// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: MIT

//go:build windows
// +build windows

package windows_event_log

import (
	"errors"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/influxdata/telegraf"
	"github.com/influxdata/telegraf/plugins/inputs"

	"github.com/aws/amazon-cloudwatch-agent/internal/logscommon"
	"github.com/aws/amazon-cloudwatch-agent/logs"
	"github.com/aws/amazon-cloudwatch-agent/plugins/inputs/windows_event_log/wineventlog"
)

const (
	forcePullInterval = 250 * time.Millisecond
)

type EventConfig struct {
	Name          string   `toml:"event_name"`
	Levels        []string `toml:"event_levels"`
	RenderFormat  string   `toml:"event_format"`
	BatchReadSize int      `toml:"batch_read_size"`
	LogGroupName  string   `toml:"log_group_name"`
	LogStreamName string   `toml:"log_stream_name"`
	Destination   string   `toml:"destination"`
	Retention     int      `toml:"retention_in_days"`
}

type Plugin struct {
	FileStateFolder string          `toml:"file_state_folder"`
	Events          []EventConfig   `toml:"event_config"`
	Destination     string          `toml:"destination"`
	Log             telegraf.Logger `toml:"-"`

	newEvents []logs.LogSrc
}

func (s *Plugin) Description() string {
	return "A plugin to collect Windows event logs"
}

func (s *Plugin) SampleConfig() string {
	return `
	file_state_folder = "c:\\path\\to\\state\\folder"

	[[inputs.windows_event_log.event_config]]
	event_name = "System"
	event_levels = ["2", "3"]
	batch_read_size = 1
	log_group_name = "System"
	log_stream_name = "STREAM_NAME"
	destination = "cloudwatchlogs"
	`
}

func (s *Plugin) Gather(acc telegraf.Accumulator) (err error) {
	return nil
}

func (s *Plugin) FindLogSrc() []logs.LogSrc {
	events := s.newEvents
	s.newEvents = nil
	return events
}

/**
 * We can do any initialization in this method.
 */
func (s *Plugin) Start(acc telegraf.Accumulator) error {
	for _, eventConfig := range s.Events {
		// Assume no 2 EventConfigs have the same combination of:
		// LogGroupName, LogStreamName, Name.
		stateFilePath, err := getStateFilePath(s, &eventConfig)
		if err != nil {
			return err
		}
		destination := eventConfig.Destination
		if destination == "" {
			destination = s.Destination
		}
		eventLog := wineventlog.NewEventLog(
			eventConfig.Name,
			eventConfig.Levels,
			eventConfig.LogGroupName,
			eventConfig.LogStreamName,
			eventConfig.RenderFormat,
			destination,
			stateFilePath,
			eventConfig.BatchReadSize,
			eventConfig.Retention,
		)
		err = eventLog.Init()
		if err != nil {
			return err
		}
		s.newEvents = append(s.newEvents, eventLog)
	}
	return nil
}

// getStateFilePath returns a unique file pathname for a given EventConfig.
func getStateFilePath(plugin *Plugin, ec *EventConfig) (string, error) {
	if plugin.FileStateFolder == "" {
		return "", errors.New("empty FileStateFolder")
	}
	err := os.MkdirAll(plugin.FileStateFolder, 0755)
	if err != nil {
		return "", err
	}
	stateFileName := logscommon.WindowsEventLogPrefix +
		escapeFileName(ec.LogGroupName+"_"+ec.LogStreamName+"_"+ec.Name)
	return filepath.Join(plugin.FileStateFolder, stateFileName), nil
}

// escapeFileName returns a valid filename string.
func escapeFileName(filePath string) string {
	escapedFilePath := filepath.ToSlash(filePath)
	escapedFilePath = strings.Replace(escapedFilePath, "/", "_", -1)
	escapedFilePath = strings.Replace(escapedFilePath, " ", "_", -1)
	escapedFilePath = strings.Replace(escapedFilePath, ":", "_", -1)
	return escapedFilePath
}

func (s *Plugin) Stop() {
}

func init() {
	inputs.Add("windows_event_log", func() telegraf.Input { return &Plugin{} })
}