package handler

import (
	"net/http"
	"strconv"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/errors"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/middleware"
)

const maxBucketList = 10000

// ListBucketsHandler handles bucket listing requests.
func (h *handler) ListBucketsHandler(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	reqInfo := middleware.GetReqInfo(ctx)

	params, err := parseListBucketParams(r)
	if err != nil {
		h.logAndSendError(ctx, w, "failed to parse params", reqInfo, err)
		return
	}

	resp, err := h.obj.ListBuckets(ctx, params)
	if err != nil {
		h.logAndSendError(ctx, w, "something went wrong", reqInfo, err)
		return
	}

	if err = middleware.EncodeToResponse(w, encodeListBuckets(reqInfo.User, resp, params)); err != nil {
		h.logAndSendError(ctx, w, "something went wrong", reqInfo, err)
	}
}

func encodeListBuckets(owner string, resp layer.ListBucketsResult, params layer.ListBucketsParams) *ListBucketsResponse {
	res := &ListBucketsResponse{
		Owner: Owner{
			ID:          owner,
			DisplayName: owner,
		},
		ContinuationToken: resp.ContinuationToken,
		Prefix:            params.Prefix,
	}

	for _, item := range resp.Containers {
		res.Buckets.Buckets = append(res.Buckets.Buckets, Bucket{
			Name:         item.Name,
			CreationDate: item.Created.UTC().Format(time.RFC3339),
			BucketRegion: item.LocationConstraint,
		})
	}
	return res
}

func parseListBucketParams(r *http.Request) (prm layer.ListBucketsParams, err error) {
	prm.MaxBuckets = maxBucketList
	strMaxBuckets := r.URL.Query().Get(middleware.QueryMaxBuckets)
	if strMaxBuckets != "" {
		if prm.MaxBuckets, err = strconv.Atoi(strMaxBuckets); err != nil || prm.MaxBuckets < 0 {
			return layer.ListBucketsParams{}, errors.GetAPIError(errors.ErrInvalidMaxKeys)
		}
	}
	prm.Prefix = r.URL.Query().Get(middleware.QueryPrefix)
	prm.BucketRegion = r.URL.Query().Get(middleware.QueryBucketRegion)
	prm.ContinuationToken = r.URL.Query().Get(middleware.QueryContinuationToken)

	return
}