package main

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

// ModelInfo contains metadata about a discovered model
type ModelInfo struct {
	ID        string `json:"id"`
	Endpoint  string `json:"endpoint"`
	MaxTokens int    `json:"max_tokens"`
}

// Message represents a chat message
type Message struct {
	Role    string `json:"role"`
	Content string `json:"content"`
}

// ChatResponse is the response from a non-streaming chat completion
type ChatResponse struct {
	Model   string `json:"model"`
	Choices []struct {
		Message Message `json:"message"`
	} `json:"choices"`
}

// StreamChunk represents a chunk from streaming chat
type StreamChunk struct {
	Model   string `json:"model"`
	Choices []struct {
		Delta struct {
			Content string `json:"content"`
		} `json:"delta"`
	} `json:"choices"`
}

// UncloseAI is the main client for OpenAI-compatible APIs
type UncloseAI struct {
	models       []ModelInfo
	ttsEndpoints []string
	apiKey       string
	timeout      time.Duration
	httpClient   *http.Client
}

// NewUncloseAI creates a new client with auto-discovery from environment variables
func NewUncloseAI() (*UncloseAI, error) {
	return NewUncloseAIWithOptions(nil, nil, "")
}

// NewUncloseAIWithOptions creates a new client with custom endpoints
func NewUncloseAIWithOptions(modelEndpoints, ttsEndpoints []string, apiKey string) (*UncloseAI, error) {
	client := &UncloseAI{
		models:       make([]ModelInfo, 0),
		ttsEndpoints: make([]string, 0),
		apiKey:       apiKey,
		timeout:      30 * time.Second,
		httpClient:   &http.Client{Timeout: 30 * time.Second},
	}

	// Discover endpoints from environment if not provided
	if modelEndpoints == nil {
		modelEndpoints = discoverEnvEndpoints("MODEL_ENDPOINT")
	}
	if ttsEndpoints == nil {
		ttsEndpoints = discoverEnvEndpoints("TTS_ENDPOINT")
	}

	// Discover models from each endpoint
	for _, endpoint := range modelEndpoints {
		if err := client.discoverModelsFromEndpoint(endpoint); err != nil {
			fmt.Printf("Warning: Failed to discover models from %s: %v\n", endpoint, err)
		}
	}

	client.ttsEndpoints = ttsEndpoints

	return client, nil
}

// discoverEnvEndpoints finds endpoints from environment variables like PREFIX_1, PREFIX_2, ...
func discoverEnvEndpoints(prefix string) []string {
	endpoints := make([]string, 0)
	for i := 1; i <= 9999; i++ {
		endpoint := os.Getenv(fmt.Sprintf("%s_%d", prefix, i))
		if endpoint == "" {
			break
		}
		endpoints = append(endpoints, endpoint)
	}
	return endpoints
}

// discoverModelsFromEndpoint discovers available models from an endpoint
func (c *UncloseAI) discoverModelsFromEndpoint(endpoint string) error {
	req, err := http.NewRequest("GET", endpoint+"/models", nil)
	if err != nil {
		return err
	}

	if c.apiKey != "" {
		req.Header.Set("Authorization", "Bearer "+c.apiKey)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("unexpected status: %d", resp.StatusCode)
	}

	var result struct {
		Data []struct {
			ID          string `json:"id"`
			MaxModelLen int    `json:"max_model_len"`
		} `json:"data"`
	}

	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return err
	}

	for _, model := range result.Data {
		maxTokens := model.MaxModelLen
		if maxTokens == 0 {
			maxTokens = 8192
		}
		c.models = append(c.models, ModelInfo{
			ID:        model.ID,
			Endpoint:  endpoint,
			MaxTokens: maxTokens,
		})
	}

	return nil
}

// ListModels returns all discovered models
func (c *UncloseAI) ListModels() []ModelInfo {
	return c.models
}

// Chat performs non-streaming chat completion
func (c *UncloseAI) Chat(ctx context.Context, messages []Message, model string, maxTokens int, temperature float64) (*ChatResponse, error) {
	modelInfo, err := c.getModelInfo(model)
	if err != nil {
		return nil, err
	}

	payload := map[string]interface{}{
		"model":       modelInfo.ID,
		"messages":    messages,
		"max_tokens":  maxTokens,
		"temperature": temperature,
		"stream":      false,
	}

	body, err := json.Marshal(payload)
	if err != nil {
		return nil, err
	}

	req, err := http.NewRequestWithContext(ctx, "POST", modelInfo.Endpoint+"/chat/completions", bytes.NewBuffer(body))
	if err != nil {
		return nil, err
	}

	req.Header.Set("Content-Type", "application/json")
	if c.apiKey != "" {
		req.Header.Set("Authorization", "Bearer "+c.apiKey)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		bodyBytes, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("unexpected status %d: %s", resp.StatusCode, string(bodyBytes))
	}

	var chatResp ChatResponse
	if err := json.NewDecoder(resp.Body).Decode(&chatResp); err != nil {
		return nil, err
	}

	return &chatResp, nil
}

// ChatStream performs streaming chat completion, returning a channel of chunks
func (c *UncloseAI) ChatStream(ctx context.Context, messages []Message, model string, maxTokens int, temperature float64) (<-chan StreamChunk, <-chan error) {
	chunkChan := make(chan StreamChunk)
	errChan := make(chan error, 1)

	go func() {
		defer close(chunkChan)
		defer close(errChan)

		modelInfo, err := c.getModelInfo(model)
		if err != nil {
			errChan <- err
			return
		}

		payload := map[string]interface{}{
			"model":       modelInfo.ID,
			"messages":    messages,
			"max_tokens":  maxTokens,
			"temperature": temperature,
			"stream":      true,
		}

		body, err := json.Marshal(payload)
		if err != nil {
			errChan <- err
			return
		}

		req, err := http.NewRequestWithContext(ctx, "POST", modelInfo.Endpoint+"/chat/completions", bytes.NewBuffer(body))
		if err != nil {
			errChan <- err
			return
		}

		req.Header.Set("Content-Type", "application/json")
		if c.apiKey != "" {
			req.Header.Set("Authorization", "Bearer "+c.apiKey)
		}

		resp, err := c.httpClient.Do(req)
		if err != nil {
			errChan <- err
			return
		}
		defer resp.Body.Close()

		if resp.StatusCode != http.StatusOK {
			bodyBytes, _ := io.ReadAll(resp.Body)
			errChan <- fmt.Errorf("unexpected status %d: %s", resp.StatusCode, string(bodyBytes))
			return
		}

		// Parse SSE stream
		scanner := bufio.NewScanner(resp.Body)
		for scanner.Scan() {
			line := scanner.Text()

			// SSE format: "data: {...}"
			if strings.HasPrefix(line, "data: ") {
				data := strings.TrimPrefix(line, "data: ")

				// Check for stream termination
				if strings.TrimSpace(data) == "[DONE]" {
					break
				}

				var chunk StreamChunk
				if err := json.Unmarshal([]byte(data), &chunk); err != nil {
					continue // Skip malformed chunks
				}

				select {
				case chunkChan <- chunk:
				case <-ctx.Done():
					return
				}
			}
		}

		if err := scanner.Err(); err != nil {
			errChan <- err
		}
	}()

	return chunkChan, errChan
}

// TTS generates speech from text
func (c *UncloseAI) TTS(text, voice, model string) ([]byte, error) {
	if len(c.ttsEndpoints) == 0 {
		return nil, fmt.Errorf("no TTS endpoints available")
	}

	endpoint := c.ttsEndpoints[0]

	payload := map[string]interface{}{
		"model": model,
		"voice": voice,
		"input": text,
	}

	body, err := json.Marshal(payload)
	if err != nil {
		return nil, err
	}

	req, err := http.NewRequest("POST", endpoint+"/audio/speech", bytes.NewBuffer(body))
	if err != nil {
		return nil, err
	}

	req.Header.Set("Content-Type", "application/json")
	if c.apiKey != "" {
		req.Header.Set("Authorization", "Bearer "+c.apiKey)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("unexpected status: %d", resp.StatusCode)
	}

	return io.ReadAll(resp.Body)
}

// getModelInfo retrieves model info by ID or returns first available
func (c *UncloseAI) getModelInfo(modelID string) (*ModelInfo, error) {
	if len(c.models) == 0 {
		return nil, fmt.Errorf("no models available")
	}

	if modelID == "" {
		return &c.models[0], nil
	}

	for i := range c.models {
		if c.models[i].ID == modelID {
			return &c.models[i], nil
		}
	}

	return nil, fmt.Errorf("model '%s' not found", modelID)
}

// Demo usage
func main() {
	fmt.Println("=== UncloseAI Go Client (with Streaming) ===\n")

	// Initialize client with auto-discovery
	client, err := NewUncloseAI()
	if err != nil {
		fmt.Printf("Error initializing client: %v\n", err)
		os.Exit(1)
	}

	models := client.ListModels()
	if len(models) == 0 {
		fmt.Println("ERROR: No models discovered. Set environment variables:")
		fmt.Println("  MODEL_ENDPOINT_1, MODEL_ENDPOINT_2, etc.")
		os.Exit(1)
	}

	fmt.Printf("Discovered %d model(s)\n", len(models))
	for _, m := range models {
		fmt.Printf("  - %s (max_tokens: %d)\n", m.ID, m.MaxTokens)
	}
	fmt.Println()

	ctx := context.Background()

	// Non-streaming chat example
	fmt.Println("=== Non-Streaming Chat ===")
	response, err := client.Chat(
		ctx,
		[]Message{
			{Role: "system", Content: "You are a helpful AI assistant."},
			{Role: "user", Content: "Explain quantum computing in one sentence."},
		},
		"", // Use first available model
		100,
		0.7,
	)

	if err != nil {
		fmt.Printf("Error: %v\n", err)
	} else {
		fmt.Printf("Model: %s\n", response.Model)
		fmt.Printf("Response: %s\n\n", response.Choices[0].Message.Content)
	}

	// Streaming chat example
	fmt.Println("=== Streaming Chat ===")
	modelID := ""
	if len(models) > 1 {
		modelID = models[1].ID
	}

	fmt.Printf("Model: %s\n", modelID)
	fmt.Print("Response: ")

	chunkChan, errChan := client.ChatStream(
		ctx,
		[]Message{
			{Role: "system", Content: "You are a coding assistant."},
			{Role: "user", Content: "Write a Go function to check if a number is prime"},
		},
		modelID,
		200,
		0.7,
	)

	for {
		select {
		case chunk, ok := <-chunkChan:
			if !ok {
				goto done
			}
			if len(chunk.Choices) > 0 {
				content := chunk.Choices[0].Delta.Content
				if content != "" {
					fmt.Print(content)
				}
			}
		case err := <-errChan:
			if err != nil {
				fmt.Printf("\nError: %v\n", err)
			}
			goto done
		}
	}

done:
	fmt.Println("\n")

	// TTS example
	if len(client.ttsEndpoints) > 0 {
		fmt.Println("=== TTS Speech Generation ===")
		audioData, err := client.TTS(
			"Hello from UncloseAI Go client! This demonstrates text to speech with streaming support.",
			"alloy",
			"tts-1",
		)

		if err != nil {
			fmt.Printf("Error: %v\n", err)
		} else {
			if err := os.WriteFile("speech.mp3", audioData, 0644); err != nil {
				fmt.Printf("[ERROR] Failed to write speech file: %v\n", err)
			} else {
				fmt.Printf("[OK] Speech file created: speech.mp3 (%d bytes)\n\n", len(audioData))
			}
		}
	}

	fmt.Println("=== Examples Complete ===")
}