package vlstorage

import (
	"flag"
	"fmt"
	"sync"
	"time"

	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logstorage"
	"github.com/VictoriaMetrics/metrics"
)

var (
	retentionPeriod = flagutil.NewDuration("retentionPeriod", "7d", "Log entries with timestamps older than now-retentionPeriod are automatically deleted; "+
		"log entries with timestamps outside the retention are also rejected during data ingestion; the minimum supported retention is 1d (one day); "+
		"see https://docs.victoriametrics.com/VictoriaLogs/#retention")
	futureRetention = flagutil.NewDuration("futureRetention", "2d", "Log entries with timestamps bigger than now+futureRetention are rejected during data ingestion; "+
		"see https://docs.victoriametrics.com/VictoriaLogs/#retention")
	storageDataPath = flag.String("storageDataPath", "victoria-logs-data", "Path to directory with the VictoriaLogs data; "+
		"see https://docs.victoriametrics.com/VictoriaLogs/#storage")
	inmemoryDataFlushInterval = flag.Duration("inmemoryDataFlushInterval", 5*time.Second, "The interval for guaranteed saving of in-memory data to disk. "+
		"The saved data survives unclean shutdown such as OOM crash, hardware reset, SIGKILL, etc. "+
		"Bigger intervals may help increasing lifetime of flash storage with limited write cycles (e.g. Raspberry PI). "+
		"Smaller intervals increase disk IO load. Minimum supported value is 1s")
	logNewStreams = flag.Bool("logNewStreams", false, "Whether to log creation of new streams; this can be useful for debugging of high cardinality issues with log streams; "+
		"see https://docs.victoriametrics.com/VictoriaLogs/keyConcepts.html#stream-fields ; see also -logIngestedRows")
	logIngestedRows = flag.Bool("logIngestedRows", false, "Whether to log all the ingested log entries; this can be useful for debugging of data ingestion; "+
		"see https://docs.victoriametrics.com/VictoriaLogs/#data-ingestion ; see also -logNewStreams")
)

// Init initializes vlstorage.
//
// Stop must be called when vlstorage is no longer needed
func Init() {
	if strg != nil {
		logger.Panicf("BUG: Init() has been already called")
	}

	if retentionPeriod.Msecs < 24*3600*1000 {
		logger.Fatalf("-retentionPeriod cannot be smaller than a day; got %s", retentionPeriod)
	}
	cfg := &logstorage.StorageConfig{
		Retention:       time.Millisecond * time.Duration(retentionPeriod.Msecs),
		FlushInterval:   *inmemoryDataFlushInterval,
		FutureRetention: time.Millisecond * time.Duration(futureRetention.Msecs),
		LogNewStreams:   *logNewStreams,
		LogIngestedRows: *logIngestedRows,
	}
	strg = logstorage.MustOpenStorage(*storageDataPath, cfg)
	storageMetrics = initStorageMetrics(strg)
	metrics.RegisterSet(storageMetrics)
}

// Stop stops vlstorage.
func Stop() {
	metrics.UnregisterSet(storageMetrics)
	storageMetrics = nil

	strg.MustClose()
	strg = nil
}

var strg *logstorage.Storage
var storageMetrics *metrics.Set

// MustAddRows adds lr to vlstorage
func MustAddRows(lr *logstorage.LogRows) {
	strg.MustAddRows(lr)
}

// RunQuery runs the given q and calls processBlock for the returned data blocks
func RunQuery(tenantIDs []logstorage.TenantID, q *logstorage.Query, stopCh <-chan struct{}, processBlock func(columns []logstorage.BlockColumn)) {
	strg.RunQuery(tenantIDs, q, stopCh, processBlock)
}

func initStorageMetrics(strg *logstorage.Storage) *metrics.Set {
	ssCache := &logstorage.StorageStats{}
	var ssCacheLock sync.Mutex
	var lastUpdateTime time.Time

	m := func() *logstorage.StorageStats {
		ssCacheLock.Lock()
		defer ssCacheLock.Unlock()
		if time.Since(lastUpdateTime) < time.Second {
			return ssCache
		}
		var ss logstorage.StorageStats
		strg.UpdateStats(&ss)
		ssCache = &ss
		lastUpdateTime = time.Now()
		return ssCache
	}

	ms := metrics.NewSet()

	ms.NewGauge(fmt.Sprintf(`vl_free_disk_space_bytes{path=%q}`, *storageDataPath), func() float64 {
		return float64(fs.MustGetFreeSpace(*storageDataPath))
	})

	ms.NewGauge(`vl_rows{type="inmemory"}`, func() float64 {
		return float64(m().InmemoryRowsCount)
	})
	ms.NewGauge(`vl_rows{type="file"}`, func() float64 {
		return float64(m().FileRowsCount)
	})
	ms.NewGauge(`vl_parts{type="inmemory"}`, func() float64 {
		return float64(m().InmemoryParts)
	})
	ms.NewGauge(`vl_parts{type="file"}`, func() float64 {
		return float64(m().FileParts)
	})
	ms.NewGauge(`vl_blocks{type="inmemory"}`, func() float64 {
		return float64(m().InmemoryBlocks)
	})
	ms.NewGauge(`vl_blocks{type="file"}`, func() float64 {
		return float64(m().FileBlocks)
	})
	ms.NewGauge(`vl_partitions`, func() float64 {
		return float64(m().PartitionsCount)
	})
	ms.NewGauge(`vl_streams_created_total`, func() float64 {
		return float64(m().StreamsCreatedTotal)
	})

	ms.NewGauge(`vl_compressed_data_size_bytes{type="inmemory"}`, func() float64 {
		return float64(m().CompressedInmemorySize)
	})
	ms.NewGauge(`vl_compressed_data_size_bytes{type="file"}`, func() float64 {
		return float64(m().CompressedFileSize)
	})
	ms.NewGauge(`vl_uncompressed_data_size_bytes{type="inmemory"}`, func() float64 {
		return float64(m().UncompressedInmemorySize)
	})
	ms.NewGauge(`vl_uncompressed_data_size_bytes{type="file"}`, func() float64 {
		return float64(m().UncompressedFileSize)
	})

	ms.NewGauge(`vl_rows_dropped_total{reason="too_big_timestamp"}`, func() float64 {
		return float64(m().RowsDroppedTooBigTimestamp)
	})
	ms.NewGauge(`vl_rows_dropped_total{reason="too_small_timestamp"}`, func() float64 {
		return float64(m().RowsDroppedTooSmallTimestamp)
	})

	return ms
}