package oauth

import (
	"bookra/apps/auth-service/internal/config"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
)

type GoogleUser struct {
	ID            string `json:"id"`
	Email         string `json:"email"`
	Name          string `json:"name"`
	Picture       string `json:"picture"`
	VerifiedEmail bool   `json:"verified_email"`
}

type GoogleProvider struct {
	config *oauth2.Config
}

func NewGoogleProvider(cfg *config.Config) *GoogleProvider {
	if cfg.GoogleClientID == "" || cfg.GoogleClientSecret == "" {
		return nil
	}

	redirectURL := cfg.GoogleRedirectURL
	if redirectURL == "" {
		redirectURL = cfg.FrontendURL + "/auth/oauth/google/callback"
	}

	return &GoogleProvider{
		config: &oauth2.Config{
			ClientID:     cfg.GoogleClientID,
			ClientSecret: cfg.GoogleClientSecret,
			RedirectURL:  redirectURL,
			Scopes: []string{
				"openid",
				"https://www.googleapis.com/auth/userinfo.email",
				"https://www.googleapis.com/auth/userinfo.profile",
			},
			Endpoint: google.Endpoint,
		},
	}
}

func (p *GoogleProvider) Enabled() bool {
	return p != nil && p.config != nil
}

func (p *GoogleProvider) GetAuthURL(state string) string {
	return p.config.AuthCodeURL(state, oauth2.AccessTypeOnline)
}

func (p *GoogleProvider) ExchangeCode(ctx context.Context, code string) (*GoogleUser, error) {
	token, err := p.config.Exchange(ctx, code)
	if err != nil {
		return nil, fmt.Errorf("exchange code: %w", err)
	}

	client := p.config.Client(ctx, token)
	resp, err := client.Get("https://www.googleapis.com/oauth2/v2/userinfo")
	if err != nil {
		return nil, fmt.Errorf("fetch userinfo: %w", err)
	}
	defer resp.Body.Close()

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

	var user GoogleUser
	if err := json.NewDecoder(resp.Body).Decode(&user); err != nil {
		return nil, fmt.Errorf("decode userinfo: %w", err)
	}

	return &user, nil
}

func (p *GoogleProvider) ParseUser(user *GoogleUser) (providerID, email, name string) {
	return user.ID, user.Email, user.Name
}