package service

import (
	"context"
	"encoding/json"
	"fmt"
	"testing"

	"github.com/gochat/gochat/internal/llm"
	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
)

// --- Mock LLM Provider for assistant response tests ---
type mockResponseLLM struct {
	response *llm.ChatResponse
	err      error
}

func (m *mockResponseLLM) ChatCompletion(_ context.Context, _ llm.ChatRequest) (*llm.ChatResponse, error) {
	return m.response, m.err
}
func (m *mockResponseLLM) CreateEmbedding(_ context.Context, _ llm.EmbeddingRequest) (*llm.EmbeddingResponse, error) {
	return nil, nil
}
func (m *mockResponseLLM) ChatCompletionStream(_ context.Context, _ llm.ChatRequest, _ func(llm.StreamChunk) error) error {
	return nil
}

func setupAssistantResponseTestDB(t *testing.T) *gorm.DB {
	t.Helper()
	dbName := fmt.Sprintf("file:%s?mode=memory&cache=private", t.Name())
	db, err := gorm.Open(sqlite.Open(dbName), &gorm.Config{})
	require.NoError(t, err)
	require.NoError(t, db.AutoMigrate(
		&model.CaptainPreference{},
		&model.CaptainAssistant{},
		&model.Conversation{},
		&model.Message{},
		&model.Inbox{},
		&model.Contact{},
		&model.Account{},
	))
	return db
}

func setupAssistantResponseService(t *testing.T, mockLLM *mockResponseLLM) (*CaptainAssistantResponseService, *gorm.DB) {
	t.Helper()
	db := setupAssistantResponseTestDB(t)
	assistantRepo := repository.NewCaptainAssistantRepo(db)
	responseRepo := repository.NewCaptainAssistantResponseRepo(db)
	convRepo := repository.NewConversationRepo(db)
	msgRepo := repository.NewMessageRepo(db)
	prefRepo := repository.NewCaptainPreferenceRepo(db)
	svc := NewCaptainAssistantResponseService(assistantRepo, responseRepo, convRepo, msgRepo, prefRepo, mockLLM)
	return svc, db
}

func seedAssistantResponseData(t *testing.T, db *gorm.DB, accountID uint) (*model.CaptainAssistant, *model.Conversation, *model.Message) {
	t.Helper()
	inbox := &model.Inbox{AccountID: accountID, Name: "Support Inbox", ChannelType: "web_widget"}
	require.NoError(t, db.Create(inbox).Error)
	contact := &model.Contact{AccountID: accountID, Name: "Customer"}
	require.NoError(t, db.Create(contact).Error)
	conv := &model.Conversation{AccountID: accountID, InboxID: inbox.ID, Status: "open"}
	require.NoError(t, db.Create(conv).Error)
	msg := &model.Message{
		ConversationID: conv.ID,
		AccountID:      accountID,
		InboxID:        inbox.ID,
		SenderType:     "contact",
		Content:        "How do I reset my password?",
		ContentType:    "text",
		MessageType:    "incoming",
	}
	require.NoError(t, db.Create(msg).Error)

	// Create assistant with config
	cfg := &model.AssistantConfig{Instructions: "Be helpful and concise", Temperature: 0.7}
	cfgJSON, err := json.Marshal(cfg)
	require.NoError(t, err)
	assistant := &model.CaptainAssistant{
		AccountID: accountID,
		Name:      "Support Bot",
		Config:    cfgJSON,
		Status:    model.AssistantStatusActive,
	}
	require.NoError(t, db.Create(assistant).Error)

	return assistant, conv, msg
}

func TestCaptainAssistantResponseService_ProcessResponse(t *testing.T) {
	mockLLM := &mockResponseLLM{
		response: &llm.ChatResponse{
			Choices: []llm.ChatChoice{
				{
					Message: llm.ChatMessage{
						Role:    "assistant",
						Content: "To reset your password, go to Settings > Security > Reset Password.",
					},
				},
			},
		},
	}
	svc, db := setupAssistantResponseService(t, mockLLM)
	ctx := context.Background()

	assistant, conv, _ := seedAssistantResponseData(t, db, 1)

	req := &ProcessResponseRequest{
		ConversationID: conv.ID,
		AssistantID:    assistant.ID,
		SendMessage:    false,
	}

	result, err := svc.ProcessResponse(ctx, 1, req)
	require.NoError(t, err)
	assert.Equal(t, "To reset your password, go to Settings > Security > Reset Password.", result.Content)
	assert.Equal(t, conv.ID, result.ConversationID)
	assert.Equal(t, assistant.ID, result.AssistantID)
	assert.False(t, result.Sent) // send_message=false
	assert.Zero(t, result.MessageID)
}

func TestCaptainAssistantResponseService_ProcessResponse_WithSendMessage(t *testing.T) {
	mockLLM := &mockResponseLLM{
		response: &llm.ChatResponse{
			Choices: []llm.ChatChoice{
				{
					Message: llm.ChatMessage{
						Role:    "assistant",
						Content: "Here is how to reset your password.",
					},
				},
			},
		},
	}
	svc, db := setupAssistantResponseService(t, mockLLM)
	ctx := context.Background()

	assistant, conv, _ := seedAssistantResponseData(t, db, 1)

	req := &ProcessResponseRequest{
		ConversationID: conv.ID,
		AssistantID:    assistant.ID,
		SendMessage:    true,
	}

	result, err := svc.ProcessResponse(ctx, 1, req)
	require.NoError(t, err)
	assert.Equal(t, "Here is how to reset your password.", result.Content)
	assert.True(t, result.Sent)
	assert.NotZero(t, result.MessageID)
}

func TestCaptainAssistantResponseService_ProcessResponse_AssistantNotFound(t *testing.T) {
	mockLLM := &mockResponseLLM{}
	svc, db := setupAssistantResponseService(t, mockLLM)
	ctx := context.Background()

	// Create conversation but no assistant
	inbox := &model.Inbox{AccountID: 1, Name: "Inbox", ChannelType: "web_widget"}
	require.NoError(t, db.Create(inbox).Error)
	conv := &model.Conversation{AccountID: 1, InboxID: inbox.ID, Status: "open"}
	require.NoError(t, db.Create(conv).Error)

	req := &ProcessResponseRequest{
		ConversationID: conv.ID,
		AssistantID:    999, // nonexistent
		SendMessage:    false,
	}

	_, err := svc.ProcessResponse(ctx, 1, req)
	assert.Error(t, err)
	assert.Contains(t, err.Error(), "assistant not found")
}

func TestCaptainAssistantResponseService_ProcessResponse_LLMError(t *testing.T) {
	mockLLM := &mockResponseLLM{err: fmt.Errorf("LLM service unavailable")}
	svc, db := setupAssistantResponseService(t, mockLLM)
	ctx := context.Background()

	assistant, conv, _ := seedAssistantResponseData(t, db, 1)

	req := &ProcessResponseRequest{
		ConversationID: conv.ID,
		AssistantID:    assistant.ID,
		SendMessage:    false,
	}

	_, err := svc.ProcessResponse(ctx, 1, req)
	assert.Error(t, err)
	assert.Contains(t, err.Error(), "generate response")
}

func TestCaptainAssistantResponseService_ProcessResponse_NoLLMContent(t *testing.T) {
	mockLLM := &mockResponseLLM{
		response: &llm.ChatResponse{Choices: []llm.ChatChoice{}}, // empty choices
	}
	svc, db := setupAssistantResponseService(t, mockLLM)
	ctx := context.Background()

	assistant, conv, _ := seedAssistantResponseData(t, db, 1)

	req := &ProcessResponseRequest{
		ConversationID: conv.ID,
		AssistantID:    assistant.ID,
		SendMessage:    false,
	}

	_, err := svc.ProcessResponse(ctx, 1, req)
	assert.Error(t, err)
	assert.Contains(t, err.Error(), "no LLM response")
}