build(docs): introduce release script

This change introduces a new NPM run script to automatically generate
the release changelog, as well as bump version numbers across the
code-base and create the release tag.

This script runs [Standard Version] to execute this, which is a tool
designed around automating substantial parts of the release process.
This can be done by running:

    npm run release -- [<standard-version args>]

Standard Version expects the project to adhere to the [Semantic
Versioning] convention which TF-A does not, so you may need to specify
the version manually, e.g.:

    npm run release -- --release-as 2.6.0

Individual steps of the release process may also be skipped at-will,
which may be necessary when, for example, tweaking the changelog:

    npm run release -- --skip.commit --skip.tag

Standard Version is configured by the `.versionrc.js` file, which
contains information about the Conventional Commits types and scopes
used by the project, and how they map to the changelog.

To maintain continuity with the existing changelog style - at least to
the extent possible in the move from manual to automatic creation - a
customized changelog template has been introduced, based on the
Conventional Commits template provided by Standard Version.

This template package extends the Conventional Commits template package
by introducing support for parsing the Conventional Commits scopes into
changelog sections, similarly to how they were previously organized.

[Standard Version]:
https://github.com/conventional-changelog/standard-version
[Semantic Versioning]: https://semver.org

Change-Id: I5bafa512daedc631baae951651c38c1c62046b0a
Signed-off-by: Chris Kay <chris.kay@arm.com>

9 files changed, 304 insertions, 0 deletions

diff --git a/tools/conventional-changelog-tf-a/index.js b/tools/conventional-changelog-tf-a/index.js
new file mode 100644
index 000000000..2a9d5b4d8
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/index.js
@@ -0,0 +1,222 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/* eslint-env es6 */
+
+"use strict";
+
+const Handlebars = require("handlebars");
+const Q = require("q");
+const _ = require("lodash");
+
+const ccConventionalChangelog = require("conventional-changelog-conventionalcommits/conventional-changelog");
+const ccParserOpts = require("conventional-changelog-conventionalcommits/parser-opts");
+const ccRecommendedBumpOpts = require("conventional-changelog-conventionalcommits/conventional-recommended-bump");
+const ccWriterOpts = require("conventional-changelog-conventionalcommits/writer-opts");
+
+const execa = require("execa");
+
+const readFileSync = require("fs").readFileSync;
+const resolve = require("path").resolve;
+
+/*
+ * Register a Handlebars helper that lets us generate Markdown lists that can support multi-line
+ * strings. This is driven by inconsistent formatting of breaking changes, which may be multiple
+ * lines long and can terminate the list early unintentionally.
+ */
+Handlebars.registerHelper("tf-a-mdlist", function (indent, options) {
+    const spaces = new Array(indent + 1).join(" ");
+    const first = spaces + "- ";
+    const nth = spaces + "  ";
+
+    return first + options.fn(this).replace(/\n(?!\s*\n)/gm, `\n${nth}`).trim() + "\n";
+});
+
+/*
+ * Register a Handlebars helper that concatenates multiple variables. We use this to generate the
+ * title for the section partials.
+ */
+Handlebars.registerHelper("tf-a-concat", function () {
+    let argv = Array.prototype.slice.call(arguments, 0);
+
+    argv.pop();
+
+    return argv.join("");
+});
+
+function writerOpts(config) {
+    /*
+     * Flatten the configuration's sections list. This helps us iterate over all of the sections
+     * when we don't care about the hierarchy.
+     */
+
+    const flattenSections = function (sections) {
+        return sections.flatMap(section => {
+            const subsections = flattenSections(section.sections || []);
+
+            return [section].concat(subsections);
+        })
+    };
+
+    const flattenedSections = flattenSections(config.sections);
+
+    /*
+     * Register a helper to return a restructured version of the note groups that includes notes
+     * categorized by their section.
+     */
+    Handlebars.registerHelper("tf-a-notes", function (noteGroups, options) {
+        const generateTemplateData = function (sections, notes) {
+            return (sections || []).flatMap(section => {
+                const templateData = {
+                    title: section.title,
+                    sections: generateTemplateData(section.sections, notes),
+                    notes: notes.filter(note => section.scopes?.includes(note.commit.scope)),
+                };
+
+                /*
+                 * Don't return a section if it contains no notes and no sub-sections.
+                 */
+                if ((templateData.sections.length == 0) && (templateData.notes.length == 0)) {
+                    return [];
+                }
+
+                return [templateData];
+            });
+        };
+
+        return noteGroups.map(noteGroup => {
+            return {
+                title: noteGroup.title,
+                sections: generateTemplateData(config.sections, noteGroup.notes),
+                notes: noteGroup.notes.filter(note =>
+                    !flattenedSections.some(section => section.scopes?.includes(note.commit.scope))),
+            };
+        });
+    });
+
+    /*
+     * Register a helper to return a restructured version of the commit groups that includes commits
+     * categorized by their section.
+     */
+    Handlebars.registerHelper("tf-a-commits", function (commitGroups, options) {
+        const generateTemplateData = function (sections, commits) {
+            return (sections || []).flatMap(section => {
+                const templateData = {
+                    title: section.title,
+                    sections: generateTemplateData(section.sections, commits),
+                    commits: commits.filter(commit => section.scopes?.includes(commit.scope)),
+                };
+
+                /*
+                 * Don't return a section if it contains no notes and no sub-sections.
+                 */
+                if ((templateData.sections.length == 0) && (templateData.commits.length == 0)) {
+                    return [];
+                }
+
+                return [templateData];
+            });
+        };
+
+        return commitGroups.map(commitGroup => {
+            return {
+                title: commitGroup.title,
+                sections: generateTemplateData(config.sections, commitGroup.commits),
+                commits: commitGroup.commits.filter(commit =>
+                    !flattenedSections.some(section => section.scopes?.includes(commit.scope))),
+            };
+        });
+    });
+
+    const writerOpts = ccWriterOpts(config)
+        .then(writerOpts => {
+            const ccWriterOptsTransform = writerOpts.transform;
+
+            /*
+             * These configuration properties can't be injected directly into the template because
+             * they themselves are templates. Instead, we register them as partials, which allows
+             * them to be evaluated as part of the templates they're used in.
+             */
+            Handlebars.registerPartial("commitUrl", config.commitUrlFormat);
+            Handlebars.registerPartial("compareUrl", config.compareUrlFormat);
+            Handlebars.registerPartial("issueUrl", config.issueUrlFormat);
+
+            /*
+             * Register the partials that allow us to recursively create changelog sections.
+             */
+
+            const notePartial = readFileSync(resolve(__dirname, "./templates/note.hbs"), "utf-8");
+            const noteSectionPartial = readFileSync(resolve(__dirname, "./templates/note-section.hbs"), "utf-8");
+            const commitSectionPartial = readFileSync(resolve(__dirname, "./templates/commit-section.hbs"), "utf-8");
+
+            Handlebars.registerPartial("tf-a-note", notePartial);
+            Handlebars.registerPartial("tf-a-note-section", noteSectionPartial);
+            Handlebars.registerPartial("tf-a-commit-section", commitSectionPartial);
+
+            /*
+             * Override the base templates so that we can generate a changelog that looks at least
+             * similar to the pre-Conventional Commits TF-A changelog.
+             */
+            writerOpts.mainTemplate = readFileSync(resolve(__dirname, "./templates/template.hbs"), "utf-8");
+            writerOpts.headerPartial = readFileSync(resolve(__dirname, "./templates/header.hbs"), "utf-8");
+            writerOpts.commitPartial = readFileSync(resolve(__dirname, "./templates/commit.hbs"), "utf-8");
+            writerOpts.footerPartial = readFileSync(resolve(__dirname, "./templates/footer.hbs"), "utf-8");
+
+            writerOpts.transform = function (commit, context) {
+                /*
+                 * Fix up commit trailers, which for some reason are not correctly recognized and
+                 * end up showing up in the breaking changes.
+                 */
+
+                commit.notes.forEach(note => {
+                    const trailers = execa.sync("git", ["interpret-trailers", "--parse"], {
+                        input: note.text
+                    }).stdout;
+
+                    note.text = note.text.replace(trailers, "").trim();
+                });
+
+                return ccWriterOptsTransform(commit, context);
+            };
+
+            return writerOpts;
+        });
+
+    return writerOpts;
+}
+
+module.exports = function (parameter) {
+    const config = parameter || {};
+
+    return Q.all([
+        ccConventionalChangelog(config),
+        ccParserOpts(config),
+        ccRecommendedBumpOpts(config),
+        writerOpts(config)
+    ]).spread((
+        conventionalChangelog,
+        parserOpts,
+        recommendedBumpOpts,
+        writerOpts
+    ) => {
+        if (_.isFunction(parameter)) {
+            return parameter(null, {
+                gitRawCommitsOpts: { noMerges: null },
+                conventionalChangelog,
+                parserOpts,
+                recommendedBumpOpts,
+                writerOpts
+            });
+        } else {
+            return {
+                conventionalChangelog,
+                parserOpts,
+                recommendedBumpOpts,
+                writerOpts
+            };
+        }
+    });
+};
diff --git a/tools/conventional-changelog-tf-a/package.json b/tools/conventional-changelog-tf-a/package.json
new file mode 100644
index 000000000..3ad853d51
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/package.json
@@ -0,0 +1,12 @@
+{
+  "name": "conventional-changelog-tf-a",
+  "version": "1.0.0",
+  "private": true,
+  "main": "index.js",
+  "dependencies": {
+    "conventional-changelog-conventionalcommits": "^4.6.1",
+    "execa": "^5.1.1",
+    "lodash": "^4.17.21",
+    "q": "^1.5.1"
+  }
+}
diff --git a/tools/conventional-changelog-tf-a/templates/commit-section.hbs b/tools/conventional-changelog-tf-a/templates/commit-section.hbs
new file mode 100644
index 000000000..86b33351a
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/templates/commit-section.hbs
@@ -0,0 +1,17 @@
+{{#if title ~}}
+{{ header }}
+
+{{#if commits.length ~}}
+  {{#each commits ~}}
+    {{#tf-a-mdlist 0}}{{> commit root=@root showScope=../topLevel }}{{/tf-a-mdlist ~}}
+  {{/each}}
+
+{{/if ~}}
+
+{{#if sections.length ~}}
+  {{#each sections ~}}
+    {{#tf-a-mdlist 0}}{{> tf-a-commit-section root=@root header=(tf-a-concat "**" title "**") }}{{/tf-a-mdlist}}
+  {{/each}}
+{{/if ~}}
+
+{{/if}}
diff --git a/tools/conventional-changelog-tf-a/templates/commit.hbs b/tools/conventional-changelog-tf-a/templates/commit.hbs
new file mode 100644
index 000000000..faf264a32
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/templates/commit.hbs
@@ -0,0 +1,15 @@
+{{#if scope }}
+  {{~#if showScope }}**{{ scope }}:** {{/if}}
+{{~/if}}
+
+{{~#if subject }}
+  {{~ subject }}
+{{~else}}
+  {{~ header }}
+{{~/if}}
+
+{{~#if hash }} {{#if @root.linkReferences ~}}
+  ([{{ shortHash }}]({{> commitUrl root=@root }}))
+{{~else}}
+  {{~ shortHash }}
+{{~/if}}{{~/if}}
diff --git a/tools/conventional-changelog-tf-a/templates/footer.hbs b/tools/conventional-changelog-tf-a/templates/footer.hbs
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/templates/footer.hbs
diff --git a/tools/conventional-changelog-tf-a/templates/header.hbs b/tools/conventional-changelog-tf-a/templates/header.hbs
new file mode 100644
index 000000000..67cb297e0
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/templates/header.hbs
@@ -0,0 +1,13 @@
+{{#if isPatch~}}
+  ###
+{{~else~}}
+  ##
+{{~/if}} {{#if @root.linkCompare~}}
+  [{{version}}]({{> compareUrl root=@root}})
+{{~else}}
+  {{~version}}
+{{~/if}}
+{{~#if title}} "{{title}}"
+{{~/if}}
+{{~#if date}} ({{date}})
+{{/if}}
diff --git a/tools/conventional-changelog-tf-a/templates/note-section.hbs b/tools/conventional-changelog-tf-a/templates/note-section.hbs
new file mode 100644
index 000000000..f501c9647
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/templates/note-section.hbs
@@ -0,0 +1,13 @@
+{{ header }}
+
+{{#if notes.length ~}}
+  {{#each notes ~}}
+    {{#tf-a-mdlist 0}}{{> tf-a-note root=@root showScope=../topLevel }}{{/tf-a-mdlist}}
+  {{/each ~}}
+{{/if ~}}
+
+{{#if sections.length ~}}
+  {{#each sections ~}}
+    {{#tf-a-mdlist 0}}{{> tf-a-note-section root=@root header=(tf-a-concat "**" title "**") }}{{/tf-a-mdlist}}
+  {{/each~}}
+{{/if}}
diff --git a/tools/conventional-changelog-tf-a/templates/note.hbs b/tools/conventional-changelog-tf-a/templates/note.hbs
new file mode 100644
index 000000000..c780ee854
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/templates/note.hbs
@@ -0,0 +1,3 @@
+{{ text }}
+
+**See:** {{#with commit }}{{> commit root=@root showScope=../showScope }}{{/with}}
diff --git a/tools/conventional-changelog-tf-a/templates/template.hbs b/tools/conventional-changelog-tf-a/templates/template.hbs
new file mode 100644
index 000000000..95fb68c4c
--- /dev/null
+++ b/tools/conventional-changelog-tf-a/templates/template.hbs
@@ -0,0 +1,9 @@
+{{> header }}
+
+{{#each (tf-a-notes noteGroups) ~}}
+{{> tf-a-note-section root=@root header=(tf-a-concat "### ⚠ " title) topLevel=true }}
+{{/each ~}}
+
+{{#each (tf-a-commits commitGroups) ~}}
+{{> tf-a-commit-section root=@root header=(tf-a-concat "### " title) topLevel=true }}
+{{/each ~}}