MakePackage()
        {
            var packageDir = Graph.Instance.ProcessState.WorkingDirectory;
            var bamDir = System.IO.Path.Combine(packageDir, BamSubFolder);
            if (System.IO.Directory.Exists(bamDir))
            {
                throw new Exception("A Bam package already exists at {0}", packageDir);
            }

            var packageNameArgument = new Options.PackageName();
            var packageName = CommandLineProcessor.Evaluate(packageNameArgument);
            if (null == packageName)
            {
                throw new Exception("No name was defined. Use {0} on the command line to specify it.", (packageNameArgument as ICommandLineArgument).LongName);
            }

            var packageVersion = CommandLineProcessor.Evaluate(new Options.PackageVersion());
            var definition = new PackageDefinition(bamDir, packageName, packageVersion);

            System.IO.Directory.CreateDirectory(bamDir);
            definition.Write();

            var scriptsDir = System.IO.Path.Combine(bamDir, ScriptsSubFolder);
            System.IO.Directory.CreateDirectory(scriptsDir);

            var initialScriptFile = System.IO.Path.Combine(scriptsDir, packageName) + ".cs";
            using (System.IO.TextWriter writer = new System.IO.StreamWriter(initialScriptFile))
            {
                writer.WriteLine("using Bam.Core;");
                writer.WriteLine("namespace {0}", packageName);
                writer.WriteLine("{");
                writer.WriteLine("    // write modules here ...");
                writer.WriteLine("}");
            }
        }
        /// <summary>
        /// Based on the dependents lists in the XML file, resolve all dependents by reading more
        /// package definition files.
        /// </summary>
        /// <param name="current">Current.</param>
        /// <param name="authenticated">Authenticated.</param>
        /// <param name="candidatePackageDefinitions">Candidate package definitions.</param>
        public static void ResolveDependencies(
            PackageDefinition current,
            Array<PackageDefinition> authenticated,
            Array<PackageDefinition> candidatePackageDefinitions)
        {
            var matchingPackages = authenticated.Where(item => item.Name == current.Name);
            if (null != current.Version)
            {
                matchingPackages = matchingPackages.Where(item => item.Version == current.Version);
            }
            if (matchingPackages.FirstOrDefault() != null)
            {
                return;
            }

            if (!current.SupportedPlatforms.Includes(OSUtilities.CurrentOS))
            {
                throw new Exception("Package {0} is not supported on {1}", current.FullName, OSUtilities.CurrentOS.ToString());
            }

            authenticated.Add(current);
            foreach (var dependent in current.Dependents)
            {
                var depName = dependent.Item1;
                var depVersion = dependent.Item2;
                var candidates = candidatePackageDefinitions.Where(item => item.Name == depName);
                if (depVersion != null)
                {
                    candidates = candidates.Where(item => item.Version == depVersion);
                }
                var candidateCount = candidates.Count();
                if (0 == candidateCount)
                {
                    var message = new System.Text.StringBuilder();
                    message.AppendFormat("Unable to find a candidate package with name '{0}'", depName);
                    if (null != depVersion)
                    {
                        message.AppendFormat(" and version {0}", depVersion);
                    }
                    message.AppendLine();
                    var packageRepos = new StringArray();
                    Graph.Instance.PackageRepositories.ToList().ForEach(item => packageRepos.AddUnique(item));
                    message.AppendLine("Searched in the package repositories:");
                    message.AppendLine(packageRepos.ToString("\n"));
                    throw new Exception(message.ToString());
                }
                if (candidateCount > 1)
                {
                    var message = new System.Text.StringBuilder();
                    message.AppendFormat("There are {0} identical candidate packages with name '{1}'", candidateCount, depName);
                    if (null != depVersion)
                    {
                        message.AppendFormat(" and version {0}", depVersion);
                    }
                    message.AppendLine(" from the following package definition files:");
                    foreach (var candidate in candidates)
                    {
                        message.AppendFormat(candidate.XMLFilename);
                        message.AppendLine();
                    }
                    var packageRepos = new StringArray();
                    Graph.Instance.PackageRepositories.ToList().ForEach(item => packageRepos.AddUnique(item));
                    message.AppendLine("Found in the package repositories:");
                    message.AppendLine(packageRepos.ToString("\n"));
                    throw new Exception(message.ToString());
                }

                ResolveDependencies(candidates.First(), authenticated, candidatePackageDefinitions);
            }
        }
        IdentifyAllPackages(
            bool allowDuplicates = false,
            bool enforceBamAssemblyVersions = true)
        {
            var packageRepos = new System.Collections.Generic.Queue<string>();
            foreach (var repo in Graph.Instance.PackageRepositories)
            {
                if (packageRepos.Contains(repo))
                {
                    continue;
                }
                packageRepos.Enqueue(repo);
            }

            var masterDefinitionFile = GetMasterPackage(enforceBamAssemblyVersions: enforceBamAssemblyVersions);
            foreach (var repo in masterDefinitionFile.PackageRepositories)
            {
                if (packageRepos.Contains(repo))
                {
                    continue;
                }
                packageRepos.Enqueue(repo);
            }

            // read the definition files of any package found in the package roots
            var candidatePackageDefinitions = new Array<PackageDefinition>();
            candidatePackageDefinitions.Add(masterDefinitionFile);
            while (packageRepos.Count > 0)
            {
                var repo = packageRepos.Dequeue();
                if (!System.IO.Directory.Exists(repo))
                {
                    throw new Exception("Package repository directory {0} does not exist", repo);
                }
                var candidatePackageDirs = System.IO.Directory.GetDirectories(repo, BamSubFolder, System.IO.SearchOption.AllDirectories);

                Graph.Instance.PackageRepositories.Add(repo);

                foreach (var bamDir in candidatePackageDirs)
                {
                    var packageDir = System.IO.Path.GetDirectoryName(bamDir);
                    var packageDefinitionPath = GetPackageDefinitionPathname(packageDir);

                    // ignore any duplicates (can be found due to nested repositories)
                    if (null != candidatePackageDefinitions.Where(item => item.XMLFilename == packageDefinitionPath).FirstOrDefault())
                    {
                        continue;
                    }

                    var definitionFile = new PackageDefinition(packageDefinitionPath, !Graph.Instance.ForceDefinitionFileUpdate);
                    definitionFile.Read(true, enforceBamAssemblyVersions);
                    candidatePackageDefinitions.Add(definitionFile);

                    foreach (var newRepo in definitionFile.PackageRepositories)
                    {
                        if (Graph.Instance.PackageRepositories.Contains(newRepo))
                        {
                            continue;
                        }
                        packageRepos.Enqueue(newRepo);
                    }
                }
            }

            // defaults come from
            // - the master definition file
            // - command line args (these trump the mdf)
            // and only requires resolving when referenced
            var packageDefinitions = new Array<PackageDefinition>();
            PackageDefinition.ResolveDependencies(masterDefinitionFile, packageDefinitions, candidatePackageDefinitions);

            // now resolve any duplicate names using defaults
            // unless duplicates are allowed
            var duplicatePackageNames = packageDefinitions.GroupBy(item => item.Name).Where(item => item.Count() > 1).Select(item => item.Key);
            if ((duplicatePackageNames.Count() > 0) && !allowDuplicates)
            {
                var versionSpeciferArgs = new Options.PackageDefaultVersion();
                var packageVersionSpecifiers = CommandLineProcessor.Evaluate(versionSpeciferArgs);
                var toRemove = new Array<PackageDefinition>();

                foreach (var dupName in duplicatePackageNames)
                {
                    var duplicates = packageDefinitions.Where(item => item.Name == dupName);
                    PackageDefinition resolvedDuplicate = null;
                    // command line specifications take precedence to resolve a duplicate
                    foreach (var specifier in packageVersionSpecifiers)
                    {
                        if (!specifier.Contains(dupName))
                        {
                            continue;
                        }

                        foreach (var dupPackage in duplicates)
                        {
                            if (specifier[1] == dupPackage.Version)
                            {
                                resolvedDuplicate = dupPackage;
                                break;
                            }
                        }

                        if (resolvedDuplicate != null)
                        {
                            break;
                        }

                        var noMatchMessage = new System.Text.StringBuilder();
                        noMatchMessage.AppendFormat("Command line version specified, {0}, could not resolve to one of the available versions of package {1}:", specifier[1], duplicates.First().Name);
                        noMatchMessage.AppendLine();
                        foreach (var dup in duplicates)
                        {
                            noMatchMessage.AppendFormat("\t{0}", dup.Version);
                            noMatchMessage.AppendLine();
                        }
                        throw new Exception(noMatchMessage.ToString());
                    }

                    if (resolvedDuplicate != null)
                    {
                        toRemove.AddRange(packageDefinitions.Where(item => (item.Name == dupName) && (item != resolvedDuplicate)));
                        continue;
                    }

                    // now look at the master dependency file, for any 'default' specifications
                    var masterDependency = masterDefinitionFile.Dependents.Where(item => item.Item1 == dupName && item.Item3.HasValue && item.Item3.Value).FirstOrDefault();
                    if (null != masterDependency)
                    {
                        toRemove.AddRange(packageDefinitions.Where(item => (item.Name == dupName) && (item.Version != masterDependency.Item2)));
                        continue;
                    }

                    var resolveErrorMessage = new System.Text.StringBuilder();
                    resolveErrorMessage.AppendFormat("Unable to resolve to a single version of package {0}. Use --{0}.version=<version> to resolve. Available versions of the package are:", duplicates.First().Name);
                    resolveErrorMessage.AppendLine();
                    foreach (var dup in duplicates)
                    {
                        resolveErrorMessage.AppendFormat("\t{0}", dup.Version);
                        resolveErrorMessage.AppendLine();
                    }
                    throw new Exception(resolveErrorMessage.ToString());
                }

                packageDefinitions.RemoveAll(toRemove);
            }

            Graph.Instance.SetPackageDefinitions(packageDefinitions);
        }
        GetMasterPackage(
            bool enforceBamAssemblyVersions = true)
        {
            var workingDir = Graph.Instance.ProcessState.WorkingDirectory;
            var isWorkingPackageWellDefined = IsPackageDirectory(workingDir);
            if (!isWorkingPackageWellDefined)
            {
                throw new Exception("Working directory package is not well defined");
            }

            var masterDefinitionFile = new PackageDefinition(GetPackageDefinitionPathname(workingDir), !Graph.Instance.ForceDefinitionFileUpdate);
            masterDefinitionFile.Read(true, enforceBamAssemblyVersions);
            return masterDefinitionFile;
        }