lion-turtle/leadercraft-ranker/main.go

// NGnius 2020-01-30

package main // leadercraft-server

import (
    "flag"
	"fmt"
	"os"
	"os/signal"
)

const (
	// Version the current version
	Version = "0.1"
	// Name the program name
	Name = "leadercraft-s"
)

var (
	isClosing bool
	printVersionAndExit bool
)

func init() {
	initArgs()
}

func main() {
	parseArgs()
	sqlInitErr := sqlInit()
	if sqlInitErr != nil {
		fmt.Printf("Failed to initialise SQL connection: %s\n", sqlInitErr)
		os.Exit(1)
	}
	// handle interrupt (terminate) signal
	signalChan := make(chan os.Signal)
	signal.Notify(signalChan, os.Interrupt)
	go func() {
		s := <-signalChan
		fmt.Println("Received terminate signal " + s.String())
		isClosing = true
		sqlClose()
	}()
    // get new rankings
    rows, err := db.Query("SELECT * FROM Entries WHERE rank=-1 ORDER BY time ASC;")
	if err == nil {
        var entries []*Entry
		count := 0
        for rows.Next() {
            entries = append(entries, &Entry{})
            scanErr := rows.Scan(entries[count].Intake()...)
            if scanErr == nil {
                updateBoardEntries(entries[count])
                count++
            } else {
                fmt.Println(scanErr)
            }
        }
	} else {
        fmt.Println(err)
    }
}

func initArgs() {
	flag.BoolVar(&printVersionAndExit, "version", false, "Print version and exit")
	flag.StringVar(&sqlConnection, "conn", sqlConnectionDefault, "Database connection string")
	flag.StringVar(&sqlServer, "sql", sqlServerDefault, "SQL Database type")
}

func parseArgs() {
	flag.Parse()
	if printVersionAndExit {
		fmt.Println(Name + " v" + Version)
		os.Exit(0)
	}
}

func updateBoardEntries(entry *Entry) {
    // get nearest entry that's lower and steal it's rank
    nearestEntry := &Entry{}
    scanErr := db.QueryRow("SELECT * FROM Entries WHERE score < $1 AND rank!= -1 AND board=$2 ORDER BY score DESC LIMIT 1;", entry.Score, entry.Board).Scan(nearestEntry.Intake()...)
    if (scanErr == nil) {
        entry.Rank = nearestEntry.Rank
        entry.Commit()
        // update all ranks lower than itself
        tx, _ := db.Begin()
        stmt, _ := tx.Prepare("UPDATE Entries SET rank=rank+1 WHERE rank >=$1 AND id!=$2 AND board=$3;")
        _, err := stmt.Exec(entry.Rank, entry.ID, entry.Board)
        if err != nil {
            tx.Rollback()
            fmt.Println(err)
        } else {
            tx.Commit()
        }
    } else {
        // nothing to beat
        scanErr = db.QueryRow("SELECT * FROM Entries WHERE score >= $1 AND rank!= -1 AND board=$2 ORDER BY score ASC LIMIT 1;", entry.Score, entry.Board).Scan(nearestEntry.Intake()...)
        if (scanErr == nil) {
            entry.Rank = nearestEntry.Rank + 1
            entry.Commit()
        } else {
            // no other entries
            entry.Rank = 1
            entry.Commit()
            //fmt.Println(scanErr)
        }
    }
}