// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package dsync

import "context"

// LockArgs is minimal required values for any dsync compatible lock operation.
type LockArgs struct {
	// Unique ID of lock/unlock request.
	UID string

	// Resources contains single or multiple entries to be locked/unlocked.
	Resources []string

	// Source contains the line number, function and file name of the code
	// on the client node that requested the lock.
	Source string

	// Owner represents unique ID for this instance, an owner who originally requested
	// the locked resource, useful primarily in figuring our stale locks.
	Owner string

	// Quorum represents the expected quorum for this lock type.
	Quorum int
}

// NetLocker is dsync compatible locker interface.
type NetLocker interface {
	// Do read lock for given LockArgs.  It should return
	// * a boolean to indicate success/failure of the operation
	// * an error on failure of lock request operation.
	RLock(ctx context.Context, args LockArgs) (bool, error)

	// Do write lock for given LockArgs. It should return
	// * a boolean to indicate success/failure of the operation
	// * an error on failure of lock request operation.
	Lock(ctx context.Context, args LockArgs) (bool, error)

	// Do read unlock for given LockArgs. It should return
	// * a boolean to indicate success/failure of the operation
	// * an error on failure of unlock request operation.
	// Canceling the context will abort the remote call.
	// In that case, the resource may or may not be unlocked.
	RUnlock(ctx context.Context, args LockArgs) (bool, error)

	// Do write unlock for given LockArgs. It should return
	// * a boolean to indicate success/failure of the operation
	// * an error on failure of unlock request operation.
	// Canceling the context will abort the remote call.
	// In that case, the resource may or may not be unlocked.
	Unlock(ctx context.Context, args LockArgs) (bool, error)

	// Refresh the given lock to prevent it from becoming stale
	Refresh(ctx context.Context, args LockArgs) (bool, error)

	// Unlock (read/write) forcefully for given LockArgs. It should return
	// * a boolean to indicate success/failure of the operation
	// * an error on failure of unlock request operation.
	ForceUnlock(ctx context.Context, args LockArgs) (bool, error)

	// Returns underlying endpoint of this lock client instance.
	String() string

	// Close closes any underlying connection to the service endpoint
	Close() error

	// Is the underlying connection online? (is always true for any local lockers)
	IsOnline() bool

	// Is the underlying locker local to this server?
	IsLocal() bool
}