package org.unix4j.unix.ls;

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

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

/**
 * Options for the {@link Ls ls} command.
 * <p>
 * For most applications, it may be more convenient to use {@link Ls#Options} 
 * instead of the option constants defined here.
 * <p>
 * <table>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -a}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --allFiles}</td><td>&nbsp;</td><td>Lists all files in the given directory, including hidden files
                        (those whose names start with \".\" in Unix). By default, these 
                        files are excluded from the list.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -h}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --humanReadable}</td><td>&nbsp;</td><td>Print sizes in human readable format. (e.g., 1K, 234M, 2G, etc.)</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -l}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --longFormat}</td><td>&nbsp;</td><td>Long format, displaying file types, permissions, number of hard 
                        links, owner, group, size, date, and filename.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -R}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --recurseSubdirs}</td><td>&nbsp;</td><td>Recursively lists subdirectories encountered.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -r}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --reverseOrder}</td><td>&nbsp;</td><td>Reverses the order of the sort to get reverse collating sequence or 
                        oldest first.</td></tr>
 * <tr valign="top"><td width="10px"></td><td nowrap="nowrap">{@code -t}</td><td>&nbsp;&nbsp;</td><td nowrap="nowrap">{@code --timeSorted}</td><td>&nbsp;</td><td>Sorts with the primary key being time modified (most recently 
                        modified first) and the secondary key being filename in the 
                        collating sequence.</td></tr>
 * </table>
 */
public enum LsOption implements Option, LsOptions {
        /**
         * Option <b>{@code --allFiles}</b>, <b>{@code -a}</b>: 
         * Lists all files in the given directory, including hidden files
                        (those whose names start with \".\" in Unix). By default, these 
                        files are excluded from the list.
         */
        allFiles('a'),
        /**
         * Option <b>{@code --humanReadable}</b>, <b>{@code -h}</b>: 
         * Print sizes in human readable format. (e.g., 1K, 234M, 2G, etc.)
         */
        humanReadable('h'),
        /**
         * Option <b>{@code --longFormat}</b>, <b>{@code -l}</b>: 
         * Long format, displaying file types, permissions, number of hard 
                        links, owner, group, size, date, and filename.
         */
        longFormat('l'),
        /**
         * Option <b>{@code --recurseSubdirs}</b>, <b>{@code -R}</b>: 
         * Recursively lists subdirectories encountered.
         */
        recurseSubdirs('R'),
        /**
         * Option <b>{@code --reverseOrder}</b>, <b>{@code -r}</b>: 
         * Reverses the order of the sort to get reverse collating sequence or 
                        oldest first.
         */
        reverseOrder('r'),
        /**
         * Option <b>{@code --timeSorted}</b>, <b>{@code -t}</b>: 
         * Sorts with the primary key being time modified (most recently 
                        modified first) and the secondary key being filename in the 
                        collating sequence.
         */
        timeSorted('t');
        
        private final char acronym;
        private LsOption(char acronym) {
                this.acronym = acronym;
        }
        @Override
        public Class<LsOption> optionType() {
                return LsOption.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 LsOption findByAcronym(char acronym) {
                for (final LsOption opt : values()) {
                        if (opt.acronym() == acronym) return opt;
                }
                return null;
        }
        @Override
        public char acronym() {
                return acronym;
        }
        @Override
        public boolean isSet(LsOption option) {
                return equals(option);
        }
        /**
         * Returns a new set with {@code this} active option.
         * 
         * @return a new set containing this option
         */
        @Override
        public EnumSet<LsOption> 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<LsOption> 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(LsOption option) {
                return true;
        }
}