package main

import (
    "bufio"
	"bytes"
	_ "github.com/go-sql-driver/mysql"
	"database/sql"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"strings"
)

var (
	// Actual messages
	msgs = make(chan string, 1000000)

	// Indicate when consumer has finishes
	done = make(chan bool)

	db_host     string
	db_user     string
	db_password string
	db_name     string
	db_charset  string
)

func produce() {
	r := bufio.NewReaderSize(io.Reader(os.Stdin), 32*1024*1024)
	var query bytes.Buffer
	for {
		line, err := r.ReadString('\n')
		if err == nil {
			// Based on pt-query-digest's output:
			// Start of a new '#' block indicates the previous query has
			// ended. This is slightly more robust than looking for a trailing
			// semi-colon, in case the query doesn't end in one.
			if len(line) > 0 && line[0] == '#' {
				s := strings.TrimSpace(query.String())
				if len(s) > 1 {
					select {
					case msgs <- s:
						/* nothing */
					default:
						log.Println("Channel full; dropping message")
					}
				}
				query.Reset()
			} else {
				query.WriteString(" " + line)
			}
			continue
		}
		if err != nil && err != io.EOF {
			fmt.Println("Error reading from stdin: " + err.Error())
			break
		}
		if err != nil && err == io.EOF {
			break
		}
	}
	fmt.Println("Done with produce")
	close(msgs)
}

func consume() {
	defer func() {
		done <- true
	}()

	for {
		select {
		case msg, ok := <-msgs:
			if !ok {
				return
			}

			// Creating a new connection for every query. Trying to exercise MySQL's connection
			// handling a bit
			db, e := sql.Open("mysql", db_user+":"+db_password+"@tcp("+db_host+":3306)/"+db_name+"?charset="+db_charset+"&multiStatements=true"
			if e != nil {
				panic(e)
			}

			_, err := db.Exec(msg)
			if err != nil {
				log.Println(msg)
				log.Println(err.Error())
			}
			db.Close()
		}
	}

}

func main() {
	var threads = flag.Int("threads", 8, "Execution threads")
	flag.StringVar(&db_host, "db-host", "", "DB Host")
	flag.StringVar(&db_user, "db-user", "", "DB Username")
	flag.StringVar(&db_password, "db-password", "", "DB Password")
	flag.StringVar(&db_name, "db-name", "", "DB Name")
	flag.StringVar(&db_charset, "db-charset", "", "DB Character set")
	var error_log = flag.String("log", "", "Error log file location and name")
	var help = flag.Bool("h", false, "Help")
	flag.Parse()

	if *help == true {
		flag.Usage()
		return
	}

	if db_host == "" || db_user == "" || db_password == "" || db_name == "" || db_charset == "" || *error_log == "" {
		flag.Usage()
		return
	}

	logFile, err := os.OpenFile(*error_log, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
	if err != nil {
		panic(err.Error() + " opening log file: " + *error_log)
	}
	log.SetOutput(logFile)
	log.SetFlags(log.LstdFlags)

	fmt.Println(fmt.Sprintf("Starting go-execution with %d threads", *threads))
	go produce()
	for i := 0; i < *threads; i++ {
		go consume()
	}

	for i := 0; i < *threads; i++ {
		<-done
	}

	fmt.Println("Done with consume")
}