// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.

package com.yahoo.vespa.hosted.node.admin.task.util.process;

import java.util.List;
import java.util.function.Function;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * A CommandResult is the result of the execution of a CommandLine.
 *
 * @author hakonhall
 */
public class CommandResult {
    private static final Pattern NEWLINE = Pattern.compile("\\n");

    private final CommandLine commandLine;
    private final int exitCode;
    private final String output;

    public CommandResult(CommandLine commandLine, int exitCode, String output) {
        this.commandLine = commandLine;
        this.exitCode = exitCode;
        this.output = output;
    }

    public int getExitCode() {
        return exitCode;
    }

    /** Returns the output with leading and trailing white-space removed. */
    public String getOutput() { return output.trim(); }

    public String getUntrimmedOutput() { return output; }

    /** Returns the output lines of the command, omitting trailing empty lines. */
    public List<String> getOutputLines() {
        return getOutputLinesStream().toList();
    }

    /** Returns the output lines as a stream, omitting trailing empty lines. */
    public Stream<String> getOutputLinesStream() {
        if (output.isEmpty()) {
            // For some reason an empty string => one-element list.
            return Stream.empty();
        }

        // For some reason this removes trailing empty elements, but that's OK with us.
        return NEWLINE.splitAsStream(output);
    }

    /**
     * Map this CommandResult to an instance of type R.
     *
     * If a RuntimeException is thrown by the mapper, it is wrapped in an
     * UnexpectedOutputException that includes a snippet of the output in the message.
     *
     * This method is intended to be used as part of the verification of the output.
     */
    public <R> R map(Function<CommandResult, R> mapper) {
        try {
            return mapper.apply(this);
        } catch (RuntimeException e) {
            throw new UnexpectedOutputException(e, "Failed to map output", commandLine.toString(), output);
        }
    }

    /**
     * Map the output to an instance of type R according to mapper, wrapping any
     * RuntimeException in UnexpectedOutputException w/output snippet. See map() for details.
     */
    public <R> R mapOutput(Function<String, R> mapper) { return map(result -> mapper.apply(result.getOutput())); }

    /**
     * Map each output line to an instance of type R according to mapper, wrapping any
     * RuntimeException in UnexpectedOutputException w/output snippet. See map() for details.
     */
    public <R> List<R> mapEachLine(Function<String, R> mapper) {
        return map(result -> result.getOutputLinesStream().map(mapper).toList());
    }

    /**
     * Convenience method for getting the CommandLine, whose execution resulted in
     * this CommandResult instance.
     *
     * Warning: the CommandLine is mutable and may be changed by the caller of the execution
     * through other references! This is just a convenience method for getting that instance.
     */
    public CommandLine getCommandLine() { return commandLine; }
}