choco_outdated.csx

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text.RegularExpressions;

ILookup<string, string> localPackages,
                        remotePackages;

using (var process = new Process())
{
    process.StartInfo =
        new ProcessStartInfo
        (
            "clist",
            "-localonly"
        );

    process.StartInfo.UseShellExecute = false;
    process.StartInfo.RedirectStandardOutput = true;

    process.Start();

    localPackages = GetPackagesFromCList(process)
        .ToLookup(x => x[0], x => x[1]);
}

using (var process = new Process())
{
    process.StartInfo =
        new ProcessStartInfo
        (
            "clist",
            string.Join(" ", localPackages.Select(x => x.Key)
                                            .ToArray())
        );

    process.StartInfo.UseShellExecute = false;
    process.StartInfo.RedirectStandardOutput = true;

    process.Start();

    remotePackages = GetPackagesFromCList(process)
        .Where(x => localPackages.Contains(x[0]))
        .ToLookup(x => x[0], x => x[1]);
}

foreach (var item in remotePackages)
{
    string localVersionStr, remoteVersionStr;

	// no matching package
    if (!localPackages.Contains(item.Key))
        continue;

	var localItem = localPackages[item.Key];

	// no non-matching version
    if (item.All(v => localItem.Contains(v)))
	    continue;

    {
        var localVersions = localItem.Distinct()
                                     .ToArray();

        localVersionStr =
            localVersions.Count() > 1 ?
            "s: " + string.Join(", ", localVersions) :
            ": " + localVersions[0];
    }

    {
        var remoteVersions = item.Distinct()
                                 .ToArray();

        remoteVersionStr =
            remoteVersions.Count() > 1 ?
            "s: " + string.Join(", ", remoteVersions) :
            ": " + remoteVersions[0];
    }

    Console.WriteLine
            (
                @"
Package {0}:
local version{1}
remote version{2}",
                item.Key,
                localVersionStr,
                remoteVersionStr
            );
}

private static IEnumerable<string[]> GetPackagesFromCList
    (Process process)
{
    string[] output =
        process.StandardOutput
                .ReadToEnd()
                .Split
                (
                    new[] { Environment.NewLine },
                    StringSplitOptions.RemoveEmptyEntries
                );

    return
        output.Select(l => Regex.Split(l, @"\s+"));
}