definitions

type BaseProcessor struct {
	ID string // ID is the unique identifier of the processor.
}

type EngineFileHandler interface {
	// GetInputFile returns the file path of the input file being processed.
	GetInputFile() string

	// GetOutputFile returns the file path of the output file generated by the processing.
	GetOutputFile() string

	// Close closes any resources associated with the file handler.
	Close()

	// GenerateNewFileHandler creates and returns a new file handler, typically used for handling parallel processing paths.
	// Returns:
	//   - A new instance of EngineFileHandler.
	//   - An error if the operation fails.
	GenerateNewFileHandler() (EngineFileHandler, error)
}

type EngineFlowObject struct {
	Metadata map[string]interface{} `json:"metadata"`
}

type EngineIncomingObject struct {
	FlowID    uuid.UUID
	Metadata  map[string]interface{}
	Reader    io.Reader
	SessionID uuid.UUID
}

type EngineInterface interface {
	Submit(flowID uuid.UUID, metadata map[string]interface{}, reader io.Reader) uuid.UUID
	SessionUpdates() <-chan SessionUpdate
}

type Flow struct {
	ID          uuid.UUID         `json:"id"`          // ID uniquely identifies the flow.
	Name        string            `json:"name"`        // Name is the human-readable name of the flow.
	Description string            `json:"description"` // Description provides a brief explanation of the flow's purpose.
	Processors  []SimpleProcessor `json:"processors"`  // Processors is the list of processors that are part of the flow, executed in order.
}

type FlowManager interface {
	// GetFirstProcessorsForFlow retrieves the first processors in the execution order for a given flow.
	// Parameters:
	//   - flowID: The UUID of the flow.
	// Returns:
	//   - A slice of SimpleProcessor representing the first processors in the flow.
	//   - An error if the operation fails.
	GetFirstProcessorsForFlow(flowID uuid.UUID) ([]SimpleProcessor, error)

	// GetLastProcessorForFlow retrieves the last processor in the execution order for a given flow.
	// Parameters:
	//   - flowID: The UUID of the flow.
	// Returns:
	//   - A pointer to a SimpleProcessor representing the last processor in the flow.
	//   - An error if the operation fails.
	GetLastProcessorForFlow(flowID uuid.UUID) (*SimpleProcessor, error)

	// ListFlows retrieves a paginated list of flows.
	// Parameters:
	//   - pagination: A pointer to a PaginationRequest containing pagination information.
	// Returns:
	//   - A PaginatedData struct containing a slice of Flow pointers and the total count of flows.
	//   - An error if the operation fails.
	ListFlows(pagination *PaginationRequest) (PaginatedData[*Flow], error)

	// GetFlowByID retrieves a flow by its UUID.
	// Parameters:
	//   - flowID: The UUID of the flow to retrieve.
	// Returns:
	//   - A pointer to the Flow struct representing the retrieved flow.
	//   - An error if the operation fails.
	GetFlowByID(flowID uuid.UUID) (*Flow, error)

	// GetProcessorByID retrieves a processor by its UUID within a specific flow.
	// Parameters:
	//   - flowID: The UUID of the flow containing the processor.
	//   - processorID: The UUID of the processor to retrieve.
	// Returns:
	//   - A pointer to a SimpleProcessor representing the retrieved processor.
	//   - An error if the operation fails.
	GetProcessorByID(flowID uuid.UUID, processorID uuid.UUID) (*SimpleProcessor, error)

	// GetNextProcessors retrieves the processors that follow a specific processor in a flow.
	// Parameters:
	//   - flowID: The UUID of the flow containing the processors.
	//   - processorID: The UUID of the processor whose successors are to be retrieved.
	// Returns:
	//   - A slice of SimpleProcessor representing the next processors in the flow.
	//   - An error if the operation fails.
	GetNextProcessors(flowID uuid.UUID, processorID uuid.UUID) ([]SimpleProcessor, error)

	// AddProcessorToFlowBefore adds a processor to a flow before a specified reference processor.
	// Parameters:
	//   - flowID: The UUID of the flow to which the processor will be added.
	//   - processor: A pointer to the SimpleProcessor to add to the flow.
	//   - referenceProcessorID: The UUID of the processor before which the new processor will be added.
	// Returns:
	//   - An error if the operation fails.
	AddProcessorToFlowBefore(flowID uuid.UUID, processor *SimpleProcessor, referenceProcessorID uuid.UUID) error

	// AddProcessorToFlowAfter adds a processor to a flow after a specified reference processor.
	// Parameters:
	//   - flowID: The UUID of the flow to which the processor will be added.
	//   - processor: A pointer to the SimpleProcessor to add to the flow.
	//   - referenceProcessorID: The UUID of the processor after which the new processor will be added.
	// Returns:
	//   - An error if the operation fails.
	AddProcessorToFlowAfter(flowID uuid.UUID, processor *SimpleProcessor, referenceProcessorID uuid.UUID) error

	// SaveFlow saves the given flow and its associated processors to the persistent storage.
	// Parameters:
	//   - flow: A pointer to the Flow struct representing the flow to be saved.
	// Returns:
	//   - An error if the operation fails.
	SaveFlow(flow *Flow) error
}

type LogEntry struct {
	SessionID     uuid.UUID        `json:"session_id"`
	ProcessorName string           `json:"processor_name"`
	ProcessorID   string           `json:"processor_id"`
	FlowID        uuid.UUID        `json:"flow_id"`
	InputFile     string           `json:"input_file"`
	OutputFile    string           `json:"output_file"`
	FlowObject    EngineFlowObject `json:"flow_object"`
	RetryCount    int              `json:"retry_count"`
}

type PaginatedData[T any] struct {
	Data       []T `json:"data"`       // Data is the slice of items for the current page.
	TotalCount int `json:"totalCount"` // TotalCount is the total number of items available.
}

type PaginationRequest struct {
	Page    int `json:"page" query:"page"`        // Page number of the paginated data.
	PerPage int `json:"perPage" query:"per_page"` // Number of items per page.
}

type Processor interface {
	// GetID returns the ID of the processor.
	// Returns:
	// - string: The ID of the processor.
	GetID() string

	// Name returns the name of the processor.
	// Returns:
	// - string: The name of the processor.
	Name() string

	// Execute executes the processor logic.
	// Parameters:
	// - info: The EngineFlowObject containing the execution information.
	// - fileHandler: The ProcessorFileHandler for handling file operations.
	// - log: The logger for logging information.
	// Returns:
	// - *EngineFlowObject: The updated EngineFlowObject after execution.
	// - error: An error if the execution fails.
	Execute(info *EngineFlowObject, fileHandler ProcessorFileHandler, log *logrus.Logger) (*EngineFlowObject, error)

	// SetConfig sets the configuration for the processor.
	// Parameters:
	// - config: A map containing the configuration settings.
	// Returns:
	// - error: An error if setting the configuration fails.
	SetConfig(config map[string]interface{}) error
}

type ProcessorFactory interface {
	// GetProcessor retrieves a processor by its type name.
	// Parameters:
	// - typeName: The type name of the processor to retrieve.
	// Returns:
	// - Processor: The retrieved processor.
	// - error: An error if the retrieval fails.
	GetProcessor(typeName string) (Processor, error)

	// RegisterProcessor registers a new processor.
	// Parameters:
	// - processor: The processor to register.
	RegisterProcessor(processor Processor)

	// RegisterProcessorWithTypeName registers a new processor with a specific type name.
	// Parameters:
	// - typeName: The type name to associate with the processor.
	// - processor: The processor to register.
	RegisterProcessorWithTypeName(typeName string, processor Processor)
}

type ProcessorFileHandler interface {
	// Read reads data from a file.
	// Returns:
	// - io.Reader: The reader for reading data.
	// - error: An error if the read operation fails.
	Read() (io.Reader, error)

	// Write writes data to a file.
	// Returns:
	// - io.Writer: The writer for writing data.
	// - error: An error if the write operation fails.
	Write() (io.Writer, error)
}

type ScheduleConfig struct {
	Type     ScheduleType
	CronExpr string // Used only if Type == CronDriven
}

type ScheduleType int

type SessionUpdate struct {
	SessionID uuid.UUID `json:"session_id"`
	Finished  bool      `json:"finished"`
	Error     error     `json:"error"`
}

type SimpleProcessor struct {
	ID         uuid.UUID              `json:"id"`          // ID uniquely identifies the processor.
	FlowID     uuid.UUID              `json:"flow_id"`     // FlowID is the ID of the flow to which the processor belongs.
	Name       string                 `json:"name"`        // Name is the human-readable name of the processor.
	Type       string                 `json:"type"`        // Type indicates the type of the processor, typically used to determine its implementation.
	FlowOrder  int                    `json:"flow_order"`  // FlowOrder specifies the order in which the processor is executed within the flow.
	Config     map[string]interface{} `json:"config"`      // Config holds the specific configuration for the processor.
	MaxRetries int                    `json:"max_retries"` // MaxRetries specifies the maximum number of retries allowed for this processor in case of failure.
	LogLevel   logrus.Level           `json:"log_level"`   // LogLevel defines the logging level used for this processor.
}

type TriggerProcessor interface {
	Processor
	GetScheduleConfig() ScheduleConfig
	HandleSessionUpdate(update SessionUpdate)
}

type WriteAheadLogger interface {
	WriteEntry(entry LogEntry)
	ReadEntries() ([]LogEntry, error)
}