package main

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"

	"github.com/joho/godotenv"
)

type Message struct {
	Role    string `json:"role"`
	Content string `json:"content"`
}

type APIRequest struct {
	Model      string    `json:"model"`
	System     string    `json:"system,omitempty"`
	MaxTokens  int       `json:"max_tokens"`
	Messages   []Message `json:"messages"`
	Stream     bool      `json:"stream"`
}

type ContentBlock struct {
	Text string `json:"text"`
	Type string `json:"type"`
}

type APIResponse struct {
	Content []ContentBlock `json:"content"`
	Error   *struct {
		Type    string `json:"type"`
		Message string `json:"message"`
	} `json:"error,omitempty"`
}

type StreamEvent struct {
	Type  string          `json:"type"`
	Delta *StreamDelta    `json:"delta,omitempty"`
	Error *StreamError    `json:"error,omitempty"`
}

type StreamDelta struct {
	Type string `json:"type"`
	Text string `json:"text"`
}

type StreamError struct {
	Type    string `json:"type"`
	Message string `json:"message"`
}

var conversationHistory []Message

func loadConfig() error {
	// Try loading config from multiple locations in order
	homeDir, err := os.UserHomeDir()
	if err != nil {
		return fmt.Errorf("failed to get home directory: %w", err)
	}

	configPaths := []string{
		filepath.Join(homeDir, ".config", "prompt", "config"), // XDG standard
		filepath.Join(homeDir, ".prompt.env"),       // Home directory
		".env",                                      // Current directory (for project-specific overrides)
	}

	var lastErr error
	for _, path := range configPaths {
		err := godotenv.Load(path)
		if err == nil {
			return nil // Successfully loaded
		}
		lastErr = err
	}

	return lastErr
}

func main() {
	// Load config file
	err := loadConfig()
	if err != nil {
		fmt.Fprintf(os.Stderr, "Warning: Could not load config file: %v\n", err)
	}

	// Get configuration from environment
	apiKey := os.Getenv("ANTHROPIC_API_KEY")
	if apiKey == "" {
		fmt.Fprintln(os.Stderr, "Error: ANTHROPIC_API_KEY not set in .env file")
		os.Exit(1)
	}

	model := os.Getenv("MODEL")
	if model == "" {
		model = "claude-sonnet-4-5-20250929"
	}

	systemPrompt := os.Getenv("SYSTEM_PROMPT")

	// Get initial prompt from command-line arguments
	if len(os.Args) < 2 {
		fmt.Fprintln(os.Stderr, "Usage: prompt <your prompt>")
		os.Exit(1)
	}

	initialPrompt := strings.Join(os.Args[1:], " ")

	// Add initial user message to conversation history
	conversationHistory = append(conversationHistory, Message{
		Role:    "user",
		Content: initialPrompt,
	})

	// Send initial message
	response, err := sendMessage(apiKey, model, systemPrompt)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
		os.Exit(1)
	}

	fmt.Println(response)

	// Add assistant's response to conversation history
	conversationHistory = append(conversationHistory, Message{
		Role:    "assistant",
		Content: response,
	})

	// Interactive conversation loop
	reader := bufio.NewReader(os.Stdin)
	for {
		fmt.Println()
		fmt.Print("\033[32mYou (or 'exit' to quit): \033[0m")

		userInput, err := reader.ReadString('\n')
		if err != nil {
			break
		}

		userInput = strings.TrimSpace(userInput)

		// Check if user wants to exit
		if userInput == "exit" || userInput == "quit" || userInput == "" {
			fmt.Println("Goodbye!")
			break
		}

		// Add user input to conversation history
		conversationHistory = append(conversationHistory, Message{
			Role:    "user",
			Content: userInput,
		})

		// Send message and get response
		response, err := sendMessage(apiKey, model, systemPrompt)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
			continue
		}

		fmt.Println(response)

		// Add assistant's response to conversation history
		conversationHistory = append(conversationHistory, Message{
			Role:    "assistant",
			Content: response,
		})
	}
}

func sendMessage(apiKey, model, systemPrompt string) (string, error) {
	// Build API request with streaming enabled
	request := APIRequest{
		Model:     model,
		System:    systemPrompt,
		MaxTokens: 2048,
		Messages:  conversationHistory,
		Stream:    true,
	}

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

	// Make API call
	req, err := http.NewRequest("POST", "https://api.anthropic.com/v1/messages", bytes.NewBuffer(jsonData))
	if err != nil {
		return "", fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("x-api-key", apiKey)
	req.Header.Set("anthropic-version", "2023-06-01")
	req.Header.Set("content-type", "application/json")

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

	// Check for HTTP errors
	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return "", fmt.Errorf("API error (status %d): %s", resp.StatusCode, string(body))
	}

	// Read and parse streaming response
	var fullResponse strings.Builder
	reader := bufio.NewReader(resp.Body)

	for {
		line, err := reader.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break
			}
			return "", fmt.Errorf("failed to read stream: %w", err)
		}

		line = strings.TrimSpace(line)

		// Skip empty lines and non-data lines
		if line == "" || !strings.HasPrefix(line, "data: ") {
			continue
		}

		// Extract JSON data
		data := strings.TrimPrefix(line, "data: ")

		// Skip the [DONE] message
		if data == "[DONE]" {
			break
		}

		// Parse the event
		var event StreamEvent
		if err := json.Unmarshal([]byte(data), &event); err != nil {
			continue // Skip malformed events
		}

		// Check for errors
		if event.Error != nil {
			return "", fmt.Errorf("API error: %s - %s", event.Error.Type, event.Error.Message)
		}

		// Print text deltas as they arrive
		if event.Type == "content_block_delta" && event.Delta != nil && event.Delta.Type == "text_delta" {
			fmt.Print(event.Delta.Text)
			fullResponse.WriteString(event.Delta.Text)
		}
	}

	fmt.Println() // Add newline after streaming response

	return fullResponse.String(), nil
}