package opentsdb

import (
	"fmt"
	"net"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/influxdata/influxdb/client/v2"
	"github.com/influxdata/telegraf/plugins/outputs"
	"github.com/influxdata/telegraf"
)

type OpenTSDB struct {
	Prefix string

	Host string
	Port int

	Debug bool
}

var sampleConfig = `
  # prefix for metrics keys
  prefix = "my.specific.prefix."

  ## Telnet Mode ##
  # DNS name of the OpenTSDB server in telnet mode
  host = "opentsdb.example.com"

  # Port of the OpenTSDB server in telnet mode
  port = 4242

  # Debug true - Prints OpenTSDB communication
  debug = false
`

type MetricLine struct {
	Metric    string
	Timestamp int64
	Value     string
	Tags      string
}

func (o *OpenTSDB) Connect() error {
	// Test Connection to OpenTSDB Server
	uri := fmt.Sprintf("%s:%d", o.Host, o.Port)
	tcpAddr, err := net.ResolveTCPAddr("tcp", uri)
	if err != nil {
		return fmt.Errorf("OpenTSDB: TCP address cannot be resolved")
	}
	connection, err := net.DialTCP("tcp", nil, tcpAddr)
	if err != nil {
		return fmt.Errorf("OpenTSDB: Telnet connect fail")
	}
	defer connection.Close()
	return nil
}

func (o *OpenTSDB) Write(points []*client.Point) error {
	if len(points) == 0 {
		return nil
	}
	now := time.Now()

	// Send Data with telnet / socket communication
	uri := fmt.Sprintf("%s:%d", o.Host, o.Port)
	tcpAddr, _ := net.ResolveTCPAddr("tcp", uri)
	connection, err := net.DialTCP("tcp", nil, tcpAddr)
	if err != nil {
		return fmt.Errorf("OpenTSDB: Telnet connect fail")
	}
	defer connection.Close()

	for _, pt := range points {
		for _, metric := range buildMetrics(pt, now, o.Prefix) {
			messageLine := fmt.Sprintf("put %s %v %s %s\n",
				metric.Metric, metric.Timestamp, metric.Value, metric.Tags)
			if o.Debug {
				fmt.Print(messageLine)
			}
			_, err := connection.Write([]byte(messageLine))
			if err != nil {
				return fmt.Errorf("OpenTSDB: Telnet writing error %s", err.Error())
			}
		}
	}

	return nil
}

func buildTags(ptTags map[string]string) []string {
	tags := make([]string, len(ptTags))
	index := 0
	for k, v := range ptTags {
		tags[index] = fmt.Sprintf("%s=%s", k, v)
		index += 1
	}
	sort.Strings(tags)
	return tags
}

func buildMetrics(pt *client.Point, now time.Time, prefix string) []*MetricLine {
	ret := []*MetricLine{}
	for fieldName, value := range pt.Fields() {
		metric := &MetricLine{
			Metric:    fmt.Sprintf("%s%s_%s", prefix, pt.Name(), fieldName),
			Timestamp: now.Unix(),
		}

		metricValue, buildError := buildValue(value)
		if buildError != nil {
			fmt.Printf("OpenTSDB: %s\n", buildError.Error())
			continue
		}
		metric.Value = metricValue
		tagsSlice := buildTags(pt.Tags())
		metric.Tags = fmt.Sprint(strings.Join(tagsSlice, " "))
		ret = append(ret, metric)
	}
	return ret
}

func buildValue(v interface{}) (string, error) {
	var retv string
	switch p := v.(type) {
	case int64:
		retv = IntToString(int64(p))
	case uint64:
		retv = UIntToString(uint64(p))
	case float64:
		retv = FloatToString(float64(p))
	default:
		return retv, fmt.Errorf("unexpected type %T with value %v for OpenTSDB", v, v)
	}
	return retv, nil
}

func IntToString(input_num int64) string {
	return strconv.FormatInt(input_num, 10)
}

func UIntToString(input_num uint64) string {
	return strconv.FormatUint(input_num, 10)
}

func FloatToString(input_num float64) string {
	return strconv.FormatFloat(input_num, 'f', 6, 64)
}

func (o *OpenTSDB) SampleConfig() string {
	return sampleConfig
}

func (o *OpenTSDB) Description() string {
	return "Configuration for OpenTSDB server to send metrics to"
}

func (o *OpenTSDB) Close() error {
	return nil
}

func init() {
	outputs.Add("opentsdb", func() telegraf.Output {
		return &OpenTSDB{}
	})
}