package promptkit_test

import (
	"context"
	"errors"
	"testing"

	"go.maximumdirect.net/promptkit"
)

func TestCoordinatePublicBoundary(t *testing.T) {
	ctx := context.Background()
	engine := newSimpleEngine(t, "question", promptkit.WithLLMClient(&fakeLLMClient{response: &promptkit.GenerateResponse{Content: "answer"}}))
	initial, err := engine.Run(ctx, promptkit.RunRequest{PromptID: "prompt", CaptureExchange: true})
	if err != nil {
		t.Fatal(err)
	}
	for _, request := range []promptkit.CoordinateRequest{{}, {Start: &promptkit.Exchange{}, Next: func(context.Context, promptkit.ConversationTurn) (*promptkit.RunRequest, error) { return nil, nil }}, {Start: initial.Exchange, AdditionalTurns: -1, Next: func(context.Context, promptkit.ConversationTurn) (*promptkit.RunRequest, error) { return nil, nil }}} {
		if _, err := engine.Coordinate(ctx, request); !errors.Is(err, promptkit.ErrInvalidRequest) {
			t.Fatalf("invalid request error = %v", err)
		}
	}
	if _, err := (*promptkit.Engine)(nil).Coordinate(ctx, promptkit.CoordinateRequest{}); !errors.Is(err, promptkit.ErrInvalidConfig) {
		t.Fatalf("nil engine error = %v", err)
	}
	callbacks := 0
	selected := &promptkit.RunRequest{PromptID: "prompt", ContinueFrom: &promptkit.Exchange{}}
	result, err := engine.Coordinate(ctx, promptkit.CoordinateRequest{Start: initial.Exchange, AdditionalTurns: 2, Next: func(_ context.Context, turn promptkit.ConversationTurn) (*promptkit.RunRequest, error) {
		callbacks++
		if callbacks == 1 {
			if turn.Result != nil || turn.RemainingTurns != 2 {
				t.Fatalf("initial turn = %#v", turn)
			}
			return selected, nil
		}
		if turn.Result == nil || turn.Exchange.Details().ParentRunID == "" {
			t.Fatalf("delivered turn = %#v", turn)
		}
		if callbacks == 2 {
			turn.Result.Exchange = nil
			*turn.Exchange = promptkit.Exchange{}
			return selected, nil
		}
		if turn.Result.ParentRunID == initial.RunID {
			t.Fatal("callback mutation redirected branch")
		}
		return nil, nil
	}})
	if err != nil || result.Outcome != promptkit.CoordinationStopped || callbacks != 3 || selected.ContinueFrom == nil {
		t.Fatalf("result=%#v error=%v callbacks=%d", result, err, callbacks)
	}
	stop, err := engine.Coordinate(ctx, promptkit.CoordinateRequest{Start: initial.Exchange, Next: func(context.Context, promptkit.ConversationTurn) (*promptkit.RunRequest, error) { return nil, nil }})
	if err != nil || stop.Outcome != promptkit.CoordinationStopped {
		t.Fatalf("zero budget = %#v, %v", stop, err)
	}
	sentinel := errors.New("callback")
	_, err = engine.Coordinate(ctx, promptkit.CoordinateRequest{Start: initial.Exchange, Next: func(context.Context, promptkit.ConversationTurn) (*promptkit.RunRequest, error) { return nil, sentinel }})
	if !errors.Is(err, sentinel) {
		t.Fatalf("callback error = %v", err)
	}
}