package ai

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

type geminiProvider struct {
	apiKey string
	model  string
	client *http.Client
}

func newGemini(apiKey, model string) *geminiProvider {
	if model == "" {
		model = "gemini-2.0-flash"
	}
	return &geminiProvider{
		apiKey: apiKey,
		model:  model,
		client: &http.Client{},
	}
}

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

func (p *geminiProvider) Summarize(ctx context.Context, prompt string, _ GenOptions) (string, error) {
	url := fmt.Sprintf(
		"https://generativelanguage.googleapis.com/v1beta/models/%s:generateContent?key=%s",
		p.model, p.apiKey,
	)
	body := map[string]interface{}{
		"contents": []map[string]interface{}{
			{"parts": []map[string]string{{"text": prompt}}},
		},
	}
	b, _ := json.Marshal(body)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(b))
	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()

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

	var result struct {
		Candidates []struct {
			Content struct {
				Parts []struct {
					Text string `json:"text"`
				} `json:"parts"`
			} `json:"content"`
		} `json:"candidates"`
	}
	if err := json.Unmarshal(raw, &result); err != nil {
		return "", err
	}
	if len(result.Candidates) == 0 || len(result.Candidates[0].Content.Parts) == 0 {
		return "", nil
	}
	return result.Candidates[0].Content.Parts[0].Text, nil
}

func (p *geminiProvider) ListModels(ctx context.Context) ([]string, error) {
	url := fmt.Sprintf("https://generativelanguage.googleapis.com/v1beta/models?key=%s", p.apiKey)
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}
	resp, err := p.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	raw, _ := io.ReadAll(resp.Body)
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("gemini list models error %d: %s", resp.StatusCode, raw)
	}
	var result struct {
		Models []struct {
			Name               string   `json:"name"`
			SupportedMethods   []string `json:"supportedGenerationMethods"`
		} `json:"models"`
	}
	if err := json.Unmarshal(raw, &result); err != nil {
		return nil, err
	}
	var names []string
	for _, m := range result.Models {
		for _, method := range m.SupportedMethods {
			if method == "generateContent" {
				// name is "models/gemini-xxx", strip prefix
				id := m.Name
				if len(id) > 7 {
					id = id[7:] // strip "models/"
				}
				names = append(names, id)
				break
			}
		}
	}
	return names, nil
}