//
//  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"
	"strings"
)

// GPUStackModel implements ModelDriver for GPUStack
type GPUStackModel struct {
	baseModel BaseModel
}

func NewGPUStackModel(baseURL map[string]string, urlSuffix URLSuffix) *GPUStackModel {
	return &GPUStackModel{
		baseModel: BaseModel{
			BaseURL:          baseURL,
			URLSuffix:        urlSuffix,
			AllowEmptyAPIKey: true,
			httpClient:       NewDriverHTTPClient(),
		},
	}
}

func (g *GPUStackModel) NewInstance(baseURL map[string]string) ModelDriver {
	return NewGPUStackModel(baseURL, g.baseModel.URLSuffix)
}

func (g *GPUStackModel) Name() string {
	return "gpustack"
}

// ChatWithMessages sends multiple messages and returns the response.
func (g *GPUStackModel) ChatWithMessages(modelName string, messages []Message, apiConfig *APIConfig, chatModelConfig *ChatConfig) (*ChatResponse, error) {
	if err := g.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}
	if strings.TrimSpace(modelName) == "" {
		return nil, fmt.Errorf("model name is required")
	}
	if len(messages) == 0 {
		return nil, fmt.Errorf("messages is empty")
	}

	baseURL, err := g.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return nil, err
	}
	baseURL = strings.TrimSuffix(baseURL, "/")
	url := fmt.Sprintf("%s/%s", baseURL, g.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, http.MethodPost, url, bytes.NewBuffer(jsonData))
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	if auth := BearerAuth(apiConfig); auth != "" {
		req.Header.Set("Authorization", auth)
	}

	resp, err := g.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")
	}

	reasonContent := ""
	if r, ok := messageMap["reasoning_content"].(string); ok {
		reasonContent = r
	}

	return &ChatResponse{
		Answer:        &content,
		ReasonContent: &reasonContent,
	}, nil
}

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

	if sender == nil {
		return fmt.Errorf("sender is required")
	}
	if strings.TrimSpace(modelName) == "" {
		return fmt.Errorf("model name is required")
	}
	if len(messages) == 0 {
		return fmt.Errorf("messages is empty")
	}

	baseURL, err := g.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return err
	}
	baseURL = strings.TrimSuffix(baseURL, "/")
	url := fmt.Sprintf("%s/%s", baseURL, g.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(), http.MethodPost, url, bytes.NewBuffer(jsonData))
	if err != nil {
		return fmt.Errorf("failed to create request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	if auth := BearerAuth(apiConfig); auth != "" {
		req.Header.Set("Authorization", auth)
	}
	req.Header.Set("Accept", "text/event-stream")

	resp, err := g.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))
	}

	sawTerminal := false
	done, err := ParseSSEStream[map[string]interface{}](resp.Body, func(event map[string]interface{}) error {
		if apiErr, ok := event["error"]; ok {
			return fmt.Errorf("gpustack: upstream stream error: %v", apiErr)
		}

		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
		}

		if r, ok := delta["reasoning_content"].(string); ok && r != "" {
			if err := sender(nil, &r); 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("gpustack: stream ended before [DONE] or finish_reason")
	}

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

type gpustackModelInfo struct {
	ID string `json:"id"`
}

type gpustackModelsResponse struct {
	Data []DSModel `json:"data"`
}

func (g *GPUStackModel) ListModels(apiConfig *APIConfig) ([]ListModelResponse, error) {
	if err := g.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}

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

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

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	if auth := BearerAuth(apiConfig); auth != "" {
		req.Header.Set("Authorization", auth)
	}

	resp, err := g.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 parsed gpustackModelsResponse
	if err = json.Unmarshal(body, &parsed); err != nil {
		return nil, fmt.Errorf("failed to parse response: %w", err)
	}

	return ParseListModel(ModelList{Models: parsed.Data}), nil
}

func (g *GPUStackModel) CheckConnection(apiConfig *APIConfig) error {
	_, err := g.ListModels(apiConfig)
	return err
}

// gpustackEmbeddingData is one element in a GPUStack embeddings response.
type gpustackEmbeddingData struct {
	Embedding []float64 `json:"embedding"`
	Index     *int      `json:"index"`
}

// gpustackEmbeddingResponse is the JSON body returned by GPUStack embeddings API.
type gpustackEmbeddingResponse struct {
	Data []gpustackEmbeddingData `json:"data"`
}

// Embed requests embedding vectors via GPUStack's v1-openai/embeddings endpoint.
func (g *GPUStackModel) Embed(
	modelName *string,
	texts []string,
	apiConfig *APIConfig,
	embeddingConfig *EmbeddingConfig,
) ([]EmbeddingData, error) {
	if err := g.baseModel.APIConfigCheck(apiConfig); err != nil {
		return nil, err
	}

	if len(texts) == 0 {
		return []EmbeddingData{}, nil
	}
	if modelName == nil || strings.TrimSpace(*modelName) == "" {
		return nil, fmt.Errorf("model name is required")
	}

	baseURL, err := g.baseModel.GetBaseURL(apiConfig)
	if err != nil {
		return nil, err
	}
	baseURL = strings.TrimSuffix(baseURL, "/")
	if g.baseModel.URLSuffix.Embedding == "" {
		return nil, fmt.Errorf("gpustack: embedding URL suffix is not configured")
	}
	url := fmt.Sprintf("%s/%s", baseURL, strings.TrimPrefix(g.baseModel.URLSuffix.Embedding, "/"))

	reqBody := map[string]interface{}{
		"model": *modelName,
		"input": texts,
	}
	if embeddingConfig != nil && embeddingConfig.Dimension > 0 {
		reqBody["dimensions"] = embeddingConfig.Dimension
	}

	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, http.MethodPost, url, bytes.NewBuffer(jsonData))
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	if auth := BearerAuth(apiConfig); auth != "" {
		req.Header.Set("Authorization", auth)
	}

	resp, err := g.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("gpustack embeddings API error: %s, body: %s", resp.Status, string(body))
	}

	var parsed gpustackEmbeddingResponse
	if err = json.Unmarshal(body, &parsed); err != nil {
		return nil, fmt.Errorf("failed to parse response: %w", err)
	}

	embeddings := make([]EmbeddingData, len(texts))
	filled := make([]bool, len(texts))
	for _, item := range parsed.Data {
		if item.Index == nil {
			return nil, fmt.Errorf("gpustack: missing embedding index in response item")
		}
		idx := *item.Index
		if idx < 0 || idx >= len(texts) {
			return nil, fmt.Errorf("gpustack: embedding response index %d out of range for %d inputs", idx, len(texts))
		}
		if filled[idx] {
			return nil, fmt.Errorf("gpustack: duplicate embedding index %d in response", idx)
		}
		if len(item.Embedding) == 0 {
			return nil, fmt.Errorf("gpustack: empty embedding vector for input index %d", idx)
		}
		embeddings[idx] = EmbeddingData{
			Embedding: item.Embedding,
			Index:     idx,
		}
		filled[idx] = true
	}
	for i, ok := range filled {
		if !ok {
			return nil, fmt.Errorf("gpustack: missing embedding for input index %d", i)
		}
	}
	return embeddings, nil
}

func (g *GPUStackModel) Rerank(modelName *string, query string, documents []string, apiConfig *APIConfig, rerankConfig *RerankConfig) (*RerankResponse, error) {
	return nil, fmt.Errorf("%s, no such method", g.Name())
}

func (g *GPUStackModel) Balance(apiConfig *APIConfig) (map[string]interface{}, error) {
	return nil, fmt.Errorf("%s, no such method", g.Name())
}

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

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

func (g *GPUStackModel) AudioSpeech(modelName *string, audioContent *string, apiConfig *APIConfig, ttsConfig *TTSConfig) (*TTSResponse, error) {
	return nil, fmt.Errorf("%s, no such method", g.Name())
}

func (g *GPUStackModel) AudioSpeechWithSender(modelName *string, audioContent *string, apiConfig *APIConfig, ttsConfig *TTSConfig, sender func(*string, *string) error) error {
	return fmt.Errorf("%s, no such method", g.Name())
}

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

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

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

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