package main

import (
	"bytes"
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"time"

	influxdb2 "github.com/influxdata/influxdb-client-go/v2"
	"github.com/tormoder/fit"
)

type config struct {
	InFolder      string `json:"in_folder"`
	OutFolder     string `json:"out_folder"`
	InfluxdbHost  string `json:"influxdb_host"`
	InfluxdbPort  int    `json:"influxdb_port"`
	InfluxdbToken string `json:"influxdb_token"`
}

var (
	logger       log.Logger = *log.Default()
	config_path  string
	config_cache = config{
		InFolder:      "",
		OutFolder:     "",
		InfluxdbHost:  "",
		InfluxdbPort:  8086,
		InfluxdbToken: "",
	}
)

func read_config() {
	data, err := os.ReadFile(config_path)
	if err != nil {
		logger.Printf("Unable to read %s", config_path)
		return
	}
	err = json.Unmarshal(data, &config_cache)
	if err != nil {
		logger.Print("Unable to evaluate config data")
		return
	}
}

func init() {
	logger.SetPrefix("FitDecoder: ")
	logger.Println("Starting")

}

func move_file(source_path, dest_path string) error {
	inputFile, err := os.Open(source_path)
	if err != nil {
		return fmt.Errorf("couldn't open source file: %s", err)
	}
	outputFile, err := os.Create(dest_path)
	if err != nil {
		inputFile.Close()
		return fmt.Errorf("couldn't open dest file: %s", err)
	}
	defer outputFile.Close()
	_, err = io.Copy(outputFile, inputFile)
	inputFile.Close()
	if err != nil {
		return fmt.Errorf("writing to output file failed: %s", err)
	}
	// The copy was successful, so now delete the original file
	err = os.Remove(source_path)
	if err != nil {
		return fmt.Errorf("failed removing original file: %s", err)
	}
	return nil
}

func fit_decode(path string) ([]fit.SessionMsg, error) {
	var res []fit.SessionMsg
	data, err := os.ReadFile(path)
	if err != nil {
		logger.Printf("cannot read file %s (%s).", path, err.Error())
		return res, err
	}

	// Decode the FIT file data
	fit, err := fit.Decode(bytes.NewReader(data))
	if err != nil {
		logger.Printf("cannot decode file %s (%s).", path, err.Error())
		return res, err
	}
	// Get the actual activity
	activity, err := fit.Activity()
	if err != nil {
		logger.Printf("cannot get activity from %s (%s).", path, err.Error())
		return res, err
	}

	for _, session := range activity.Sessions {
		if session.Sport == 2 {
			res = append(res, *session)
		}
	}
	return res, nil
}

func main() {

	logger.Print(os.Getwd())
	flag.StringVar(&config_path, "c", "./config/config.json", "Specify path to find the config file. Default is ./config/config.json")
	flag.Parse()
	read_config()

	influxdb_url := "http://" + config_cache.InfluxdbHost + ":" + strconv.Itoa(config_cache.InfluxdbPort)
	client := influxdb2.NewClient(influxdb_url, config_cache.InfluxdbToken)
	// always close client at the end
	defer client.Close()

	// get blocking write client
	writeAPI := client.WriteAPIBlocking("tkl", "home")

	ctx := context.Background()

	// open in folder
	dir, err := os.Open(config_cache.InFolder)
	if err != nil {
		logger.Fatalf("cannot open directory %s (%s)", config_cache.InFolder, err.Error())
	}

	// create out folder
	err = os.MkdirAll(config_cache.OutFolder, os.ModePerm)
	if err != nil {
		logger.Fatalf("cannot create directory %s (%s)", config_cache.OutFolder, err.Error())
	}

	for {
		time.Sleep(time.Second)

		var files []fs.FileInfo
		files, err = dir.Readdir(0)
		if err != nil {
			logger.Printf("cannot read %s (%s).", config_cache.InFolder, err)
		}
		for _, file := range files {
			// Read our FIT test file data
			path := filepath.Join(config_cache.InFolder, file.Name())
			var sessions []fit.SessionMsg
			sessions, err = fit_decode(path)
			if err != nil {
				log.Printf("cannot process %s (%s).", path, err.Error())
			} else {
				for _, session := range sessions {
					ser, _ := json.Marshal(&session)
					var data map[string]interface{}
					json.Unmarshal(ser, &data)

					point := influxdb2.NewPointWithMeasurement("activity")
					point.AddTag("activity", "bicycle")
					for k, v := range data {
						point.AddField(k, v)
					}
					point.SetTime(session.Timestamp)
					err = writeAPI.WritePoint(ctx, point)
					if err != nil {
						logger.Print(err)
						continue
					}

				}
				err = writeAPI.Flush(ctx)
				if err != nil {
					logger.Print(err)
					continue
				}
				new_path := filepath.Join(config_cache.OutFolder, file.Name())
				err = move_file(path, new_path)
				if err != nil {
					logger.Printf("cannot move file %s to %s (%s).", path, new_path, err.Error())
				}
			}
		}
	}
}