package main

import (
	"bytes"
	"database/sql"
	"fmt"
	_ "github.com/go-sql-driver/mysql"
	influx "github.com/influxdata/influxdb1-client/v2"
	druid "github.com/shunfei/godruid"
	"log"
	"net/http"
	"os"
	"strconv"
	"time"
)

// All the required ENV Vars must be defined here.
type Config struct {
	JOB_NAME, TZ, WINDOW_SIZE                                          string
	MYSQL_HOST, MYSQL_USER, MYSQL_PASSWORD, MYSQL_DB, MYSQL_TABLE      string
	DRUID_HOST                                                         string
	INFLUX_HOST, INFLUX_PORT, INFLUX_DB, INFLUX_RP, INFLUX_MEASUREMENT string
	DVO_API_CHECKIN_ENDPOINT                                           string
}

type Stats struct {
	Views, Clicks, Leads sql.NullFloat64
}

// Initialize a Druid Client given host.
// Args: druidHost - the hostname of druid instance
// Returns: pointer to the initialized Druid client.
func initDruidClient(druidHost string) *druid.Client {
	client := druid.Client{
		Url:   fmt.Sprintf("http://%s:8082", druidHost),
		Debug: true,
	}
	return &client
}

// Initialize a MySql Db. Fail if can't connect.
// Args: appConfig - pointer to the app Config struct
// Returns: pointer to the initialized MySql Db
func initMySqlDb(appConfig *Config) *sql.DB {
	connectionStr := fmt.Sprintf("%s:%s@tcp(%s:3306)/%s", appConfig.MYSQL_USER, appConfig.MYSQL_PASSWORD, appConfig.MYSQL_HOST, appConfig.MYSQL_DB)
	db, err := sql.Open("mysql", connectionStr)
	if err != nil {
		log.Fatal(err)
	}

	err = db.Ping()
	if err != nil {
		log.Fatal(err)
	}
	log.Print("mysql datasource connected!")
	return db
}

// Initialize an InfluxDB client. Fail if can't connect.
// Args: appConfig - pointer to the app Config
// Returns: pointer to the initialized InfluxDB Client
func initInfluxClient(appConfig *Config) *influx.Client {
	// Make client
	c, err := influx.NewHTTPClient(influx.HTTPConfig{
		Addr: fmt.Sprintf("http://%s:%s", appConfig.INFLUX_HOST, appConfig.INFLUX_PORT),
	})
	if err != nil {
		log.Println("Error creating InfluxDB Client")
		log.Fatal(err)
	}
	_, _, err = c.Ping(0)
	if err != nil {
		log.Println("Error pinging InfluxDB")
		log.Fatal(err)
	}
	return &c
}

// Builds and runs the Druid query, and stores the results into a Stats struct.
// If the Druid query fails or returns nothing, then use 0 values for stats.
// Args: client - pointer to the initialized druid client
//       interval - the date string to get the values for
// Returns: Stats struct containing Druid values (Views, Clicks, Leads)
func getDruidStatsForInterval(client *druid.Client, interval string) Stats {
	var druidStats Stats
	query := &druid.QueryGroupBy{
		DataSource:  "RevenueReport",
		Intervals:   []string{fmt.Sprintf("%s/PT1H", interval)},
		Granularity: druid.GranPeriod{Type: "period", Period: "PT1H", TimeZone: "America/Toronto"},
		Aggregations: []druid.Aggregation{
			druid.AggLongSum("Views", "Views"),
			druid.AggLongSum("Clicks", "Clicks"),
			druid.AggDoubleSum("Leads", "Leads"),
		},
	}
	err := client.Query(query)
	if err != nil {
		log.Println("Error while running the Druid Query", err.Error())
	}
	//log.Println("requst", client.LastRequest)
	//log.Println("response", client.LastResponse)

	if (err != nil) || len(query.QueryResult) == 0 {
		log.Println("Druid query returned no results! Using 0 values.")
		druidStats.Views = sql.NullFloat64{Float64: float64(0), Valid: true}
		druidStats.Clicks = sql.NullFloat64{Float64: float64(0), Valid: true}
		druidStats.Leads = sql.NullFloat64{Float64: float64(0), Valid: true}
		return druidStats
	}

	views := query.QueryResult[0].Event["Views"].(float64)
	clicks := query.QueryResult[0].Event["Clicks"].(float64)
	leads := query.QueryResult[0].Event["Leads"].(float64)

	druidStats.Views = sql.NullFloat64{Float64: views, Valid: true}
	druidStats.Clicks = sql.NullFloat64{Float64: clicks, Valid: true}
	druidStats.Leads = sql.NullFloat64{Float64: leads, Valid: true}
	return druidStats
}

// Prepare a sql statement to be used repeatedly later.
// Args: db - pointer to the initialized sql DB
// Returns: a sql Prepared statement
func getSqlPreparedStatement(db *sql.DB, table string) *sql.Stmt {
	query := fmt.Sprintf(`
		SELECT SUM(Views) as views, SUM(Clicks) as clicks, SUM(Leads) as leads
		FROM %s
		WHERE Stamp = ? AND CampaignID <> 278258
	`, table)
	stmt, err := db.Prepare(query)
	if err != nil {
		log.Println("Error while preparing sql query")
		log.Fatal(err)
	}
	return stmt
}

// Runs the MySql query from a prepared statement and stores the results into a Stats struct
// Args: stmt - pointer to the sql prepared statement
//       interval - the date string to get the values for
// Returns: Stats struct containing MySql values (Views, Clicks, Leads)
func getMySqlStatsForInterval(stmt *sql.Stmt, interval string) Stats {
	var mySqlStats Stats
	//log.Println("running sql...")
	err := stmt.QueryRow(interval).Scan(&mySqlStats.Views, &mySqlStats.Clicks, &mySqlStats.Leads)
	if err != nil {
		log.Println("Error while running sql query")
		log.Fatal(err)
	}
	//log.Println(mySqlStats)
	return mySqlStats
}

// Write the MySql and Druid Stats to InfluxDB.
// Args: influxClient - pointer to the initialized InfluxDB client
//       appConfig - pointer to the app Config
//       mySqlStats - Stats struct contianing MySql values (Views, Leads, Clicks)
//       druidStats - Stats struct contianing Druid values (Views, Leads, Clicks)
//       t - timestamp object rounded down to the hour
// Returns: the name of the measurement that was written to
func writeToInflux(influxClient *influx.Client, appConfig *Config, mySqlStats *Stats, druidStats *Stats, t time.Time) string {
	// Create a new InfluxDB point batch
	bp, _ := influx.NewBatchPoints(influx.BatchPointsConfig{
		Database:        appConfig.INFLUX_DB,
		Precision:       "s",
		RetentionPolicy: appConfig.INFLUX_RP,
	})
	// Create a single point
	tags := map[string]string{}
	fields := map[string]interface{}{
		"m.views":  int64(mySqlStats.Views.Float64),
		"m.clicks": int64(mySqlStats.Clicks.Float64),
		"m.leads":  int64(mySqlStats.Leads.Float64),
		"d.views":  int64(druidStats.Views.Float64),
		"d.clicks": int64(druidStats.Clicks.Float64),
		"d.leads":  int64(druidStats.Leads.Float64),
	}
	pt, err := influx.NewPoint(appConfig.INFLUX_MEASUREMENT, tags, fields, t)
	if err != nil {
		log.Println("Failed to crate valid Influx Point.", err.Error())
	}
	log.Println(pt.String())

	// Add to batch
	bp.AddPoint(pt)
	// Write the batch
	err = (*influxClient).Write(bp)
	if err != nil {
		log.Println("Failed to write point to Influx.", err.Error())
	}
	return appConfig.INFLUX_MEASUREMENT
}

// A helper to perform checkin for execution of this job.
// Args: jobName - the name of this job
//       endPoint - the checkin api endpoint url
func checkInJob(jobName string, endPoint string) {
	log.Println("Cheking-in to", endPoint)

	var jsonStr = []byte(`{"source":"` + jobName + `"}`)
	req, err := http.NewRequest("POST", endPoint, bytes.NewBuffer(jsonStr))
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		log.Println(err.Error())
	}
	defer resp.Body.Close()
	log.Println("Checkin response Status:", resp.Status)
}

// A helper to check if a env var is defined. If not defined, show error.
// Args: key - the env var to check for
// Returns if exists, the value of the var
func getEnv(key string) string {
	value := os.Getenv(key)
	if len(value) == 0 {
		log.Fatalf("Env var %s is required and missing.", key)
	}
	log.Printf("%s=%s", key, value)
	return value
}

// A helper to check and assign all required ENV vars to the Config struct
// Returns a pointer to the Config struct
func loadConfig() *Config {
	conf := Config{
		JOB_NAME:                 getEnv("JOB_NAME"),
		TZ:                       getEnv("TZ"),
		WINDOW_SIZE:              getEnv("WINDOW_SIZE"),
		MYSQL_HOST:               getEnv("MYSQL_HOST"),
		MYSQL_USER:               getEnv("MYSQL_USER"),
		MYSQL_PASSWORD:           getEnv("MYSQL_PASSWORD"),
		MYSQL_DB:                 getEnv("MYSQL_DB"),
		MYSQL_TABLE:              getEnv("MYSQL_TABLE"),
		DRUID_HOST:               getEnv("DRUID_HOST"),
		INFLUX_HOST:              getEnv("INFLUX_HOST"),
		INFLUX_PORT:              getEnv("INFLUX_PORT"),
		INFLUX_DB:                getEnv("INFLUX_DB"),
		INFLUX_RP:                getEnv("INFLUX_RP"),
		INFLUX_MEASUREMENT:       getEnv("INFLUX_MEASUREMENT"),
		DVO_API_CHECKIN_ENDPOINT: getEnv("DVO_API_CHECKIN_ENDPOINT"),
	}
	return &conf
}

func main() {

	// setup
	appConfig := loadConfig()

	loc, _ := time.LoadLocation(appConfig.TZ)
	windowSize, err := strconv.Atoi(appConfig.WINDOW_SIZE)
	if err != nil {
		log.Fatal(err)
	}

	// druid
	druidClient := initDruidClient(appConfig.DRUID_HOST)

	// mysql
	mySqlDb := initMySqlDb(appConfig)
	preparedStmt := getSqlPreparedStatement(mySqlDb, appConfig.MYSQL_TABLE)

	// influx
	influxClient := initInfluxClient(appConfig)

	// main logic
	now := time.Now().UTC()
	startTime := now.Add(time.Duration(windowSize) * -time.Hour)
	endTime := now.Add(1 * -time.Hour) // skip the current hour

	for d := endTime; d.Before(startTime) == false; d = d.Add(-1 * time.Hour) {
		// get the formatted hour for mysql and druid
		estHrMysql := fmt.Sprintf("%s:00:00", d.In(loc).Format("2006-01-02 15")) // using GO constant format https://golang.org/src/pkg/time/format.go
		utcHrDruid := fmt.Sprintf("%s", d.Format("2006-01-02T15Z"))
		log.Printf("Mysql date: %s | Druid date: %s\n", estHrMysql, utcHrDruid)

		// get the mysql stats for this hour
		mySqlStats := getMySqlStatsForInterval(preparedStmt, estHrMysql)

		if mySqlStats.Views.Valid {
			log.Printf("MYSQL STATS: Views: %f | Clicks: %f | Leads: %f", mySqlStats.Views.Float64, mySqlStats.Clicks.Float64, mySqlStats.Leads.Float64)
		} else {
			log.Println("no sql row was returned for this hour")
		}

		// get the druid stats for this hour
		druidStats := getDruidStatsForInterval(druidClient, utcHrDruid)
		// store in influx
		if druidStats.Views.Valid {
			log.Printf("DRUID STATS: Views: %f | Clicks: %f | Leads: %f", druidStats.Views.Float64, druidStats.Clicks.Float64, druidStats.Leads.Float64)
		} else {
			log.Println("no druid result was returned for this hour")
		}

		// store results in influx
		if mySqlStats.Views.Valid && druidStats.Views.Valid {
			_ = writeToInflux(influxClient, appConfig, &mySqlStats, &druidStats, d.In(loc).Truncate(time.Hour))
		}
	}

	// checkin job
	checkInJob(appConfig.JOB_NAME, appConfig.DVO_API_CHECKIN_ENDPOINT)
}