// 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.
// Copyright 2007, 2008 The Apache Software Foundation
//
// 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 org.apache.tapestry5.corelib.components;

import org.apache.tapestry5.ComponentAction;
import org.apache.tapestry5.MarkupWriter;
import org.apache.tapestry5.PropertyOverrides;
import org.apache.tapestry5.ValueEncoder;
import org.apache.tapestry5.annotations.Environmental;
import org.apache.tapestry5.annotations.Parameter;
import org.apache.tapestry5.annotations.Property;
import org.apache.tapestry5.beanmodel.PropertyModel;
import org.apache.tapestry5.grid.GridDataSource;
import org.apache.tapestry5.grid.GridModel;
import org.apache.tapestry5.services.FormSupport;

import java.util.List;

/**
 * Renders out a series of rows within the table.
 *
 * Inside a {@link Form}, a series of row index numbers are stored into the form
 * ( {@linkplain FormSupport#store(Object, ComponentAction) as
 * ComponentActions}). This can be a problem in situations where the data set
 * can shift between the form render and the form submission, with a risk of
 * applying changes to the wrong objects.
 *
 * For this reason, when using GridRows inside a Form, you should generally
 * provide a {@link org.apache.tapestry5.ValueEncoder} (via the encoder
 * parameter), or use an entity type for the "row" parameter for which
 * Tapestry can provide a ValueEncoder automatically. This will allow Tapestry
 * to use a unique ID for each row that doesn't change when rows are reordered.
 *
 * @tapestrydoc
 */
@SuppressWarnings({"unchecked"})
public class GridRows
{
    private int startRow;

    private boolean recordStateByIndex;

    private boolean recordStateByEncoder;

    /**
     * This action is used when a {@link org.apache.tapestry5.ValueEncoder} is not provided.
     */
    static class SetupForRowByIndex implements ComponentAction<GridRows>
    {
        private static final long serialVersionUID = -3216282071752371975L;

        private final int rowIndex;

        public SetupForRowByIndex(int rowIndex)
        {
            this.rowIndex = rowIndex;
        }

        public void execute(GridRows component)
        {
            component.setupForRow(rowIndex);
        }

        @Override
        public String toString()
        {
            return String.format("GridRows.SetupForRowByIndex[%d]", rowIndex);
        }
    }

    /**
     * This action is used when a {@link org.apache.tapestry5.ValueEncoder} is provided.
     */
    static class SetupForRowWithClientValue implements ComponentAction<GridRows>
    {
        private final String clientValue;

        SetupForRowWithClientValue(String clientValue)
        {
            this.clientValue = clientValue;
        }

        public void execute(GridRows component)
        {
            component.setupForRowWithClientValue(clientValue);
        }

        @Override
        public String toString()
        {
            return String.format("GridRows.SetupForRowWithClientValue[%s]", clientValue);
        }
    }

    /**
     * Parameter used to set the CSS class for each row (each &lt;tr&gt; element) within the &lt;tbody&gt;). This is not
     * cached, so it will be recomputed for each row.
     */
    @Parameter(cache = false)
    private String rowClass;

    /**
     * Object that provides access to the bean and data models used to render the Grid.
     */
    @Parameter(value = "componentResources.container")
    private GridModel gridModel;

    /**
     * Where to search for property override blocks.
     */
    @Parameter(required = true, allowNull = false)
    @Property
    private PropertyOverrides overrides;

    /**
     * Number of rows displayed on each page. Long result sets are split across multiple pages.
     */
    @Parameter(required = true)
    private int rowsPerPage;

    /**
     * The current page number within the available pages (indexed from 1).
     */
    @Parameter(required = true)
    private int currentPage;

    /**
     * The current row being rendered, this is primarily an output parameter used to allow the Grid, and the Grid's
     * container, to know what object is being rendered.
     */
    @Parameter(required = true)
    @Property(write = false)
    private Object row;

    /**
     * If true, then the CSS class on each &lt;TD&gt; cell will be omitted, which can reduce the amount of output from
     * the component overall by a considerable amount. Leave this as false, the default, when you are leveraging the CSS
     * to customize the look and feel of particular columns.
     */
    @Parameter
    private boolean lean;

    /**
     * If true and the component is enclosed by a Form, then the normal state saving logic is turned off. Defaults to
     * false, enabling state saving logic within Forms. This can be set to false when form elements within the Grid are
     * not related to the current row of the grid, or where another component (such as {@link
     * org.apache.tapestry5.corelib.components.Hidden}) is used to maintain row state.
     */
    @Parameter(name = "volatile")
    private boolean volatileState;

    /**
     * A ValueEncoder used to convert server-side objects (provided by the
     * "row" parameter) into unique client-side strings (typically IDs) and
     * back. In general, when using Grid and Form together, you should either
     * provide the encoder parameter or use a "row" type for which Tapestry is
     * configured to provide a ValueEncoder automatically. Otherwise Tapestry
     * must fall back to using the plain index of each row, rather
     * than the ValueEncoder-provided unique ID, for recording state into the
     * form.
     */
    @Parameter
    private ValueEncoder encoder;


    /**
     * Optional output parameter (only set during rendering) that identifies the current row index. This is the index on
     * the page (i.e., always numbered from zero) as opposed to the row index inside the {@link
     * org.apache.tapestry5.grid.GridDataSource}.
     */
    @Parameter
    private int rowIndex;

    /**
     * Optional output parameter that stores the current column index.
     */
    @Parameter
    @Property
    private int columnIndex;

    @Environmental(false)
    private FormSupport formSupport;


    private int endRow;

    /**
     * Index into the {@link org.apache.tapestry5.grid.GridDataSource}.
     */
    private int dataRowIndex;

    private String propertyName;

    @Property(write = false)
    private PropertyModel columnModel;

    void onBeginRenderFromRow(MarkupWriter writer)
    {

        if (dataRowIndex == startRow)
        {
            writer.attributes("data-grid-row", "first");
        }

        if (dataRowIndex == endRow)
        {
            writer.attributes("data-grid-row", "last");
        }

        // Not a cached parameter, so careful to only access it once.

        String rc = rowClass;

        if (rc != null)
        {
            writer.attributes("class", rc);
        }
    }

    void onBeginRenderFromColumn(MarkupWriter writer)
    {

        String id = gridModel.getDataModel().get(propertyName).getId();

        if (!lean)
        {
            writer.attributes("data-grid-property", id);
        }

        switch (gridModel.getSortModel().getColumnSort(id))
        {
            case ASCENDING:
                writer.attributes("data-grid-column-sort", "ascending");
                break;

            case DESCENDING:
                writer.attributes("data-grid-column-sort", "descending");
                break;

            default:
        }
    }

    void setupRender()
    {
        GridDataSource dataSource = gridModel.getDataSource();

        int numberOfRowsRequiredToShowCurrentPage = 1 + (currentPage - 1) * rowsPerPage;
        int numberOfRowsRequiredToFillCurrentPage = currentPage * rowsPerPage;

        int availableRowsWithLimit = dataSource.getAvailableRows(numberOfRowsRequiredToFillCurrentPage);

        // This can sometimes happen when the number of items shifts between requests.

        if (numberOfRowsRequiredToShowCurrentPage > availableRowsWithLimit)
        {
            int maxPages = ((availableRowsWithLimit - 1) / rowsPerPage) + 1;
            currentPage = maxPages;
        }
        startRow = (currentPage - 1) * rowsPerPage;
        endRow = Math.min(availableRowsWithLimit - 1, startRow + rowsPerPage - 1);

        dataRowIndex = startRow;

        boolean recordingStateInsideForm = !volatileState && formSupport != null;

        recordStateByIndex = recordingStateInsideForm && (encoder == null);
        recordStateByEncoder = recordingStateInsideForm && (encoder != null);
    }

    /**
     * Callback method, used when recording state to a form, or called directly when not recording state.
     */
    void setupForRow(int rowIndex)
    {
        row = gridModel.getDataSource().getRowValue(rowIndex);
    }

    /**
     * Callback method that bypasses the data source and converts a primary key back into a row value (via {@link
     * org.apache.tapestry5.ValueEncoder#toValue(String)}).
     */
    void setupForRowWithClientValue(String clientValue)
    {
        row = encoder.toValue(clientValue);

        if (row == null)
            throw new IllegalArgumentException(
                    String.format("%s returned null for client value '%s'.", encoder, clientValue));
    }


    boolean beginRender()
    {
        // Setup for this row.

        setupForRow(dataRowIndex);

        // Update the index parameter (which starts from zero).
        rowIndex = dataRowIndex - startRow;


        if (row != null)
        {
            // When needed, store a callback used when the form is submitted.

            if (recordStateByIndex)
                formSupport.store(this, new SetupForRowByIndex(dataRowIndex));

            if (recordStateByEncoder)
            {
                String key = encoder.toClient(row);
                formSupport.store(this, new SetupForRowWithClientValue(key));
            }
        }

        // If the row is null, it's because the rowIndex is too large (see the notes
        // on GridDataSource).  When row is null, return false to not render anything for this iteration
        // of the loop.

        return row != null;
    }

    boolean afterRender()
    {
        dataRowIndex++;

        // Abort the loop when we hit a null row, or when we've exhausted the range we need to
        // display.

        return row == null || dataRowIndex > endRow;
    }

    public List<String> getPropertyNames()
    {
        return gridModel.getDataModel().getPropertyNames();
    }

    public String getPropertyName()
    {
        return propertyName;
    }

    public void setPropertyName(String propertyName)
    {
        this.propertyName = propertyName;

        columnModel = gridModel.getDataModel().get(propertyName);
    }
}