package main

import (
    "database/sql"
    _ "github.com/mattn/go-sqlite3"
    "log"
    "io"
    "fmt"
    "os"
    "crypto/sha1"
    "time"
    "path/filepath"
    "strconv"
    "encoding/hex"
    "encoding/binary"
    "hash"
    "reflect"
)

const sampleSize = 16 * 1024
const sampleThreshold = 48 * 1024

func copyHash(src hash.Hash) hash.Hash {
    typ := reflect.TypeOf(src)
    val := reflect.ValueOf(src)
    if typ.Kind() == reflect.Ptr {
        typ = typ.Elem()
        val = val.Elem()
    }
    elem := reflect.New(typ).Elem()
    elem.Set(val)
    return elem.Addr().Interface().(hash.Hash)
}

func hash_directory (searchDir, database string) {
	db, dberr := sql.Open("sqlite3", database)
	if dberr != nil {
		log.Fatal(dberr)
	}
	defer db.Close()
	err := filepath.Walk(searchDir,
		func(path string, info os.FileInfo, err error) error {
			if err != nil {
				log.Fatal(err)
				return err
			}
			if !info.IsDir() {
				fmt.Printf("Name: %s\n", info.Name())
				f, err := os.Open(path)
				if err != nil {
					log.Fatal(err)
				}
				defer f.Close()
				h := sha1.New()
				if _, err := io.Copy(h, f); err != nil {
					log.Fatal(err)
				}
				qh := copyHash(h)
				if info.Size() > int64(sampleThreshold) {
						qh.Reset()
						buffer := make([]byte, sampleSize)
						f.Read(buffer)
						qh.Write(buffer)
						f.Seek(info.Size()/2-sampleSize/2, 0)
						f.Read(buffer)
						qh.Write(buffer)
						f.Seek(int64(-sampleSize), 2)
						f.Read(buffer)
						qh.Write(buffer)
				}
				buffer := make([]byte, 8)
				binary.PutVarint(buffer, info.Size())
				qh.Write(buffer)
				quickSum := hex.EncodeToString(qh.Sum(nil))

				hashSum := hex.EncodeToString(h.Sum(nil))
				fmt.Printf("SHA1:  %x\n", hashSum)
				fmt.Printf("qSHA1: %x\n", quickSum)
				fmt.Printf("Size:  %d\n", info.Size())
				fmt.Printf("Time:  %s\n\n", info.ModTime().Format(time.RFC3339))
				sqlStatement := "INSERT INTO hashes (hash_sha1, filename, filesize_bytes, path, changedate )"+
				"VALUES ('"+hashSum+"','"+info.Name()+"','"+strconv.FormatInt(info.Size(),10)+"','"+path+"','"+info.ModTime().Format(time.RFC3339)+"');"

				_, err = db.Exec(sqlStatement)
				if err != nil {
					log.Printf("%q: %s\n", err, sqlStatement)
					return nil
				}

			}
			return nil
		})
	if err != nil {
		log.Fatal(err)
	}
}

func main() {
	dbname := "./sneakerhash.db"
	os.Remove(dbname)
	db, err := sql.Open("sqlite3", dbname)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()
	sqlStatement := `
	create table hashes (
	  hash_sha1 text not null primary key,
	  filename text,
	  filesize_bytes integer,
	  path text,
	  changedate datetime
	);`
	_, err = db.Exec(sqlStatement)
	if err != nil {
		log.Printf("%q: %s\n", err, sqlStatement)
		return
	}
	hash_directory(".", dbname)
}