PagingImpl.java
/*
* Copyright (c) 2023. Roland T. Lichti, Kaiserpfalz EDV-Service.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package de.kaiserpfalzedv.commons.core.resources;
import org.eclipse.microprofile.openapi.annotations.media.Schema;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import de.kaiserpfalzedv.commons.api.resources.Paging;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.EqualsAndHashCode;
import lombok.Getter;
import lombok.ToString;
import lombok.extern.jackson.Jacksonized;
/**
* DispatchmentFile contains all data to a single dispatchment
*
* @author klenkes {@literal <rlichti@kaiserpfalz-edv.de>}
* @since 2.0.0 2023-01-06
*/
@Schema(
description = "Paging data including calculating next/previous and first/last pages available.",
example = "{\n" +
" \"start\": 0, \n" +
" \"size\": 100, \n" +
" \"count\": 83, \n" +
" \"total\": 83,\n" +
"}",
title = "Pagination data for transfer lists"
)
@Jacksonized
@JsonInclude(JsonInclude.Include.NON_ABSENT)
@Builder(toBuilder = true)
@AllArgsConstructor
@Getter
@ToString
@EqualsAndHashCode
public class PagingImpl implements Paging {
private static final long serialVersionUID = 0L;
@Builder.Default
private final long start = 0;
@Builder.Default
private final long size = 20;
private final long count;
private final long total;
@Override
@JsonIgnore
@Schema(hidden = true)
public Paging firstPage() {
return this.toBuilder()
.start(0)
.count(this.calculatePageSize(0))
.build();
}
@Override
@JsonIgnore
@Schema(hidden = true)
public Paging previousPage() {
if (this.start - this.size <= 0) {
return this.firstPage();
}
return this.toBuilder()
.start(this.start - this.size)
.count(this.calculatePageSize(this.start - this.size))
.build();
}
@Override
@JsonIgnore
@Schema(hidden = true)
public Paging nextPage() {
return this.calculateNextPage(this.start + this.size);
}
@Override
@JsonIgnore
@Schema(hidden = true)
public Paging lastPage() {
return this.calculateNextPage(this.total / this.size * this.size);
}
private long calculatePageSize(final long start) {
if (start >= this.total) {
return 0;
}
if (start + this.size >= this.total) {
return this.total - start;
}
return this.size;
}
private Paging calculateNextPage(final long start) {
return this.toBuilder()
.start(start)
.count(this.calculatePageSize(start))
.build();
}
}