// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0

package processorhelper // import "go.opentelemetry.io/collector/processor/processorhelper"

import (
	"context"
	"errors"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"

	"go.opentelemetry.io/collector/component"
	"go.opentelemetry.io/collector/consumer"
	"go.opentelemetry.io/collector/pdata/plog"
	"go.opentelemetry.io/collector/processor"
)

// ProcessLogsFunc is a helper function that processes the incoming data and returns the data to be sent to the next component.
// If error is returned then returned data are ignored. It MUST not call the next component.
type ProcessLogsFunc func(context.Context, plog.Logs) (plog.Logs, error)

type logProcessor struct {
	component.StartFunc
	component.ShutdownFunc
	consumer.Logs
}

// NewLogsProcessor creates a processor.Logs that ensure context propagation and the right tags are set.
func NewLogsProcessor(
	_ context.Context,
	set processor.Settings,
	_ component.Config,
	nextConsumer consumer.Logs,
	logsFunc ProcessLogsFunc,
	options ...Option,
) (processor.Logs, error) {
	// TODO: Add observability metrics support
	if logsFunc == nil {
		return nil, errors.New("nil logsFunc")
	}

	obs, err := newObsReport(ObsReportSettings{
		ProcessorID:             set.ID,
		ProcessorCreateSettings: set,
	})
	if err != nil {
		return nil, err
	}
	obs.otelAttrs = append(obs.otelAttrs, attribute.String("otel.signal", "logs"))

	eventOptions := spanAttributes(set.ID)
	bs := fromOptions(options)
	logsConsumer, err := consumer.NewLogs(func(ctx context.Context, ld plog.Logs) error {
		span := trace.SpanFromContext(ctx)
		span.AddEvent("Start processing.", eventOptions)
		recordsIn := ld.LogRecordCount()

		ld, err = logsFunc(ctx, ld)
		span.AddEvent("End processing.", eventOptions)
		if err != nil {
			if errors.Is(err, ErrSkipProcessingData) {
				return nil
			}
			return err
		}
		recordsOut := ld.LogRecordCount()
		obs.recordInOut(ctx, recordsIn, recordsOut)
		return nextConsumer.ConsumeLogs(ctx, ld)
	}, bs.consumerOptions...)
	if err != nil {
		return nil, err
	}

	return &logProcessor{
		StartFunc:    bs.StartFunc,
		ShutdownFunc: bs.ShutdownFunc,
		Logs:         logsConsumer,
	}, nil
}
