package promptkit_test

import (
	"context"
	"reflect"
	"sync"
	"testing"

	"go.maximumdirect.net/promptkit"
)

func TestComposeObserversCopiesAndOrders(t *testing.T) {
	if promptkit.ComposeObservers() != nil || promptkit.ComposeObservers(nil, nil) != nil {
		t.Fatal("empty composition is not nil")
	}
	var calls []int
	first := func(promptkit.ExecutionEvent) { calls = append(calls, 1) }
	second := func(promptkit.ExecutionEvent) { calls = append(calls, 2) }
	values := []promptkit.ExecutionObserver{first, nil, second, first}
	observer := promptkit.ComposeObservers(values...)
	values[0] = second
	observer(promptkit.ExecutionEvent{})
	if !reflect.DeepEqual(calls, []int{1, 2, 1}) {
		t.Fatalf("calls=%v", calls)
	}
	defer func() {
		if recover() != "panic" || len(calls) != 3 {
			t.Errorf("panic or calls=%v", calls)
		}
	}()
	promptkit.ComposeObservers(func(promptkit.ExecutionEvent) { panic("panic") }, second)(promptkit.ExecutionEvent{})
}

func TestComposeObserversSparseSelection(t *testing.T) {
	for _, selected := range []int{0, 1, 2} {
		calls := 0
		observers := make([]promptkit.ExecutionObserver, 1024)
		callback := func(promptkit.ExecutionEvent) { calls++ }
		for index := 0; index < selected; index++ {
			observers[len(observers)-1-index] = callback
		}
		composed := promptkit.ComposeObservers(observers...)
		for index := range observers {
			observers[index] = func(promptkit.ExecutionEvent) { calls += 100 }
		}
		if selected == 0 {
			if composed != nil {
				t.Fatal("all-nil composition must be nil")
			}
			continue
		}
		composed(promptkit.ExecutionEvent{})
		if calls != selected {
			t.Fatalf("selected %d callbacks, got %d calls", selected, calls)
		}
	}
}

func TestCoordinateObserverCompositionAndNestedSelection(t *testing.T) {
	engine := newSimpleEngine(t, "question", promptkit.WithLLMClient(&fakeLLMClient{response: &promptkit.GenerateResponse{Content: "answer"}}))
	ctx := context.Background()
	initial, err := engine.Run(ctx, promptkit.RunRequest{PromptID: "prompt", CaptureExchange: true})
	if err != nil {
		t.Fatal(err)
	}
	var sequence []string
	var nested int
	request := &promptkit.RunRequest{PromptID: "prompt", Observer: func(promptkit.ExecutionEvent) { sequence = append(sequence, "request") }}
	result, err := engine.Coordinate(ctx, promptkit.CoordinateRequest{Start: initial.Exchange, AdditionalTurns: 1, Observer: func(promptkit.ExecutionEvent) { sequence = append(sequence, "coordinator") }, Next: func(ctx context.Context, turn promptkit.ConversationTurn) (*promptkit.RunRequest, error) {
		if turn.Result == nil {
			return request, nil
		}
		_, err := engine.Run(ctx, promptkit.RunRequest{PromptID: "prompt", Observer: func(promptkit.ExecutionEvent) { nested++ }})
		return nil, err
	}})
	if err != nil || result.Outcome != promptkit.CoordinationStopped || nested != 3 || !reflect.DeepEqual(sequence, []string{"request", "coordinator", "request", "coordinator", "request", "coordinator"}) {
		t.Fatalf("result=%#v error=%v events=%v nested=%d", result, err, sequence, nested)
	}
	if request.ContinueFrom != nil {
		t.Fatal("coordinator changed caller request")
	}
}

func TestComposedObserversSupportConcurrentRuns(t *testing.T) {
	var mu sync.Mutex
	count := 0
	observer := promptkit.ComposeObservers(func(promptkit.ExecutionEvent) { mu.Lock(); count++; mu.Unlock() })
	engine := newSimpleEngine(t, "question", promptkit.WithLLMClient(&preparedRecordingClient{response: &promptkit.GenerateResponse{Content: "answer"}}))
	var wg sync.WaitGroup
	for i := 0; i < 8; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			if _, err := engine.Run(context.Background(), promptkit.RunRequest{PromptID: "prompt", Observer: observer}); err != nil {
				t.Error(err)
			}
		}()
	}
	wg.Wait()
	if count != 24 {
		t.Fatalf("event count=%d", count)
	}
}