// Copyright 2019 Drone.IO Inc. All rights reserved.
// Use of this source code is governed by the Drone Non-Commercial License
// that can be found in the LICENSE file.

package token

import (
	"context"
	"time"

	"github.com/drone/drone/core"

	"github.com/drone/go-scm/scm"
	"github.com/drone/go-scm/scm/transport/oauth2"
)

// expiryDelta determines how earlier a token should be considered
// expired than its actual expiration time. It is used to avoid late
// expirations due to client-server time mismatches.
const expiryDelta = time.Minute

type renewer struct {
	refresh *oauth2.Refresher
	users   core.UserStore
}

// Renewer returns a new Renewer.
func Renewer(refresh *oauth2.Refresher, store core.UserStore) core.Renewer {
	return &renewer{
		refresh: refresh,
		users:   store,
	}
}

func (r *renewer) Renew(ctx context.Context, user *core.User, force bool) error {
	if r.refresh == nil {
		return nil
	}
	t := &scm.Token{
		Token:   user.Token,
		Refresh: user.Refresh,
		Expires: time.Unix(user.Expiry, 0),
	}
	if expired(t) == false && force == false {
		return nil
	}
	err := r.refresh.Refresh(t)
	if err != nil {
		return err
	}
	user.Token = t.Token
	user.Refresh = t.Refresh
	user.Expiry = t.Expires.Unix()
	return r.users.Update(ctx, user)
}

// expired reports whether the token is expired.
func expired(token *scm.Token) bool {
	if len(token.Refresh) == 0 {
		return false
	}
	if token.Expires.IsZero() && len(token.Token) != 0 {
		return false
	}
	return token.Expires.Add(-expiryDelta).
		Before(time.Now())
}