//
//  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//

package models

import (
	"bufio"
	"bytes"
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"
)

// StepFunModel implements ModelDriver for StepFun (阶跃星辰).
type StepFunModel struct {
	baseModel BaseModel
}

// NewStepFunModel creates a new StepFun model instance.
func NewStepFunModel(baseURL map[string]string, urlSuffix URLSuffix) *StepFunModel {
	transport := http.DefaultTransport.(*http.Transport).Clone()
	transport.MaxIdleConns = 100
	transport.MaxIdleConnsPerHost = 10
	transport.IdleConnTimeout = 90 * time.Second
	transport.DisableCompression = false
	transport.ResponseHeaderTimeout = 60 * time.Second

	return &StepFunModel{
		baseModel: BaseModel{
			BaseURL:   baseURL,
			URLSuffix: urlSuffix,
			httpClient: &http.Client{
				Transport: transport,
			},
		},
	}
}

func (s *StepFunModel) NewInstance(baseURL map[string]string) ModelDriver {
	return NewStepFunModel(baseURL, s.baseModel.URLSuffix)
}

func (s *StepFunModel) Name() string {
	return "stepfun"
}

// ChatWithMessages sends multiple messages with roles and returns the response.
func (s *StepFunModel) ChatWithMessages(modelName string, messages []Message, apiConfig *APIConfig, chatModelConfig *ChatConfig) (*ChatResponse, error) {
	if err := s.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}

	if len(messages) == 0 {
		return nil, fmt.Errorf("messages is empty")
	}

	baseURL, err := s.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return nil, err
	}
	baseURL = strings.TrimSuffix(baseURL, "/")
	url := fmt.Sprintf("%s/%s", baseURL, s.baseModel.URLSuffix.Chat)

	apiMessages := make([]map[string]interface{}, len(messages))
	for i, msg := range messages {
		apiMessages[i] = map[string]interface{}{
			"role":    msg.Role,
			"content": msg.Content,
		}
	}

	reqBody := map[string]interface{}{
		"model":    modelName,
		"messages": apiMessages,
		"stream":   false,
	}

	if chatModelConfig != nil {
		if chatModelConfig.MaxTokens != nil {
			reqBody["max_tokens"] = *chatModelConfig.MaxTokens
		}
		if chatModelConfig.Temperature != nil {
			reqBody["temperature"] = *chatModelConfig.Temperature
		}
		if chatModelConfig.TopP != nil {
			reqBody["top_p"] = *chatModelConfig.TopP
		}
		if chatModelConfig.Stop != nil {
			reqBody["stop"] = *chatModelConfig.Stop
		}
	}

	jsonData, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal request: %w", err)
	}

	ctx, cancel := context.WithTimeout(context.Background(), nonStreamCallTimeout)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, "POST", url, bytes.NewBuffer(jsonData))
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", *apiConfig.ApiKey))

	resp, err := s.baseModel.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("failed to send request: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("API request failed with status %d: %s", resp.StatusCode, string(body))
	}

	var result map[string]interface{}
	if err = json.Unmarshal(body, &result); err != nil {
		return nil, fmt.Errorf("failed to parse response: %w", err)
	}

	choices, ok := result["choices"].([]interface{})
	if !ok || len(choices) == 0 {
		return nil, fmt.Errorf("no choices in response")
	}

	firstChoice, ok := choices[0].(map[string]interface{})
	if !ok {
		return nil, fmt.Errorf("invalid choice format")
	}

	messageMap, ok := firstChoice["message"].(map[string]interface{})
	if !ok {
		return nil, fmt.Errorf("invalid message format")
	}

	content, ok := messageMap["content"].(string)
	if !ok {
		return nil, fmt.Errorf("invalid content format")
	}

	emptyReason := ""
	return &ChatResponse{
		Answer:        &content,
		ReasonContent: &emptyReason,
	}, nil
}

// ChatStreamlyWithSender sends messages and streams the response
func (s *StepFunModel) ChatStreamlyWithSender(modelName string, messages []Message, apiConfig *APIConfig, chatModelConfig *ChatConfig, sender func(*string, *string) error) error {
	if err := s.baseModel.APIConfigCheck(apiConfig); err != nil {
		return err
	}

	if sender == nil {
		return fmt.Errorf("sender is required")
	}

	if len(messages) == 0 {
		return fmt.Errorf("messages is empty")
	}

	baseURL, err := s.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return err
	}
	baseURL = strings.TrimSuffix(baseURL, "/")
	url := fmt.Sprintf("%s/%s", baseURL, s.baseModel.URLSuffix.Chat)

	apiMessages := make([]map[string]interface{}, len(messages))
	for i, msg := range messages {
		apiMessages[i] = map[string]interface{}{
			"role":    msg.Role,
			"content": msg.Content,
		}
	}

	reqBody := map[string]interface{}{
		"model":    modelName,
		"messages": apiMessages,
		"stream":   true,
	}

	if chatModelConfig != nil {
		if chatModelConfig.Stream != nil && !*chatModelConfig.Stream {
			return fmt.Errorf("stream must be true in ChatStreamlyWithSender")
		}

		if chatModelConfig.MaxTokens != nil {
			reqBody["max_tokens"] = *chatModelConfig.MaxTokens
		}
		if chatModelConfig.Temperature != nil {
			reqBody["temperature"] = *chatModelConfig.Temperature
		}
		if chatModelConfig.TopP != nil {
			reqBody["top_p"] = *chatModelConfig.TopP
		}
		if chatModelConfig.Stop != nil {
			reqBody["stop"] = *chatModelConfig.Stop
		}
	}

	jsonData, err := json.Marshal(reqBody)
	if err != nil {
		return fmt.Errorf("failed to marshal request: %w", err)
	}

	req, err := http.NewRequestWithContext(context.Background(), "POST", url, bytes.NewBuffer(jsonData))
	if err != nil {
		return fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", *apiConfig.ApiKey))

	resp, err := s.baseModel.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("failed to send request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("API request failed with status %d: %s", resp.StatusCode, string(body))
	}

	scanner := bufio.NewScanner(resp.Body)
	scanner.Buffer(make([]byte, 64*1024), 1024*1024)
	sawTerminal := false
	for scanner.Scan() {
		line := scanner.Text()

		if !strings.HasPrefix(line, "data:") {
			continue
		}

		data := strings.TrimSpace(line[5:])

		if data == "[DONE]" {
			sawTerminal = true
			break
		}

		var event map[string]interface{}
		if err = json.Unmarshal([]byte(data), &event); err != nil {
			continue
		}

		choices, ok := event["choices"].([]interface{})
		if !ok || len(choices) == 0 {
			continue
		}

		firstChoice, ok := choices[0].(map[string]interface{})
		if !ok {
			continue
		}

		delta, ok := firstChoice["delta"].(map[string]interface{})
		if !ok {
			continue
		}

		content, ok := delta["content"].(string)
		if ok && content != "" {
			if err := sender(&content, nil); err != nil {
				return err
			}
		}

		finishReason, ok := firstChoice["finish_reason"].(string)
		if ok && finishReason != "" {
			sawTerminal = true
			break
		}
	}

	if err := scanner.Err(); err != nil {
		return fmt.Errorf("failed to scan response body: %w", err)
	}
	if !sawTerminal {
		return fmt.Errorf("stepfun: stream ended before [DONE] or finish_reason")
	}

	endOfStream := "[DONE]"
	if err := sender(&endOfStream, nil); err != nil {
		return err
	}

	return nil
}

// Embed is left as a stub.
func (s *StepFunModel) Embed(modelName *string, texts []string, apiConfig *APIConfig, embeddingConfig *EmbeddingConfig) ([]EmbeddingData, error) {
	return nil, fmt.Errorf("not implemented")
}

// ListModels returns the list of model ids visible to the API key.
func (s *StepFunModel) ListModels(apiConfig *APIConfig) ([]ListModelResponse, error) {
	if err := s.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}

	baseURL, err := s.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return nil, err
	}
	baseURL = strings.TrimSuffix(baseURL, "/")
	url := fmt.Sprintf("%s/%s", baseURL, s.baseModel.URLSuffix.Models)

	ctx, cancel := context.WithTimeout(context.Background(), nonStreamCallTimeout)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", *apiConfig.ApiKey))

	resp, err := s.baseModel.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("failed to send request: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("API request failed with status %d: %s", resp.StatusCode, string(body))
	}

	var result map[string]interface{}
	if err = json.Unmarshal(body, &result); err != nil {
		return nil, fmt.Errorf("failed to parse response: %w", err)
	}

	data, ok := result["data"].([]interface{})
	if !ok {
		return nil, fmt.Errorf("invalid models list format")
	}

	models := make([]ListModelResponse, 0)
	for _, model := range data {
		modelMap, ok := model.(map[string]interface{})
		if !ok {
			continue
		}
		modelName, ok := modelMap["id"].(string)
		if !ok {
			continue
		}
		models = append(models, ListModelResponse{Name: modelName})
	}

	return models, nil
}

// Balance is not exposed by the StepFun API, so this returns "no such method".
func (s *StepFunModel) Balance(apiConfig *APIConfig) (map[string]interface{}, error) {
	return nil, fmt.Errorf("no such method")
}

// CheckConnection runs a lightweight ListModels call to verify the API key.
func (s *StepFunModel) CheckConnection(apiConfig *APIConfig) error {
	_, err := s.ListModels(apiConfig)
	if err != nil {
		return err
	}
	return nil
}

// Rerank calculates similarity scores between query and documents. StepFun
// does not expose a public rerank API, so this returns "no such method".
func (s *StepFunModel) Rerank(modelName *string, query string, documents []string, apiConfig *APIConfig, rerankConfig *RerankConfig) (*RerankResponse, error) {
	return nil, fmt.Errorf("no such method")
}

// TranscribeAudio transcribe audio
func (s *StepFunModel) TranscribeAudio(modelName *string, file *string, apiConfig *APIConfig, asrConfig *ASRConfig) (*ASRResponse, error) {
	return nil, fmt.Errorf("%s, no such method", s.Name())
}

func (s *StepFunModel) TranscribeAudioWithSender(modelName *string, file *string, apiConfig *APIConfig, asrConfig *ASRConfig, sender func(*string, *string) error) error {
	return fmt.Errorf("%s, no such method", s.Name())
}

// AudioSpeech convert text to audio
func (s *StepFunModel) AudioSpeech(modelName *string, audioContent *string, apiConfig *APIConfig, ttsConfig *TTSConfig) (*TTSResponse, error) {
	if err := s.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}

	// TODO Test it
	if audioContent == nil || *audioContent == "" {
		return nil, fmt.Errorf("audio content is empty")
	}

	resolvedBaseURL, err := s.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return nil, err
	}
	url := fmt.Sprintf("%s/%s", resolvedBaseURL, s.baseModel.URLSuffix.TTS)

	reqBody := map[string]interface{}{
		"model": *modelName,
		"input": *audioContent,
	}

	if ttsConfig != nil && ttsConfig.Params != nil {
		for key, value := range ttsConfig.Params {
			reqBody[key] = value
		}
	}
	if ttsConfig != nil && ttsConfig.Format != "" {
		reqBody["response_format"] = ttsConfig.Format
	}

	jsonData, err := json.Marshal(reqBody)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal request: %w", err)
	}

	req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", *apiConfig.ApiKey))

	resp, err := s.baseModel.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("failed to send request: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response body: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("%s - %s", resp.Status, string(body))
	}

	return &TTSResponse{Audio: body}, nil
}

// AudioSpeechWithSender for Streaming TTS
func (s *StepFunModel) AudioSpeechWithSender(modelName *string, audioContent *string, apiConfig *APIConfig, ttsConfig *TTSConfig, sender func(*string, *string) error) error {
	if err := s.baseModel.APIConfigCheck(apiConfig); err != nil {
		return err
	}

	if audioContent == nil || *audioContent == "" {
		return fmt.Errorf("audio content is empty")
	}

	resolvedBaseURL, err := s.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return err
	}
	url := fmt.Sprintf("%s/%s", resolvedBaseURL, s.baseModel.URLSuffix.TTS)

	reqBody := map[string]interface{}{
		"model":         *modelName,
		"input":         *audioContent,
		"stream_format": "sse",
	}

	if ttsConfig != nil && ttsConfig.Params != nil {
		for key, value := range ttsConfig.Params {
			reqBody[key] = value
		}
	}
	if ttsConfig != nil && ttsConfig.Format != "" {
		reqBody["response_format"] = ttsConfig.Format
	}

	jsonData, err := json.Marshal(reqBody)
	if err != nil {
		return fmt.Errorf("failed to marshal request: %w", err)
	}

	req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
	if err != nil {
		return fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", *apiConfig.ApiKey))

	resp, err := s.baseModel.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("failed to send request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("StepFun stream TTS API error: %d - %s", resp.StatusCode, string(body))
	}

	scanner := bufio.NewScanner(resp.Body)
	scanner.Buffer(make([]byte, 64*1024), 8*1024*1024)

	for scanner.Scan() {
		line := scanner.Text()

		if !strings.HasPrefix(line, "data: ") {
			continue
		}

		dataStr := strings.TrimSpace(line[6:])
		// [DONE]
		if dataStr == "" || dataStr == "[DONE]" {
			continue
		}

		// Parse
		var event struct {
			Type  string `json:"type"`
			Audio string `json:"audio"`
		}

		if err := json.Unmarshal([]byte(dataStr), &event); err != nil {
			continue
		}

		if event.Type == "speech.audio.error" {
			return fmt.Errorf("StepFun stream encountered an error during generation")
		}

		// Extract the Base64 string containing the audio and decode it
		if event.Type == "speech.audio.delta" && event.Audio != "" {
			audioBytes, err := base64.StdEncoding.DecodeString(event.Audio)
			if err == nil && len(audioBytes) > 0 {
				chunk := string(audioBytes)
				if errSend := sender(&chunk, nil); errSend != nil {
					return errSend
				}
			}
		}
	}

	if err := scanner.Err(); err != nil {
		return fmt.Errorf("error reading StepFun stream: %w", err)
	}

	return nil
}

// OCRFile OCR file
func (s *StepFunModel) OCRFile(modelName *string, content []byte, url *string, apiConfig *APIConfig, ocrConfig *OCRConfig) (*OCRFileResponse, error) {
	return nil, fmt.Errorf("%s, no such method", s.Name())
}

// ParseFile parse file
func (s *StepFunModel) ParseFile(modelName *string, content []byte, url *string, apiConfig *APIConfig, parseFileConfig *ParseFileConfig) (*ParseFileResponse, error) {
	return nil, fmt.Errorf("%s, no such method", s.Name())
}

func (s *StepFunModel) ListTasks(apiConfig *APIConfig) ([]ListTaskStatus, error) {
	return nil, fmt.Errorf("%s, no such method", s.Name())
}

func (s *StepFunModel) ShowTask(taskID string, apiConfig *APIConfig) (*TaskResponse, error) {
	return nil, fmt.Errorf("%s, no such method", s.Name())
}