package github

import (
	"context"
	"encoding/json"
	"io"
	"net/http"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/github"

	"base/internal/pkg/oauth/types"
)

type client struct {
	oauthConfig *oauth2.Config
}

func New(config oauth2.Config) types.Oauth {
	oauthConfig := &oauth2.Config{
		ClientID:     config.ClientID,
		ClientSecret: config.ClientSecret,
		Endpoint:     github.Endpoint,
		RedirectURL:  config.RedirectURL,
		Scopes:       config.Scopes,
	}
	return &client{oauthConfig: oauthConfig}
}

func (g client) GetConsentAuthUrl(ctx context.Context, state string) string {
	return g.oauthConfig.AuthCodeURL(state, oauth2.AccessTypeOffline)
}

func (g client) ExchangeCodeWithToken(ctx context.Context, code string) (*types.Token, error) {
	exchange, err := g.oauthConfig.Exchange(ctx, code, oauth2.AccessTypeOffline)
	if err != nil {
		return nil, err
	}
	token, err := g.oauthConfig.TokenSource(ctx, exchange).Token()
	if err != nil {
		return nil, err
	}
	return &types.Token{
		AccessToken:  token.AccessToken,
		TokenType:    token.TokenType,
		RefreshToken: token.RefreshToken,
		ExpiresIn:    token.ExpiresIn,
	}, nil
}

func (g client) GetUserInfo(ctx context.Context, token, _ string) (types.UserInfo, error) {
	oauthClient := g.oauthConfig.Client(ctx, &oauth2.Token{AccessToken: token})

	resp, err := oauthClient.Get("https://api.github.com/user")
	if err != nil {
		return nil, err
	}

	defer resp.Body.Close()

	data, readErr := io.ReadAll(resp.Body)
	if readErr != nil {
		return nil, readErr
	}

	var user UserInfo
	if err = json.Unmarshal(data, &user); err != nil {
		return nil, err
	}

	// GitHub /user often returns null for email; fetch from /user/emails (requires user:email scope)
	if user.GEmail == "" {
		user.GEmail = g.fetchPrimaryEmail(ctx, oauthClient)
	}

	return &user, nil
}

// fetchPrimaryEmail gets the primary email from GitHub /user/emails (requires user:email scope).
func (g client) fetchPrimaryEmail(_ context.Context, oauthClient *http.Client) string {
	resp, err := oauthClient.Get("https://api.github.com/user/emails")
	if err != nil {
		return ""
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return ""
	}
	var emails []struct {
		Email    string `json:"email"`
		Primary  bool   `json:"primary"`
		Verified bool   `json:"verified"`
	}
	if err := json.Unmarshal(data, &emails); err != nil {
		return ""
	}
	for _, e := range emails {
		if e.Primary && e.Verified {
			return e.Email
		}
	}
	if len(emails) > 0 {
		return emails[0].Email
	}
	return ""
}