Port & adapters-like refactoring

build.gradle

@@ -20,10 +20,11 @@ dependencies {
     compile 'ch.qos.logback:logback-classic:1.0.1'
     compile 'ch.qos.logback:logback-core:1.0.1'
 
+    compile 'com.google.guava:guava:21.0'
+
     compileOnly "org.projectlombok:lombok:1.16.10"
 
     testCompile 'org.spockframework:spock-core:1.0-groovy-2.4'
     testCompile 'org.codehaus.groovy:groovy:2.4.7'
     testCompile 'cglib:cglib:3.2.2'
-
 }

src/main/java/com/softwaremill/java_fp_example/contest/your_github_login/LICENSE-template.txt → src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/LICENSE.txt

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2017 <twój login na GitHubie>
+Copyright (c) 2017 mszarlinski
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/adapter/jsoup/JsoupElement.java

@@ -0,0 +1,41 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.adapter.jsoup;
+
+import com.google.common.base.Strings;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.Element;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.Elements;
+import javaslang.collection.List;
+import javaslang.control.Option;
+
+class JsoupElement implements Element {
+
+    private final org.jsoup.nodes.Element wrapped;
+
+    static Element from(org.jsoup.nodes.Element element) {
+        return new JsoupElement(element);
+    }
+
+    private JsoupElement(org.jsoup.nodes.Element element) {
+        this.wrapped = element;
+    }
+
+    @Override
+    public boolean hasAttr(String attrName, String attrValue) {
+        return attr(attrName)
+                .filter(val -> val.equals(attrValue))
+                .isDefined();
+    }
+
+    @Override
+    public Option<String> attr(String attrName) {
+        return Option.of(wrapped.attr(attrName))
+                .filter(s -> !Strings.isNullOrEmpty(s));
+    }
+
+    @Override
+    public Elements childrenByTag(String tagName) {
+        return JsoupElements.from(wrapped.getElementsByTag(tagName)
+                .stream()
+                .map(JsoupElement::new)
+                .collect(List.collector()));
+    }
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/adapter/jsoup/JsoupElements.java

@@ -0,0 +1,37 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.adapter.jsoup;
+
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.DummyElement;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.DummyElements;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.Element;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.Elements;
+import javaslang.collection.List;
+
+class JsoupElements implements Elements {
+
+    private final List<JsoupElement> wrapped;
+
+    static Elements from(List<JsoupElement> elements) {
+        if (elements.isEmpty()) {
+            return DummyElements.INSTANCE;
+        } else {
+            return new JsoupElements(elements);
+        }
+    }
+
+    private JsoupElements(List<JsoupElement> wrapped) {
+        this.wrapped = wrapped;
+    }
+
+    @Override
+    public Element first() {
+        return wrapped.headOption()
+                .map(h -> (Element) h)
+                .getOrElse(DummyElement.INSTANCE);
+    }
+
+    @Override
+    public Elements filterByAttribute(String attrName, String attrValue) {
+        return JsoupElements.from(wrapped.filter(e -> e.hasAttr(attrName, attrValue)));
+    }
+
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/adapter/jsoup/JsoupWebPage.java

@@ -0,0 +1,25 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.adapter.jsoup;
+
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.DummyElement;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.Element;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.WebPage;
+import javaslang.control.Option;
+import org.jsoup.nodes.Document;
+
+class JsoupWebPage implements WebPage {
+
+    private final Document wrapped;
+
+    JsoupWebPage(Document document) {
+        this.wrapped = document;
+    }
+
+    @Override
+    public Element head() {
+        return Option.of(wrapped.head())
+                .map(JsoupElement::from)
+                .getOrElse(DummyElement.INSTANCE);
+    }
+
+
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/adapter/jsoup/JsoupWebPageLoader.java

@@ -0,0 +1,23 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.adapter.jsoup;
+
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.WebPageLoader;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.WebPage;
+import javaslang.control.Try;
+import org.jsoup.Jsoup;
+
+import java.net.URL;
+import java.time.Duration;
+
+class JsoupWebPageLoader implements WebPageLoader {
+
+    private final int webPageLoadingTimeoutMillis;
+
+    JsoupWebPageLoader(Duration webPageLoadingTimeout) {
+        this.webPageLoadingTimeoutMillis = (int) webPageLoadingTimeout.toMillis();
+    }
+
+    @Override
+    public Try<WebPage> tryLoadWebPage(String url) {
+        return Try.of(() -> new JsoupWebPage(Jsoup.parse(new URL(url), webPageLoadingTimeoutMillis)));
+    }
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/FacebookImage.java

@@ -0,0 +1,44 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.base.Objects;
+
+/**
+ * Immutable value object representing a FB image.
+ */
+public class FacebookImage {
+
+    public final static String FACEBOOK_IMAGE_TAG = "og:image";
+
+    public static final FacebookImage DEFAULT = new FacebookImage("https://softwaremill.com/images/logo-vertical.023d8496.png");
+
+    private final String url;
+
+    public FacebookImage(String url) {
+        this.url = url;
+    }
+
+    public String getUrl() {
+        return url;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        FacebookImage that = (FacebookImage) o;
+        return Objects.equal(url, that.url);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(url);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this)
+                .add("url", url)
+                .toString();
+    }
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/FacebookImageProvider.java

@@ -0,0 +1,49 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain;
+
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.Element;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.Elements;
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.WebPage;
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+import static java.lang.String.format;
+
+/**
+ * Component responsible for extracting FB image from given page.
+ */
+@Slf4j
+public class FacebookImageProvider {
+
+    private final WebPageLoader webPageLoader;
+
+    public FacebookImageProvider(WebPageLoader webPageLoader) {
+        this.webPageLoader = webPageLoader;
+    }
+
+    public FacebookImage getImageUrlFromPage(String pageUrl) {
+        return webPageLoader.tryLoadWebPage(pageUrl)
+                .map(WebPage::head)
+                .map(metasWithImage())
+                .map(Elements::first)
+                .map(fbImage())
+                .onFailure(logError(pageUrl))
+                .getOrElse(FacebookImage.DEFAULT);
+    }
+
+    private Function<Element, Elements> metasWithImage() {
+        return h -> h.childrenByTag("meta")
+                .filterByAttribute("property", FacebookImage.FACEBOOK_IMAGE_TAG);
+    }
+
+    private Function<Element, FacebookImage> fbImage() {
+        return e -> e.attr("content")
+                .map(FacebookImage::new)
+                .getOrElse(FacebookImage.DEFAULT);
+    }
+
+    private Consumer<Throwable> logError(String pageUrl) {
+        return t -> log.warn(format("Failed to extract image from %s", pageUrl), t);
+    }
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/WebPageLoader.java

@@ -0,0 +1,8 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain;
+
+import com.softwaremill.java_fp_example.contest.mszarlinski.domain.web.WebPage;
+import javaslang.control.Try;
+
+public interface WebPageLoader {
+    Try<WebPage> tryLoadWebPage(String url);
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/web/DummyElement.java

@@ -0,0 +1,23 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain.web;
+
+import javaslang.control.Option;
+
+public class DummyElement implements Element {
+
+    public static final Element INSTANCE = new DummyElement();
+
+    @Override
+    public boolean hasAttr(String attrName, String attrValue) {
+        return false;
+    }
+
+    @Override
+    public Option<String> attr(String attrName) {
+        return Option.none();
+    }
+
+    @Override
+    public Elements childrenByTag(String tagName) {
+        return DummyElements.INSTANCE;
+    }
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/web/DummyElements.java

@@ -0,0 +1,16 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain.web;
+
+public class DummyElements implements Elements {
+
+    public static final Elements INSTANCE = new DummyElements();
+
+    @Override
+    public Element first() {
+        return DummyElement.INSTANCE;
+    }
+
+    @Override
+    public Elements filterByAttribute(String attrName, String attrValue) {
+        return this;
+    }
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/web/Element.java

@@ -0,0 +1,11 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain.web;
+
+import javaslang.control.Option;
+
+public interface Element {
+    boolean hasAttr(String attrName, String attrValue);
+
+    Option<String> attr(String attrName);
+
+    Elements childrenByTag(String tagName);
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/web/Elements.java

@@ -0,0 +1,8 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain.web;
+
+public interface Elements {
+
+    Element first();
+
+    Elements filterByAttribute(String attrName, String attrValue);
+}

src/main/java/com/softwaremill/java_fp_example/contest/mszarlinski/domain/web/WebPage.java

@@ -0,0 +1,6 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain.web;
+
+public interface WebPage {
+
+    Element head();
+}

src/test/groovy/com/softwaremill/java_fp_example/contest/mszarlinski/domain/FacebookImageProviderSpec.groovy

@@ -0,0 +1,32 @@
+package com.softwaremill.java_fp_example.contest.mszarlinski.domain
+
+import com.softwaremill.java_fp_example.contest.mszarlinski.adapter.jsoup.JsoupWebPageLoader
+import spock.lang.Specification
+import spock.lang.Unroll
+
+import java.time.Duration
+
+import static com.softwaremill.java_fp_example.DefaultImage.DEFAULT_IMAGE
+
+class FacebookImageProviderSpec extends Specification {
+
+    @Unroll
+    def "should test Provider version with address #postAddress"() {
+        given:
+            FacebookImageProvider provider = new FacebookImageProvider(
+                    new JsoupWebPageLoader(Duration.ofSeconds(10)))
+
+        when:
+            def image = provider.getImageUrlFromPage(postAddress)
+
+        then:
+            image.url == expectedImageUrl
+
+        where:
+            postAddress                                                || expectedImageUrl
+            "https://softwaremill.com/the-wrong-abstraction-recap/"    || "https://softwaremill.com/images/uploads/2017/02/street-shoe-chewing-gum.0526d557.jpg"
+            "https://softwaremill.com/using-kafka-as-a-message-queue/" || "https://softwaremill.com/images/uploads/2017/02/kmq.93f842cf.png"
+            "https://twitter.com/softwaremill"                         || DEFAULT_IMAGE
+            "http://i-do-not-exist.pl"                                 || DEFAULT_IMAGE
+    }
+}