content: /*
   * Copyright (C) 2020 ActiveJ LLC.
   *
   * 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 io.activej.config;
  
  import io.activej.common.builder.AbstractBuilder;
  import io.activej.inject.Key;
  import io.activej.inject.KeyPattern;
  import io.activej.inject.module.AbstractModule;
  import io.activej.launcher.annotation.OnStart;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.io.PrintStream;
  import java.io.Writer;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.NoSuchElementException;
  import java.util.concurrent.CompletionStage;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.function.Consumer;
  
  import static io.activej.common.Checks.checkArgument;
  import static io.activej.common.Checks.checkState;
  
  /**
   * Supplies config to your application, looks after usage of config, prevents usage of config in any part of lifecycle except for startup.
   */
  public final class ConfigModule extends AbstractModule {
  	private static final Logger logger = LoggerFactory.getLogger(ConfigModule.class);
  
  	private Path effectiveConfigPath;
  	private Consumer<String> effectiveConfigConsumer;
  
  	public static final class ProtectedConfig implements Config {
  		private final Config config;
  		private final Map<String, Config> children;
  		private final AtomicBoolean started;
  
  		ProtectedConfig(Config config, AtomicBoolean started) {
  			this.config = config;
  			this.started = started;
  			this.children = new LinkedHashMap<>();
  			config.getChildren().forEach((key, value) ->
  				this.children.put(key, new ProtectedConfig(value, started)));
  		}
  
  		@Override
  		public String getValue(String defaultValue) {
  			checkState(!started.get(), "Config must be used during application start-up time only");
  			return config.getValue(defaultValue);
  		}
  
  		@Override
  		public String getValue() throws NoSuchElementException {
  			checkState(!started.get(), "Config must be used during application start-up time only");
  			return config.getValue();
  		}
  
  		@Override
  		public Map<String, Config> getChildren() {
  			return children;
  		}
  
  		@Override
  		public Config provideNoKeyChild(String key) {
  			checkArgument(!children.containsKey(key), "Children already contain key '%s'", key);
  			return new ProtectedConfig(config.provideNoKeyChild(key), started);
  		}
  	}
  
  	public static ConfigModule create() {
  		return builder().build();
  	}
  
  	public static Builder builder() {
  		return new ConfigModule().new Builder();
  	}
  
  	public final class Builder extends AbstractBuilder<Builder, ConfigModule> {
  		private Builder() {}
  
  		public Builder withEffectiveConfigConsumer(Consumer<String> consumer) {
  			checkNotBuilt(this);
  			effectiveConfigConsumer = consumer;
  			return this;
  		}
  
  		public Builder withEffectiveConfigLogger(Writer writer) {
  			checkNotBuilt(this);
  			return withEffectiveConfigConsumer(effectiveConfig -> {
  				try {
  					writer.write(effectiveConfig);
  				} catch (IOException e) {
  					throw new RuntimeException(e);
  				}
  			});
  		}
  
  		public Builder withEffectiveConfigLogger(PrintStream writer) {
  			checkNotBuilt(this);
  			return withEffectiveConfigConsumer(writer::print);
  		}
  
  		public Builder withEffectiveConfigLogger() {
  			checkNotBuilt(this);
  			return withEffectiveConfigConsumer(effectiveConfig ->
  				logger.info("Effective Config:\n\n{}", effectiveConfig));
  		}
  
  		@Override
  		protected ConfigModule doBuild() {
  			return ConfigModule.this;
  		}
  	}
  
  	public ConfigModule saveEffectiveConfigTo(String file) {
  		return saveEffectiveConfigTo(Paths.get(file));
  	}
  
  	public ConfigModule saveEffectiveConfigTo(Path file) {
  		this.effectiveConfigPath = file;
  		return this;
  	}
  
  	@SuppressWarnings("unchecked")
  	@Override
  	protected void configure() {
  		transform(KeyPattern.of(Config.class, null), (bindings, scope, key, binding) -> {
  			Key<CompletionStage<Void>> completionStageKey = new Key<>(OnStart.class) {};
  			return binding
  				.addDependencies(completionStageKey)
  				.mapInstance(List.of(completionStageKey), (args, config) -> {
  					CompletionStage<Void> onStart = (CompletionStage<Void>) args[0];
  					AtomicBoolean started = new AtomicBoolean();
  					ProtectedConfig protectedConfig = new ProtectedConfig(FullPathConfig.wrap(config), started);
  					EffectiveConfig effectiveConfig = EffectiveConfig.wrap(protectedConfig);
  					onStart.thenRun(() -> save(effectiveConfig, started));
  					return effectiveConfig;
  				});
  		});
  	}
  
  	private void save(EffectiveConfig effectiveConfig, AtomicBoolean started) {
  		started.set(true);
  		if (effectiveConfigPath != null) {
  			logger.info("Saving effective config to {}", effectiveConfigPath);
  			effectiveConfig.saveEffectiveConfigTo(effectiveConfigPath);
  		}
  		if (effectiveConfigConsumer != null) {
  			effectiveConfigConsumer.accept(effectiveConfig.renderEffectiveConfig());
  		}
  	}
  }
  