Expose content type resolver api to plugins (#1752)

Expose an api which makes it easy to detect the content type of files. The api is based on the spotter api, but does not expose spotter classes.

Co-authored-by: René Pfeuffer <rene.pfeuffer@cloudogu.com>

scm-core/src/main/java/sonia/scm/io/ContentType.java

@@ -0,0 +1,71 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.io;
+
+import java.util.Optional;
+
+/**
+ * Detected type of content.
+ *
+ * @since 2.23.0
+ */
+public interface ContentType {
+
+  /**
+   * Returns the primary part of the content type (e.g.: text of text/plain).
+   *
+   * @return primary content type part
+   */
+  String getPrimary();
+
+  /**
+   * Returns the secondary part of the content type (e.g.: plain of text/plain).
+   *
+   * @return secondary content type part
+   */
+  String getSecondary();
+
+  /**
+   * Returns the raw presentation of the content type (e.g.: text/plain).
+   *
+   * @return raw presentation
+   */
+  String getRaw();
+
+  /**
+   * Returns {@code true} if the content type is text based.
+   *
+   * @return {@code true} for text content
+   */
+  boolean isText();
+
+  /**
+   * Returns an optional with the programming language
+   * or empty if the content is not programming language.
+   *
+   * @return programming language or empty
+   */
+  Optional<String> getLanguage();
+}

scm-core/src/main/java/sonia/scm/io/ContentTypeResolver.java

@@ -0,0 +1,52 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.io;
+
+/**
+ * ContentTypeResolver is able to detect the {@link ContentType} of files based on their path and (optinally) a few starting bytes. These files do not have to be real files on the file system, but can be hypothetical constructs ("What content type is most probable for a file named like this").
+ *
+ * @since 2.23.0
+ */
+public interface ContentTypeResolver {
+
+  /**
+   * Detects the {@link ContentType} of the given path, by only using path based strategies.
+   *
+   * @param path path of the file
+   *
+   * @return {@link ContentType} of path
+   */
+  ContentType resolve(String path);
+
+  /**
+   * Detects the {@link ContentType} of the given path, by using path and content based strategies.
+   *
+   * @param path path of the file
+   * @param contentPrefix first few bytes of the content
+   *
+   * @return {@link ContentType} of path and content prefix
+   */
+  ContentType resolve(String path, byte[] contentPrefix);
+}