package asses

import (
	"context"
	"crypto/md5"
	"encoding/base64"
	"io"
	"log"
	"math/rand"
	"os"
	"path"
	"time"
)

func One(ctx context.Context, p string) error {
	shortp := path.Join("...", path.Dir(p), path.Base(p))

	last, err := checkLast(ctx, p)
	if err != nil {
		return err
	}

	if last.T.IsZero() {
		log.Printf("asses.One(%s) // never seen before", shortp)
	} else if cksum, err := Cksum(p); err != nil {
		return err
	} else if cksum != last.Cksum {
		log.Printf("asses.One(%s) // cksum changed", shortp)
	} else if threshold := 20 + time.Duration(rand.Int()%10)*24*time.Hour; time.Since(last.T) < threshold {
		log.Printf("asses.One(%s) // lt %v since last review", shortp, threshold.Hours())
		return nil
	}

	log.Printf("asses.deport(%s)...", shortp)
	if err := deport(ctx, p); err != nil {
		return err
	}

	cksum, err := Cksum(p)
	if err != nil {
		return err
	}
	return checked(ctx, p, cksum)
}

func Cksum(p string) (string, error) {
	f, err := os.Open(p)
	if err != nil {
		return "", err
	}
	defer f.Close()

	hasher := md5.New()
	_, err = io.Copy(hasher, f)
	return base64.StdEncoding.EncodeToString(hasher.Sum(nil)), err
}