feat: support multiple branches and distribution channels

- Allow to configure multiple branches to release from
- Allow to define a distribution channel associated with each branch
- Manage the availability on distribution channels based on git merges
- Support regular releases, maintenance releases and pre-releases
- Add the `addChannel` plugin step to make an existing release available on a different distribution channel

BREAKING CHANGE: the `branch` option has been removed in favor of `branches`

The new `branches` option expect either an Array or a single branch definition. To migrate your configuration:
- If you want to publish package from multiple branches, please the configuration documentation
- If you use the default configuration and want to publish only from `master`: nothing to change
- If you use the `branch` configuration and want to publish only from one branch: replace `branch` by `branches` (`"branch": "my-release-branch"` => `"branches": "my-release-branch"`)

lib/utils.js

@@ -1,4 +1,5 @@
-const {isFunction} = require('lodash');
+const {isFunction, union, template} = require('lodash');
+const semver = require('semver');
 const hideSensitive = require('./hide-sensitive');
 
 function extractErrors(err) {
@@ -17,4 +18,71 @@ function hideSensitiveValues(env, objs) {
   });
 }
 
-module.exports = {extractErrors, hideSensitiveValues};
+function tagsToVersions(tags) {
+  return tags.map(({version}) => version);
+}
+
+function isMajorRange(range) {
+  return /^\d\.x(?:\.x)?$/i.test(range);
+}
+
+function isMaintenanceRange(range) {
+  return /^\d\.[\dx](?:\.x)?$/i.test(range);
+}
+
+function getUpperBound(range) {
+  return semver.valid(range) ? range : ((semver.validRange(range) || '').match(/<(\d\.\d\.\d)$/) || [])[1];
+}
+
+function getLowerBound(range) {
+  return ((semver.validRange(range) || '').match(/(\d\.\d\.\d)/) || [])[1];
+}
+
+function highest(version1, version2) {
+  return version1 && version2 ? (semver.gt(version1, version2) ? version1 : version2) : version1 || version2;
+}
+
+function lowest(version1, version2) {
+  return version1 && version2 ? (semver.lt(version1, version2) ? version1 : version2) : version1 || version2;
+}
+
+function getLatestVersion(versions, {withPrerelease} = {}) {
+  return versions.filter(version => withPrerelease || !semver.prerelease(version)).sort(semver.rcompare)[0];
+}
+
+function getEarliestVersion(versions, {withPrerelease} = {}) {
+  return versions.filter(version => withPrerelease || !semver.prerelease(version)).sort(semver.compare)[0];
+}
+
+function getFirstVersion(versions, lowerBranches) {
+  const lowerVersion = union(...lowerBranches.map(({tags}) => tagsToVersions(tags))).sort(semver.rcompare);
+  if (lowerVersion[0]) {
+    return versions.sort(semver.compare).find(version => semver.gt(version, lowerVersion[0]));
+  }
+  return getEarliestVersion(versions);
+}
+
+function getRange(min, max) {
+  return `>=${min}${max ? ` <${max}` : ''}`;
+}
+
+function makeTag(tagFormat, version, channel) {
+  return template(tagFormat)({version: `${version}${channel ? `@${channel}` : ''}`});
+}
+
+module.exports = {
+  extractErrors,
+  hideSensitiveValues,
+  tagsToVersions,
+  isMajorRange,
+  isMaintenanceRange,
+  getUpperBound,
+  getLowerBound,
+  highest,
+  lowest,
+  getLatestVersion,
+  getEarliestVersion,
+  getFirstVersion,
+  getRange,
+  makeTag,
+};