// md2pg imports a Maildir format file into a PostgreSQL DB
package main

import (
	"bytes"
	"database/sql"
	"expvar"
	"flag"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/golang/glog"
	_ "github.com/lib/pq"

	"xinu.tv/email"
	"xinu.tv/set"
	"xinu.tv/types"
)

var (
	maildir   = flag.String("maildir", "", "Maildir root")
	username  = flag.String("user", "wathiede", "username for email we're importing")
	skipFiles = flag.String("skip", "maildirfolder,log,msgid.cache,razor-agent.log",
		"comma separated files to skip")

	total  = expvar.NewInt("bytes-parsed")
	cnt    = expvar.NewInt("messages-parsed")
	dupCnt = expvar.NewInt("duplicates-found")
)

var (
	CRCR = []byte("\n\n")
	// Maximum bytes we parse when decoding
	// email message, 50MB.
	maxMessageSize      int64 = 50 << 20
	insertOriginalQuery       = `INSERT INTO
    original (uid, hash, header_size, total_size, blob)
VALUES (
    $1, $2, $3, $4, $5
);`
)

func LoadReader(db *sql.DB, uid int, r io.Reader) error {
	stmt, err := db.Prepare(insertOriginalQuery)
	if err != nil {
		return err
	}

	b, err := ioutil.ReadAll(&io.LimitedReader{R: r, N: maxMessageSize})
	if err != nil {
		return err
	}

	hdr_size := bytes.Index(b, CRCR)
	chksum, err := email.HashReader(bytes.NewReader(b))
	if err != nil {
		return err
	}

	n := len(b)
	if _, err := stmt.Exec(uid, chksum, hdr_size, n, b); err != nil {
		return err
	}
	return nil
}

func Load(db *sql.DB, uid int, root string, skip *set.StringSet) error {
	dup := set.NewStrings()
	start := time.Now()
	defer func() {
		glog.Infof("%s messages processed in %s", cnt, time.Since(start))
		glog.Infof("%s dups found", dupCnt)
	}()

	txn, err := db.Begin()
	if err != nil {
		return err
	}

	stmt, err := txn.Prepare(insertOriginalQuery)
	if err != nil {
		if err := txn.Rollback(); err != nil {
			glog.Errorln("txn.Prepare stmt error rolling back", err)
		}
		return err
	}

	hstmt, err := txn.Prepare("INSERT INTO files (hash, path) VALUES ($1, $2);")
	if err != nil {
		if err := txn.Rollback(); err != nil {
			glog.Errorln("txn.Prepare hstmt error rolling back", err)
		}
		return err
	}

	err = filepath.Walk(root,
		func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return err
			}

			if info.IsDir() {
				return nil
			}
			base := filepath.Base(path)
			if skip.Contains(base) {
				return nil
			}

			r, err := os.Open(path)
			if err != nil {
				return err
			}
			defer r.Close()

			b, err := ioutil.ReadAll(&io.LimitedReader{R: r, N: maxMessageSize})
			if err != nil {
				return err
			}

			hdr_size := bytes.Index(b, CRCR)
			chksum, err := email.HashReader(bytes.NewReader(b))
			if err != nil {
				glog.Errorf("%s not an mail file", path)
				glog.Infof("%q", err.Error())
				return nil
			}

			if _, err := hstmt.Exec(chksum, path); err != nil {
				return err
			}

			if dup.Contains(chksum) {
				glog.Warningln("Dup ", chksum, path[len(root)+1:], len(b))
				dupCnt.Add(1)
				return nil
			}
			dup.Add(chksum)

			n := len(b)
			total.Add(int64(n))
			delta := time.Since(start)
			i, err := strconv.Atoi(cnt.String())
			if err != nil {
				return err
			}
			if i%1000 == 0 {
				t, err := strconv.Atoi(total.String())
				if err != nil {
					return err
				}
				glog.Infof("%d messages processed in %s: %.2f msg/s %s/s", i,
					delta, float64(i)/delta.Seconds(),
					types.Base2Size(float64(t)/delta.Seconds()))
			}
			if _, err := stmt.Exec(uid, chksum, hdr_size, n, b); err != nil {
				return err
			}

			cnt.Add(1)
			return nil
		})

	/*
		if _, err := stmt.Exec(); err != nil {
			if err := txn.Rollback(); err != nil {
				glog.Errorln("stmt.Exec error rolling back", err)
			}
			return err
		}
	*/

	if err := stmt.Close(); err != nil {
		if err := txn.Rollback(); err != nil {
			glog.Errorln("stmt.Close error rolling back", err)
		}
		return err
	}

	if err := hstmt.Close(); err != nil {
		if err := txn.Rollback(); err != nil {
			glog.Errorln("stmt.Close error rolling back", err)
		}
		return err
	}

	return txn.Commit()
}

func GetUid(db *sql.DB, username string) (int, error) {
	var uid int
	err := db.QueryRow("SELECT uid FROM person WHERE username=$1", username).Scan(&uid)
	switch {
	case err == sql.ErrNoRows, err != nil:
		return -1, err
	}
	return uid, nil
}

func main() {
	defer glog.Flush()
	flag.Parse()

	// TODO(wathiede): make a set of flags.
	db, err := sql.Open("postgres", "user=gomail dbname=gomail sslmode=disable")
	if err != nil {
		glog.Fatal(err)
	}

	uid, err := GetUid(db, *username)
	if err != nil {
		glog.Fatal(err)
	}

	glog.Infoln("Using uid", uid, "for", *username)
	if *maildir == "" {
		if err := LoadReader(db, uid, os.Stdin); err != nil {
			glog.Fatal(err)
		}
		return
	}

	// Load all files in maildir
	skip := set.NewStrings(strings.Split(*skipFiles, ",")...)
	glog.Infoln("Skip files", skip)

	if err := Load(db, uid, *maildir, skip); err != nil {
		glog.Fatal(err)
	}
}