/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.example;
import com.google.common.base.Function;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.io.Resources;
import io.airlift.json.JsonCodec;
import javax.inject.Inject;
import java.io.IOException;
import java.net.URI;
import java.net.URL;
import java.util.List;
import java.util.Map;
import java.util.Set;
import static com.google.common.collect.Iterables.transform;
import static com.google.common.collect.Maps.transformValues;
import static com.google.common.collect.Maps.uniqueIndex;
import static java.nio.charset.StandardCharsets.UTF_8;
import static java.util.Objects.requireNonNull;
public class ExampleClient
{
/**
* SchemaName -> (TableName -> TableMetadata)
*/
private final Supplier<Map<String, Map<String, ExampleTable>>> schemas;
@Inject
public ExampleClient(ExampleConfig config, JsonCodec<Map<String, List<ExampleTable>>> catalogCodec)
throws IOException
{
requireNonNull(config, "config is null");
requireNonNull(catalogCodec, "catalogCodec is null");
schemas = Suppliers.memoize(schemasSupplier(catalogCodec, config.getMetadata()));
}
public Set<String> getSchemaNames()
{
return schemas.get().keySet();
}
public Set<String> getTableNames(String schema)
{
requireNonNull(schema, "schema is null");
Map<String, ExampleTable> tables = schemas.get().get(schema);
if (tables == null) {
return ImmutableSet.of();
}
return tables.keySet();
}
public ExampleTable getTable(String schema, String tableName)
{
requireNonNull(schema, "schema is null");
requireNonNull(tableName, "tableName is null");
Map<String, ExampleTable> tables = schemas.get().get(schema);
if (tables == null) {
return null;
}
return tables.get(tableName);
}
private static Supplier<Map<String, Map<String, ExampleTable>>> schemasSupplier(final JsonCodec<Map<String, List<ExampleTable>>> catalogCodec, final URI metadataUri)
{
return () -> {
try {
return lookupSchemas(metadataUri, catalogCodec);
}
catch (IOException e) {
throw Throwables.propagate(e);
}
};
}
private static Map<String, Map<String, ExampleTable>> lookupSchemas(URI metadataUri, JsonCodec<Map<String, List<ExampleTable>>> catalogCodec)
throws IOException
{
URL result = metadataUri.toURL();
String json = Resources.toString(result, UTF_8);
Map<String, List<ExampleTable>> catalog = catalogCodec.fromJson(json);
return ImmutableMap.copyOf(transformValues(catalog, resolveAndIndexTables(metadataUri)));
}
private static Function<List<ExampleTable>, Map<String, ExampleTable>> resolveAndIndexTables(final URI metadataUri)
{
return tables -> {
Iterable<ExampleTable> resolvedTables = transform(tables, tableUriResolver(metadataUri));
return ImmutableMap.copyOf(uniqueIndex(resolvedTables, ExampleTable::getName));
};
}
private static Function<ExampleTable, ExampleTable> tableUriResolver(final URI baseUri)
{
return table -> {
List<URI> sources = ImmutableList.copyOf(transform(table.getSources(), baseUri::resolve));
return new ExampleTable(table.getName(), table.getColumns(), sources);
};
}
}