// Copyright 2014 by Sascha L. Teichmann
// Use of this source code is governed by the MIT license
// that can be found in the LICENSE file.

package main

import (
	"flag"
	"fmt"
	"log"
	"os"

	"bitbucket.org/s_l_teichmann/mtredisalize/common"
)

func usage() {
	fmt.Fprintf(os.Stderr,
		"Usage: %s [<options>] <source database> <dest database>\n", os.Args[0])
	fmt.Fprintln(os.Stderr, "Options:")
	flag.PrintDefaults()
}

func copyProducerToConsumer(producer BlockProducer, consumer BlockConsumer) (err error) {
	var block Block
	i := 0
	for {
		if err = producer.Next(&block); err != nil {
			if err == ErrNoMoreBlocks {
				err = nil
				break
			}
			return
		}
		if err = consumer.Consume(&block); err != nil {
			return
		}
		i++
		if i%1000 == 0 {
			log.Printf("%i blocks transferred.\n", i)
		}
	}
	log.Printf("%i blocks transferred in total.\n", i)

	return
}

func main() {
	var (
		srcBackend     string
		dstBackend     string
		srcInterleaved bool
		dstInterleaved bool
	)

	flag.Usage = usage

	flag.StringVar(&srcBackend, "source-backend", "sqlite",
		"type of source database (leveldb, sqlite)")
	flag.StringVar(&srcBackend, "sb", "sqlite",
		"type of source database (leveldb, sqlite). Shorthand")
	flag.StringVar(&dstBackend, "dest-backend", "leveldb",
		"type of destination database (leveldb, sqlite)")
	flag.StringVar(&dstBackend, "db", "leveldb",
		"type of destination database (leveldb, sqlite). Shorthand")
	flag.BoolVar(&srcInterleaved, "source-interleaved", false,
		"Is source database interleaved?")
	flag.BoolVar(&srcInterleaved, "si", false,
		"Is source database interleaved? Shorthand")
	flag.BoolVar(&dstInterleaved, "dest-interleaved", true,
		"Should dest database be interleaved?")
	flag.BoolVar(&dstInterleaved, "di", true,
		"Should source database be interleaved? Shorthand")

	flag.Parse()

	if flag.NArg() < 2 {
		log.Fatal("Missing source and/or destination database.")
	}

	var (
		producer BlockProducer
		consumer BlockConsumer
		err      error
	)

	if srcBackend == "sqlite" {
		if producer, err = NewSQLiteBlockProducer(
			flag.Arg(0),
			common.SelectKeySplitter(srcInterleaved)); err != nil {
			log.Fatalf("Cannot open '%s': %s", flag.Arg(0), err)
		}
	} else { // LevelDB
		if producer, err = NewLevelDBBlockProducer(
			flag.Arg(0),
			common.SelectKeySplitter(srcInterleaved),
			common.SelectKeyDecoder(srcInterleaved)); err != nil {
			log.Fatalf("Cannot open '%s': %s", flag.Arg(0), err)
		}
	}
	defer producer.Close()

	if dstBackend == "sqlite" {
		if consumer, err = NewSQLiteBlockConsumer(
			flag.Arg(1), common.SelectKeyJoiner(dstInterleaved)); err != nil {
			log.Fatalf("Cannot open '%s': %s", flag.Arg(1), err)
		}
	} else { // LevelDB
		if consumer, err = NewLevelDBBlockConsumer(
			flag.Arg(1),
			common.SelectKeyJoiner(dstInterleaved),
			common.SelectKeyEncoder(dstInterleaved)); err != nil {
			log.Fatalf("Cannot open '%s': %s", flag.Arg(1), err)
		}
	}
	defer consumer.Close()

	if err = copyProducerToConsumer(producer, consumer); err != nil {
		log.Fatalf("Database transfer failed: %s\n", err)
	}
}