Support command line arguments as a configuration source

src/main/java/com/teragrep/cnf_01/ArgsConfiguration.java

@@ -0,0 +1,116 @@
+/*
+ * Teragrep Configuration Library for Java (cnf_01)
+ * Copyright (C) 2024 Suomen Kanuuna Oy
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *
+ * Additional permission under GNU Affero General Public License version 3
+ * section 7
+ *
+ * If you modify this Program, or any covered work, by linking or combining it
+ * with other code, such other code is not for that reason alone subject to any
+ * of the requirements of the GNU Affero GPL version 3 as long as this Program
+ * is the same Program as licensed from Suomen Kanuuna Oy without any additional
+ * modifications.
+ *
+ * Supplemented terms under GNU Affero General Public License version 3
+ * section 7
+ *
+ * Origin of the software must be attributed to Suomen Kanuuna Oy. Any modified
+ * versions must be marked as "Modified version of" The Program.
+ *
+ * Names of the licensors and authors may not be used for publicity purposes.
+ *
+ * No rights are granted for use of trade names, trademarks, or service marks
+ * which are in The Program if any.
+ *
+ * Licensee must indemnify licensors and authors for any liability that these
+ * contractual assumptions impose on licensors and authors.
+ *
+ * To the extent this program is licensed as part of the Commercial versions of
+ * Teragrep, the applicable Commercial License may apply to this file if you as
+ * a licensee so wish it.
+ */
+package com.teragrep.cnf_01;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public final class ArgsConfiguration implements Configuration {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(ArgsConfiguration.class);
+
+    private final String[] args;
+
+    public ArgsConfiguration(final String[] args) {
+        this.args = Arrays.copyOf(args, args.length);
+    }
+
+    /**
+     * Produces a Map of configurations from the args.
+     *
+     * @return immutable map of the args
+     * @throws ConfigurationException If the args are not given in the format of this regex: ([a-z]+)(=.+)
+     */
+    @Override
+    public Map<String, String> asMap() throws ConfigurationException {
+        final Map<String, String> map = new HashMap<>();
+
+        if (args.length != 0) {
+            final Pattern ptn = Pattern.compile("([a-z]+)(=.+)");
+            for (final String arg : args) {
+                final Matcher matcher = ptn.matcher(arg);
+                if (!matcher.matches()) {
+                    throw new ConfigurationException(
+                            String
+                                    .format(
+                                            "Can't parse argument '%s'. Args have to be given in \"key=value\" format.",
+                                            arg
+                                    )
+                    );
+                }
+                map.put(matcher.group(1), matcher.group(2).substring(1));
+            }
+        }
+        LOGGER.debug("Returning configuration map generated from command-line arguments.");
+        LOGGER.trace("Returning configuration map <[{}]>", map);
+
+        return Collections.unmodifiableMap(map);
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        else if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        final ArgsConfiguration config = (ArgsConfiguration) o;
+        return Arrays.equals(args, config.args);
+    }
+
+    @Override
+    public int hashCode() {
+        return Arrays.hashCode(args);
+    }
+}

src/main/java/com/teragrep/cnf_01/ConfigurationException.java

@@ -50,4 +50,8 @@ public final class ConfigurationException extends Exception {
     public ConfigurationException(final String message, final Throwable cause) {
         super(message, cause);
     }
+
+    public ConfigurationException(final String message) {
+        super(message);
+    }
 }

src/test/java/com/teragrep/cnf_01/ArgsConfigurationTest.java

@@ -0,0 +1,167 @@
+/*
+ * Teragrep Configuration Library for Java (cnf_01)
+ * Copyright (C) 2024 Suomen Kanuuna Oy
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ *
+ * Additional permission under GNU Affero General Public License version 3
+ * section 7
+ *
+ * If you modify this Program, or any covered work, by linking or combining it
+ * with other code, such other code is not for that reason alone subject to any
+ * of the requirements of the GNU Affero GPL version 3 as long as this Program
+ * is the same Program as licensed from Suomen Kanuuna Oy without any additional
+ * modifications.
+ *
+ * Supplemented terms under GNU Affero General Public License version 3
+ * section 7
+ *
+ * Origin of the software must be attributed to Suomen Kanuuna Oy. Any modified
+ * versions must be marked as "Modified version of" The Program.
+ *
+ * Names of the licensors and authors may not be used for publicity purposes.
+ *
+ * No rights are granted for use of trade names, trademarks, or service marks
+ * which are in The Program if any.
+ *
+ * Licensee must indemnify licensors and authors for any liability that these
+ * contractual assumptions impose on licensors and authors.
+ *
+ * To the extent this program is licensed as part of the Commercial versions of
+ * Teragrep, the applicable Commercial License may apply to this file if you as
+ * a licensee so wish it.
+ */
+package com.teragrep.cnf_01;
+
+import nl.jqno.equalsverifier.EqualsVerifier;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.Map;
+
+public class ArgsConfigurationTest {
+
+    @Test
+    public void testValidArgs() {
+        String param = "bar=foo";
+        String[] args = {
+                "foo=bar", param
+        };
+
+        ArgsConfiguration config = new ArgsConfiguration(args);
+        // modifying the original doesn't have effect on the result
+        args[1] = "biz=buz";
+
+        Map<String, String> map = Assertions.assertDoesNotThrow(config::asMap);
+
+        Assertions.assertEquals(2, map.size());
+        Assertions.assertTrue(map.containsKey("foo"));
+        Assertions.assertTrue(map.containsKey("bar"));
+        Assertions.assertEquals("bar", map.get("foo"));
+        Assertions.assertEquals("foo", map.get("bar"));
+    }
+
+    @Test
+    public void testInvalidArgs() {
+        String[] args = {
+                "foo", "bar"
+        };
+
+        ArgsConfiguration config = new ArgsConfiguration(args);
+
+        ConfigurationException exception = Assertions.assertThrows(ConfigurationException.class, config::asMap);
+
+        Assertions
+                .assertEquals(
+                        "Can't parse argument 'foo'. Args have to be given in \"key=value\" format.",
+                        exception.getMessage()
+                );
+    }
+
+    @Test
+    public void testEmptyArgs() {
+        String[] args = new String[0];
+        ArgsConfiguration config = new ArgsConfiguration(args);
+
+        Map<String, String> map = Assertions.assertDoesNotThrow(config::asMap);
+        Assertions.assertTrue(map.isEmpty());
+    }
+
+    @Test
+    public void testImmutability() {
+        String[] args = new String[0];
+        ArgsConfiguration config = new ArgsConfiguration(args);
+
+        Map<String, String> map = Assertions.assertDoesNotThrow(config::asMap);
+        Assertions.assertThrows(UnsupportedOperationException.class, () -> map.put("foo", "bar")); // The map is immutable
+    }
+
+    @Test
+    public void testEquals() {
+        String[] args = {
+                "foo=bar", "bar=foo"
+        };
+        ArgsConfiguration config = new ArgsConfiguration(args);
+
+        String[] args2 = {
+                "foo=bar", "bar=foo"
+        };
+        ArgsConfiguration config2 = new ArgsConfiguration(args2);
+
+        Assertions.assertDoesNotThrow(config::asMap);
+
+        Assertions.assertEquals(config, config2);
+    }
+
+    @Test
+    public void testNotEquals() {
+        String[] args = {
+                "foo=bar", "bar=foo"
+        };
+        String[] args2 = {
+                ""
+        };
+
+        ArgsConfiguration config = new ArgsConfiguration(args);
+        ArgsConfiguration config2 = new ArgsConfiguration(args2);
+
+        Assertions.assertNotEquals(config, config2);
+    }
+
+    @Test
+    public void testHashCode() {
+        String[] args = {
+                "foo=bar", "bar=foo"
+        };
+        String[] args2 = {
+                "foo=bar", "bar=foo"
+        };
+        String[] args3 = {
+                ""
+        };
+
+        ArgsConfiguration config = new ArgsConfiguration(args);
+        ArgsConfiguration config2 = new ArgsConfiguration(args2);
+        ArgsConfiguration config3 = new ArgsConfiguration(args3);
+
+        Assertions.assertEquals(config.hashCode(), config2.hashCode());
+        Assertions.assertNotEquals(config.hashCode(), config3.hashCode());
+    }
+
+    @Test
+    public void testEqualsVerifier() {
+        EqualsVerifier.forClass(ArgsConfiguration.class).withNonnullFields("args").verify();
+    }
+}