mgr

type CDNMgr interface {
	// TriggerCDN will trigger CDN to download the file from sourceUrl.
	// In common, it will including the following steps:
	// 1). download the source file
	// 2). update the taskInfo
	// 3). write the file to disk
	TriggerCDN(ctx context.Context, taskInfo *types.TaskInfo) error

	// GetStatus get the status of the file.
	GetStatus(ctx context.Context, taskID string) (cdnStatus string, err error)

	// Delete delete the file from disk with specified taskID.
	Delete(ctx context.Context, taskID string) error
}

type DfgetTaskMgr interface {
	// Add a new dfgetTask, we use clientID to identify a dfgetTask uniquely.
	// ClientID should be generated by dfget, supernode will use it directly.
	// NOTE: We should create a new dfgetTask for each download process,
	//       even if the downloads initiated by the same machine.
	Add(ctx context.Context, dfgetTask *types.DfGetTask) error

	// Get get a dfgetTask info with specified clientID.
	Get(ctx context.Context, clientID string) (dfgetTask *types.DfGetTask, err error)

	// List return the list of dfgetTask.
	List(ctx context.Context, filter map[string]string) (dfgetTaskList []*types.DfGetTask, err error)

	// Delete a dfgetTask with clientID.
	Delete(ctx context.Context, clientID string) error

	// UpdateStatus update the status of dfgetTask with specified clientID.
	// Supernode will update the status of dfgetTask in the following situations:
	// 1. after init the dfgetTask
	// 2. when success/fail to download some pieces
	// 3. when the entire download process ends in success or failure
	UpdateStatus(ctx context.Context, clientID string, status string) error
}

type PeerMgr interface {
	// Register a peer with specified peerInfo.
	// Supernode will generate a unique peerID for every Peer with PeerInfo provided.
	Register(ctx context.Context, peerInfo *types.PeerInfo) (peerID string, err error)

	// DeRegister offline a peer service and
	// NOTE: update the info related for scheduler.
	DeRegister(ctx context.Context, peerID string) error

	// Get the peer Info with specified peerID.
	Get(ctx context.Context, peerID string) (*types.PeerInfo, error)

	// List return a list of peers info with filter.
	List(ctx context.Context, filter map[string]string) (peerList []*types.PeerInfo, err error)

	// Update the status of specified peer.
	//
	// Supernode will update the status of peer in the following situations:
	// 1) When an exception occurs to the peer server.
	// 2) When peer sends a request take the server offline.
	//
	// NOTE: update the info related for scheduler.
	Update(ctx context.Context, peerID string, peerInfo *types.PeerInfo) error
}

type ProgressMgr interface {
	// InitProgress init the correlation information between peers and pieces, etc.
	InitProgress(ctx context.Context, taskID, clientID string) error

	// UpdateProgress update the correlation information between peers and pieces.
	// 1. update the info about srcCid to tell the scheduler that corresponding peer has the piece now.
	// 2. update the info about dstCid to tell the scheduler that someone has downloaded the piece form here.
	// Scheduler will calculate the load and times of error/success for every peer to make better decisions.
	UpdateProgress(ctx context.Context, taskID, srcCid, dstCid string, pieceRange string, pieceStatus string) error

	// GetPieceByCid get all pieces with specified clientID.
	GetPiecesByCid(ctx context.Context, clientID string) (pieceRanges []string, err error)

	// GetPeersByPieceRange get all peers info with specified taskID and pieceRange.
	GetPeersByPieceRange(ctx context.Context, taskID, pieceRange string) (peersInfo []*types.PeerInfo, err error)

	// GetPeersBytaskID get all peers info with specified taskID.
	GetPeersBytaskID(ctx context.Context, taskID string) (peersInfo []*types.PeerInfo, err error)
}

type SchedulerMgr interface {
	// Schedule get scheduler result with specified taskID, clientID through some rules.
	Schedule(ctx context.Context, taskID, clientID string) ([]*types.PieceInfo, error)
}

type TaskMgr interface {
	// Register a task represents that someone wants to download a file.
	// Supernode will get the task file meta and return taskID.
	// NOTE: If supernode cannot find the task file, the CDN download will be triggered.
	Register(ctx context.Context, task *types.TaskInfo) (taskID string, err error)

	// Get the task Info with specified taskID.
	Get(ctx context.Context, taskID string) (*types.TaskInfo, error)

	// List returns the list tasks with filter.
	List(ctx context.Context, filter map[string]string) ([]*types.TaskInfo, error)

	// CheckTaskStatus check whether the taskID corresponding file exists.
	CheckTaskStatus(ctx context.Context, taskID string) (bool, error)

	// DeleteTask delete a task
	// NOTE: delete the related peers and dfgetTask info is necessary.
	DeleteTask(ctx context.Context, taskID string) error

	// update the task info with specified info.
	// In common, there are several situations that we will use this method:
	// 1. when finished to download, update task status.
	// 2. for operation usage.
	UpdateTaskInfo(ctx context.Context, taskID string, taskInfo *types.TaskInfo) error

	// GetPieces get the pieces to be downloaded based on the scheduling result,
	// just like this: which pieces can be downloaded from which peers.
	GetPieces(ctx context.Context, taskID, clientID string) ([]*types.PieceInfo, error)

	// UpdatePieceStatus update the piece status with specified parameters.
	// A task file is divided into several pieces logically.
	// We use a sting called pieceRange to identify a piece.
	// A pieceRange separated by a dash, like this: 0-45565, etc.
	UpdatePieceStatus(ctx context.Context, taskID, pieceRange, clientID string) error
}