package org.unix4j.unix.sed;

import java.util.Collections;
import java.util.EnumSet;
import java.util.Iterator;

import org.unix4j.option.Option;
import org.unix4j.unix.Sed;

/**
 * Options for the {@link Sed sed} command.
 * <p>
 * For most applications, it may be more convenient to use {@link Sed#Options} 
 * instead of the option constants defined here.
 * <p>
 * <table>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -n}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --quiet}</td><td>&nbsp;</td><td>Suppress the default output (in which each line, after it is 
                        examined for editing, is written to standard output). Only lines 
                        explicitly selected for output are written.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -g}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --global}</td><td>&nbsp;</td><td>Globally substitute for all non-overlapping instances of the regexp 
                        rather than just the first one. 
                        <p>
                        (This option is ignored if the occurrence operand is specified).</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -p}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --print}</td><td>&nbsp;</td><td>Write the matched line to standard output.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -l}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --lineNumber}</td><td>&nbsp;</td><td>Writes the current line number on a separate line to the standard 
                        output.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -I}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --ignoreCase}</td><td>&nbsp;</td><td>Use case insensitive pattern matching.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -s}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --substitute}</td><td>&nbsp;</td><td>Substitutes the replacement string for instances of the regexp in 
                        the matched line.
<p>
                        The characters "$0" appearing in the replacement are replaced
                        by the line matching the regexp.  The characters "$n", where n is a
                        digit other than zero, are replaced by the text matched by the
                        corresponding backreference expression (aka group).  The special
                        meaning of "$n" in this context can be suppressed by preceding it
                        by a backslash.
<p>
                        A line can be split by substituting a newline ('\n') into it. 
                        <p>
                        A substitution is considered to have been performed even if the 
                        replacement string is identical to the string that it replaces.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -a}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --append}</td><td>&nbsp;</td><td>Append string2 as a separate line after the matched line.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -i}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --insert}</td><td>&nbsp;</td><td>Insert string2 as a separate line before the matched line.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -c}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --change}</td><td>&nbsp;</td><td>Write string2 as a separate line instead of the matched line.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -d}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --delete}</td><td>&nbsp;</td><td>Delete the matched line.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -y}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --translate}</td><td>&nbsp;</td><td>Replace all occurrences of characters in string1 with the 
                        corresponding characters in string2. If the number of characters in 
                        the two strings are not equal, or if any of the characters in 
                        string1 appear more than once, the results are undefined.</td></tr>
 * </table>
 */
public enum SedOption implements Option, SedOptions {
        /**
         * Option <b>{@code --quiet}</b>, <b>{@code -n}</b>: 
         * Suppress the default output (in which each line, after it is 
                        examined for editing, is written to standard output). Only lines 
                        explicitly selected for output are written.
         */
        quiet('n'),
        /**
         * Option <b>{@code --global}</b>, <b>{@code -g}</b>: 
         * Globally substitute for all non-overlapping instances of the regexp 
                        rather than just the first one. 
                        <p>
                        (This option is ignored if the occurrence operand is specified).
         */
        global('g'),
        /**
         * Option <b>{@code --print}</b>, <b>{@code -p}</b>: 
         * Write the matched line to standard output.
         */
        print('p'),
        /**
         * Option <b>{@code --lineNumber}</b>, <b>{@code -l}</b>: 
         * Writes the current line number on a separate line to the standard 
                        output.
         */
        lineNumber('l'),
        /**
         * Option <b>{@code --ignoreCase}</b>, <b>{@code -I}</b>: 
         * Use case insensitive pattern matching.
         */
        ignoreCase('I'),
        /**
         * Option <b>{@code --substitute}</b>, <b>{@code -s}</b>: 
         * Substitutes the replacement string for instances of the regexp in 
                        the matched line.
<p>
                        The characters "$0" appearing in the replacement are replaced
                        by the line matching the regexp.  The characters "$n", where n is a
                        digit other than zero, are replaced by the text matched by the
                        corresponding backreference expression (aka group).  The special
                        meaning of "$n" in this context can be suppressed by preceding it
                        by a backslash.
<p>
                        A line can be split by substituting a newline ('\n') into it. 
                        <p>
                        A substitution is considered to have been performed even if the 
                        replacement string is identical to the string that it replaces.
         */
        substitute('s'),
        /**
         * Option <b>{@code --append}</b>, <b>{@code -a}</b>: 
         * Append string2 as a separate line after the matched line.
         */
        append('a'),
        /**
         * Option <b>{@code --insert}</b>, <b>{@code -i}</b>: 
         * Insert string2 as a separate line before the matched line.
         */
        insert('i'),
        /**
         * Option <b>{@code --change}</b>, <b>{@code -c}</b>: 
         * Write string2 as a separate line instead of the matched line.
         */
        change('c'),
        /**
         * Option <b>{@code --delete}</b>, <b>{@code -d}</b>: 
         * Delete the matched line.
         */
        delete('d'),
        /**
         * Option <b>{@code --translate}</b>, <b>{@code -y}</b>: 
         * Replace all occurrences of characters in string1 with the 
                        corresponding characters in string2. If the number of characters in 
                        the two strings are not equal, or if any of the characters in 
                        string1 appear more than once, the results are undefined.
         */
        translate('y');
        
        private final char acronym;
        private SedOption(char acronym) {
                this.acronym = acronym;
        }
        @Override
        public Class<SedOption> optionType() {
                return SedOption.class;
        }
        /**
         * Returns the option with the given {@code acronym}, or {@code null} if no
         * such option is found.
         * 
         * @param acronym the option {@link #acronym() acronym}
         * @return      the option with the given {@code acronym} or {@code null} if it
         *                      is not found
         */
        public static SedOption findByAcronym(char acronym) {
                for (final SedOption opt : values()) {
                        if (opt.acronym() == acronym) return opt;
                }
                return null;
        }
        @Override
        public char acronym() {
                return acronym;
        }
        @Override
        public boolean isSet(SedOption option) {
                return equals(option);
        }
        /**
         * Returns a new set with {@code this} active option.
         * 
         * @return a new set containing this option
         */
        @Override
        public EnumSet<SedOption> asSet() {
                return EnumSet.of(this);
        }
        
        /**
         * Returns an immutable iterator returning o single element: {@code this} 
         * option.
         * 
         * @return an immutable iterator with {@code this} active option.
         */
        @Override
        public Iterator<SedOption> iterator() {
                return Collections.singleton(this).iterator();
        }
        
        /**
         * Returns 1 as this is a set with a single element: {@code this} option
         * 
         * @return one
         */
        @Override
        public int size() {
                return 1;
        }

        /**
         * Returns true if the {@link Option#acronym() acronym} should be used for
         * the specified {@code option} in string representations. 
         * <p>
         * This method returns always true for all options.
         *  
         * @param option
         *            the option of interest
         * @return always true indicating that option acronyms should be used in
         *                      string representations for all options
         */
        @Override
        public boolean useAcronymFor(SedOption option) {
                return true;
        }
}