TablePrinter.java

/**
 *  Copyright 2005-2016 Red Hat, Inc.
 *
 *  Red Hat licenses this file to you 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 io.fabric8.utils;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

/**
 * A helper class to pretty print a table of values to the console
 */
public class TablePrinter {
    private List<Column> columns = new ArrayList<>();
    private Map<String, Column> columnMap = new HashMap<>();
    private String columnSeparator = "  ";
    private List<String[]> rows = new ArrayList<>();

    /**
     * Defines the columns of the table
     */
    public void columns(String... headers) {
        for (String header : headers) {
            // force lazy creation
            column(header);
        }
    }

    /**
     * Looks up the column using the header name and returns the column object so it
     * can be configured
     */
    public Column column(String header) {
        synchronized (columns) {
            Column answer = columnMap.get(header);
            if (answer == null) {
                answer = new Column(header);
                columns.add(answer);
                columnMap.put(header, answer);
            }
            return answer;
        }
    }

    /**
     * Looks up the column using its index; lazily creating one if required
     */
    public Column column(int index) {
        if (index < 0) {
            throw new IllegalArgumentException("index must be >= 0");
        }
        synchronized (columns) {
            Column answer = null;
            if (index < columns.size()) {
                answer = columns.get(index);
            }
            if (answer == null) {
                answer = new Column("");
                columns.add(answer);
            }
            return answer;
        }
    }

    /**
     * Adds a new row of values
     */
    public void row(String... values) {
        int columnIndex = 0;
        for (String value : values) {
            Column column = column(columnIndex++);
            if (value != null) {
                int length = value.length();
                column.ensureWidth(length);
            }
        }
        rows.add(values);
    }

    public void print() {
        print(System.out);
    }


    /**
     * Prints the table as a text string
     */
    public String asText() {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        print(new PrintStream(out));
        return new String(out.toByteArray());
    }

    /**
     * Returns a list of text lines for easier printing on other output formats
     */
    public List<String> asTextLines() {
        String text = asText();
        List<String> list = new ArrayList<>();
        StringTokenizer iter = new StringTokenizer(text, "\n");
        while (iter.hasMoreTokens()) {
            list.add(iter.nextToken());
        }
        return list;
    }

    public void print(final PrintStream out) {
        print(new TableWriter() {
            @Override
            public String toString() {
                return "PrintStreamTableWriter()";
            }

            @Override
            public void print(String text) {
                out.print(text);
            }

            @Override
            public void println() {
                out.println();
            }
        });
    }

    public void print(TableWriter out) {
        boolean first = true;
        for (Column column : columns) {
            if (first) {
                first = false;
            } else {
                out.print(columnSeparator);
            }
            column.printHeader(out);
        }
        out.println();
        for (String[] row : rows) {
            first = true;

            int i = 0;
            for (Column column : columns) {
                if (first) {
                    first = false;
                } else {
                    out.print(columnSeparator);
                }
                String value = null;
                if (i < row.length) {
                    value = row[i];
                }
                if (value == null) {
                    value = "";
                }
                i++;
                column.printValue(out, value);
            }
            out.println();
        }
    }


    public interface TableWriter {
        void print(String text);

        void println();
    }

    public static class Column {
        private final String headerText;
        private String header;
        private String headerFlags = "-";
        private String rowFlags = "-";
        private int width = 1;

        public Column(String header) {
            this.header = header;
            this.headerText = "[" + header + "]";
            ensureWidth(headerText.length());
        }

        public String getHeader() {
            return header;
        }

        public String getHeaderFlags() {
            return headerFlags;
        }

        public void setHeaderFlags(String headerFlags) {
            this.headerFlags = headerFlags;
        }

        public String getRowFlags() {
            return rowFlags;
        }

        public void setRowFlags(String rowFlags) {
            this.rowFlags = rowFlags;
        }

        public int getWidth() {
            return width;
        }

        public void setWidth(int width) {
            this.width = width;
        }

        /**
         * Ensures the column is wide enough for the given value
         */
        public void ensureWidth(int length) {
            if (length > width) {
                width = length;
            }

        }

        /**
         * Prints the header value
         */
        public void printHeader(TableWriter out) {
            String formatText = "%" + headerFlags + width + "s";
            String text = String.format(formatText, headerText);
            out.print(text);
        }

        /**
         * Prints a value
         */
        public void printValue(TableWriter out, String value) {
            String formatText = "%" + rowFlags + width + "s";
            String text = String.format(formatText, value);
            out.print(text);
        }
    }
}