add changelog script git-log.js and gitignore python virtual environments (#6092)

* add changelog script git-log.js

* apply PR feedback and remove HISTORY.md

.gitignore

@@ -17,3 +17,6 @@ bones/
 .vs/
 .vscode/
 .config/
+
+# Python virtual environments
+**/*env/

tools/changelog/.gitignore

@@ -0,0 +1,3 @@
+# Ignore input and output files for git-log.js
+*.txt
+*.md

tools/changelog/README.md

@@ -0,0 +1,55 @@
+# Generating repository changelogs
+
+This script uses the developer's clone of the repository to generate a changelog via `git log`.
+
+## Requirements:
+- Node.js > 10.0.0
+- Current clone of https://github.com/microsoft/botframework-sdk
+- Current clone of the repository and branch to generate a changelog from
+
+## Preferred setup:
+- **Each repository should only permit squash merges**
+  - In most scenarios, the developer calling the script will need to manually update the final contents with better descriptions.
+  - If the repository accepts all PR merge types, the developer will need to perform more manual edits due to the commit messages. 
+  - Squash merges on GitHub result in commit messages like the following: `"Fix fetch in token server used in E2E Streaming Test (#2944)"`
+  - Other merges will result in commit messages such as: `"Merge pull request #1411 from <fork/branch>"`
+  - This results in a non-descriptive format:
+  ```md
+  - Merge pull request #4661 from microsoft/johtaylo/private-cloud-patch [[PR 4661]](https://github.com/microsoft/botbuilder-dotnet/pull/4661)
+  ```
+- **Developers should generate the changelog from the branch that is about to be released**
+  - Instead of generating it on the default or development branch (e.g `main`), the script should be run on the version branch (e.g. `4.11`).
+
+## Steps
+_The steps below use [botbuilder-dotnet](https://github.com/microsoft/botbuilder-dotnet) as an example._
+- Clone the target repository and switch to the selected branch for generating a changelog.
+  - `git clone -b 4.11 https://github.com/microsoft/botbuilder-dotnet && cd botbuilder-dotnet`
+- Run `git log` with the following flags and arguments.
+  - `git log --show-pulls --pretty=tformat:"%s" c6ff4a4.. > dotnet.txt`
+  - `c6ff4a4..` represents the desired range of commits to log **after commit `c6ff4a4`**.
+  - In this example, `c6ff4a4` was the latest commit included in the previous changelog. 
+- Move the `dotnet.txt` file to the folder containing [git-log.js](./git-log.js).
+- Navigate to `botframework-sdk\tools\changelog` in your CLI.
+- Execute the following command to generate the changelog.
+  - `node git-log.js dotnet.txt`
+  - With this command, the changelog can be found as `dotnet.md`.
+  - `git-log.js` takes an optional second argument which is used as the filename for the output. (Note: the files content will still be [Markdown](https://daringfireball.net/projects/markdown))
+
+The contents of the file should look like the following snippet generated for the 4.11.0 release of the Bot Framework SDK for .NET:
+
+```md
+- Teams: MeetingParticipantInfo.InMeeting might be null, if unknown [[PR 4868]](https://github.com/microsoft/botbuilder-dotnet/pull/4868)
+- Fix issues with ExpectReplies and Invoke [[PR 4845]](https://github.com/microsoft/botbuilder-dotnet/pull/4845)
+- Enable middleware in TestScript and refactor BeginSkill tests [[PR 4866]](https://github.com/microsoft/botbuilder-dotnet/pull/4866)
+```
+
+## Questions and Help
+For bug reports, feature requests or other feedback, please file an issue in https://github.com/microsoft/botframework-sdk.
+
+## Additional reading
+- [About merge methods on GitHub](https://docs.github.com/en/free-pro-team@latest/github/administering-a-repository/about-merge-methods-on-github)
+  - [Squashing your merge commits](https://docs.github.com/en/free-pro-team@latest/github/administering-a-repository/about-merge-methods-on-github#squashing-your-merge-commits)
+- [Configuring commit squashing for pull requests](https://docs.github.com/en/free-pro-team@latest/github/administering-a-repository/configuring-commit-squashing-for-pull-requests)
+- [Git - git-log Documentation](https://git-scm.com/docs/git-log)
+  - [Commit Limiting](https://git-scm.com/docs/git-log#_commit_limiting) (e.g. `--since`, `--before` options)
+- [Git - gitrevisions Documentation](https://git-scm.com/docs/gitrevisions)

tools/changelog/git-log.js

@@ -0,0 +1,87 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+const { createReadStream, createWriteStream, existsSync } = require('fs');
+const { once } = require('events');
+const { join } = require('path');
+const { argv, exit } = require('process');
+const { createInterface } = require('readline');
+
+// Remove first two elements from argv, which are `node` and `script.js`.
+// Currently the script takes two arguments, which are assigned to
+// gitLogFromRepo and optionalOutputName.
+const [ gitLogFromRepo, optionalOutputName ] = argv.slice(2);
+
+if (!gitLogFromRepo) {
+    throw new TypeError('The captured output of `git log` must be passed in.');
+}
+
+if (!existsSync(join(__dirname, gitLogFromRepo))) {
+    throw new ReferenceError(`The provided file "${gitLogFromRepo}" was not found in ${__dirname}`);
+}
+
+// Determine the changelogFile (which contains the formatted merges to main)
+// and the repository URL.
+let changelogFile;
+let repository;
+if (gitLogFromRepo.startsWith('dotnet')) {
+    changelogFile = optionalOutputName || 'dotnet.md';
+    repository = 'botbuilder-dotnet';
+} else if (gitLogFromRepo.startsWith('js')) {
+    changelogFile = optionalOutputName || 'js.md';
+    repository = 'botbuilder-js';
+} else if (gitLogFromRepo.startsWith('python')) {
+    changelogFile = optionalOutputName || 'python.md';
+    repository = 'botbuilder-python';
+} else if (gitLogFromRepo.startsWith('java')) {
+    changelogFile = optionalOutputName || 'java.md';
+    repository = 'botbuilder-java';
+} else if (gitLogFromRepo.startsWith('bf-cli')) {
+    changelogFile = optionalOutputName || 'bf-cli.md';
+    repository = 'botframework-cli';
+}
+
+// git log --show-pulls --pretty=tformat:"%s" --since=2020-08-13 > dotnet.txt
+// git log --show-pulls --pretty=tformat:"%s" --since=2020-08-07 > js.txt
+// git log --show-pulls --pretty=tformat:"%s" --since=2020-08-10 > python.txt
+// git log --show-pulls --pretty=tformat:"%s" --since=2020-08-17 > java.txt
+// git log --show-pulls --pretty=tformat:"%s" --since=2020-08-10 > bf-cli.txt
+
+const preparedStream = createWriteStream(changelogFile);
+(async function processLineByLine() {
+  try {
+    const rl = createInterface({
+      input: createReadStream(gitLogFromRepo),
+      crlfDelay: Infinity
+    });
+    
+    rl.on('line', (line) => {
+        // Check for squash merges first. This generates a bulletpoint that
+        // by default uses the title of the PR and appends the PR number to
+        // the end of the commit message.
+        // E.g. "Fix fetch in token server used in E2E Streaming Test (#2944)"
+        const matches = /(?<message>.*)\s\(#(?<num>\d*)\)$/gim.exec(line);
+        if (matches) {
+            const { message, num } = matches.groups;
+            preparedStream.write(`- ${message} [[PR ${num}]](https://github.com/microsoft/${repository}/pull/${num})\n`);
+        } else {
+            // This second check is for PRs that were not squashed and merged.
+            // E.g. "Merge pull request #1411 from <fork/branch>"
+            const otherFormatMatches = /^(?<message>Merge pull request #(?<num>\d*) from.*)/gim.exec(line);
+            if (otherFormatMatches) {
+                const { message, num } = otherFormatMatches.groups;
+                preparedStream.write(`- ${message} [[PR ${num}]](https://github.com/microsoft/${repository}/pull/${num})\n`)
+            }
+        }
+    });
+
+    await once(rl, 'close');
+    console.log(`Changelog "${changelogFile}" created.`);
+  } catch (err) {
+    const errMsgPrefix = `An error occurred during the creation of the changelog.
+Please file an issue in https://github.com/microsoft/botframework-sdk and provide the necessary reproduction steps.\n`
+    console.error(errMsgPrefix);
+    console.error(err);
+    exit(1);
+  }
+})();