package inmemory

import (
	"bytes"
	"crypto/sha256"
	"fmt"
	"io"
	"strings"
	"time"

	mstorage "github.com/minio-io/minio/pkg/storage"
)

type storage struct {
	bucketdata map[string]storedBucket
	objectdata map[string]storedObject
}

type storedBucket struct {
	metadata mstorage.BucketMetadata
	//	owner    string // TODO
	//	id       string // TODO
}

type storedObject struct {
	metadata mstorage.ObjectMetadata
	data     []byte
}

func (storage *storage) CopyObjectToWriter(w io.Writer, bucket string, object string) (int64, error) {
	// TODO synchronize access
	// get object
	key := bucket + ":" + object
	if val, ok := storage.objectdata[key]; ok {
		objectBuffer := bytes.NewBuffer(val.data)
		written, err := io.Copy(w, objectBuffer)
		return written, err
	} else {
		return 0, mstorage.ObjectNotFound{Bucket: bucket, Path: object}
	}
}

func (storage *storage) StoreObject(bucket string, key string, data io.Reader) error {
	objectKey := bucket + ":" + key

	if _, ok := storage.bucketdata[bucket]; ok == false {
		return mstorage.BucketNotFound{Bucket: bucket}
	}

	if _, ok := storage.objectdata[objectKey]; ok == true {
		return mstorage.ObjectExists{Bucket: bucket, Key: key}
	}
	var bytesBuffer bytes.Buffer
	var newObject = storedObject{}
	if _, ok := io.Copy(&bytesBuffer, data); ok == nil {
		size := bytesBuffer.Len()
		etag := fmt.Sprintf("%x", sha256.Sum256(bytesBuffer.Bytes()))
		newObject.metadata = mstorage.ObjectMetadata{
			Bucket:  bucket,
			Key:     key,
			Created: time.Now(),
			Size:    size,
			ETag:    etag,
		}
		newObject.data = bytesBuffer.Bytes()
	}
	storage.objectdata[objectKey] = newObject
	return nil
}

func (storage *storage) StoreBucket(bucketName string) error {
	if !mstorage.IsValidBucket(bucketName) {
		return mstorage.BucketNameInvalid{Bucket: bucketName}
	}

	if _, ok := storage.bucketdata[bucketName]; ok == true {
		return mstorage.BucketExists{Bucket: bucketName}
	}

	var newBucket = storedBucket{}
	newBucket.metadata = mstorage.BucketMetadata{}
	newBucket.metadata.Name = bucketName
	newBucket.metadata.Created = time.Now()
	storage.bucketdata[bucketName] = newBucket

	return nil
}

func (storage *storage) ListObjects(bucket, prefix string, count int) []mstorage.ObjectMetadata {
	// TODO prefix and count handling
	var results []mstorage.ObjectMetadata
	for key, object := range storage.objectdata {
		if bucket == object.metadata.Bucket {
			if strings.HasPrefix(key, bucket+":") {
				results = append(results, object.metadata)
			}
		}
		if len(results) == count {
			return results
		}
	}
	return results
}

func (storage *storage) ListBuckets(prefix string) []mstorage.BucketMetadata {
	// TODO prefix handling
	var results []mstorage.BucketMetadata
	for _, bucket := range storage.bucketdata {
		results = append(results, bucket.metadata)
	}
	return results
}

func Start() (chan<- string, <-chan error, *storage) {
	ctrlChannel := make(chan string)
	errorChannel := make(chan error)
	go start(ctrlChannel, errorChannel)
	return ctrlChannel, errorChannel, &storage{
		bucketdata: make(map[string]storedBucket),
		objectdata: make(map[string]storedObject),
	}
}

func start(ctrlChannel <-chan string, errorChannel chan<- error) {
	close(errorChannel)
}

func (storage *storage) GetObjectMetadata(bucket, key string) (mstorage.ObjectMetadata, error) {
	objectKey := bucket + ":" + key

	if object, ok := storage.objectdata[objectKey]; ok == true {
		return object.metadata, nil
	} else {
		return mstorage.ObjectMetadata{}, mstorage.ObjectNotFound{Bucket: bucket, Path: key}
	}
}