types

type ChangeDescription struct {
	// updated details's value is the current value, not the previous value.
	UpdatedFields map[string]interface{}
	RemovedFields []string
}

type Event struct {
	// Oid represent the unique document key filed "_id"
	Oid           string
	Document      interface{}
	DocBytes      []byte
	OperationType OperType

	// The timestamp from the oplog entry associated with the event.
	ClusterTime TimeStamp

	// event token for resume after.
	Token EventToken

	// changed fields details in this event, describes which fields is updated or removed.
	ChangeDesc *ChangeDescription
}

type EventDetail struct {
	Detail        JsonString             `json:"detail"`
	UpdatedFields map[string]interface{} `json:"update_fields"`
	RemovedFields []string               `json:"deleted_fields"`
}

type EventStream struct {
	Token         EventToken          `bson:"_id"`
	OperationType OperType            `bson:"operationType"`
	ClusterTime   primitive.Timestamp `bson:"clusterTime"`
	Namespace     Namespace           `bson:"ns"`
	DocumentKey   Key                 `bson:"documentKey"`
	UpdateDesc    UpdateDescription   `bson:"updateDescription"`
}

type EventToken struct {
	// Hex value of document's _id
	Data string `bson:"_data"`
}

type JsonString string

type Key struct {
	// the unique document id, as is "_id"
	ID primitive.ObjectID `bson:"_id"`
}

type ListOptions struct {
	// Filter helps you filter out which kind of data's change event you want
	// to receive, such as the filter :
	// {"bk_obj_id":"biz"} means you can only receives the data that has this kv.
	// Note: the filter's key must be a exist document key filed in the collection's
	// document
	Filter map[string]interface{}

	// list the documents only with these fields.
	Fields []string

	// EventStruct is the point data struct that the event decoded into.
	// Note: must be a point value.
	EventStruct interface{}

	// Collection defines which collection you want you watch.
	Collection string

	// Step defines the list step when the client try to list all the data defines in the
	// namespace. default value is `DefaultListStep`, value range [200,2000]
	PageSize *int
}

type ListWatchOptions struct {
	Options

	// Step defines the list step when the client try to list all the data defines in the
	// namespace. default value is `DefaultListStep`, value range [200,2000]
	PageSize *int
}

type Namespace struct {
	Database   string `bson:"db"`
	Collection string `bson:"coll"`
}

type OperType string

type Options struct {
	// reference doc:
	// https://docs.mongodb.com/manual/reference/method/db.collection.watch/#change-stream-with-full-document-update-lookup
	// default value is true
	MajorityCommitted *bool

	// The maximum amount of time in milliseconds the server waits for new
	// data changes to report to the change stream cursor before returning
	// an empty batch.
	// default value is 1000ms
	MaxAwaitTime *time.Duration

	// OperationType describe which kind of operation you want to watch,
	// such as a "insert" operation or a "replace" operation.
	// If you don't set, it will means watch  all kinds of operations.
	OperationType *OperType

	// Filter helps you filter out which kind of data's change event you want
	// to receive, such as the filter :
	// {"bk_obj_id":"biz"} means you can only receives the data that has this kv.
	// Note: the filter's key must be a exist document key filed in the collection's
	// document
	Filter map[string]interface{}

	// EventStruct is the point data struct that the event decoded into.
	// Note: must be a point value.
	EventStruct interface{}

	// Collection defines which collection you want you watch.
	Collection string

	// StartAfterToken describe where you want to watch the event.
	// Note: the returned event does'nt contains the token represented,
	// and will returns event just after this token.
	StartAfterToken *EventToken

	// Ensures that this watch will provide events that occurred after this timestamp.
	StartAtTime *TimeStamp
}

type TimeStamp struct {
	// the most significant 32 bits are a time_t value (seconds since the Unix epoch)
	Sec uint32 `json:"sec"`
	// the least significant 32 bits are an incrementing ordinal for operations within a given second.
	Nano uint32 `json:"nano"`
}

type UpdateDescription struct {
	// document's fields which is updated in a change stream
	UpdatedFields map[string]interface{} `json:"updatedFields" bson:"updatedFields"`
	// document's fields which is removed in a change stream
	RemovedFields []string `json:"removedFields" bson:"removedFields"`
}

type WatchOptions struct {
	Options
}

type Watcher struct {
	EventChan <-chan *Event
}