package llm

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

type GeminiProvider struct {
	apiKey  string
	baseURL string
	client  *http.Client
}

func NewGeminiProvider(apiKey, baseURL string) *GeminiProvider {
	if baseURL == "" {
		baseURL = "https://generativelanguage.googleapis.com/v1beta/models"
	}
	return &GeminiProvider{
		apiKey:  apiKey,
		baseURL: baseURL,
		client:  &http.Client{},
	}
}

func (p *GeminiProvider) Name() string {
	return "gemini"
}

func (p *GeminiProvider) GenerateReply(ctx context.Context, model string, systemPrompt, userPrompt string) (string, error) {
	url := fmt.Sprintf("%s/%s:generateContent?key=%s", p.baseURL, model, p.apiKey)

	reqBody := map[string]interface{}{
		"systemInstruction": map[string]interface{}{
			"parts": []map[string]interface{}{
				{"text": systemPrompt},
			},
		},
		"contents": []map[string]interface{}{
			{
				"role": "user",
				"parts": []map[string]interface{}{
					{"text": userPrompt},
				},
			},
		},
	}
	bs, _ := json.Marshal(reqBody)

	req, err := http.NewRequestWithContext(ctx, "POST", url, bytes.NewReader(bs))
	if err != nil {
		return "", err
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := p.client.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return "", fmt.Errorf("gemini error %d: %s", resp.StatusCode, string(body))
	}

	var result struct {
		Candidates []struct {
			Content struct {
				Parts []struct {
					Text string `json:"text"`
				} `json:"parts"`
			} `json:"content"`
		} `json:"candidates"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
		return "", err
	}
	if len(result.Candidates) == 0 || len(result.Candidates[0].Content.Parts) == 0 {
		return "", fmt.Errorf("gemini returned empty content")
	}
	return result.Candidates[0].Content.Parts[0].Text, nil
}