package notify

import (
	"b612.me/stario"
	"context"
	"errors"
	"net"
	"sync/atomic"
)

type clientSessionRuntime struct {
	transport             *transportBinding
	transportAttached     bool
	conn                  net.Conn
	stopCtx               context.Context
	stopFn                context.CancelFunc
	transportStopCtx      context.Context
	transportStopFn       context.CancelFunc
	queue                 *stario.StarQueue
	inboundDispatcher     *inboundDispatcher
	epoch                 uint64
	suppressGoodByeOnStop *atomic.Bool
}

func newClientSessionRuntimeBase(stopCtx context.Context, stopFn context.CancelFunc) *clientSessionRuntime {
	return &clientSessionRuntime{
		stopCtx:               stopCtx,
		stopFn:                stopFn,
		inboundDispatcher:     newInboundDispatcher(),
		suppressGoodByeOnStop: &atomic.Bool{},
	}
}

func prepareClientSessionRuntime(rt *clientSessionRuntime) *clientSessionRuntime {
	if rt == nil {
		return nil
	}
	if rt.inboundDispatcher == nil {
		rt.inboundDispatcher = newInboundDispatcher()
	}
	if rt.suppressGoodByeOnStop == nil {
		rt.suppressGoodByeOnStop = &atomic.Bool{}
	}
	if rt.transport == nil && rt.conn != nil {
		rt.transport = newTransportBinding(rt.conn, rt.queue)
	}
	normalizeClientSessionRuntimeTransportState(rt)
	ensureClientSessionRuntimeTransportLifecycle(rt)
	return rt
}

func (c *ClientCommon) setClientSessionRuntime(rt *clientSessionRuntime) {
	if c == nil || rt == nil {
		return
	}
	var oldBinding *transportBinding
	if prev := c.clientSessionRuntimeSnapshot(); prev != nil && prev.transport != nil && prev.transport != rt.transport {
		oldBinding = prev.transport
	}
	rt = prepareClientSessionRuntime(rt)
	c.sessionRuntime.Store(rt)
	c.stopCtx = rt.stopCtx
	c.stopFn = rt.stopFn
	if rt.transport != nil {
		c.queue = rt.transport.queueSnapshot()
		c.conn = rt.transport.connSnapshot()
	} else {
		c.queue = rt.queue
		c.conn = rt.conn
	}
	if oldBinding != nil {
		oldBinding.stopBackgroundWorkers()
	}
}

func (c *ClientCommon) resetClientSessionRuntimeBase() {
	if c == nil {
		return
	}
	stopCtx, stopFn := context.WithCancel(context.Background())
	c.sessionRuntime.Store(newClientSessionRuntimeBase(stopCtx, stopFn))
	c.conn = nil
	c.queue = nil
	c.stopCtx = stopCtx
	c.stopFn = stopFn
}

func (c *ClientCommon) cleanupFailedClientStart() {
	if c == nil {
		return
	}
	rt := c.clientSessionRuntimeSnapshot()
	if rt != nil && rt.stopFn != nil {
		rt.stopFn()
	}
	c.cleanupClientSessionResources()
	c.rollbackClientSessionStart()
	c.resetClientSessionRuntimeBase()
}

func newClientSessionRuntime(conn net.Conn, stopCtx context.Context, stopFn context.CancelFunc, queue *stario.StarQueue, epoch uint64) *clientSessionRuntime {
	return prepareClientSessionRuntime(&clientSessionRuntime{
		transport:             newTransportBinding(conn, queue),
		transportAttached:     conn != nil,
		conn:                  conn,
		stopCtx:               stopCtx,
		stopFn:                stopFn,
		queue:                 queue,
		inboundDispatcher:     newInboundDispatcher(),
		epoch:                 epoch,
		suppressGoodByeOnStop: &atomic.Bool{},
	})
}

func (rt *clientSessionRuntime) runtimeShouldSuppressGoodByeOnStop() bool {
	if rt == nil || rt.suppressGoodByeOnStop == nil {
		return false
	}
	return rt.suppressGoodByeOnStop.Load()
}

func (rt *clientSessionRuntime) markRuntimeSuppressGoodByeOnStop() {
	if rt == nil || rt.suppressGoodByeOnStop == nil {
		return
	}
	rt.suppressGoodByeOnStop.Store(true)
}

func (c *ClientCommon) retireClientSessionRuntime(rt *clientSessionRuntime, suppressGoodBye bool) {
	if c == nil || rt == nil {
		return
	}
	if suppressGoodBye {
		rt.markRuntimeSuppressGoodByeOnStop()
	}
	if rt.transportStopFn != nil {
		rt.transportStopFn()
	}
}

func (c *ClientCommon) clearClientSessionRuntimeTransport() {
	if c == nil {
		return
	}
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return
	}
	if rt.transportStopFn != nil {
		rt.transportStopFn()
	}
	next := *rt
	next.transport = nil
	next.transportAttached = false
	next.conn = nil
	next.transportStopCtx = nil
	next.transportStopFn = nil
	c.setClientSessionRuntime(&next)
}

func (c *ClientCommon) clearClientSessionRuntimeQueue() {
	if c == nil {
		return
	}
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return
	}
	next := *rt
	next.queue = nil
	if next.transport != nil {
		next.transport = newTransportBinding(next.transport.connSnapshot(), nil)
	}
	c.setClientSessionRuntime(&next)
}

func (c *ClientCommon) attachClientSessionTransport(conn net.Conn) error {
	if c == nil {
		return errors.New("client is nil")
	}
	if conn == nil {
		return errors.New("conn is nil")
	}
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return errors.New("client session runtime is nil")
	}
	if rt.queue == nil {
		return errClientSessionQueueUnavailable
	}
	oldBinding := rt.transport
	if rt.transportStopFn != nil {
		rt.transportStopFn()
	}
	next := *rt
	next.transport = newTransportBinding(conn, rt.queue)
	next.transportAttached = true
	next.conn = conn
	next.transportStopCtx = nil
	next.transportStopFn = nil
	next.suppressGoodByeOnStop = &atomic.Bool{}
	c.setClientSessionRuntime(&next)
	if oldConn := oldBinding.connSnapshot(); oldConn != nil && oldConn != conn {
		_ = oldConn.Close()
	}
	return c.startClientTransportRuntime(c.clientSessionRuntimeSnapshot())
}

func (c *ClientCommon) clientSessionRuntimeSnapshot() *clientSessionRuntime {
	if c == nil {
		return nil
	}
	return c.sessionRuntime.Load()
}

func normalizeClientSessionRuntimeTransportState(rt *clientSessionRuntime) {
	if rt == nil {
		return
	}
	if rt.transport != nil {
		rt.transportAttached = rt.transport.connSnapshot() != nil
		return
	}
	rt.transportAttached = rt.conn != nil
}

func ensureClientSessionRuntimeTransportLifecycle(rt *clientSessionRuntime) {
	if rt == nil {
		return
	}
	if rt.conn == nil {
		rt.transportStopCtx = nil
		rt.transportStopFn = nil
		return
	}
	if rt.transportStopCtx != nil && rt.transportStopFn != nil {
		return
	}
	parent := rt.stopCtx
	if parent == nil {
		parent = context.Background()
	}
	rt.transportStopCtx, rt.transportStopFn = context.WithCancel(parent)
}

func (c *ClientCommon) clientTransportConnSnapshot() net.Conn {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return nil
	}
	if rt.transport != nil {
		return rt.transport.connSnapshot()
	}
	return rt.conn
}

func (c *ClientCommon) clientInboundDispatcherSnapshot() *inboundDispatcher {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return nil
	}
	return rt.inboundDispatcher
}

func (c *ClientCommon) clientStopContextSnapshot() context.Context {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return nil
	}
	return rt.stopCtx
}

func (c *ClientCommon) clientStopFuncSnapshot() context.CancelFunc {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return nil
	}
	return rt.stopFn
}

func (c *ClientCommon) clientQueueSnapshot() *stario.StarQueue {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return nil
	}
	if rt.transport != nil {
		return rt.transport.queueSnapshot()
	}
	return rt.queue
}

func (c *ClientCommon) clientTransportBindingSnapshot() *transportBinding {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return nil
	}
	if rt.transport != nil {
		return rt.transport
	}
	if rt.conn == nil {
		return nil
	}
	return newTransportBinding(rt.conn, rt.queue)
}

func (c *ClientCommon) clientTransportStopContextSnapshot() context.Context {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return nil
	}
	if rt.transportStopCtx != nil {
		return rt.transportStopCtx
	}
	return rt.stopCtx
}

func (c *ClientCommon) clientTransportAttachedSnapshot() bool {
	rt := c.clientSessionRuntimeSnapshot()
	if rt == nil {
		return false
	}
	return rt.transportAttached
}