// Copyright 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package events_test

import (
	"sync"
	"sync/atomic"

	"github.com/apid/apid-core"
	"github.com/apid/apid-core/events"
	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"

	"strconv"
)

var _ = Describe("Events Service", func() {

	Context("local", func() {

		var em apid.EventsService

		BeforeEach(func() {
			em = events.CreateService()
		})

		AfterEach(func() {
			if em != nil {
				em.Close()
				em = nil
			}
		})

		It("should ignore event with no listeners", func() {
			em.Emit("no listeners", &test_event{"test"})
		})

		It("should publish an event to a listener", func(done Done) {
			h := test_handler{
				"handler",
				func(event apid.Event) {
					close(done)
				},
			}

			em.Listen("selector", &h)
			em.Emit("selector", &test_event{"test"})
		})

		It("should publish an event to a listener func", func(done Done) {
			h := func(event apid.Event) {
				close(done)
			}

			em.ListenFunc("selector", h)
			em.Emit("selector", &test_event{"test"})
		})

		It("should publish multiple events to a listener", func(done Done) {
			count := int32(0)
			h := test_handler{
				"handler",
				func(event apid.Event) {
					defer GinkgoRecover()

					c := atomic.AddInt32(&count, 1)
					if c > 1 {
						close(done)
					}
				},
			}

			em.Listen("selector", &h)
			em.Emit("selector", &test_event{"test1"})
			em.Emit("selector", &test_event{"test2"})
		})

		It("EmitWithCallback should call the callback when done with delivery", func(done Done) {
			delivered := func(event apid.Event) {
				close(done)
			}

			em.EmitWithCallback("selector", &test_event{"test1"}, delivered)
		})

		It("should publish only one event to a listenOnce", func(done Done) {
			count := 0
			h := func(event apid.Event) {
				defer GinkgoRecover()
				count++
			}

			delivered := func(event apid.Event) {
				defer GinkgoRecover()
				Expect(count).To(Equal(1))
				close(done)
			}

			em.ListenOnceFunc("selector", h)
			em.Emit("selector", &test_event{"test1"})
			em.EmitWithCallback("selector", &test_event{"test2"}, delivered)
		})

		It("should publish an event to multiple listeners", func(done Done) {
			mut := sync.Mutex{}
			hitH1 := false
			hitH2 := false
			h1 := test_handler{
				"handler 1",
				func(event apid.Event) {
					defer GinkgoRecover()
					mut.Lock()
					defer mut.Unlock()
					hitH1 = true
					if hitH1 && hitH2 {
						close(done)
					}
				},
			}
			h2 := test_handler{
				"handler 2",
				func(event apid.Event) {
					defer GinkgoRecover()
					mut.Lock()
					defer mut.Unlock()
					hitH2 = true
					if hitH1 && hitH2 {
						close(done)
					}
				},
			}

			em.Listen("selector", &h1)
			em.Listen("selector", &h2)
			em.Emit("selector", &test_event{"test"})
		})

		It("should publish an event delivered event", func(done Done) {
			testEvent := &test_event{"test"}
			var testSelector apid.EventSelector = "selector"

			dummy := func(event apid.Event) {}
			em.ListenFunc(testSelector, dummy)

			h := test_handler{
				"event delivered handler",
				func(event apid.Event) {
					defer GinkgoRecover()

					e, ok := event.(apid.EventDeliveryEvent)

					Expect(ok).To(BeTrue())
					Expect(e.Event).To(Equal(testEvent))
					Expect(e.Selector).To(Equal(testSelector))

					close(done)
				},
			}

			em.Listen(apid.EventDeliveredSelector, &h)
			em.Emit(testSelector, testEvent)
		})

		It("should be able to remove a listener", func(done Done) {
			event1 := &test_event{"test1"}
			event2 := &test_event{"test2"}
			event3 := &test_event{"test3"}

			dummy := func(event apid.Event) {}
			em.ListenFunc("selector", dummy)

			h := test_handler{
				"handler",
				func(event apid.Event) {
					defer GinkgoRecover()

					Expect(event).NotTo(Equal(event2))
					if event == event3 {
						close(done)
					}
				},
			}
			em.Listen("selector", &h)

			// need to drive test like this because of async delivery
			var td apid.EventHandler
			td = &test_handler{
				"test driver",
				func(event apid.Event) {
					defer GinkgoRecover()

					e := event.(apid.EventDeliveryEvent)
					if e.Event == event1 {
						em.StopListening("selector", &h)
						em.Emit("selector", event2)
					} else if e.Event == event2 {
						em.StopListening(apid.EventDeliveredSelector, td)
						em.Listen("selector", &h)
						em.Emit("selector", event3)
					}
				},
			}
			em.Listen(apid.EventDeliveredSelector, td)

			em.Emit("selector", event1)
		})

		It("should deliver events according selector", func(done Done) {
			e1 := &test_event{"test1"}
			e2 := &test_event{"test2"}

			count := int32(0)

			h1 := test_handler{
				"handler1",
				func(event apid.Event) {
					defer GinkgoRecover()

					c := atomic.AddInt32(&count, 1)
					Expect(event).Should(Equal(e1))
					if c == 2 {
						close(done)
					}
				},
			}

			h2 := test_handler{
				"handler2",
				func(event apid.Event) {
					defer GinkgoRecover()

					c := atomic.AddInt32(&count, 1)
					Expect(event).Should(Equal(e2))
					if c == 2 {
						close(done)
					}
				},
			}

			em.Listen("selector1", &h1)
			em.Listen("selector2", &h2)

			em.Emit("selector2", e2)
			em.Emit("selector1", e1)
		})
	})

	Context("plugins", func() {

		BeforeEach(func() {
		})

		AfterEach(func() {
			apid.Events().Close()
		})

		It("should publish PluginsInitialized event", func(done Done) {
			xData := make(map[string]interface{})
			xData["schemaVersion"] = "1.2.3"
			p := func(s apid.Services) (pd apid.PluginData, err error) {
				pd = apid.PluginData{
					Name:      "test plugin",
					Version:   "1.0.0",
					ExtraData: xData,
				}
				return
			}
			apid.RegisterPlugin(p)

			h := func(event apid.Event) {
				defer GinkgoRecover()

				if pie, ok := event.(apid.PluginsInitializedEvent); ok {

					Expect(len(pie.Plugins)).Should(Equal(1))
					p := pie.Plugins[0]
					Expect(p.Name).To(Equal("test plugin"))
					Expect(p.Version).To(Equal("1.0.0"))
					Expect(p.ExtraData["schemaVersion"]).To(Equal("1.2.3"))

					close(done)
				}
			}
			apid.Events().ListenFunc(apid.SystemEventsSelector, h)

			apid.InitializePlugins("")
		})

		It("shutdown event should be emitted and listened successfully", func(done Done) {
			h := func(event apid.Event) {
				defer GinkgoRecover()

				if pie, ok := event.(apid.ShutdownEvent); ok {
					Expect(pie.Description).Should(Equal("apid is going to shutdown"))
				} else {
					Fail("Received wrong event")
				}
			}
			apid.Events().ListenFunc(apid.ShutdownEventSelector, h)
			<- apid.Events().Emit(apid.ShutdownEventSelector, apid.ShutdownEvent{"apid is going to shutdown"})
			close(done)
		})

		It("handlers registered by plugins should execute before apid shutdown", func(done Done) {
			pluginNum := 10
			count := int32(0)
			countP := &count

			// create and register plugins, listen to shutdown event
			for i:=0; i<pluginNum; i++ {
				apid.RegisterPlugin(createDummyPlugin(i))
				h := func(event apid.Event) {
					if pie, ok := event.(apid.ShutdownEvent); ok {
						Expect(pie.Description).Should(Equal("apid is going to shutdown"))
						atomic.AddInt32(countP, 1)
					} else {
						Fail("Received wrong event")
					}
				}
				apid.Events().ListenFunc(apid.ShutdownEventSelector, h)
			}


			apid.InitializePlugins("")

			apid.ShutdownPluginsAndWait()

			// handlers of all registered plugins have executed
			Expect(count).Should(Equal(int32(pluginNum)))
			close(done)
		})

		It("should be able to read apid version from PluginsInitialized event", func(done Done) {
			xData := make(map[string]interface{})
			xData["schemaVersion"] = "1.2.3"
			p := func(s apid.Services) (pd apid.PluginData, err error) {
				pd = apid.PluginData{
					Name:      "test plugin",
					Version:   "1.0.0",
					ExtraData: xData,
				}
				return
			}
			apid.RegisterPlugin(p)

			apidVersion := "dummy_version"

			h := func(event apid.Event) {
				defer GinkgoRecover()

				if pie, ok := event.(apid.PluginsInitializedEvent); ok {
					Expect(pie.ApidVersion).To(Equal(apidVersion))
					close(done)
				}
			}
			apid.Events().ListenFunc(apid.SystemEventsSelector, h)

			apid.InitializePlugins(apidVersion)
		})
	})
})

func createDummyPlugin(id int) apid.PluginInitFunc{
	xData := make(map[string]interface{})
	xData["schemaVersion"] = "1.2.3"
	p := func(s apid.Services) (pd apid.PluginData, err error) {
		pd = apid.PluginData{
			Name: "test plugin " + strconv.Itoa(id),
			Version: "1.0.0",
			ExtraData: xData,
		}
		return
	}
	return p
}

type test_handler struct {
	description string
	f           func(event apid.Event)
}

func (t *test_handler) String() string {
	return t.description
}

func (t *test_handler) Handle(event apid.Event) {
	t.f(event)
}

type test_event struct {
	description string
}