CHANGELOG parser by date

skate-plugin/build.gradle.kts

@@ -33,3 +33,8 @@ tasks {
 
   publishPlugin { token.set(System.getenv("PUBLISH_TOKEN")) }
 }
+
+dependencies {
+  testImplementation(libs.junit)
+  testImplementation(libs.truth)
+}

skate-plugin/src/main/kotlin/com/slack/sgp/intellij/ChangelogParser.kt

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2023 Slack Technologies, 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
+ *
+ *    https://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 com.slack.sgp.intellij
+
+import java.time.LocalDate
+
+/**
+ * Reads a CHANGELOG.md file and produces a subset of it, based on a specified previous entry date.
+ *
+ * If a previous entry date is supplied and is found within the changelog, this function will return
+ * a new changelog that contains entries only up to and including this date. If the previous entry
+ * date is not found, the entire changelog is returned.
+ *
+ * @param changeLogString The entire changelog, as a string, where each entry is expected to start
+ *   with a date line.
+ * @param previousEntry The date of the previous entry. Can be null, in which case the entire
+ *   changelog is returned.
+ * @return A ParseResult object containing the filtered changelog string and the date of the latest
+ *   entry.
+ */
+private val LOCAL_DATE_REGEX = "^\\d{4}-\\d{2}-\\d{2}\$".toRegex()
+private val String.isLocalDate: Boolean
+  get() {
+    return LOCAL_DATE_REGEX.matches(this)
+  }
+
+object ChangelogParser {
+  fun readFile(changeLogString: String, previousEntry: LocalDate? = null): ParseResult {
+    /*
+    date format: yyyy-mm-dd
+    */
+
+    if (previousEntry != null && !changeLogString.contains(previousEntry.toString())) {
+      return ParseResult(
+        changeLogString,
+        LocalDate.parse(changeLogString.lines().firstOrNull { it.isLocalDate })
+      )
+    }
+
+    var previous: LocalDate? = null
+    var entryCount = 0
+    val changeLogSubstring =
+      buildString {
+          var currentBlock = StringBuilder()
+          for (line in changeLogString.lines()) {
+            if (line.isLocalDate) {
+              val localDate = LocalDate.parse(line)
+              if (localDate == previousEntry) {
+                break
+              }
+              if (previous != null) {
+                append(currentBlock.toString())
+              }
+              currentBlock = StringBuilder()
+              if (previous == null) {
+                previous = localDate
+              }
+              entryCount++
+            }
+            currentBlock.appendLine(line)
+          }
+          if (entryCount == 0) {
+            append(currentBlock.toString())
+          }
+        }
+        .trimEnd()
+    return ParseResult(changeLogSubstring.takeIf { it.isNotBlank() }, previous ?: LocalDate.now())
+  }
+
+  data class ParseResult(val changeLogString: String?, val latestEntry: LocalDate)
+}

skate-plugin/src/test/kotlin/com/slack/sgp/intellij/ChangeLogParserTest.kt

@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2023 Slack Technologies, 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
+ *
+ *    https://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 com.slack.sgp.intellij
+
+import com.google.common.truth.Truth.assertThat
+import java.time.LocalDate
+import org.junit.Test
+
+class ChangeLogParserTest {
+  @Test
+  fun `no entries and null changelogstring`() {
+    val (changeLogString, latestEntry) = ChangelogParser.readFile("", null)
+    assertThat(changeLogString).isNull()
+    assertThat(latestEntry).isEqualTo(LocalDate.now())
+  }
+
+  @Test
+  fun `one entry, no previous entries`() {
+    val input =
+      """
+      2023-06-28
+
+      * Bug fixes
+      * New features
+      """
+        .trimIndent()
+
+    val expectedDate = LocalDate.of(2023, 6, 28)
+    val (changeLogString, latestEntry) = ChangelogParser.readFile(input, null)
+    assertThat(changeLogString).isNull()
+    assertThat(latestEntry).isEqualTo(expectedDate)
+  }
+
+  @Test
+  fun `mutliple entries, and no previous entries`() {
+    val input =
+      """
+      2023-06-28
+
+      * Bug fixes
+      * New features
+
+      2023-06-27
+
+      * Other changes
+      """
+        .trimIndent()
+    val expectedDate = LocalDate.of(2023, 6, 28)
+    val expectedString =
+      """
+      2023-06-28
+
+      * Bug fixes
+      * New features
+      """
+        .trimIndent()
+    val (changeLogString, latestEntry) = ChangelogParser.readFile(input, null)
+    assertThat(changeLogString).isEqualTo(expectedString)
+    assertThat(latestEntry).isEqualTo(expectedDate)
+  }
+
+  @Test
+  fun `multiple entries, where the previous is the same as the latest`() {
+    val input =
+      """
+      2023-06-28
+
+      * Bug fixes
+      * New features
+
+      2023-06-27
+
+      * Other changes
+      """
+        .trimIndent()
+    val expectedDate = LocalDate.of(2023, 6, 28)
+    val (changeLogString, latestEntry) = ChangelogParser.readFile(input, LocalDate.of(2023, 6, 28))
+    assertThat(changeLogString).isNull()
+    assertThat(latestEntry).isEqualTo(expectedDate)
+  }
+
+  @Test
+  fun `test with a previous entry not in the change log`() {
+    val input =
+      """
+      2023-06-28
+
+      * Bug fixes
+      * New features
+
+      2023-06-27
+
+      * Other changes
+      """
+        .trimIndent()
+    val expectedDate = LocalDate.of(2023, 6, 28)
+    val expectedString =
+      """
+      2023-06-28
+
+      * Bug fixes
+      * New features
+
+      2023-06-27
+
+      * Other changes
+      """
+        .trimIndent()
+    val (changeLogString, latestEntry) = ChangelogParser.readFile(input, LocalDate.of(2023, 6, 29))
+    assertThat(changeLogString).isEqualTo(expectedString)
+    assertThat(latestEntry).isEqualTo(expectedDate)
+  }
+}