package amon

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"strings"

	"github.com/influxdb/influxdb/client/v2"
	"github.com/influxdb/telegraf/duration"
	"github.com/influxdb/telegraf/outputs"
)

type Amon struct {
	ServerKey  string
	AmonInstance string
	Timeout duration.Duration

	client *http.Client
}

var sampleConfig = `
  # Amon Server Key
  serverkey = "my-server-key" # required.

  # Amon Insance URL
  amoninstance = "https://youramoninstance" # required

  # Connection timeout.
  # timeout = "5s"
`

type TimeSeries struct {
	Series []*Metric `json:"series"`
}

type Metric struct {
	Metric string   `json:"metric"`
	Points [1]Point `json:"points"`
}

type Point [2]float64


func (a *Amon) Connect() error {
	if a.ServerKey == "" || a.AmonInstance == "" {
		return fmt.Errorf("serverkey and amoninstance are required fields for amon output")
	}
	a.client = &http.Client{
		Timeout: a.Timeout.Duration,
	}
	return nil
}

func (a *Amon) Write(points []*client.Point) error {
	if len(points) == 0 {
		return nil
	}
	ts := TimeSeries{}
	var tempSeries = make([]*Metric, len(points))
	var acceptablePoints = 0
	for _, pt := range points {
		metric := &Metric{
			Metric: strings.Replace(pt.Name(), "_", ".", -1),
		}
		if p, err := buildPoint(pt); err == nil {
			metric.Points[0] = p
			tempSeries[acceptablePoints] = metric
			acceptablePoints += 1
		} else {
			log.Printf("unable to build Metric for %s, skipping\n", pt.Name())
		}
	}
	ts.Series = make([]*Metric, acceptablePoints)
	copy(ts.Series, tempSeries[0:])
	tsBytes, err := json.Marshal(ts)
	if err != nil {
		return fmt.Errorf("unable to marshal TimeSeries, %s\n", err.Error())
	}
	req, err := http.NewRequest("POST", a.authenticatedUrl(), bytes.NewBuffer(tsBytes))
	if err != nil {
		return fmt.Errorf("unable to create http.Request, %s\n", err.Error())
	}
	req.Header.Add("Content-Type", "application/json")

	resp, err := a.client.Do(req)
	if err != nil {
		return fmt.Errorf("error POSTing metrics, %s\n", err.Error())
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode > 209 {
		return fmt.Errorf("received bad status code, %d\n", resp.StatusCode)
	}

	return nil
}

func (a *Amon) SampleConfig() string {
	return sampleConfig
}

func (a *Amon) Description() string {
	return "Configuration for Amon Server to send metrics to."
}

func (a *Amon) authenticatedUrl() string {
	
	return fmt.Sprintf("%s/api/system/%s", a.AmonInstance, a.ServerKey)
}

func buildPoint(pt *client.Point) (Point, error) {
	var p Point
	if err := p.setValue(pt.Fields()["value"]); err != nil {
		return p, fmt.Errorf("unable to extract value from Fields, %s", err.Error())
	}
	p[0] = float64(pt.Time().Unix())
	return p, nil
}

func (p *Point) setValue(v interface{}) error {
	switch d := v.(type) {
	case int:
		p[1] = float64(int(d))
	case int32:
		p[1] = float64(int32(d))
	case int64:
		p[1] = float64(int64(d))
	case float32:
		p[1] = float64(d)
	case float64:
		p[1] = float64(d)
	default:
		return fmt.Errorf("undeterminable type")
	}
	return nil
}

func (a *Amon) Close() error {
	return nil
}

func init() {
	outputs.Add("amon", func() outputs.Output {
		return &Amon{}
	})
}