//
//  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 (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"ragflow/internal/common"
	"strings"
)

// MoonshotModel implements ModelDriver for Moonshot
type MoonshotModel struct {
	baseModel BaseModel
}

// NewMoonshotModel creates a new Moonshot model instance
func NewMoonshotModel(baseURL map[string]string, urlSuffix URLSuffix) *MoonshotModel {
	return &MoonshotModel{
		baseModel: BaseModel{
			BaseURL:    baseURL,
			URLSuffix:  urlSuffix,
			httpClient: NewDriverHTTPClient(),
		},
	}
}

func (m *MoonshotModel) NewInstance(baseURL map[string]string) ModelDriver {
	return NewMoonshotModel(baseURL, m.baseModel.URLSuffix)
}

func (m *MoonshotModel) Name() string {
	return "moonshot"
}

type MoonshotChatResponse struct {
	ID      string `json:"id"`
	Object  string `json:"object"`
	Created int64  `json:"created"`
	Model   string `json:"model"`
	Choices []struct {
		Index   int `json:"index"`
		Message struct {
			Role             string           `json:"role"`
			Content          *string          `json:"content"`
			ToolCalls        []map[string]any `json:"tool_calls"`
			ReasoningContent *string          `json:"reasoning_content"`
		} `json:"message"`
		FinishReason string `json:"finish_reason"`
	} `json:"choices"`
	Usage struct {
		PromptTokens     int `json:"prompt_tokens"`
		CompletionTokens int `json:"completion_tokens"`
		TotalTokens      int `json:"total_tokens"`
		CachedTokens     int `json:"cached_tokens"`
	} `json:"usage"`
}

func validateMoonshotModelName(modelName string) (string, error) {
	if strings.TrimSpace(modelName) == "" {
		return "", fmt.Errorf("model name is required")
	}
	return strings.TrimSpace(modelName), nil
}

func (m *MoonshotModel) ChatWithMessages(ctx context.Context, modelName string, messages []Message, apiConfig *APIConfig, chatModelConfig *ChatConfig, modelUsage *common.ModelUsage) (*ChatResponse, error) {
	if err := m.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}
	apiKey := strings.TrimSpace(*apiConfig.ApiKey)
	modelName, err := validateMoonshotModelName(modelName)
	if err != nil {
		return nil, err
	}
	if len(messages) == 0 {
		return nil, fmt.Errorf("messages is empty")
	}

	resolvedBaseURL, err := m.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return nil, err
	}
	url := fmt.Sprintf("%s/%s", resolvedBaseURL, m.baseModel.URLSuffix.Chat)
	reqBody := buildRequestBody(chatModelConfig, modelName, messages, false)

	if chatModelConfig != nil {
		if chatModelConfig.Thinking != nil {
			if *chatModelConfig.Thinking {
				reqBody["thinking"] = map[string]interface{}{
					"type": "enabled",
				}
			} else {
				reqBody["thinking"] = map[string]interface{}{
					"type": "disabled",
				}
			}
		}

	}

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

	ctx, cancel := context.WithTimeout(ctx, 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", apiKey))

	resp, err := m.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))
	}

	return parseChatCompletionResponse(body, chatModelConfig, modelUsage, func(body []byte, chatConfig *ChatConfig) (chatResponseParts, error) {
		var result MoonshotChatResponse
		if err := json.Unmarshal(body, &result); err != nil {
			return chatResponseParts{}, fmt.Errorf("failed to parse response: %w", err)
		}

		if len(result.Choices) == 0 {
			return chatResponseParts{}, fmt.Errorf("no choices in response")
		}

		choice := &result.Choices[0]
		content := ""
		if choice.Message.Content != nil {
			content = *choice.Message.Content
		}

		reasonContent := ""
		if chatConfig != nil && chatConfig.Thinking != nil && *chatConfig.Thinking {
			if choice.Message.ReasoningContent != nil {
				reasonContent = *choice.Message.ReasoningContent
			}
			if reasonContent != "" && reasonContent[0] == '\n' {
				reasonContent = reasonContent[1:]
			}
		}

		totalTokens := result.Usage.TotalTokens
		if totalTokens == 0 {
			totalTokens = result.Usage.PromptTokens + result.Usage.CompletionTokens
		}
		var usage *TokenUsage
		if totalTokens > 0 {
			usage = &TokenUsage{
				PromptTokens:     result.Usage.PromptTokens,
				CompletionTokens: result.Usage.CompletionTokens,
				TotalTokens:      totalTokens,
			}
		}

		return chatResponseParts{
			RequestID:     result.ID,
			Content:       &content,
			ReasonContent: &reasonContent,
			ToolCalls:     choice.Message.ToolCalls,
			Usage:         usage,
		}, nil
	})
}

// ChatStreamlyWithSender sends messages and streams response via sender function (best performance, no channel)
func (m *MoonshotModel) ChatStreamlyWithSender(ctx context.Context, modelName string, messages []Message, apiConfig *APIConfig, chatModelConfig *ChatConfig, modelUsage *common.ModelUsage, sender func(*string, *string) error) error {
	if err := m.baseModel.APIConfigCheck(apiConfig); err != nil {
		return err
	}
	apiKey := strings.TrimSpace(*apiConfig.ApiKey)
	modelName, err := validateMoonshotModelName(modelName)
	if err != nil {
		return err
	}
	if len(messages) == 0 {
		return fmt.Errorf("messages is empty")
	}
	if sender == nil {
		return fmt.Errorf("sender is required")
	}

	resolvedBaseURL, err := m.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return err
	}
	url := fmt.Sprintf("%s/%s", resolvedBaseURL, m.baseModel.URLSuffix.Chat)
	reqBody := buildRequestBody(chatModelConfig, modelName, messages, true)

	if chatModelConfig != nil {
		if chatModelConfig.Thinking != nil {
			if *chatModelConfig.Thinking {
				reqBody["thinking"] = map[string]interface{}{
					"type": "enabled",
				}
			} else {
				reqBody["thinking"] = map[string]interface{}{
					"type": "disabled",
				}
			}
		}
	}

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

	ctx, cancel := context.WithTimeout(ctx, streamCallTimeout)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, "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", apiKey))
	req.Header.Set("Accept", "text/event-stream")

	resp, err := m.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))
	}

	// SSE parsing: read line by line
	sawTerminal := false
	if chatModelConfig != nil {
		chatModelConfig.ToolCallsResult = nil
	}
	accumulatedToolCalls := make(map[int]map[string]any)
	done, err := ParseSSEStream[map[string]interface{}](resp.Body, func(event map[string]interface{}) error {
		tokenUsage, found, usageErr := decodeOpenAICompatibleStreamUsage(event)
		if usageErr != nil {
			return usageErr
		}
		if found {
			applyStreamUsage(chatModelConfig, modelUsage, tokenUsage)
		}

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

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

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

		accumulateToolCallDeltas(delta, accumulatedToolCalls)

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

		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
		}

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

	setSortedToolCallsResult(chatModelConfig, accumulatedToolCalls)

	// Send [DONE] marker for OpenAI compatibility
	endOfStream := "[DONE]"
	if err = sender(&endOfStream, nil); err != nil {
		return err
	}

	return nil
}

// Embed embeds a list of texts into embeddings
func (m *MoonshotModel) Embed(ctx context.Context, modelName *string, texts []string, apiConfig *APIConfig, embeddingConfig *EmbeddingConfig, modelUsage *common.ModelUsage) ([]EmbeddingData, error) {
	return nil, fmt.Errorf("not implemented")
}

func (m *MoonshotModel) ListModels(ctx context.Context, apiConfig *APIConfig) ([]ListModelResponse, error) {
	if err := m.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}
	apiKey := strings.TrimSpace(*apiConfig.ApiKey)

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

	ctx, cancel := context.WithTimeout(ctx, 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", apiKey))
	req.Header.Set("Accept", "application/json")

	resp, err := m.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))
	}

	// Parse response
	var modelList ModelList
	if err = json.Unmarshal(body, &modelList); err != nil {
		return nil, fmt.Errorf("failed to parse response: %w", err)
	}
	if modelList.Models == nil {
		return nil, fmt.Errorf("invalid models list format")
	}
	models := ParseListModel(modelList)
	if len(models) == 0 {
		return nil, fmt.Errorf("invalid models list format")
	}
	return models, nil
}

func (m *MoonshotModel) Balance(ctx context.Context, apiConfig *APIConfig) (map[string]interface{}, error) {
	if err := m.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}
	apiKey := strings.TrimSpace(*apiConfig.ApiKey)

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

	ctx, cancel := context.WithTimeout(ctx, 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", apiKey))
	req.Header.Set("Accept", "application/json")

	resp, err := m.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 struct {
		Data *struct {
			AvailableBalance *float64 `json:"available_balance"`
		} `json:"data"`
	}
	if err = json.Unmarshal(body, &result); err != nil {
		return nil, fmt.Errorf("failed to parse response: %w", err)
	}
	if result.Data == nil || result.Data.AvailableBalance == nil {
		return nil, fmt.Errorf("balance response missing available_balance")
	}

	var response = map[string]interface{}{
		"balance":  *result.Data.AvailableBalance,
		"currency": "CNY",
	}

	return response, nil
}

func (m *MoonshotModel) CheckConnection(ctx context.Context, apiConfig *APIConfig) error {
	_, err := m.ListModels(ctx, apiConfig)
	if err != nil {
		return err
	}
	return nil
}

// Rerank calculates similarity scores between query and documents
func (m *MoonshotModel) Rerank(ctx context.Context, modelName *string, query string, documents []string, apiConfig *APIConfig, rerankConfig *RerankConfig, modelUsage *common.ModelUsage) (*RerankResponse, error) {
	return nil, fmt.Errorf("%s, Rerank not implemented", m.Name())
}

// TranscribeAudio transcribe audio
func (m *MoonshotModel) TranscribeAudio(ctx context.Context, modelName *string, file *string, apiConfig *APIConfig, asrConfig *ASRConfig, modelUsage *common.ModelUsage) (*ASRResponse, error) {
	return nil, fmt.Errorf("%s, no such method", m.Name())
}

func (m *MoonshotModel) TranscribeAudioWithSender(ctx context.Context, modelName *string, file *string, apiConfig *APIConfig, asrConfig *ASRConfig, modelUsage *common.ModelUsage, sender func(*string, *string) error) error {
	return fmt.Errorf("%s, no such method", m.Name())
}

// AudioSpeech convert text to audio
func (m *MoonshotModel) AudioSpeech(ctx context.Context, modelName *string, audioContent *string, apiConfig *APIConfig, ttsConfig *TTSConfig, modelUsage *common.ModelUsage) (*TTSResponse, error) {
	return nil, fmt.Errorf("%s, no such method", m.Name())
}

func (m *MoonshotModel) AudioSpeechWithSender(ctx context.Context, modelName *string, audioContent *string, apiConfig *APIConfig, ttsConfig *TTSConfig, modelUsage *common.ModelUsage, sender func(*string, *string) error) error {
	return fmt.Errorf("%s, no such method", m.Name())
}

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

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

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

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