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package org.apache.james.modules.objectstorage;

import java.io.FileNotFoundException;
import java.util.function.Function;

import javax.inject.Inject;
import javax.inject.Provider;

import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.james.blob.api.BlobId;
import org.apache.james.blob.objectstorage.ContainerName;
import org.apache.james.blob.objectstorage.ObjectStorageBlobsDAO;
import org.apache.james.blob.objectstorage.swift.SwiftKeystone2ObjectStorage;
import org.apache.james.blob.objectstorage.swift.SwiftKeystone3ObjectStorage;
import org.apache.james.blob.objectstorage.swift.SwiftTempAuthObjectStorage;
import org.apache.james.utils.PropertiesProvider;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;

public class ObjectStorageBlobsDAOProvider implements Provider<ObjectStorageBlobsDAO> {
    static final String OBJECTSTORAGE_CONFIGURATION_NAME = "objectstorage";

    static final String OBJECTSTORAGE_NAMESPACE = "objectstorage.namespace";
    static final String OBJECTSTORAGE_PROVIDER = "objectstorage.provider";
    static final String OBJECTSTORAGE_SWIFT_AUTH_API = "objectstorage.swift.authapi";

    public static final String OBJECTSTORAGE_PROVIDER_SWIFT = "swift";

    private final Configuration configuration;
    private final BlobId.Factory blobIdFactory;
    private final ImmutableMap<String, Function<ContainerName, ObjectStorageBlobsDAO>> providersByName;
    private final ImmutableMap<String, Function<ContainerName, ObjectStorageBlobsDAO>> swiftAuthApiByName;

    @Inject
    public ObjectStorageBlobsDAOProvider(PropertiesProvider propertiesProvider,
                                         BlobId.Factory blobIdFactory) throws ConfigurationException {
        providersByName = ImmutableMap.<String, Function<ContainerName, ObjectStorageBlobsDAO>>builder()
            .put(OBJECTSTORAGE_PROVIDER_SWIFT, this::getSwiftObjectStorageBlobsDao)
            .build();
        swiftAuthApiByName = ImmutableMap.<String, Function<ContainerName, ObjectStorageBlobsDAO>>builder()
            .put(SwiftTempAuthObjectStorage.AUTH_API_NAME, this::getTempAuthBlobsDao)
            .put(SwiftKeystone2ObjectStorage.AUTH_API_NAME, this::getKeystone2BlobsDao)
            .put(SwiftKeystone3ObjectStorage.AUTH_API_NAME, this::getKeystone3Configuration)
            .build();

        this.blobIdFactory = blobIdFactory;
        try {
            this.configuration = propertiesProvider.getConfiguration(OBJECTSTORAGE_CONFIGURATION_NAME);
        } catch (FileNotFoundException e) {
            throw new ConfigurationException(OBJECTSTORAGE_CONFIGURATION_NAME + " configuration " +
                "was not found");
        }
    }

    @Override
    public ObjectStorageBlobsDAO get() {
        String provider = configuration.getString(OBJECTSTORAGE_PROVIDER, null);
        String namespace = configuration.getString(OBJECTSTORAGE_NAMESPACE, null);
        Preconditions.checkArgument(provider != null,
            "Mandatory configuration value " + OBJECTSTORAGE_PROVIDER + " is missing from " + OBJECTSTORAGE_CONFIGURATION_NAME + " configuration");
        Preconditions.checkArgument(namespace != null,
            "Mandatory configuration value " + OBJECTSTORAGE_NAMESPACE + " is missing from " + OBJECTSTORAGE_CONFIGURATION_NAME + " configuration");

        return providersByName.get(provider).apply(ContainerName.of(namespace));
    }

    private ObjectStorageBlobsDAO getSwiftObjectStorageBlobsDao(ContainerName containerName) {
        String authApi = configuration.getString(OBJECTSTORAGE_SWIFT_AUTH_API, null);
        Preconditions.checkArgument(authApi != null,
            "Mandatory configuration value " + OBJECTSTORAGE_PROVIDER + " is missing from " + OBJECTSTORAGE_CONFIGURATION_NAME + " configuration");
        return swiftAuthApiByName.get(authApi).apply(containerName);
    }

    private ObjectStorageBlobsDAO getTempAuthBlobsDao(ContainerName containerName) {
        return ObjectStorageBlobsDAO.builder(SwiftTmpAuthConfigurationReader.readSwiftConfiguration(configuration))
            .blobIdFactory(blobIdFactory)
            .container(containerName)
            .build();

    }

    private ObjectStorageBlobsDAO getKeystone2BlobsDao(ContainerName containerName) {
        return ObjectStorageBlobsDAO.builder(SwiftKeystone2ConfigurationReader.readSwiftConfiguration(configuration))
            .blobIdFactory(blobIdFactory)
            .container(containerName)
            .build();
    }

    private ObjectStorageBlobsDAO getKeystone3Configuration(ContainerName containerName) {
        return ObjectStorageBlobsDAO.builder(SwiftKeystone3ConfigurationReader.readSwiftConfiguration(configuration))
            .blobIdFactory(blobIdFactory)
            .container(containerName)
            .build();
    }
}