// Copyright 2017 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package openid

import (
	"net/http"
	"sync"
	"time"

	"gitea.dev/modules/hostmatcher"
	"gitea.dev/modules/proxy"
	"gitea.dev/modules/setting"

	"github.com/yohcop/openid-go"
)

// For the demo, we use in-memory infinite storage nonce and discovery
// cache. In your app, do not use this as it will eat up memory and
// never
// free it. Use your own implementation, on a better database system.
// If you have multiple servers for example, you may need to share at
// least
// the nonceStore between them.
var (
	nonceStore     = openid.NewSimpleNonceStore()
	discoveryCache = newTimedDiscoveryCache(24 * time.Hour)

	// openIDInstance does discovery/verification via an SSRF-protected client, so a user-supplied
	// OpenID identifier can't reach internal/loopback/reserved addresses. It honors the operator's
	// [security] ALLOWED_HOST_LIST (empty defaults to "external"), matching the avatar/webhook/migration
	// clients, and validates the proxy path too. Lazy: reads proxy/settings once.
	openIDInstance = sync.OnceValue(func() *openid.OpenID {
		allowList := hostmatcher.ParseHostMatchList("security.ALLOWED_HOST_LIST", setting.Security.AllowedHostList)
		return openid.NewOpenID(&http.Client{
			Timeout:   30 * time.Second,
			Transport: hostmatcher.NewHTTPTransport("openid", allowList, nil, proxy.Proxy(), setting.Proxy.ProxyURLFixed, nil),
		})
	})
)

// Verify handles response from OpenID provider
func Verify(fullURL string) (id string, err error) {
	return openIDInstance().Verify(fullURL, discoveryCache, nonceStore)
}

// Normalize normalizes an OpenID URI
func Normalize(url string) (id string, err error) {
	return openid.Normalize(url)
}

// RedirectURL redirects browser
func RedirectURL(id, callbackURL, realm string) (string, error) {
	return openIDInstance().RedirectURL(id, callbackURL, realm)
}