package app

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

func completeChat(ctx context.Context, base, key, model, prompt string) (string, error) {
	body, _ := json.Marshal(map[string]any{
		"model": model,
		"messages": []map[string]string{
			{"role": "user", "content": prompt},
		},
	})
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, strings.TrimRight(base, "/")+"/chat/completions", bytes.NewReader(body))
	if err != nil {
		return "", err
	}
	req.Header.Set("Content-Type", "application/json")
	if key != "" {
		req.Header.Set("Authorization", "Bearer "+key)
	}
	client := &http.Client{Timeout: 60 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
	if resp.StatusCode >= 300 {
		return "", fmt.Errorf("llm %d: %s", resp.StatusCode, truncate(string(raw), 200))
	}
	var out struct {
		Choices []struct {
			Message struct {
				Content string `json:"content"`
			} `json:"message"`
		} `json:"choices"`
	}
	if err := json.Unmarshal(raw, &out); err != nil {
		return "", err
	}
	if len(out.Choices) == 0 {
		return "", fmt.Errorf("llm: empty choices")
	}
	return out.Choices[0].Message.Content, nil
}

func truncate(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n]
}