package state

import (
	"testing"
)

// verifyWatch will set up a watch channel, call the given function, and then
// make sure the watch fires.
func verifyWatch(t *testing.T, watch Watch, fn func()) {
	ch := make(chan struct{}, 1)
	watch.Wait(ch)

	fn()

	select {
	case <-ch:
	default:
		t.Fatalf("watch should have been notified")
	}
}

// verifyNoWatch will set up a watch channel, call the given function, and then
// make sure the watch never fires.
func verifyNoWatch(t *testing.T, watch Watch, fn func()) {
	ch := make(chan struct{}, 1)
	watch.Wait(ch)

	fn()

	select {
	case <-ch:
		t.Fatalf("watch should not been notified")
	default:
	}
}

func TestWatch_FullTableWatch(t *testing.T) {
	w := NewFullTableWatch()

	// Test the basic trigger with a single watcher.
	verifyWatch(t, w, func() {
		w.Notify()
	})

	// Run multiple watchers and make sure they both fire.
	verifyWatch(t, w, func() {
		verifyWatch(t, w, func() {
			w.Notify()
		})
	})

	// Make sure clear works.
	ch := make(chan struct{}, 1)
	w.Wait(ch)
	w.Clear(ch)
	w.Notify()
	select {
	case <-ch:
		t.Fatalf("watch should not have been notified")
	default:
	}

	// Make sure notify is a one shot.
	w.Wait(ch)
	w.Notify()
	select {
	case <-ch:
	default:
		t.Fatalf("watch should have been notified")
	}
	w.Notify()
	select {
	case <-ch:
		t.Fatalf("watch should not have been notified")
	default:
	}
}

func TestWatch_DumbWatchManager(t *testing.T) {
	watches := map[string]*FullTableWatch{
		"alice": NewFullTableWatch(),
		"bob":   NewFullTableWatch(),
		"carol": NewFullTableWatch(),
	}

	// Notify with nothing armed and make sure nothing triggers.
	func() {
		w := NewDumbWatchManager(watches)
		verifyNoWatch(t, watches["alice"], func() {
			verifyNoWatch(t, watches["bob"], func() {
				verifyNoWatch(t, watches["carol"], func() {
					w.Notify()
				})
			})
		})
	}()

	// Trigger one watch.
	func() {
		w := NewDumbWatchManager(watches)
		verifyWatch(t, watches["alice"], func() {
			verifyNoWatch(t, watches["bob"], func() {
				verifyNoWatch(t, watches["carol"], func() {
					w.Arm("alice")
					w.Notify()
				})
			})
		})
	}()

	// Trigger two watches.
	func() {
		w := NewDumbWatchManager(watches)
		verifyWatch(t, watches["alice"], func() {
			verifyNoWatch(t, watches["bob"], func() {
				verifyWatch(t, watches["carol"], func() {
					w.Arm("alice")
					w.Arm("carol")
					w.Notify()
				})
			})
		})
	}()

	// Trigger all three watches.
	func() {
		w := NewDumbWatchManager(watches)
		verifyWatch(t, watches["alice"], func() {
			verifyWatch(t, watches["bob"], func() {
				verifyWatch(t, watches["carol"], func() {
					w.Arm("alice")
					w.Arm("bob")
					w.Arm("carol")
					w.Notify()
				})
			})
		})
	}()

	// Trigger multiple times.
	func() {
		w := NewDumbWatchManager(watches)
		verifyWatch(t, watches["alice"], func() {
			verifyNoWatch(t, watches["bob"], func() {
				verifyNoWatch(t, watches["carol"], func() {
					w.Arm("alice")
					w.Arm("alice")
					w.Notify()
				})
			})
		})
	}()

	// Make sure it panics when asked to arm an unknown table.
	func() {
		defer func() {
			if r := recover(); r == nil {
				t.Fatalf("didn't get expected panic")
			}
		}()
		w := NewDumbWatchManager(watches)
		w.Arm("nope")
	}()
}

func TestWatch_PrefixWatch(t *testing.T) {
	w := NewPrefixWatch()

	// Hit a specific key.
	verifyWatch(t, w.GetSubwatch(""), func() {
		verifyWatch(t, w.GetSubwatch("foo/bar/baz"), func() {
			verifyNoWatch(t, w.GetSubwatch("foo/bar/zoo"), func() {
				verifyNoWatch(t, w.GetSubwatch("nope"), func() {
					w.Notify("foo/bar/baz", false)
				})
			})
		})
	})

	// Make sure cleanup is happening. All that should be left is the
	// full-table watch and the un-fired watches.
	fn := func(k string, v interface{}) bool {
		if k != "" && k != "foo/bar/zoo" && k != "nope" {
			t.Fatalf("unexpected watch: %s", k)
		}
		return false
	}
	w.watches.WalkPrefix("", fn)

	// Delete a subtree.
	verifyWatch(t, w.GetSubwatch(""), func() {
		verifyWatch(t, w.GetSubwatch("foo/bar/baz"), func() {
			verifyWatch(t, w.GetSubwatch("foo/bar/zoo"), func() {
				verifyNoWatch(t, w.GetSubwatch("nope"), func() {
					w.Notify("foo/", true)
				})
			})
		})
	})

	// Hit an unknown key.
	verifyWatch(t, w.GetSubwatch(""), func() {
		verifyNoWatch(t, w.GetSubwatch("foo/bar/baz"), func() {
			verifyNoWatch(t, w.GetSubwatch("foo/bar/zoo"), func() {
				verifyNoWatch(t, w.GetSubwatch("nope"), func() {
					w.Notify("not/in/there", false)
				})
			})
		})
	})
}

type MockWatch struct {
	Waits map[chan struct{}] int
	Clears map[chan struct{}] int
}

func NewMockWatch() *MockWatch {
	return &MockWatch{
		Waits:  make(map[chan struct{}] int),
		Clears: make(map[chan struct{}] int),
	}
}

func (m *MockWatch) Wait(notifyCh chan struct{}) {
	if _, ok := m.Waits[notifyCh]; ok {
		m.Waits[notifyCh]++
	} else {
		m.Waits[notifyCh] = 1
	}
}

func (m *MockWatch) Clear(notifyCh chan struct{}) {
	if _, ok := m.Clears[notifyCh]; ok {
		m.Clears[notifyCh]++
	} else {
		m.Clears[notifyCh] = 1
	}
}

func TestWatch_MultiWatch(t *testing.T) {
	w1, w2 := NewMockWatch(), NewMockWatch()
	w := NewMultiWatch(w1, w2)

	// Do some activity.
	c1, c2 := make(chan struct{}), make(chan struct{})
	w.Wait(c1)
	w.Clear(c1)
	w.Wait(c1)
	w.Wait(c2)
	w.Clear(c1)
	w.Clear(c2)

	// Make sure all the events were forwarded.
	if cnt, ok := w1.Waits[c1]; !ok || cnt != 2 {
		t.Fatalf("bad: %d", w1.Waits[c1])
	}
	if cnt, ok := w1.Clears[c1]; !ok || cnt != 2 {
		t.Fatalf("bad: %d", w1.Clears[c1])
	}
	if cnt, ok := w1.Waits[c2]; !ok || cnt != 1 {
		t.Fatalf("bad: %d", w1.Waits[c2])
	}
	if cnt, ok := w1.Clears[c2]; !ok || cnt != 1 {
		t.Fatalf("bad: %d", w1.Clears[c2])
	}
	if cnt, ok := w2.Waits[c1]; !ok || cnt != 2 {
		t.Fatalf("bad: %d", w2.Waits[c1])
	}
	if cnt, ok := w2.Clears[c1]; !ok || cnt != 2 {
		t.Fatalf("bad: %d", w2.Clears[c1])
	}
	if cnt, ok := w2.Waits[c2]; !ok || cnt != 1 {
		t.Fatalf("bad: %d", w2.Waits[c2])
	}
	if cnt, ok := w2.Clears[c2]; !ok || cnt != 1 {
		t.Fatalf("bad: %d", w2.Clears[c2])
	}
}