package llm

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
)

// Client calls an OpenAI-compatible chat completion API.
type Client struct {
	BaseURL string
	APIKey  string
	Model   string
	Temperature float64
	HTTP    *http.Client
}

// NewClient creates a new LLM client.
func NewClient(baseURL, apiKey, model string) *Client {
	return &Client{
		BaseURL: strings.TrimRight(baseURL, "/"),
		APIKey:  apiKey,
		Model:   model,
		HTTP:    &http.Client{},
	}
}

// WithTemperature sets the temperature for LLM requests.
// A value of 0 (the zero value) means the field is omitted from the request,
// causing the server to use its default temperature.
// If not set (zero value), the server default is used.
func (c *Client) WithTemperature(t float64) *Client {
	c.Temperature = t
	return c
}

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

// ChatRequest is the request payload.
type ChatRequest struct {
	Model       string    `json:"model"`
	Messages    []Message `json:"messages"`
	Temperature float64   `json:"temperature,omitempty"`
}

// ChatResponse is the response from the API.
type ChatResponse struct {
	Choices []struct {
		Message struct {
			Content string `json:"content"`
		} `json:"message"`
	} `json:"choices"`
}

// Complete sends a chat completion request and returns the assistant's response content.
func (c *Client) Complete(messages []Message) (string, error) {
	reqBody := ChatRequest{
		Model:       c.Model,
		Temperature: c.Temperature,
		Messages:    messages,
		
	}

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

	url := c.BaseURL + "/chat/completions"
	req, err := http.NewRequest("POST", url, bytes.NewReader(data))
	if err != nil {
		return "", fmt.Errorf("create request: %w", err)
	}
	req.Header.Set("Authorization", "Bearer "+c.APIKey)
	req.Header.Set("Content-Type", "application/json")

	resp, err := c.HTTP.Do(req)
	if err != nil {
		return "", fmt.Errorf("LLM request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		body, _ := io.ReadAll(resp.Body)
		return "", fmt.Errorf("LLM API error (status %d): %s", resp.StatusCode, string(body))
	}

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

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

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

	return chatResp.Choices[0].Message.Content, nil
}