list_iterator.go

// Copyright 2022 API7.ai, Inc
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package cloud

import (
	"context"
	"encoding/json"
	"net/url"
	"strconv"

	"github.com/pkg/errors"
	"net/http"
)

var (
	// DefaultPagination is the default paging.
	DefaultPagination = Pagination{
		Page:     1,
		PageSize: 10,
	}
)

// Pagination indicates the paging.
type Pagination struct {
	// Page is the start page.
	Page int
	// PageSize is the page size (how many items will be in a page).
	PageSize int
}

func (paging *Pagination) step() {
	paging.Page++
}

// Filter indicates conditions to filter out list results.
type Filter struct {
	// Search indicates the search condition for filtering out list results.
	Search string
}

type listResponse struct {
	List  []json.RawMessage `json:"list"`
	Count uint64            `json:"count"`
}

type listIterator struct {
	ctx      context.Context
	resource string
	client   httpClient
	path     string
	paging   Pagination
	filter   *Filter
	eof      bool
	items    []json.RawMessage
	headers  http.Header
}

func (iter *listIterator) Next() (json.RawMessage, error) {
	if iter.eof {
		return nil, nil
	}

	if len(iter.items) == 0 {
		var lr listResponse

		query := make(url.Values)
		query.Set("page", strconv.Itoa(iter.paging.Page))
		query.Set("page_size", strconv.Itoa(iter.paging.PageSize))

		if iter.filter != nil {
			if iter.filter.Search != "" {
				query.Set("search", iter.filter.Search)
			}
		}

		err := iter.client.sendGetRequest(iter.ctx, iter.path, query.Encode(), jsonPayloadDecodeFactory(&lr), iter.headers)
		if err != nil {
			return nil, errors.Wrap(err, "list resources")
		}

		iter.items = lr.List

		if len(iter.items) == 0 {
			iter.eof = true
			return nil, nil
		}
		(&iter.paging).step()
	}

	res := iter.items[0]
	iter.items[0] = nil
	iter.items = iter.items[1:]
	return res, nil
}