package dialogue

import (
	"testing"
	"time"
)

func parked(text string, asked time.Time) *PendingQuestion {
	return &PendingQuestion{
		Intent:    IntentReminder,
		Missing:   []Slot{SlotTime},
		Utterance: text,
		Asked:     asked,
		TTL:       time.Minute,
	}
}

func TestStackPushPeekPop(t *testing.T) {
	s := NewClarifyStore(time.Minute)
	if dropped := s.Push("voice", parked("напомни позвонить маме", pendingBase)); dropped != nil {
		t.Fatalf("first push dropped %q", dropped.Utterance)
	}
	if dropped := s.Push("voice", parked("погода в риме", pendingBase)); dropped != nil {
		t.Fatalf("second push dropped %q", dropped.Utterance)
	}
	if got := s.Depth("voice"); got != 2 {
		t.Fatalf("depth = %d, want 2", got)
	}
	if got := s.Peek("voice", pendingBase); got == nil || got.Utterance != "погода в риме" {
		t.Fatalf("peek = %+v, want the newest", got)
	}
	// Peek must not consume: two peeks are the same question.
	if got := s.Peek("voice", pendingBase); got == nil || got.Utterance != "погода в риме" {
		t.Fatalf("second peek = %+v, want the newest still", got)
	}
	got := s.Pop("voice", pendingBase)
	if got == nil || got.Utterance != "погода в риме" {
		t.Fatalf("pop = %+v, want the newest", got)
	}
	// The flow underneath survived the one on top of it.
	if got := s.Peek("voice", pendingBase); got == nil || got.Utterance != "напомни позвонить маме" {
		t.Fatalf("after pop, peek = %+v, want the suspended flow", got)
	}
	if got := s.Pop("voice", pendingBase); got == nil {
		t.Fatal("pop of the last entry returned nil")
	}
	if s.Peek("voice", pendingBase) != nil || s.Depth("voice") != 0 {
		t.Error("stack not empty after popping everything")
	}
	if s.Pop("voice", pendingBase) != nil {
		t.Error("pop of an empty stack returned something")
	}
}

// A popped entry is gone: it must not come back on the next peek.
func TestStackPoppedEntryIsGone(t *testing.T) {
	s := NewClarifyStore(time.Minute)
	s.Push("voice", parked("напомни", pendingBase))
	s.Pop("voice", pendingBase)
	if got := s.Peek("voice", pendingBase); got != nil {
		t.Errorf("peek after pop = %+v, want nil", got)
	}
}

// Past MaxStackDepth the oldest entry comes back to the caller instead of
// vanishing — it is the caller's job to say it was dropped.
func TestStackDepthBoundReturnsTheDroppedEntry(t *testing.T) {
	s := NewClarifyStore(time.Minute)
	for i := 0; i < MaxStackDepth; i++ {
		if dropped := s.Push("voice", parked("first", pendingBase)); dropped != nil {
			t.Fatalf("push %d dropped early", i)
		}
	}
	dropped := s.Push("voice", parked("newest", pendingBase))
	if dropped == nil {
		t.Fatal("push past the bound dropped an entry silently")
	}
	if dropped.Utterance != "first" {
		t.Errorf("dropped %q, want the oldest", dropped.Utterance)
	}
	if got := s.Depth("voice"); got != MaxStackDepth {
		t.Errorf("depth = %d, want %d", got, MaxStackDepth)
	}
	if got := s.Peek("voice", pendingBase); got == nil || got.Utterance != "newest" {
		t.Errorf("peek = %+v, want the newest", got)
	}
}

// Put still replaces rather than stacks: a re-ask is another question about the
// same action, so the daemon's depth stays one.
func TestPutReplacesTopWithoutGrowing(t *testing.T) {
	s := NewClarifyStore(time.Minute)
	s.Put("voice", parked("напомни", pendingBase))
	s.Put("voice", parked("напомни ещё раз", pendingBase))
	if got := s.Depth("voice"); got != 1 {
		t.Fatalf("depth = %d, want 1", got)
	}
	if got := s.Peek("voice", pendingBase); got == nil || got.Utterance != "напомни ещё раз" {
		t.Fatalf("peek = %+v, want the replacement", got)
	}
}

// An expired top takes the stack with it, and TakeExpired is what reports it —
// the whole exchange timed out, and one notice is what a reply can carry.
func TestStackExpiryDropsTheStackAndIsReported(t *testing.T) {
	s := NewClarifyStore(time.Minute)
	s.Push("voice", parked("напомни", pendingBase))
	s.Push("voice", parked("погода", pendingBase))
	late := pendingBase.Add(2 * time.Minute)
	if s.Peek("voice", late) != nil {
		t.Error("peek returned an expired question")
	}
	if s.Depth("voice") != 0 {
		t.Error("expired stack survived a peek")
	}

	s.Push("voice", parked("напомни", pendingBase))
	s.Push("voice", parked("погода", pendingBase))
	// Two died, and the count says two: the notice that reports this has a
	// plural wording since V-561, and it is chosen off this number.
	if n := s.TakeExpired("voice", late); n != 2 {
		t.Errorf("TakeExpired reported %d timed-out questions, want 2", n)
	}
	if s.Depth("voice") != 0 {
		t.Error("TakeExpired left entries behind")
	}
	if n := s.TakeExpired("voice", late); n != 0 {
		t.Errorf("TakeExpired reported twice: %d", n)
	}
	// Pop of an expired top yields nothing rather than a dead action.
	s.Push("voice", parked("напомни", pendingBase))
	if s.Pop("voice", late) != nil {
		t.Error("pop returned an expired question")
	}
}

// Delete ends the exchange, every level of it.
func TestStackDeleteDropsAll(t *testing.T) {
	s := NewClarifyStore(time.Minute)
	s.Push("voice", parked("напомни", pendingBase))
	s.Push("voice", parked("погода", pendingBase))
	s.Delete("voice")
	if s.Depth("voice") != 0 || s.Peek("voice", pendingBase) != nil {
		t.Error("Delete left questions parked")
	}
}

// Stacks are per dialogue id: the mic and the web must not read each other's.
func TestStacksAreIsolatedByID(t *testing.T) {
	s := NewClarifyStore(time.Minute)
	s.Push("voice", parked("напомни", pendingBase))
	s.Push("web", parked("погода", pendingBase))
	s.Delete("voice")
	if got := s.Peek("web", pendingBase); got == nil || got.Utterance != "погода" {
		t.Errorf("web stack = %+v, want its own question", got)
	}
}