HelpCommand.java

   1 package org.argeo.api.cli;
   2
   3 import java.io.PrintWriter;
   4 import java.io.StringWriter;
   5 import java.util.List;
   6 import java.util.function.Function;
   7
   8 import org.apache.commons.cli.HelpFormatter;
   9 import org.apache.commons.cli.Option;
  10 import org.apache.commons.cli.Options;
  11
  12 /** A special command that can describe {@link DescribedCommand}. */
  13 public class HelpCommand implements DescribedCommand<String> {
  14         /**
  15          * System property forcing the root command to this value (typically the name of
  16          * a script).
  17          */
  18         public final static String ROOT_COMMAND_PROPERTY = "org.argeo.api.cli.rootCommand";
  19
  20         final static String HELP = "help";
  21         final static Option HELP_OPTION = Option.builder().longOpt(HELP).desc("print this help").build();
  22
  23         private CommandsCli commandsCli;
  24         private CommandsCli parentCommandsCli;
  25
  26         // Help formatting
  27         private static int helpWidth = 80;
  28         private static int helpLeftPad = 4;
  29         private static int helpDescPad = 20;
  30
  31         public HelpCommand(CommandsCli parentCommandsCli, CommandsCli commandsCli) {
  32                 super();
  33                 this.parentCommandsCli = parentCommandsCli;
  34                 this.commandsCli = commandsCli;
  35         }
  36
  37         @Override
  38         public String apply(List<String> args) {
  39                 StringWriter out = new StringWriter();
  40
  41                 if (args.size() == 0) {// overview
  42                         printHelp(commandsCli, out);
  43                 } else {
  44                         String cmd = args.get(0);
  45                         Function<List<String>, ?> function = commandsCli.getCommand(cmd);
  46                         if (function == null)
  47                                 return "Command " + cmd + " not found.";
  48                         Options options;
  49                         String examples;
  50                         DescribedCommand<?> command = null;
  51                         if (function instanceof DescribedCommand) {
  52                                 command = (DescribedCommand<?>) function;
  53                                 options = command.getOptions();
  54                                 examples = command.getExamples();
  55                         } else {
  56                                 options = new Options();
  57                                 examples = null;
  58                         }
  59                         String description = getShortDescription(function);
  60                         String commandCall = getCommandUsage(cmd, command);
  61                         HelpFormatter formatter = new HelpFormatter();
  62                         formatter.printHelp(new PrintWriter(out), helpWidth, commandCall, description, options, helpLeftPad,
  63                                         helpDescPad, examples, false);
  64                 }
  65                 return out.toString();
  66         }
  67
  68         private static String getShortDescription(Function<List<String>, ?> function) {
  69                 if (function instanceof DescribedCommand) {
  70                         return ((DescribedCommand<?>) function).getDescription();
  71                 } else {
  72                         return function.toString();
  73                 }
  74         }
  75
  76         public String getCommandUsage(String cmd, DescribedCommand<?> command) {
  77                 String commandCall = getCommandCall(commandsCli) + " " + cmd;
  78                 assert command != null;
  79                 if (command != null && command.getUsage() != null) {
  80                         commandCall = commandCall + " " + command.getUsage();
  81                 }
  82                 return commandCall;
  83         }
  84
  85         @Override
  86         public String getDescription() {
  87                 return "Shows this help or describes a command";
  88         }
  89
  90         @Override
  91         public String getUsage() {
  92                 return "[command]";
  93         }
  94
  95         public CommandsCli getParentCommandsCli() {
  96                 return parentCommandsCli;
  97         }
  98
  99         protected String getCommandCall(CommandsCli commandsCli) {
 100                 HelpCommand hc = commandsCli.getHelpCommand();
 101                 if (hc.getParentCommandsCli() != null) {
 102                         return getCommandCall(hc.getParentCommandsCli()) + " " + commandsCli.getCommandName();
 103                 } else {
 104                         String rootCommand = System.getProperty(ROOT_COMMAND_PROPERTY);
 105                         if (rootCommand != null)
 106                                 return rootCommand;
 107                         return commandsCli.getCommandName();
 108                 }
 109         }
 110
 111         public static void printHelp(DescribedCommand<?> command, StringWriter out) {
 112                 String usage = "java " + command.getClass().getName()
 113                                 + (command.getUsage() != null ? " " + command.getUsage() : "");
 114                 HelpFormatter formatter = new HelpFormatter();
 115                 Options options = command.getOptions();
 116                 options.addOption(HelpCommand.HELP_OPTION);
 117                 formatter.printHelp(new PrintWriter(out), helpWidth, usage, command.getDescription(), options, helpLeftPad,
 118                                 helpDescPad, command.getExamples(), false);
 119
 120         }
 121
 122         public static void printHelp(CommandsCli commandsCli, String commandName, StringWriter out) {
 123                 if (commandName == null) {
 124                         printHelp(commandsCli, out);
 125                         return;
 126                 }
 127                 DescribedCommand<?> command = (DescribedCommand<?>) commandsCli.getCommand(commandName);
 128                 String usage = commandsCli.getHelpCommand().getCommandUsage(commandName, command);
 129                 HelpFormatter formatter = new HelpFormatter();
 130                 Options options = command.getOptions();
 131                 options.addOption(HelpCommand.HELP_OPTION);
 132                 formatter.printHelp(new PrintWriter(out), helpWidth, usage, command.getDescription(), options, helpLeftPad,
 133                                 helpDescPad, command.getExamples(), false);
 134
 135         }
 136
 137         public static void printHelp(CommandsCli commandsCli, StringWriter out) {
 138                 out.append(commandsCli.getDescription()).append('\n');
 139                 String leftPad = spaces(helpLeftPad);
 140                 for (String cmd : commandsCli.getSubCommands()) {
 141                         Function<List<String>, ?> function = commandsCli.getCommand(cmd);
 142                         assert function != null;
 143                         out.append(leftPad);
 144                         out.append(cmd);
 145                         // TODO deal with long commands
 146                         out.append(spaces(helpDescPad - cmd.length()));
 147                         out.append(getShortDescription(function));
 148                         out.append('\n');
 149                 }
 150         }
 151
 152         private static String spaces(int count) {
 153                 // Java 11
 154                 // return " ".repeat(count);
 155                 if (count <= 0)
 156                         return "";
 157                 else {
 158                         StringBuilder sb = new StringBuilder(count);
 159                         for (int i = 0; i < count; i++)
 160                                 sb.append(' ');
 161                         return sb.toString();
 162                 }
 163         }
 164 }