSidecarMu.Lock()
	defer c.bulkDedicatedSidecarMu.Unlock()
	lane := c.bulkDedicatedLanes[laneID]
	if lane == nil {
		return
	}
	if lane.activeBulks > 0 {
		lane.activeBulks--
	}
	if lane.activeBulks == 0 && lane.sidecar == nil && lane.attachFlight == nil {
		delete(c.bulkDedicatedLanes, laneID)
	}
}

func (c *ClientCommon) clientDedicatedSidecarSnapshotForLane(laneID uint32) *bulkDedicatedSidecar {
	if c == nil {
		return nil
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	c.bulkDedicatedSidecarMu.Lock()
	defer c.bulkDedicatedSidecarMu.Unlock()
	if lane := c.bulkDedicatedLanes[laneID]; lane != nil {
		return lane.sidecar
	}
	return nil
}

func (c *ClientCommon) beginClientDedicatedSidecarAttach(laneID uint32) (*bulkDedicatedSidecar, *bulkDedicatedAttachFlight, bool) {
	if c == nil {
		return nil, nil, false
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	c.bulkDedicatedSidecarMu.Lock()
	defer c.bulkDedicatedSidecarMu.Unlock()
	if c.bulkDedicatedLanes == nil {
		c.bulkDedicatedLanes = make(map[uint32]*bulkDedicatedLane)
	}
	lane := c.bulkDedicatedLanes[laneID]
	if lane == nil {
		lane = &bulkDedicatedLane{id: laneID}
		c.bulkDedicatedLanes[laneID] = lane
	}
	if lane.sidecar != nil {
		return lane.sidecar, nil, false
	}
	if lane.attachFlight != nil {
		return nil, lane.attachFlight, false
	}
	flight := newBulkDedicatedAttachFlight()
	lane.attachFlight = flight
	return nil, flight, true
}

func (c *ClientCommon) finishClientDedicatedSidecarAttach(laneID uint32, flight *bulkDedicatedAttachFlight, err error) {
	if c == nil || flight == nil {
		return
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	c.bulkDedicatedSidecarMu.Lock()
	if lane := c.bulkDedicatedLanes[laneID]; lane != nil && lane.attachFlight == flight {
		lane.attachFlight = nil
		if lane.activeBulks == 0 && lane.sidecar == nil {
			delete(c.bulkDedicatedLanes, laneID)
		}
	}
	c.bulkDedicatedSidecarMu.Unlock()
	flight.finish(err)
}

func (c *ClientCommon) installClientDedicatedSidecar(laneID uint32, sidecar *bulkDedicatedSidecar) (*bulkDedicatedSidecar, bool) {
	if c == nil || sidecar == nil {
		return nil, false
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	c.bulkDedicatedSidecarMu.Lock()
	defer c.bulkDedicatedSidecarMu.Unlock()
	if c.bulkDedicatedLanes == nil {
		c.bulkDedicatedLanes = make(map[uint32]*bulkDedicatedLane)
	}
	lane := c.bulkDedicatedLanes[laneID]
	if lane == nil {
		lane = &bulkDedicatedLane{id: laneID}
		c.bulkDedicatedLanes[laneID] = lane
	}
	if lane.sidecar != nil {
		return lane.sidecar, false
	}
	lane.sidecar = sidecar
	return sidecar, true
}

func (c *ClientCommon) clearClientDedicatedSidecar(laneID uint32, sidecar *bulkDedicatedSidecar) bool {
	if c == nil || sidecar == nil {
		return false
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	c.bulkDedicatedSidecarMu.Lock()
	defer c.bulkDedicatedSidecarMu.Unlock()
	lane := c.bulkDedicatedLanes[laneID]
	if lane == nil || lane.sidecar != sidecar {
		return false
	}
	lane.sidecar = nil
	if lane.activeBulks == 0 && lane.attachFlight == nil {
		delete(c.bulkDedicatedLanes, laneID)
	}
	return true
}

func (c *ClientCommon) closeClientDedicatedSidecar() {
	if c == nil {
		return
	}
	c.bulkDedicatedSidecarMu.Lock()
	lanes := c.bulkDedicatedLanes
	c.bulkDedicatedLanes = make(map[uint32]*bulkDedicatedLane)
	c.bulkDedicatedSidecarMu.Unlock()
	for _, lane := range lanes {
		if lane == nil {
			continue
		}
		if lane.sidecar != nil {
			lane.sidecar.close()
		}
		if lane.attachFlight != nil {
			lane.attachFlight.finish(errServiceShutdown)
		}
	}
}

func (c *ClientCommon) handleClientDedicatedSidecarFailure(sidecar *bulkDedicatedSidecar, err error) {
	if c == nil || sidecar == nil {
		return
	}
	if !c.clearClientDedicatedSidecar(sidecar.laneID, sidecar) {
		return
	}
	runtime := c.getBulkRuntime()
	if runtime != nil && sidecar.conn != nil {
		runtime.handleDedicatedReadErrorByConn(clientFileScope(), sidecar.conn, err)
	}
	sidecar.close()
}

func (s *ServerCommon) serverDedicatedSidecarSnapshot(logical *LogicalConn) *bulkDedicatedSidecar {
	if s == nil || logical == nil {
		return nil
	}
	s.bulkDedicatedSidecarMu.Lock()
	defer s.bulkDedicatedSidecarMu.Unlock()
	return firstServerDedicatedSidecarLocked(s.bulkDedicatedSidecars[logical])
}

func firstServerDedicatedSidecarLocked(lanes map[uint32]*bulkDedicatedSidecar) *bulkDedicatedSidecar {
	var (
		selected *bulkDedicatedSidecar
		bestID   uint32
	)
	for laneID, sidecar := range lanes {
		if sidecar == nil {
			continue
		}
		if selected == nil || laneID < bestID {
			selected = sidecar
			bestID = laneID
		}
	}
	return selected
}

func (s *ServerCommon) serverDedicatedSidecarSnapshotForLane(logical *LogicalConn, laneID uint32) *bulkDedicatedSidecar {
	if s == nil || logical == nil {
		return nil
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	s.bulkDedicatedSidecarMu.Lock()
	defer s.bulkDedicatedSidecarMu.Unlock()
	if lanes := s.bulkDedicatedSidecars[logical]; lanes != nil {
		return lanes[laneID]
	}
	return nil
}

func (s *ServerCommon) installServerDedicatedSidecar(logical *LogicalConn, laneID uint32, sidecar *bulkDedicatedSidecar) *bulkDedicatedSidecar {
	if s == nil || logical == nil || sidecar == nil {
		return nil
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	s.bulkDedicatedSidecarMu.Lock()
	defer s.bulkDedicatedSidecarMu.Unlock()
	lanes := s.bulkDedicatedSidecars[logical]
	if lanes == nil {
		lanes = make(map[uint32]*bulkDedicatedSidecar)
		s.bulkDedicatedSidecars[logical] = lanes
	}
	prev := lanes[laneID]
	lanes[laneID] = sidecar
	return prev
}

func (s *ServerCommon) clearServerDedicatedSidecar(logical *LogicalConn, laneID uint32, sidecar *bulkDedicatedSidecar) bool {
	if s == nil || logical == nil || sidecar == nil {
		return false
	}
	laneID = normalizeBulkDedicatedLaneID(laneID)
	s.bulkDedicatedSidecarMu.Lock()
	defer s.bulkDedicatedSidecarMu.Unlock()
	lanes := s.bulkDedicatedSidecars[logical]
	if lanes == nil || lanes[laneID] != sidecar {
		return false
	}
	delete(lanes, laneID)
	if len(lanes) == 0 {
		delete(s.bulkDedicatedSidecars, logical)
	}
	return true
}

func (s *ServerCommon) closeServerDedicatedSidecar(logical *LogicalConn) {
	if s == nil || logical == nil {
		return
	}
	s.bulkDedicatedSidecarMu.Lock()
	lanes := s.bulkDedicatedSidecars[logical]
	delete(s.bulkDedicatedSidecars, logical)
	s.bulkDedicatedSidecarMu.Unlock()
	for _, sidecar := range lanes {
		if sidecar != nil {
			sidecar.close()
		}
	}
}

func (s *ServerCommon) closeAllServerDedicatedSidecars() {
	if s == nil {
		return
	}
	s.bulkDedicatedSidecarMu.Lock()
	lanesByLogical := s.bulkDedicatedSidecars
	s.bulkDedicatedSidecars = make(map[*LogicalConn]map[uint32]*bulkDedicatedSidecar)
	s.bulkDedicatedSidecarMu.Unlock()
	for _, lanes := range lanesByLogical {
		for _, sidecar := range lanes {
			if sidecar != nil {
				sidecar.close()
			}
		}
	}
}

func (s *ServerCommon) handleServerDedicatedSidecarFailure(logical *LogicalConn, sidecar *bulkDedicatedSidecar, err error) {
	if s == nil || logical == nil || sidecar == nil {
		return
	}
	if !s.clearServerDedicatedSidecar(logical, sidecar.laneID, sidecar) {
		return
	}
	runtime := s.getBulkRuntime()
	if runtime != nil && sidecar.conn != nil {
		runtime.handleDedicatedReadErrorByConn(serverFileScope(logical), sidecar.conn, err)
	}
	sidecar.close()
}

func (s *ServerCommon) attachServerDedicatedSidecarIfExists(logical *LogicalConn, bulk *bulkHandle) {
	if s == nil || logical == nil || bulk == nil || !bulk.Dedicated() {
		return
	}
	sidecar := s.serverDedicatedSidecarSnapshotForLane(logical, bulk.dedicatedLaneIDSnapshot())
	if sidecar == nil || sidecar.conn == nil {
		return
	}
	_ = bulk.attachDedicatedConnShared(sidecar.conn)
}