package v1

import (
	"encoding/json"
	"fmt"
	"context"
	"net/http/httptest"
	"testing"

	"github.com/gin-gonic/gin"
	"github.com/stretchr/testify/assert"

	"github.com/gochat/gochat/internal/llm"
	"github.com/gochat/gochat/internal/model"
)

// ========== Mock LLM Provider for SSE tests ==========

type mockSSELLMProvider struct {
	streamChunks []llm.StreamChunk
	streamError  error
	lastStreamReq *llm.ChatRequest
}

func (m *mockSSELLMProvider) ChatCompletion(ctx context.Context, req llm.ChatRequest) (*llm.ChatResponse, error) {
	return nil, fmt.Errorf("not implemented")
}

func (m *mockSSELLMProvider) CreateEmbedding(ctx context.Context, req llm.EmbeddingRequest) (*llm.EmbeddingResponse, error) {
	return nil, fmt.Errorf("not implemented")
}

func (m *mockSSELLMProvider) ChatCompletionStream(ctx context.Context, req llm.ChatRequest, onChunk func(llm.StreamChunk) error) error {
	m.lastStreamReq = &req
	if m.streamError != nil {
		return m.streamError
	}
	for _, chunk := range m.streamChunks {
		if err := onChunk(chunk); err != nil {
			return err
		}
	}
	return nil
}

// ========== escapeJSONString Tests ==========

func TestEscapeJSONString_双引号(t *testing.T) {
	result := escapeJSONString(`he said "hello"`)
	assert.Equal(t, `he said \"hello\"`, result)
}

func TestEscapeJSONString_反斜杠(t *testing.T) {
	result := escapeJSONString(`path\to\file`)
	assert.Equal(t, `path\\to\\file`, result)
}

func TestEscapeJSONString_换行(t *testing.T) {
	result := escapeJSONString("line1\nline2")
	assert.Equal(t, "line1\\nline2", result)
}

func TestEscapeJSONString_制表符(t *testing.T) {
	result := escapeJSONString("col1\tcol2")
	assert.Equal(t, "col1\\tcol2", result)
}

func TestEscapeJSONString_无特殊字符(t *testing.T) {
	result := escapeJSONString("plain text")
	assert.Equal(t, "plain text", result)
}

// ========== buildStreamChatMessages Tests ==========

func TestBuildStreamChatMessages_空历史(t *testing.T) {
	thread := &model.CopilotThread{
		Title: "Test Thread",
	}
	_ = thread // used indirectly via buildStreamChatMessages

	result := buildStreamChatMessages(thread, "user question")

	assert.Len(t, result, 2) // system + user
	assert.Equal(t, "system", result[0].Role)
	assert.Equal(t, "user", result[1].Role)
	assert.Equal(t, "user question", result[1].Content)
}

func TestBuildStreamChatMessages_有历史(t *testing.T) {
	thread := &model.CopilotThread{
		Title: "Test Thread",
	}
	messages := []model.CopilotMessage{
		{MessageType: model.CopilotMessageTypeUser, Message: json.RawMessage(`"previous user msg"`)},
		{MessageType: model.CopilotMessageTypeAssistant, Message: json.RawMessage(`"previous assistant msg"`)},
	}
	thread.Messages = messages

	result := buildStreamChatMessages(thread, "new question")

	// system + 2 history + new user = 4
	assert.Len(t, result, 4)
	assert.Equal(t, "system", result[0].Role)
	assert.Equal(t, "new question", result[len(result)-1].Content)
}

// ========== writeSSEMessage Tests ==========

func TestWriteSSEMessage_格式(t *testing.T) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)

	writeSSEMessage(c, "message", `{"content": "hello"}`)

	body := w.Body.String()
	assert.Contains(t, body, "event: message")
assert.Contains(t, body, `data: {"content": "hello"}`)
	// SSE format requires double newline
	assert.Contains(t, body, "\n\n")
}

func TestWriteSSEMessage_Done事件(t *testing.T) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)

	writeSSEMessage(c, "done", `{"done": true}`)

	body := w.Body.String()
	assert.Contains(t, body, "event: done")
	assert.Contains(t, body, `data: {"done": true}`)
}