Merge pull request #292 from saalfeldlab/auto-generate-release-note

[UNVERSIONED] Auto-generate release note by @hanslovsky 

Add a [kscript](https://github.com/holgerbrandl/kscript) that auto-generates release notes from pull request messages:
 1. Scan commits from current `HEAD` to tag with latest version smaller than current (SNAPSHOT) version.
 2. Filter all commit messages
 3. In each commit message, look for any of these tags, encapuslated in brackets `[$TAG]`:
    - `BREAKING`
    - `FEATURE`
    - `BUGFIX`
    - `UNVERSIONED`

The script will suggest a new SemVer version based on the presence of these tags (`UNVERSIONED` will not increase the version). For example, if `HEAD` was on 8018669, the output would be:
```
$ ./create-changelog.kts
# Paintera 0.18.0
Previous release: 0.18.0


## Changelog

### Other
 - Merge pull request #290 from uschmidt83/patch-1: Typo in Readme


## Pull Requests

### #290
Merge pull request #290 from uschmidt83/patch-1

Typo in Readme
```
It is the maintainers' (@saalfeldlab/lab @saalfeldlab/paintera @saalfeldlab/paintera-admin ) responsibility to add appropriate tags to the commit message when clicking the merge button.

A good workflow to trigger a new Paintera release would then be:
```
git checkout master && git pull
./create-changelog.kts > changelog.md
# modify changelog.md if necessary
scijava-scripts/release-version.sh # use version suggested by the changelog script if appropriate
# add changelog to release at https://github.com/saalfeldlab/paintera/releases
# modify generate-bash-completion.kts to use latest Paintera release
./generate-bash-completion.kts
# upload paintera_completion to release at https://github.com/saalfeldlab/paintera/releases
# modify generate-bash-completion.kts to use current SNAPSHOT version (can push directly to master for that one)
```

create-changelog.kts

@@ -0,0 +1,219 @@
+#!/usr/bin/env kscript
+
+@file:DependsOn("org.json:json:20180813")
+@file:DependsOn("org.apache.maven:maven-model:3.6.1")
+@file:DependsOn("org.eclipse.jgit:org.eclipse.jgit:5.4.0.201906121030-r")
+@file:DependsOn("org.slf4j:slf4j-simple:1.7.25")
+
+import org.apache.maven.model.io.xpp3.MavenXpp3Reader
+import org.eclipse.jgit.storage.file.FileRepositoryBuilder
+import org.json.JSONArray
+import org.json.JSONObject
+import java.io.BufferedReader
+import java.io.File
+import java.io.FileReader
+import java.net.HttpURLConnection
+import java.net.URL
+
+data class Change(
+		val sha: String,
+		val author: String,
+		val message: String,
+		val date: String) {
+	constructor(commit: JSONObject) : this(
+			sha = commit.getString("sha"),
+			author = (commit["author"] as JSONObject).getString("login"),
+			message = (commit["commit"] as JSONObject).getString("message"),
+			date = (((commit["commit"] as JSONObject)["author"] as JSONObject)).getString("date"))
+}
+
+fun versionFromString(str: String): Version {
+	return if (str.contains("-")) {
+		val split = str.split("-")
+		val Mmp = split[0].split(".").map { it.toInt() }.toIntArray()
+		Version(Mmp[0], Mmp[1], Mmp[2], split[1])
+	} else {
+		val Mmp = str.split(".").map { it.toInt() }.toIntArray()
+		Version(Mmp[0], Mmp[1], Mmp[2], null)
+	}
+}
+
+data class Version(
+		val major: Int,
+		val minor: Int,
+		val patch: Int,
+		val preRelease: String? = null) : Comparable<Version> {
+
+	val versionString = preRelease?.let { "$major.$minor.$patch-$preRelease" } ?: "$major.$minor.$patch"
+
+	override fun toString() = versionString
+
+	override fun compareTo(other: Version): Int {
+		val majorComp = major.compareTo(other.major)
+		if (majorComp != 0)
+			return majorComp
+		val minorComp = minor.compareTo(other.minor)
+		if (minorComp != 0)
+			return minorComp
+		val patchComp = patch.compareTo(other.patch)
+		if (patchComp != 0)
+			return patchComp
+		if (preRelease === null && other.preRelease != null)
+			return 1
+		if (other.preRelease === null && preRelease != null)
+			return -1
+		else if (other.preRelease === null && preRelease === null)
+			return 0
+		return preRelease!!.compareTo(other.preRelease!!)
+	}
+
+	fun bump(major: Boolean = false, minor: Boolean = false, patch: Boolean = false): Version {
+		if (major) return Version(this.major + 1, 0, 0, null)
+		if (minor) return Version(this.major, this.minor + 1, 0, null)
+		if (patch) return Version(this.major, this.minor, this.patch + 1, null)
+		return Version(this.major, this.minor, this.patch, this.preRelease)
+	}
+
+}
+
+val GITHUB_API_URL = "https://api.github.com";
+
+fun getTags(repo: String) = JSONArray(fromURL(URL("$GITHUB_API_URL/repos/$repo/tags"))).filterIsInstance<JSONObject>()
+
+fun getCommitTags(repo: String) = getTags(repo).filter { it.has("commit") }
+
+fun getParentsFromTag(repo: String, tag: JSONObject) = JSONObject(fromURL(URL("$GITHUB_API_URL/repos/$repo/commits/${(tag["commit"] as JSONObject)["sha"]}")))["parents"] as JSONArray
+
+fun getParentFromTag(repo: String, tag: JSONObject) = getParentsFromTag(repo, tag)
+		.also { require(it.length() == 1) { "Release tags must have exactly one parent but got $it" } }[0] as JSONObject
+
+fun compare(repo: String, shaFrom: String, shaTo: String): List<Change> {
+	val compareUrl = URL("$GITHUB_API_URL/repos/$repo/compare/$shaFrom...$shaTo")
+	val compareObj = JSONObject(fromURL(compareUrl))
+	val commits = compareObj["commits"] as JSONArray
+	return commits.map { Change(it as JSONObject) }
+}
+
+
+fun fromURL(url: URL): String {
+	val conn = url.openConnection() as HttpURLConnection;
+	conn.setRequestMethod("GET");
+	conn.setRequestProperty("Accept", "application/json");
+
+	if (conn.getResponseCode() != 200)
+		throw RuntimeException("Failed : HTTP error code : ${conn.responseCode}")
+
+	val br = conn.inputStream.bufferedReader();
+	val text = br.use(BufferedReader::readText)
+	conn.disconnect()
+	return text
+}
+
+fun generateChangelog() {
+
+	val reader = MavenXpp3Reader()
+	val model = FileReader("pom.xml").use { reader.read(it) }
+	val isSnapshot = model.version.contains("-SNAPSHOT")
+	val version = versionFromString(model.version)
+
+	val tags = getCommitTags("saalfeldlab/paintera").filter {
+		try {
+			versionFromString(it.getString("name").replace("paintera-", ""))
+			true
+		} catch (e: Exception) {
+			false
+		}
+	}
+
+	val repo = FileRepositoryBuilder().setGitDir(File(".git")).build()
+	val head = repo.resolve("HEAD")
+	val commitTo = if (isSnapshot) {
+		head.name
+	} else {
+		"paintera-${model.version}"
+				.takeUnless { t -> tags.count { it.getString("name") == t } == 0 }
+				?: head.name
+	}
+
+	val tagFrom = tags.first { versionFromString(it.getString("name").replace("paintera-", "")) < version }
+	val commitFrom = getParentFromTag("saalfeldlab/paintera", tagFrom)
+	val relevantCommits = compare(
+			repo = "saalfeldlab/paintera",
+			shaFrom = commitFrom.getString("sha"),
+			shaTo = commitTo)
+	val mergeCommits = relevantCommits.filter { it.message.startsWith("Merge pull request #") }
+
+	val breaking = mutableListOf<String>()
+	val features = mutableListOf<String>()
+	val fixes = mutableListOf<String>()
+	val unversioned = mutableListOf<String>()
+	val visitedCommits = mutableSetOf<String>()
+	val pullRequests = mutableListOf<Pair<Int, String>>()
+
+	val regex = "Merge pull request #([0-9]+)".toRegex()
+
+	for (commit in mergeCommits) {
+		if (visitedCommits.contains(commit.sha)) continue
+		visitedCommits.add(commit.sha)
+		val lines = commit.message.lines()
+		val matchResult = regex.find(lines[0])
+		val pullRequestNumber = if (matchResult === null) {
+			-1
+		} else {
+			matchResult.groupValues[1].toInt()
+		}
+		pullRequests += Pair(pullRequestNumber, commit.message)
+		var isAnything = false
+		for (line in lines) {
+			var l = line
+			val isBreaking = if (l.contains("[BREAKING]")) {
+				l = l.replace("[BREAKING]", "").trim()
+				true
+			} else false
+			val isFeature = if (l.contains("[FEATURE]")) {
+				l = l.replace("[FEATURE]", "").trim()
+				true
+			} else false
+			val isBugfix = if (l.contains("[BUGFIX]")) {
+				l = l.replace("[BUGFIX]", "").trim()
+				true
+			} else false
+			val isUnversioned = if (l.contains("[UNVERSIONED]")) {
+				l = l.replace("[UNVERSIONED]", "").trim()
+				true
+			} else false
+			isAnything = isBreaking || isFeature || isBugfix || isUnversioned
+			if (pullRequestNumber > 0) l = "$l (#$pullRequestNumber)"
+			if (isBreaking) breaking.add(l)
+			if (isFeature) features.add(l)
+			if (isBugfix) fixes.add(l)
+			if (isUnversioned) unversioned.add(l)
+		}
+		if (!isAnything) {
+			unversioned.add(commit.message.replace("\n+".toRegex(), ": "))
+		}
+	}
+
+	val versionFrom = versionFromString(tagFrom.getString("name").replace("paintera-", ""))
+	val suggestedVersion = versionFrom.bump(major = !breaking.isEmpty(), minor = !features.isEmpty(), patch = !fixes.isEmpty())
+
+	var text = "# Paintera $suggestedVersion\nPrevious release: $versionFrom\n\n\n## Changelog"
+
+	if (!breaking.isEmpty())
+		text = "$text\n\n### Breaking Changes${breaking.map { "\n - $it" }.joinToString("")}"
+
+	if (!features.isEmpty())
+		text = "$text\n\n### New Features${features.map { "\n - $it" }.joinToString("")}"
+
+	if (!fixes.isEmpty())
+		text = "$text\n\n### Bug Fixes${fixes.map { "\n - $it" }.joinToString("")}"
+
+	if (!unversioned.isEmpty())
+		text = "$text\n\n### Other${unversioned.map { "\n - $it" }.joinToString("")}"
+	val pullRequestStrings = pullRequests.map { "### #${it.first}\n${it.second}" }
+	text = "$text\n\n\n## Pull Requests\n\n${pullRequestStrings.joinToString("\n\n")}"
+
+	println(text)
+}
+
+generateChangelog()