package main

import (
	"bufio"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/peterbourgon/ff/v3"
	"github.com/robfig/cron/v3"
)

var (
	flagset = flag.NewFlagSet("shelly-proxy", flag.ContinueOnError)

	// config flags
	shellyHost = flagset.String("shellyplug-host", "192.168.33.1", "Shellyplug address (also via SHELLYPLUG_HOST)")
	shellyPort = flagset.Int("shellyplug-port", 80, "Shellyplug port (also via SHELLYPLUG_HOST)")
	//shellyAuthUser = flagset.String("shellyplug-auth-username", "", "Shellyplug authentication username (also via SHELLYPLUG_AUTH_USERNAME)")
	//shellyAuthPass = flagset.String("shellyplug-auth-password", "", "Shellyplug authentication username (also via SHELLYPLUG_AUTH_PASSWORD)")
	exporterPort = flagset.Int("exporter-port", 5000, "Exporter port (also via EXPORTER_PORT)")
	exporterName = flagset.String("exporter-name", "shelly_plug", "Exporter name (also via EXPORTER_NAME)")

	// additional flags
	_ = flagset.String("config", "", "Path to config file (ini format)")
	//versionInfo = flagset.Bool("version", false, "Show version information")

	// internal
	ss *ShellyStatus
)

type ShellyStatus struct {
	Status1 *ShellyStatus1
	Status2 *ShellyStatus2
	Version int
}

type ShellyVersion struct {
	Gen  int    `json:"gen"`
	Type string `json:"type"`
}

func main() {

	// use .env file if it exists
	if _, err := os.Stat(".env"); err == nil {
		if err := ff.Parse(flagset, os.Args[1:],
			ff.WithEnvVarPrefix(""),
			ff.WithConfigFile(".env"),
			ff.WithConfigFileParser(ff.EnvParser),
		); err != nil {
			fmt.Fprintf(os.Stderr, "error: %v\n", err)
			os.Exit(1)
		}
	} else {
		// use env variables and shelly-proxy.ini file
		if err := ff.Parse(flagset, os.Args[1:],
			ff.WithEnvVarPrefix(""),
			ff.WithConfigFileFlag("config"),
			ff.WithConfigFileParser(IniParser),
		); err != nil {
			fmt.Fprintf(os.Stderr, "error: %v\n", err)
			os.Exit(1)
		}
	}

	ss = &ShellyStatus{}
	ss.Fetch()

	c := cron.New(cron.WithLocation(time.UTC))
	if _, err := c.AddFunc("@every 1m", func() { ss.Fetch() }); err != nil {
		log.Fatalf("cron.AddFunc (%s)", err)
	}
	c.Start()

	gin.SetMode(gin.ReleaseMode)
	r := gin.Default()
	r.GET("/metrics", GetMetrics)

	if err := r.Run(fmt.Sprintf(":%d", *exporterPort)); err != nil {
		log.Fatalf("router.Run (%s)", err)
	}
}

func (s *ShellyStatus) GetVersion() int {
	if s.Version != 0 {
		return s.Version
	}
	resp, err := http.Get(fmt.Sprintf("http://%s:%d/shelly", *shellyHost, *shellyPort))
	if err != nil {
		log.Fatalf("ShellyStatus.GetVersion : http.Get (%s)", err)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		log.Fatalf("ShellyStatus.GetVersion : io.ReadAll (%s)", err)
	}

	v := ShellyVersion{}
	if err = json.Unmarshal(body, &v); err != nil {
		log.Fatalf("ShellyStatus.GetVersion : json.Unmarshal (%s)", err)
	}

	if v.Type != "" {
		s.Version = 1
		s.Status1 = &ShellyStatus1{}
	}
	if v.Gen != 0 {
		s.Version = v.Gen
		s.Status2 = &ShellyStatus2{}
	}

	return s.Version
}

func (s *ShellyStatus) Fetch() {
	switch s.GetVersion() {
	case 1:
		resp, err := http.Get(fmt.Sprintf("http://%s:%d/status", *shellyHost, *shellyPort))
		if err != nil {
			log.Fatalf("ShellyStatus.Fetch : http.Get (%s)", err)
		}

		body, err := io.ReadAll(resp.Body)
		if err != nil {
			log.Fatalf("ShellyStatus.Fetch : io.ReadAll (%s)", err)
		}

		if err = json.Unmarshal(body, s.Status1); err != nil {
			log.Fatalf("ShellyStatus.Fetch : json.Unmarshal (%s)", err)
		}
		return
	case 2:
		resp, err := http.Get(fmt.Sprintf("http://%s:%d/rpc/Shelly.GetStatus", *shellyHost, *shellyPort))
		if err != nil {
			log.Fatalf("ShellyStatus.Fetch : http.Get (%s)", err)
		}

		body, err := io.ReadAll(resp.Body)
		if err != nil {
			log.Fatalf("ShellyStatus.Fetch : io.ReadAll (%s)", err)
		}

		if err = json.Unmarshal(body, s.Status2); err != nil {
			log.Fatalf("ShellyStatus.Fetch : json.Unmarshal (%s)", err)
		}
		return
	default:
		return
	}
}

func GetMetrics(c *gin.Context) {
	switch ss.Version {
	case 1:
		c.String(http.StatusOK, `shellyplug_name %s
# HELP shellyplug_power Current power drawn in watts		
# TYPE shellyplug_power gauge
shellyplug_power %.2f
# HELP shellyplug_overpower Overpower drawn in watts/minute
# TYPE shellyplug_overpower gauge
shellyplug_overpower %.2f
# HELP shellyplug_total_power Total power consumed in watts/minute
# TYPE shellyplug_total_power counter
shellyplug_total_power %d
# HELP shellyplug_temperature Plug temperature in celsius
# TYPE shellyplug_temperature gauge
shellyplug_temperature %.2f
# HELP shellyplug_uptime Plug uptime in seconds
# TYPE shellyplug_uptime gauge
shellyplug_uptime %d
`, *exporterName, ss.Status1.Meters[0].Counters[0], float32(0), 0, ss.Status1.Temperature, ss.Status1.Uptime)
	case 2:
		c.String(http.StatusOK, `shellyplug_name %s
# HELP shellyplug_power Current power drawn in watts
# TYPE shellyplug_power gauge
shellyplug_power %.2f
# HELP shellyplug_overpower Overpower drawn in watts/minute
# TYPE shellyplug_overpower gauge
shellyplug_overpower %.2f
# HELP shellyplug_total_power Total power consumed in watts/minute
# TYPE shellyplug_total_power counter
shellyplug_total_power %d
# HELP shellyplug_temperature Plug temperature in celsius
# TYPE shellyplug_temperature gauge
shellyplug_temperature %.2f
# HELP shellyplug_uptime Plug uptime in seconds
# TYPE shellyplug_uptime gauge
shellyplug_uptime %d
`, *exporterName, ss.Status2.Switch.Power, float32(0), 0, ss.Status2.Switch.Temperature.Celsius, ss.Status2.Sys.Uptime)
	default:
		c.String(http.StatusOK, `shellyplug_name %s
# HELP shellyplug_power Current power drawn in watts
# TYPE shellyplug_power gauge
shellyplug_power %.2f
# HELP shellyplug_overpower Overpower drawn in watts/minute
# TYPE shellyplug_overpower gauge
shellyplug_overpower %.2f
# HELP shellyplug_total_power Total power consumed in watts/minute
# TYPE shellyplug_total_power counter
shellyplug_total_power %d
# HELP shellyplug_temperature Plug temperature in celsius
# TYPE shellyplug_temperature gauge
shellyplug_temperature %.2f
# HELP shellyplug_uptime Plug uptime in seconds
# TYPE shellyplug_uptime gauge
shellyplug_uptime %d
`, *exporterName, float32(0), float32(0), 0, float32(0), 0)
	}

}

// IniParser is a parser for config files in classic key/value style format. Each
// line is tokenized as a single key/value pair. The first "=" delimited
// token in the line is interpreted as the flag name, and all remaining tokens
// are interpreted as the value. Any leading hyphens on the flag name are
// ignored.
func IniParser(r io.Reader, set func(name, value string) error) error {
	s := bufio.NewScanner(r)
	for s.Scan() {
		line := strings.TrimSpace(s.Text())
		if line == "" {
			continue // skip empties
		}

		if line[0] == '#' || line[0] == ';' {
			continue // skip comments
		}

		var (
			name  string
			value string
			index = strings.IndexRune(line, '=')
		)
		if index < 0 {
			name, value = line, "true" // boolean option
		} else {
			name, value = strings.TrimSpace(line[:index]), strings.Trim(strings.TrimSpace(line[index+1:]), "\"")
		}

		if i := strings.Index(value, " #"); i >= 0 {
			value = strings.TrimSpace(value[:i])
		}

		if err := set(name, value); err != nil {
			return err
		}
	}
	return nil
}