package nfsclient

import (
	"bufio"
	"log"
	"os"
	"regexp"
	"strconv"
	"strings"

	"github.com/influxdata/telegraf"
	"github.com/influxdata/telegraf/internal/choice"
	"github.com/influxdata/telegraf/plugins/inputs"
)

type NFSClient struct {
	Fullstat          bool            `toml:"fullstat"`
	IncludeMounts     []string        `toml:"include_mounts"`
	ExcludeMounts     []string        `toml:"exclude_mounts"`
	IncludeOperations []string        `toml:"include_operations"`
	ExcludeOperations []string        `toml:"exclude_operations"`
	Log               telegraf.Logger `toml:"-"`
	nfs3Ops           map[string]bool
	nfs4Ops           map[string]bool
	mountstatsPath    string
}

const sampleConfig = `
  ## Read more low-level metrics (optional, defaults to false)
  # fullstat = false

  ## List of mounts to explictly include or exclude (optional)
  ## The pattern (Go regexp) is matched against the mount point (not the
  ## device being mounted).  If include_mounts is set, all mounts are ignored
  ## unless present in the list. If a mount is listed in both include_mounts
  ## and exclude_mounts, it is excluded.  Go regexp patterns can be used.
  # include_mounts = []
  # exclude_mounts = []

  ## List of operations to include or exclude from collecting.  This applies
  ## only when fullstat=true.  Symantics are similar to {include,exclude}_mounts:
  ## the default is to collect everything; when include_operations is set, only
  ## those OPs are collected; when exclude_operations is set, all are collected
  ## except those listed.  If include and exclude are set, the OP is excluded.
  ## See /proc/self/mountstats for a list of valid operations; note that
  ## NFSv3 and NFSv4 have different lists.  While it is not possible to
  ## have different include/exclude lists for NFSv3/4, unused elements
  ## in the list should be okay.  It is possible to have different lists
  ## for different mountpoints:  use mulitple [[input.nfsclient]] stanzas,
  ## with their own lists.  See "include_mounts" above, and be careful of
  ## duplicate metrics.
  # include_operations = []
  # exclude_operations = []
`

func (n *NFSClient) SampleConfig() string {
	return sampleConfig
}

func (n *NFSClient) Description() string {
	return "Read per-mount NFS client metrics from /proc/self/mountstats"
}

func convertToInt64(line []string) []int64 {
	/* A "line" of input data (a pre-split array of strings) is
	   processed one field at a time.  Each field is converted to
	   an int64 value, and appened to an array of return values.
	   On an error, check for ErrRange, and throw a fatal error
	   if found.  This situation indicates a pretty major issue in
	   the /proc/self/mountstats file, and returning faulty data
	   is worse than no data.  Other errors are ignored, and append
	   whatever we got in the first place (probably 0).
	   Yes, this is ugly. */

	var nline []int64

	if len(line) < 2 {
		return nline
	}

	// Skip the first field; it's handled specially as the "first" variable
	for _, l := range line[1:] {
		val, err := strconv.ParseInt(l, 10, 64)
		if err != nil {
			if numError, ok := err.(*strconv.NumError); ok {
				if numError.Err == strconv.ErrRange {
					log.Fatalf("ErrRange: line:[%v] raw:[%v] -> parsed:[%v]\n", line, l, val)
				}
			}
		}
		nline = append(nline, val)
	}
	return nline
}

func (n *NFSClient) parseStat(mountpoint string, export string, version string, line []string, acc telegraf.Accumulator) {
	tags := map[string]string{"mountpoint": mountpoint, "serverexport": export}
	nline := convertToInt64(line)

	if len(nline) == 0 {
		n.Log.Warnf("Parsing Stat line with one field: %s\n", line)
		return
	}

	first := strings.Replace(line[0], ":", "", 1)

	var eventsFields = []string{
		"inoderevalidates",
		"dentryrevalidates",
		"datainvalidates",
		"attrinvalidates",
		"vfsopen",
		"vfslookup",
		"vfsaccess",
		"vfsupdatepage",
		"vfsreadpage",
		"vfsreadpages",
		"vfswritepage",
		"vfswritepages",
		"vfsgetdents",
		"vfssetattr",
		"vfsflush",
		"vfsfsync",
		"vfslock",
		"vfsrelease",
		"congestionwait",
		"setattrtrunc",
		"extendwrite",
		"sillyrenames",
		"shortreads",
		"shortwrites",
		"delay",
		"pnfsreads",
		"pnfswrites",
	}

	var bytesFields = []string{
		"normalreadbytes",
		"normalwritebytes",
		"directreadbytes",
		"directwritebytes",
		"serverreadbytes",
		"serverwritebytes",
		"readpages",
		"writepages",
	}

	var xprtudpFields = []string{
		"bind_count",
		"rpcsends",
		"rpcreceives",
		"badxids",
		"inflightsends",
		"backlogutil",
	}

	var xprttcpFields = []string{
		"bind_count",
		"connect_count",
		"connect_time",
		"idle_time",
		"rpcsends",
		"rpcreceives",
		"badxids",
		"inflightsends",
		"backlogutil",
	}

	var nfsopFields = []string{
		"ops",
		"trans",
		"timeouts",
		"bytes_sent",
		"bytes_recv",
		"queue_time",
		"response_time",
		"total_time",
		"errors",
	}

	var fields = make(map[string]interface{})

	switch first {
	case "READ", "WRITE":
		fields["ops"] = nline[0]
		fields["retrans"] = nline[1] - nline[0]
		fields["bytes"] = nline[3] + nline[4]
		fields["rtt"] = nline[6]
		fields["exe"] = nline[7]
		tags["operation"] = first
		acc.AddFields("nfsstat", fields, tags)
	}

	if n.Fullstat {
		switch first {
		case "events":
			if len(nline) >= len(eventsFields) {
				for i, t := range eventsFields {
					fields[t] = nline[i]
				}
				acc.AddFields("nfs_events", fields, tags)
			}

		case "bytes":
			if len(nline) >= len(bytesFields) {
				for i, t := range bytesFields {
					fields[t] = nline[i]
				}
				acc.AddFields("nfs_bytes", fields, tags)
			}

		case "xprt":
			if len(line) > 1 {
				switch line[1] {
				case "tcp":
					if len(nline)+2 >= len(xprttcpFields) {
						for i, t := range xprttcpFields {
							fields[t] = nline[i+2]
						}
						acc.AddFields("nfs_xprt_tcp", fields, tags)
					}
				case "udp":
					if len(nline)+2 >= len(xprtudpFields) {
						for i, t := range xprtudpFields {
							fields[t] = nline[i+2]
						}
						acc.AddFields("nfs_xprt_udp", fields, tags)
					}
				}
			}
		}

		if (version == "3" && n.nfs3Ops[first]) || (version == "4" && n.nfs4Ops[first]) {
			tags["operation"] = first
			if len(nline) <= len(nfsopFields) {
				for i, t := range nline {
					fields[nfsopFields[i]] = t
				}
				acc.AddFields("nfs_ops", fields, tags)
			}
		}
	}
}

func (n *NFSClient) processText(scanner *bufio.Scanner, acc telegraf.Accumulator) {
	var mount string
	var version string
	var export string
	var skip bool

	for scanner.Scan() {
		line := strings.Fields(scanner.Text())
		lineLength := len(line)

		if lineLength == 0 {
			continue
		}

		skip = false

		// This denotes a new mount has been found, so set
		// mount and export, and stop skipping (for now)
		if lineLength > 4 && choice.Contains("fstype", line) && (choice.Contains("nfs", line) || choice.Contains("nfs4", line)) {
			mount = line[4]
			export = line[1]
		} else if lineLength > 5 && (choice.Contains("(nfs)", line) || choice.Contains("(nfs4)", line)) {
			version = strings.Split(line[5], "/")[1]
		}

		if mount == "" {
			continue
		}

		if len(n.IncludeMounts) > 0 {
			skip = true
			for _, RE := range n.IncludeMounts {
				matched, _ := regexp.MatchString(RE, mount)
				if matched {
					skip = false
					break
				}
			}
		}

		if !skip && len(n.ExcludeMounts) > 0 {
			for _, RE := range n.ExcludeMounts {
				matched, _ := regexp.MatchString(RE, mount)
				if matched {
					skip = true
					break
				}
			}
		}

		if !skip {
			n.parseStat(mount, export, version, line, acc)
		}
	}
}

func (n *NFSClient) getMountStatsPath() string {
	path := "/proc/self/mountstats"
	if os.Getenv("MOUNT_PROC") != "" {
		path = os.Getenv("MOUNT_PROC")
	}
	n.Log.Debugf("using [%s] for mountstats", path)
	return path
}

func (n *NFSClient) Gather(acc telegraf.Accumulator) error {
	file, err := os.Open(n.mountstatsPath)
	if err != nil {
		n.Log.Errorf("Failed opening the [%s] file: %s ", file, err)
		return err
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	n.processText(scanner, acc)

	if err := scanner.Err(); err != nil {
		n.Log.Errorf("%s", err)
		return err
	}

	return nil
}

func (n *NFSClient) Init() error {
	var nfs3Fields = []string{
		"NULL",
		"GETATTR",
		"SETATTR",
		"LOOKUP",
		"ACCESS",
		"READLINK",
		"READ",
		"WRITE",
		"CREATE",
		"MKDIR",
		"SYMLINK",
		"MKNOD",
		"REMOVE",
		"RMDIR",
		"RENAME",
		"LINK",
		"READDIR",
		"READDIRPLUS",
		"FSSTAT",
		"FSINFO",
		"PATHCONF",
		"COMMIT",
	}

	var nfs4Fields = []string{
		"NULL",
		"READ",
		"WRITE",
		"COMMIT",
		"OPEN",
		"OPEN_CONFIRM",
		"OPEN_NOATTR",
		"OPEN_DOWNGRADE",
		"CLOSE",
		"SETATTR",
		"FSINFO",
		"RENEW",
		"SETCLIENTID",
		"SETCLIENTID_CONFIRM",
		"LOCK",
		"LOCKT",
		"LOCKU",
		"ACCESS",
		"GETATTR",
		"LOOKUP",
		"LOOKUP_ROOT",
		"REMOVE",
		"RENAME",
		"LINK",
		"SYMLINK",
		"CREATE",
		"PATHCONF",
		"STATFS",
		"READLINK",
		"READDIR",
		"SERVER_CAPS",
		"DELEGRETURN",
		"GETACL",
		"SETACL",
		"FS_LOCATIONS",
		"RELEASE_LOCKOWNER",
		"SECINFO",
		"FSID_PRESENT",
		"EXCHANGE_ID",
		"CREATE_SESSION",
		"DESTROY_SESSION",
		"SEQUENCE",
		"GET_LEASE_TIME",
		"RECLAIM_COMPLETE",
		"LAYOUTGET",
		"GETDEVICEINFO",
		"LAYOUTCOMMIT",
		"LAYOUTRETURN",
		"SECINFO_NO_NAME",
		"TEST_STATEID",
		"FREE_STATEID",
		"GETDEVICELIST",
		"BIND_CONN_TO_SESSION",
		"DESTROY_CLIENTID",
		"SEEK",
		"ALLOCATE",
		"DEALLOCATE",
		"LAYOUTSTATS",
		"CLONE",
		"COPY",
		"OFFLOAD_CANCEL",
		"LOOKUPP",
		"LAYOUTERROR",
		"COPY_NOTIFY",
		"GETXATTR",
		"SETXATTR",
		"LISTXATTRS",
		"REMOVEXATTR",
	}

	nfs3Ops := make(map[string]bool)
	nfs4Ops := make(map[string]bool)

	n.mountstatsPath = n.getMountStatsPath()

	if len(n.IncludeOperations) == 0 {
		for _, Op := range nfs3Fields {
			nfs3Ops[Op] = true
		}
		for _, Op := range nfs4Fields {
			nfs4Ops[Op] = true
		}
	} else {
		for _, Op := range n.IncludeOperations {
			nfs3Ops[Op] = true
		}
		for _, Op := range n.IncludeOperations {
			nfs4Ops[Op] = true
		}
	}

	if len(n.ExcludeOperations) > 0 {
		for _, Op := range n.ExcludeOperations {
			if nfs3Ops[Op] {
				delete(nfs3Ops, Op)
			}
			if nfs4Ops[Op] {
				delete(nfs4Ops, Op)
			}
		}
	}

	if len(n.IncludeMounts) > 0 {
		n.Log.Debugf("Including these mount patterns: %v", n.IncludeMounts)
	} else {
		n.Log.Debugf("Including all mounts.")
	}

	if len(n.ExcludeMounts) > 0 {
		n.Log.Debugf("Excluding these mount patterns: %v", n.ExcludeMounts)
	} else {
		n.Log.Debugf("Not excluding any mounts.")
	}

	if len(n.IncludeOperations) > 0 {
		n.Log.Debugf("Including these operations: %v", n.IncludeOperations)
	} else {
		n.Log.Debugf("Including all operations.")
	}

	if len(n.ExcludeOperations) > 0 {
		n.Log.Debugf("Excluding these mount patterns: %v", n.ExcludeOperations)
	} else {
		n.Log.Debugf("Not excluding any operations.")
	}

	return nil
}

func init() {
	inputs.Add("nfsclient", func() telegraf.Input {
		return &NFSClient{}
	})
}