package handler

import (
	"encoding/xml"
	"net/http"

	"github.com/nspcc-dev/neofs-s3-gw/api"
	"github.com/nspcc-dev/neofs-s3-gw/api/errors"
	"github.com/nspcc-dev/neofs-s3-gw/api/layer"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
)

// DeleteObjectsRequest - xml carrying the object key names which needs to be deleted.
type DeleteObjectsRequest struct {
	// Element to enable quiet mode for the request
	Quiet bool
	// List of objects to be deleted
	Objects []ObjectIdentifier `xml:"Object"`
}

// ObjectIdentifier carries key name for the object to delete.
type ObjectIdentifier struct {
	ObjectName string `xml:"Key"`
	VersionID  string `xml:"VersionId,omitempty"`
}

// DeleteError structure.
type DeleteError struct {
	Code    string
	Message string
	Key     string
}

// DeleteObjectsResponse container for multiple object deletes.
type DeleteObjectsResponse struct {
	XMLName xml.Name `xml:"http://s3.amazonaws.com/doc/2006-03-01/ DeleteResult" json:"-"`

	// Collection of all deleted objects
	DeletedObjects []ObjectIdentifier `xml:"Deleted,omitempty"`

	// Collection of errors deleting certain objects.
	Errors []DeleteError `xml:"Error,omitempty"`
}

func (h *handler) DeleteObjectHandler(w http.ResponseWriter, r *http.Request) {
	reqInfo := api.GetReqInfo(r.Context())
	versionedObject := []*layer.VersionedObject{{
		Name:      reqInfo.ObjectName,
		VersionID: reqInfo.URL.Query().Get("versionId"),
	}}

	if err := h.checkBucketOwner(r, reqInfo.BucketName); err != nil {
		h.logAndSendError(w, "expected owner doesn't match", reqInfo, err)
		return
	}

	if errs := h.obj.DeleteObjects(r.Context(), reqInfo.BucketName, versionedObject); len(errs) != 0 && errs[0] != nil {
		h.log.Error("could not delete object",
			zap.String("request_id", reqInfo.RequestID),
			zap.String("bucket_name", reqInfo.BucketName),
			zap.String("object_name", reqInfo.ObjectName),
			zap.Error(errs[0]))

		// Ignore delete errors:

		// api.WriteErrorResponse(r.Context(), w, api.Error{
		// 	Code:           api.GetAPIError(api.ErrInternalError).Code,
		// 	Description:    err.Error(),
		// 	HTTPStatusCode: http.StatusInternalServerError,
		// }, r.URL)
	}

	w.WriteHeader(http.StatusNoContent)
}

// DeleteMultipleObjectsHandler handles multiple delete requests.
func (h *handler) DeleteMultipleObjectsHandler(w http.ResponseWriter, r *http.Request) {
	reqInfo := api.GetReqInfo(r.Context())

	// Content-Md5 is requied should be set
	// http://docs.aws.amazon.com/AmazonS3/latest/API/multiobjectdeleteapi.html
	if _, ok := r.Header[api.ContentMD5]; !ok {
		h.logAndSendError(w, "missing Content-MD5", reqInfo, errors.GetAPIError(errors.ErrMissingContentMD5))
		return
	}

	// Content-Length is required and should be non-zero
	// http://docs.aws.amazon.com/AmazonS3/latest/API/multiobjectdeleteapi.html
	if r.ContentLength <= 0 {
		h.logAndSendError(w, "missing Content-Length", reqInfo, errors.GetAPIError(errors.ErrMissingContentLength))
		return
	}

	// Unmarshal list of keys to be deleted.
	requested := &DeleteObjectsRequest{}
	if err := xml.NewDecoder(r.Body).Decode(requested); err != nil {
		h.logAndSendError(w, "couldn't decode body", reqInfo, err)
		return
	}

	removed := make(map[string]struct{})
	toRemove := make([]*layer.VersionedObject, 0, len(requested.Objects))
	for _, obj := range requested.Objects {
		versionedObj := &layer.VersionedObject{
			Name:      obj.ObjectName,
			VersionID: obj.VersionID,
		}
		toRemove = append(toRemove, versionedObj)
		removed[versionedObj.String()] = struct{}{}
	}

	response := &DeleteObjectsResponse{
		Errors:         make([]DeleteError, 0, len(toRemove)),
		DeletedObjects: make([]ObjectIdentifier, 0, len(toRemove)),
	}

	if err := h.checkBucketOwner(r, reqInfo.BucketName); err != nil {
		h.logAndSendError(w, "expected owner doesn't match", reqInfo, err)
		return
	}

	marshaler := zapcore.ArrayMarshalerFunc(func(encoder zapcore.ArrayEncoder) error {
		for _, obj := range toRemove {
			encoder.AppendString(obj.String())
		}
		return nil
	})

	if errs := h.obj.DeleteObjects(r.Context(), reqInfo.BucketName, toRemove); errs != nil && !requested.Quiet {
		additional := []zap.Field{
			zap.Array("objects", marshaler),
			zap.Errors("errors", errs),
		}
		h.logAndSendError(w, "could not delete objects", reqInfo, nil, additional...)

		for _, e := range errs {
			if err, ok := e.(*errors.DeleteError); ok {
				code := "BadRequest"
				desc := err.Error()

				response.Errors = append(response.Errors, DeleteError{
					Code:    code,
					Message: desc,
					Key:     err.Object,
				})

				delete(removed, err.Object)
			}
		}
	}

	for key := range removed {
		response.DeletedObjects = append(response.DeletedObjects, ObjectIdentifier{ObjectName: key})
	}

	if err := api.EncodeToResponse(w, response); err != nil {
		h.logAndSendError(w, "could not write response", reqInfo, err, zap.Array("objects", marshaler))
		return
	}
}

func (h *handler) DeleteBucketHandler(w http.ResponseWriter, r *http.Request) {
	reqInfo := api.GetReqInfo(r.Context())
	if err := h.checkBucketOwner(r, reqInfo.BucketName); err != nil {
		h.logAndSendError(w, "expected owner doesn't match", reqInfo, err)
		return
	}
	if err := h.obj.DeleteBucket(r.Context(), &layer.DeleteBucketParams{Name: reqInfo.BucketName}); err != nil {
		h.logAndSendError(w, "couldn't delete bucket", reqInfo, err)
	}
}