package rag_test

import (
	"context"
	"fmt"
	"testing"

	"github.com/VictorVargas/rony-llm-agent/pkg/rag"
	"github.com/VictorVargas/rony-llm-agent/pkg/rag/embeddings"
)

func TestNew_Memory(t *testing.T) {
	_, err := rag.New(rag.Config{})
	if err == nil {
		t.Fatal("expected error for missing backend")
	}

	_, err = rag.New(rag.Config{
		Backend: &mockBackend{},
	})
	if err == nil {
		t.Fatal("expected error for missing embedder")
	}

	m, err := rag.New(rag.Config{
		Backend:  &mockBackend{},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if m == nil {
		t.Fatal("expected non-nil memory")
	}
}

func TestMemory_Add(t *testing.T) {
	m, err := rag.New(rag.Config{
		Backend:  &mockBackend{},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	err = m.Add(context.Background(), rag.Fragment{
		Content: "test content",
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestMemory_Add_PassesContentToBackend(t *testing.T) {
	var gotContent string
	m, err := rag.New(rag.Config{
		Backend: &mockBackend{
			upsertFunc: func(_ context.Context, _ string, _ []float32, content string, _ map[string]string) error {
				gotContent = content
				return nil
			},
		},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	err = m.Add(context.Background(), rag.Fragment{Content: "remember this process"})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if gotContent != "remember this process" {
		t.Fatalf("expected backend to receive the fragment content, got %q", gotContent)
	}
}

func TestMemory_Add_EmbeddingErrorStillSavesWithNoVector(t *testing.T) {
	var gotVector []float32
	sawCall := false
	m, err := rag.New(rag.Config{
		Backend: &mockBackend{
			upsertFunc: func(_ context.Context, _ string, vector []float32, _ string, _ map[string]string) error {
				sawCall = true
				gotVector = vector
				return nil
			},
		},
		Embedder: &embeddings.MockEmbedder{EmbedFunc: func(ctx context.Context, text string) ([]float32, error) { return nil, fmt.Errorf("embed error") }},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	err = m.Add(context.Background(), rag.Fragment{
		Content: "test content",
	})
	if err != nil {
		t.Fatalf("expected Add to succeed so the backend can still index the text lexically, got: %v", err)
	}
	if !sawCall {
		t.Fatal("expected the backend to still be called despite the embedding failure")
	}
	if len(gotVector) != 0 {
		t.Fatalf("expected no vector to be passed through, got %v", gotVector)
	}
}

func TestMemory_Search(t *testing.T) {
	m, err := rag.New(rag.Config{
		Backend: &mockBackend{
			searchFunc: func(ctx context.Context, query string, queryVector []float32, topK int) ([]rag.SearchResult, error) {
				return []rag.SearchResult{
					{ID: "1", Content: "result 1", Score: 0.9},
				}, nil
			},
		},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	results, err := m.Search(context.Background(), "test query", 5)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(results) != 1 {
		t.Fatalf("expected 1 result, got %d", len(results))
	}
	if results[0].Content != "result 1" {
		t.Errorf("expected 'result 1', got %q", results[0].Content)
	}
}

func TestMemory_ForgetAll(t *testing.T) {
	forgetAllCalled := false
	m, err := rag.New(rag.Config{
		Backend: &mockBackend{
			forgetAllFunc: func(ctx context.Context) error {
				forgetAllCalled = true
				return nil
			},
		},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	err = m.ForgetAll(context.Background())
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !forgetAllCalled {
		t.Fatal("expected forgetAll to be called")
	}
}

func TestMemory_Search_EmbeddingErrorFallsBackToLexicalSearch(t *testing.T) {
	var gotQuery string
	var gotVector []float32
	m, err := rag.New(rag.Config{
		Backend: &mockBackend{
			searchFunc: func(_ context.Context, query string, queryVector []float32, _ int) ([]rag.SearchResult, error) {
				gotQuery = query
				gotVector = queryVector
				return []rag.SearchResult{{ID: "1", Content: "matched lexically"}}, nil
			},
		},
		Embedder: &embeddings.MockEmbedder{EmbedFunc: func(ctx context.Context, text string) ([]float32, error) {
			return nil, fmt.Errorf("embed error")
		}},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	results, err := m.Search(context.Background(), "test query", 5)
	if err != nil {
		t.Fatalf("expected Search to fall back to the backend's lexical search, got error: %v", err)
	}
	if len(results) != 1 || results[0].Content != "matched lexically" {
		t.Fatalf("expected the backend's fallback result to come through, got %v", results)
	}
	if gotQuery != "test query" {
		t.Fatalf("expected the raw query text to reach the backend, got %q", gotQuery)
	}
	if len(gotVector) != 0 {
		t.Fatalf("expected no query vector to be passed through, got %v", gotVector)
	}
}

// mockBackend implements chroma.Backend for testing.
type mockBackend struct {
	upsertFunc    func(ctx context.Context, id string, vector []float32, content string, metadata map[string]string) error
	searchFunc    func(ctx context.Context, query string, queryVector []float32, topK int) ([]rag.SearchResult, error)
	forgetAllFunc func(ctx context.Context) error
}

func (m *mockBackend) Upsert(ctx context.Context, id string, vector []float32, content string, metadata map[string]string) error {
	if m.upsertFunc != nil {
		return m.upsertFunc(ctx, id, vector, content, metadata)
	}
	return nil
}

func (m *mockBackend) Search(ctx context.Context, query string, queryVector []float32, topK int) ([]rag.SearchResult, error) {
	if m.searchFunc != nil {
		return m.searchFunc(ctx, query, queryVector, topK)
	}
	return nil, nil
}

func (m *mockBackend) Forget(ctx context.Context, id string) error {
	return nil
}

func (m *mockBackend) ForgetAll(ctx context.Context) error {
	if m.forgetAllFunc != nil {
		return m.forgetAllFunc(ctx)
	}
	return nil
}

func TestMemory_Add_MultipleFragments(t *testing.T) {
	m, err := rag.New(rag.Config{
		Backend:  &mockBackend{},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	for i := 0; i < 10; i++ {
		err = m.Add(context.Background(), rag.Fragment{
			Content: fmt.Sprintf("test content %d", i),
		})
		if err != nil {
			t.Fatalf("unexpected error on iteration %d: %v", i, err)
		}
	}
}

func TestMemory_Search_EmptyQuery(t *testing.T) {
	m, err := rag.New(rag.Config{
		Backend: &mockBackend{
			searchFunc: func(ctx context.Context, query string, queryVector []float32, topK int) ([]rag.SearchResult, error) {
				return []rag.SearchResult{}, nil
			},
		},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	results, err := m.Search(context.Background(), "", 5)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if len(results) != 0 {
		t.Fatalf("expected 0 results, got %d", len(results))
	}
}

func TestMemory_ForgetAll_Error(t *testing.T) {
	m, err := rag.New(rag.Config{
		Backend: &mockBackend{
			forgetAllFunc: func(ctx context.Context) error {
				return fmt.Errorf("forget all error")
			},
		},
		Embedder: &embeddings.MockEmbedder{},
	})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	err = m.ForgetAll(context.Background())
	if err == nil {
		t.Fatal("expected error for forget all failure")
	}
}