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// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//go:build linux && cgo && withjournald
// +build linux,cgo,withjournald

package journald

import (
	"errors"
	"time"

	"github.com/elastic/beats/v7/filebeat/input/journald/pkg/journalfield"
	"github.com/elastic/beats/v7/filebeat/input/journald/pkg/journalread"
)

// Config stores the options of a journald input.
type config struct {
	// Paths stores the paths to the journal files to be read.
	Paths []string `config:"paths"`

	// Backoff is the current interval to wait before
	// attemting to read again from the journal.
	Backoff time.Duration `config:"backoff" validate:"min=0,nonzero"`

	// MaxBackoff is the limit of the backoff time.
	MaxBackoff time.Duration `config:"max_backoff" validate:"min=0,nonzero"`

	// Seek is the method to read from journals.
	Seek journalread.SeekMode `config:"seek"`

	// CursorSeekFallback sets where to seek if registry file is not available.
	CursorSeekFallback journalread.SeekMode `config:"cursor_seek_fallback"`

	// Matches store the key value pairs to match entries.
	Matches []journalfield.Matcher `config:"include_matches"`

	// SaveRemoteHostname defines if the original source of the entry needs to be saved.
	SaveRemoteHostname bool `config:"save_remote_hostname"`
}

var errInvalidSeekFallback = errors.New("invalid setting for cursor_seek_fallback")

func defaultConfig() config {
	return config{
		Backoff:            1 * time.Second,
		MaxBackoff:         20 * time.Second,
		Seek:               journalread.SeekCursor,
		CursorSeekFallback: journalread.SeekHead,
		SaveRemoteHostname: false,
	}
}

func (c *config) Validate() error {
	if c.CursorSeekFallback != journalread.SeekHead && c.CursorSeekFallback != journalread.SeekTail {
		return errInvalidSeekFallback
	}
	return nil
}
