/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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 android.database;

import java.util.ArrayList;

A mutable cursor implementation backed by an array of Objects. Use newRow() to add rows. Automatically expands internal capacity as needed. /**
 * A mutable cursor implementation backed by an array of {@code Object}s. Use
 * {@link #newRow()} to add rows. Automatically expands internal capacity
 * as needed.
 */
public class MatrixCursor extends AbstractCursor {

    private final String[] columnNames;
    private Object[] data;
    private int rowCount = 0;
    private final int columnCount;

    
Constructs a new cursor with the given initial capacity.
Params:
columnNames – names of the columns, the ordering of which
 determines column ordering elsewhere in this cursor
initialCapacity – in rows/**
     * Constructs a new cursor with the given initial capacity.
     *
     * @param columnNames names of the columns, the ordering of which
     *  determines column ordering elsewhere in this cursor
     * @param initialCapacity in rows
     */
    public MatrixCursor(String[] columnNames, int initialCapacity) {
        this.columnNames = columnNames;
        this.columnCount = columnNames.length;

        if (initialCapacity < 1) {
            initialCapacity = 1;
        }

        this.data = new Object[columnCount * initialCapacity];
    }

    
Constructs a new cursor.
Params:
columnNames – names of the columns, the ordering of which
 determines column ordering elsewhere in this cursor/**
     * Constructs a new cursor.
     *
     * @param columnNames names of the columns, the ordering of which
     *  determines column ordering elsewhere in this cursor
     */
    public MatrixCursor(String[] columnNames) {
        this(columnNames, 16);
    }

    
Gets value at the given column for the current row.
/**
     * Gets value at the given column for the current row.
     */
    private Object get(int column) {
        if (column < 0 || column >= columnCount) {
            throw new CursorIndexOutOfBoundsException("Requested column: "
                    + column + ", # of columns: " +  columnCount);
        }
        if (mPos < 0) {
            throw new CursorIndexOutOfBoundsException("Before first row.");
        }
        if (mPos >= rowCount) {
            throw new CursorIndexOutOfBoundsException("After last row.");
        }
        return data[mPos * columnCount + column];
    }

    
Adds a new row to the end and returns a builder for that row. Not safe
for concurrent use.
Returns:
builder which can be used to set the column values for the new
 row/**
     * Adds a new row to the end and returns a builder for that row. Not safe
     * for concurrent use.
     *
     * @return builder which can be used to set the column values for the new
     *  row
     */
    public RowBuilder newRow() {
        final int row = rowCount++;
        final int endIndex = rowCount * columnCount;
        ensureCapacity(endIndex);
        return new RowBuilder(row);
    }

    
Adds a new row to the end with the given column values. Not safe
for concurrent use.
Params:
columnValues – in the same order as the the column names specified
 at cursor construction time
Throws:
IllegalArgumentException – if columnValues.length !=
 columnNames.length/**
     * Adds a new row to the end with the given column values. Not safe
     * for concurrent use.
     *
     * @throws IllegalArgumentException if {@code columnValues.length !=
     *  columnNames.length}
     * @param columnValues in the same order as the the column names specified
     *  at cursor construction time
     */
    public void addRow(Object[] columnValues) {
        if (columnValues.length != columnCount) {
            throw new IllegalArgumentException("columnNames.length = "
                    + columnCount + ", columnValues.length = "
                    + columnValues.length);
        }

        int start = rowCount++ * columnCount;
        ensureCapacity(start + columnCount);
        System.arraycopy(columnValues, 0, data, start, columnCount);
    }

    
Adds a new row to the end with the given column values. Not safe
for concurrent use.
Params:
columnValues – in the same order as the the column names specified
 at cursor construction time
Throws:
IllegalArgumentException – if columnValues.size() !=
 columnNames.length/**
     * Adds a new row to the end with the given column values. Not safe
     * for concurrent use.
     *
     * @throws IllegalArgumentException if {@code columnValues.size() !=
     *  columnNames.length}
     * @param columnValues in the same order as the the column names specified
     *  at cursor construction time
     */
    public void addRow(Iterable<?> columnValues) {
        int start = rowCount * columnCount;
        int end = start + columnCount;
        ensureCapacity(end);

        if (columnValues instanceof ArrayList<?>) {
            addRow((ArrayList<?>) columnValues, start);
            return;
        }

        int current = start;
        Object[] localData = data;
        for (Object columnValue : columnValues) {
            if (current == end) {
                // TODO: null out row?
                throw new IllegalArgumentException(
                        "columnValues.size() > columnNames.length");
            }
            localData[current++] = columnValue;
        }

        if (current != end) {
            // TODO: null out row?
            throw new IllegalArgumentException(
                    "columnValues.size() < columnNames.length");
        }

        // Increase row count here in case we encounter an exception.
        rowCount++;
    }

    
Optimization for ArrayList. /** Optimization for {@link ArrayList}. */
    private void addRow(ArrayList<?> columnValues, int start) {
        int size = columnValues.size();
        if (size != columnCount) {
            throw new IllegalArgumentException("columnNames.length = "
                    + columnCount + ", columnValues.size() = " + size);
        }

        rowCount++;
        Object[] localData = data;
        for (int i = 0; i < size; i++) {
            localData[start + i] = columnValues.get(i);
        }
    }

    
Ensures that this cursor has enough capacity. /** Ensures that this cursor has enough capacity. */
    private void ensureCapacity(int size) {
        if (size > data.length) {
            Object[] oldData = this.data;
            int newSize = data.length * 2;
            if (newSize < size) {
                newSize = size;
            }
            this.data = new Object[newSize];
            System.arraycopy(oldData, 0, this.data, 0, oldData.length);
        }
    }

    
Builds a row of values using either of these approaches:

Values can be added with explicit column ordering using add(Object), which starts from the left-most column and adds one column value at a time. This follows the same ordering as the column names specified at cursor construction time. 
Column and value pairs can be offered for possible inclusion using add(String, Object). If the cursor includes the given column, the value will be set for that column, otherwise the value is ignored. This approach is useful when matching data to a custom projection. 
 Undefined values are left as null. /**
     * Builds a row of values using either of these approaches:
     * <ul>
     * <li>Values can be added with explicit column ordering using
     * {@link #add(Object)}, which starts from the left-most column and adds one
     * column value at a time. This follows the same ordering as the column
     * names specified at cursor construction time.
     * <li>Column and value pairs can be offered for possible inclusion using
     * {@link #add(String, Object)}. If the cursor includes the given column,
     * the value will be set for that column, otherwise the value is ignored.
     * This approach is useful when matching data to a custom projection.
     * </ul>
     * Undefined values are left as {@code null}.
     */
    public class RowBuilder {
        private final int row;
        private final int endIndex;

        private int index;

        RowBuilder(int row) {
            this.row = row;
            this.index = row * columnCount;
            this.endIndex = index + columnCount;
        }

        
Sets the next column value in this row.
Throws:
CursorIndexOutOfBoundsException – if you try to add too many
 values
Returns:
this builder to support chaining/**
         * Sets the next column value in this row.
         *
         * @throws CursorIndexOutOfBoundsException if you try to add too many
         *  values
         * @return this builder to support chaining
         */
        public RowBuilder add(Object columnValue) {
            if (index == endIndex) {
                throw new CursorIndexOutOfBoundsException(
                        "No more columns left.");
            }

            data[index++] = columnValue;
            return this;
        }

        
Offer value for possible inclusion if this cursor defines the given
column. Columns not defined by the cursor are silently ignored.
Returns:
this builder to support chaining/**
         * Offer value for possible inclusion if this cursor defines the given
         * column. Columns not defined by the cursor are silently ignored.
         *
         * @return this builder to support chaining
         */
        public RowBuilder add(String columnName, Object value) {
            for (int i = 0; i < columnNames.length; i++) {
                if (columnName.equals(columnNames[i])) {
                    data[(row * columnCount) + i] = value;
                }
            }
            return this;
        }
    }

    // AbstractCursor implementation.

    @Override
    public int getCount() {
        return rowCount;
    }

    @Override
    public String[] getColumnNames() {
        return columnNames;
    }

    @Override
    public String getString(int column) {
        Object value = get(column);
        if (value == null) return null;
        return value.toString();
    }

    @Override
    public short getShort(int column) {
        Object value = get(column);
        if (value == null) return 0;
        if (value instanceof Number) return ((Number) value).shortValue();
        return Short.parseShort(value.toString());
    }

    @Override
    public int getInt(int column) {
        Object value = get(column);
        if (value == null) return 0;
        if (value instanceof Number) return ((Number) value).intValue();
        return Integer.parseInt(value.toString());
    }

    @Override
    public long getLong(int column) {
        Object value = get(column);
        if (value == null) return 0;
        if (value instanceof Number) return ((Number) value).longValue();
        return Long.parseLong(value.toString());
    }

    @Override
    public float getFloat(int column) {
        Object value = get(column);
        if (value == null) return 0.0f;
        if (value instanceof Number) return ((Number) value).floatValue();
        return Float.parseFloat(value.toString());
    }

    @Override
    public double getDouble(int column) {
        Object value = get(column);
        if (value == null) return 0.0d;
        if (value instanceof Number) return ((Number) value).doubleValue();
        return Double.parseDouble(value.toString());
    }

    @Override
    public byte[] getBlob(int column) {
        Object value = get(column);
        return (byte[]) value;
    }

    @Override
    public int getType(int column) {
        return DatabaseUtils.getTypeOfObject(get(column));
    }

    @Override
    public boolean isNull(int column) {
        return get(column) == null;
    }
}