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"
)

type ShellyStatus struct {
	Wifi            ShellyWifiStatus     `json:"wifi_sta"`
	Cloud           ShellyCloudStatus    `json:"cloud"`
	Mqtt            ShellyMqttStatus     `json:"mqtt"`
	Time            string               `json:"time"`
	Serial          int                  `json:"serial"`
	HasUpdate       bool                 `json:"has_update"`
	MAC             string               `json:"mac"`
	Relays          []ShellyRelaysStatus `json:"relays"`
	Meters          []ShellyMetersStatus `json:"meters"`
	Temperature     float32              `json:"temperature"`
	OverTemperature bool                 `json:"overtemperature"`
	Update          ShellyUpdateStatus   `json:"update"`
	RamTotal        int                  `json:"ram_total"`
	RamFree         int                  `json:"ram_free"`
	FsSize          int                  `json:"fs_size"`
	FsFree          int                  `json:"fs_free"`
	Uptime          int                  `json:"uptime"`
}

type ShellyWifiStatus struct {
	Connected bool   `json:"connected"`
	SSID      string `json:"ssid"`
	IP        string `json:"ip"`
	RSSI      int    `json:"rssi"`
}

type ShellyCloudStatus struct {
	Enabled   bool `json:"enabled"`
	Connected bool `json:"connected"`
}

type ShellyMqttStatus struct {
	Connected bool `json:"connected"`
}

type ShellyRelaysStatus struct {
	IsOn      bool `json:"ison"`
	HasTimer  bool `json:"has_timer"`
	Overpower bool `json:"overpower"`
}

type ShellyMetersStatus struct {
	Power     float32   `json:"power"`
	IsValid   bool      `json:"is_valid"`
	Timestamp int       `json:"timestamp"`
	Counters  []float32 `json:"counters"`
	Total     int       `json:"total"`
}

type ShellyUpdateStatus struct {
	Status     string `json:"status"`
	HasUpdate  bool   `json:"has_update"`
	NewVersion string `json:"new_version"`
	OldVersion string `json:"old_version"`
}

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

	// config flags
	shellyHost = flagset.String("shellyplug-host", "192.168.30.1", "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", 9000, "Exporter port (also via EXPORTER_PORT)")

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

	// internal
	ss *ShellyStatus
)

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)

	r.Run(fmt.Sprintf(":%d", exporterPort))
}

func (s *ShellyStatus) Fetch() {
	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); err != nil {
		log.Fatalf("ShellyStatus.Fetch : json.Unmarshal (%s)", err)
	}
}

func GetMetrics(c *gin.Context) {
	c.String(http.StatusOK, `# 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
`, ss.Meters[0].Counters[0], float32(0), ss.Meters[0].Total, ss.Temperature, ss.Uptime)
}

// 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
}