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A Java library for the Twitter API
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/*
Copyright (c) 2007-2009, Yusuke Yamamoto
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the Yusuke Yamamoto nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY Yusuke Yamamoto ``AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL Yusuke Yamamoto BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package twitter4j;

import twitter4j.http.HttpParameter;

import java.util.*;
import java.util.List;

/**
 * Controls pagination.

 * It is possible to use the same Paging instance in a multi-threaded
 * context only if the instance is treated immutably.

 * But basically instance of this class is NOT thread safe.
 * A client should instantiate Paging class per thread.

 *
 * @author Yusuke Yamamoto - yusuke at mac.com
 */
public class Paging implements java.io.Serializable {
    private int page = -1;
    private int count = -1;
    private long sinceId = -1;
    private long maxId = -1;
    private static final long serialVersionUID = -3285857427993796670L;

    // since only
    static char[] S = new char[]{'s'};
    // since, max_id, count, page
    static char[] SMCP = new char[]{'s', 'm', 'c', 'p'};

    static final String COUNT = "count";
    // somewhat GET list statuses requires "per_page" instead of "count"
    // @see http://apiwiki.twitter.com/Twitter-REST-API-Method%3A-GET-list-statuses
    static final String PER_PAGE = "per_page";

    /*package*/ List asPostParameterList() {
        return asPostParameterList(SMCP, COUNT);
    }

    private static HttpParameter[] NULL_PARAMETER_ARRAY = new HttpParameter[0];
    /*package*/ HttpParameter[] asPostParameterArray() {
        List list = asPostParameterList(SMCP, COUNT);
        if(list.size() == 0){
            return NULL_PARAMETER_ARRAY;
        }
        return list.toArray(new HttpParameter[list.size()]);
    }

    /*package*/ List asPostParameterList(char[] supportedParams) {
        return asPostParameterList(supportedParams, COUNT);
    }


    private static List NULL_PARAMETER_LIST = new ArrayList(0);
    /**
     * Converts the pagination parameters into a List of PostParameter.

     * This method also Validates the preset parameters, and throws
     *  IllegalStateException if any unsupported parameter is set.
     * @param supportedParams char array representation of supported parameters
     * @param perPageParamName name used for per-page parameter. getUserListStatuses() requires "per_page" instead of "count".
     * @return list of PostParameter
     */
    /*package*/ List asPostParameterList(char[] supportedParams, String perPageParamName) {
        java.util.List pagingParams = new ArrayList(supportedParams.length);
        addPostParameter(supportedParams, 's', pagingParams, "since_id", getSinceId());
        addPostParameter(supportedParams, 'm', pagingParams, "max_id", getMaxId());
        addPostParameter(supportedParams, 'c', pagingParams, perPageParamName, getCount());
        addPostParameter(supportedParams, 'p', pagingParams, "page", getPage());
        if (pagingParams.size() == 0) {
            return NULL_PARAMETER_LIST;
        } else {
            return pagingParams;
        }
    }

    /**
     * Converts the pagination parameters into a List of PostParameter.

     * This method also Validates the preset parameters, and throws
     *  IllegalStateException if any unsupported parameter is set.
     * @param supportedParams char array representation of supported parameters
     * @param perPageParamName name used for per-page parameter. getUserListStatuses() requires "per_page" instead of "count".
     * @return list of PostParameter
     */
    /*package*/ HttpParameter[] asPostParameterArray(char[] supportedParams, String perPageParamName) {
        java.util.List pagingParams = new ArrayList(supportedParams.length);
        addPostParameter(supportedParams, 's', pagingParams, "since_id", getSinceId());
        addPostParameter(supportedParams, 'm', pagingParams, "max_id", getMaxId());
        addPostParameter(supportedParams, 'c', pagingParams, perPageParamName, getCount());
        addPostParameter(supportedParams, 'p', pagingParams, "page", getPage());
        if (pagingParams.size() == 0) {
            return NULL_PARAMETER_ARRAY;
        } else {
            return pagingParams.toArray(new HttpParameter[pagingParams.size()]);
        }
    }

    private void addPostParameter(char[] supportedParams, char paramKey
            , List pagingParams, String paramName, long paramValue) {
        boolean supported = false;
        for (char supportedParam : supportedParams) {
            if (supportedParam == paramKey) {
                supported = true;
                break;
            }
        }
        if (!supported && -1 != paramValue) {
            throw new IllegalStateException("Paging parameter [" + paramName
                    + "] is not supported with this operation.");
        }
        if (-1 != paramValue) {
            pagingParams.add(new HttpParameter(paramName, String.valueOf(paramValue)));
        }
    }

    public Paging() {
    }

    public Paging(int page) {
        setPage(page);
    }

    public Paging(long sinceId) {
        setSinceId(sinceId);
    }

    public Paging(int page, int count) {
        this(page);
        setCount(count);
    }

    public Paging(int page, long sinceId) {
        this(page);
        setSinceId(sinceId);
    }

    public Paging(int page, int count, long sinceId) {
        this(page, count);
        setSinceId(sinceId);
    }

    public Paging(int page, int count, long sinceId, long maxId) {
        this(page, count, sinceId);
        setMaxId(maxId);
    }

    public int getPage() {
        return page;
    }

    public void setPage(int page) {
        if (page < 1) {
            throw new IllegalArgumentException("page should be positive integer. passed:" + page);
        }
        this.page = page;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        if (count < 1) {
            throw new IllegalArgumentException("count should be positive integer. passed:" + count);
        }
        this.count = count;
    }

    public Paging count(int count) {
        setCount(count);
        return this;
    }

    public long getSinceId() {
        return sinceId;
    }

    public void setSinceId(long sinceId) {
        if (sinceId < 1) {
            throw new IllegalArgumentException("since_id should be positive integer. passed:" + sinceId);
        }
        this.sinceId = sinceId;
    }

    public Paging sinceId(long sinceId) {
        setSinceId(sinceId);
        return this;
    }

    public long getMaxId() {
        return maxId;
    }

    public void setMaxId(long maxId) {
        if (maxId < 1) {
            throw new IllegalArgumentException("max_id should be positive integer. passed:" + maxId);
        }
        this.maxId = maxId;
    }

    public Paging maxId(long maxId) {
        setMaxId(maxId);
        return this;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof Paging)) return false;

        Paging paging = (Paging) o;

        if (count != paging.count) return false;
        if (maxId != paging.maxId) return false;
        if (page != paging.page) return false;
        if (sinceId != paging.sinceId) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = page;
        result = 31 * result + count;
        result = 31 * result + (int) (sinceId ^ (sinceId >>> 32));
        result = 31 * result + (int) (maxId ^ (maxId >>> 32));
        return result;
    }

    @Override
    public String toString() {
        return "Paging{" +
                "page=" + page +
                ", count=" + count +
                ", sinceId=" + sinceId +
                ", maxId=" + maxId +
                '}';
    }
}