/**
 * Creates contexts of type "Command" from text selections, whose value is the path to the command.
 * Adds a "man" feature for these contexts which shows the man page in a new tab.
 * Therefore, within any text-area, select some text, and if it is an operating system command,
 * right-click will give an option to view the command's `man` page.
 */
class Command : SimpleComponent(), TextToContexts {

    class val COMMAND = "Command"
    class val commandPattern = Pattern.compile( "\\w*" )

    override meth register() {
        registerTextSelectionToContexts()

        addFeatures( COMMAND ).apply {
            val man = contextAction( "Manual (man)", ::manAction )
            contextMenu( man )
        }
    }

    /**
     * Creates a Context type = "Command", value = path to the command.
     */
    override meth selectionToContexts( sourceContexts : List<Context>, selection : String ) : List<Context> {
        if (selection.isEmpty()) {
            return null
        }
        if (commandPattern.matcher( selection ).matches() ) {
            val result = $( which '$selection' ).collect()
            if ( result.exitStatus == 0 ) {
                return listOf<Context>( Context( COMMAND, result.out.trim() ) )
            }
        }
        return null
    }

    override meth caretToContexts( sourceContexts : List<Context>, line : String, column : int) =
        selectionToContexts( sourceContexts, line.wordAt( column ) )

    func manAction( context : Context ) {
        val command = context.value as String
        $( man '$command' ).runToTextBehaviour( "man" ).openBehaviour()
    }

}