public IXTable Build()

in XForm/XForm/WorkflowRunner.cs [64:172]
71 lines of code
22 McCabe index (conditional complexity)

        public IXTable Build(string tableName, XDatabaseContext outerContext, bool deferred)
        {
            // Validate the source name is recognized
            if (!Sources.Contains(tableName))
            {
                // If it wasn't in cache, check individually for it live
                if (!XDatabaseContext.StreamProvider.ContainsTable(tableName)) throw new UsageException(tableName, "Table", Sources);

                // If found, update the cache
                UpdateSources();
            }

            // If only a Date was passed for AsOfDate, look for the last version as of that day
            if(outerContext.RequestedAsOfDateTime.TimeOfDay == TimeSpan.Zero)
            {
                outerContext.RequestedAsOfDateTime = outerContext.RequestedAsOfDateTime.AddDays(1).AddSeconds(-1);
            }

            // If we previously found the latest for this table, just return it again
            LatestTableForCutoff previousLatest;
            if (_currentTableVersions.TryGet(tableName, out previousLatest)
                && previousLatest.Cutoff >= outerContext.RequestedAsOfDateTime
                && previousLatest.TableVersion.AsOfDate <= outerContext.RequestedAsOfDateTime
                && TableMetadataSerializer.UncachedExists(outerContext.StreamProvider, previousLatest.TableVersion.Path))
            {
                outerContext.NewestDependency = previousLatest.TableVersion.AsOfDate;
                return BinaryTableReader.Build(outerContext.StreamProvider, previousLatest.TableVersion.Path);
            }

            // Create a context to track what we're building now
            XDatabaseContext innerContext = XDatabaseContext.Push(outerContext);
            innerContext.CurrentTable = tableName;

            // If this is a query, there won't be a cached table - just build a pipeline to make it
            StreamAttributes queryAttributes = innerContext.StreamProvider.Attributes(innerContext.StreamProvider.Path(LocationType.Query, tableName, ".xql"));
            if (queryAttributes.Exists)
            {
                IXTable queryPipeline = innerContext.Query(innerContext.StreamProvider.ReadAllText(queryAttributes.Path));
                innerContext.Pop(outerContext);
                return queryPipeline;
            }

            // Find the latest already built result, and associated query
            ItemVersions tableVersions = innerContext.StreamProvider.ItemVersions(LocationType.Table, tableName);
            ItemVersion latestTable = tableVersions.LatestBeforeCutoff(CrawlType.Full, outerContext.RequestedAsOfDateTime);
            string latestTableQuery = null;
            if (latestTable != null)
            {
                latestTableQuery = TableMetadataSerializer.Read(outerContext.StreamProvider, latestTable.Path).Query;
            }

            // Set the dependency date to the latest table we've already built (if any)
            innerContext.NewestDependency = (latestTable == null ? DateTime.MinValue : latestTable.AsOfDate);

            // Determine the XQL to build the table and construct a builder which can do so
            string xql;
            IXTable builder;

            // Find the config to build the table and scan dependency versions to determine whether table is out-of-date
            StreamAttributes configAttributes = innerContext.StreamProvider.Attributes(innerContext.StreamProvider.Path(LocationType.Config, tableName, ".xql"));
            if (!configAttributes.Exists)
            {
                // If this is a simple source, just reading it is how to build it
                xql = $"read {XqlScanner.Escape(tableName, TokenType.Value)}";

                // Build a reader concatenating all needed pieces
                builder = ReadSource(tableName, innerContext);
            }
            else
            {
                // If there is a config, the config is how to build it
                xql = innerContext.StreamProvider.ReadAllText(configAttributes.Path);

                // Build a pipeline for the query, recursively creating dependencies
                builder = innerContext.Query(xql);
            }

            // If we don't have the table or the source, we have to throw
            if (latestTable == null && builder == null) throw new UsageException(tableName, "Table", innerContext.StreamProvider.Tables());

            // Get the path we're either reading or building
            string tablePath = innerContext.StreamProvider.Path(LocationType.Table, tableName, CrawlType.Full, innerContext.NewestDependency);

            // If we can rebuild this table and we need to (sources rebuilt, query changed, out-of-date, deleted), rebuild it
            if (builder != null)
            {
                if (latestTable == null 
                    || innerContext.RebuiltSomething 
                    || (latestTableQuery != null && xql != latestTableQuery) 
                    || IsOutOfDate(latestTable.AsOfDate, innerContext.NewestDependency) 
                    || !TableMetadataSerializer.UncachedExists(outerContext.StreamProvider, latestTable.Path))
                {
                    // If we're not running now, just return how to build it
                    if (deferred) return builder;

                    // Otherwise, build it now; we'll return the query to read the output
                    innerContext.CurrentQuery = xql;
                    Trace.WriteLine($"COMPUTE: [{innerContext.NewestDependency.ToString(StreamProviderExtensions.DateTimeFolderFormat)}] {tableName}");
                    BinaryTableWriter.Build(builder, innerContext, tablePath).RunAndDispose();
                    innerContext.RebuiltSomething = true;
                }
            }

            // Report the newest dependency in this chain to the components above
            innerContext.Pop(outerContext);

            _currentTableVersions.Add(tableName, new LatestTableForCutoff(outerContext.RequestedAsOfDateTime, new ItemVersion(LocationType.Table, tableName, CrawlType.Full, innerContext.NewestDependency)));
            return BinaryTableReader.Build(innerContext.StreamProvider, tablePath);
        }