# IntelliJ Platform Plugin Template

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<!-- Plugin description -->
**IntelliJ Platform Plugin Template** is a repository that provides a pure boilerplate for creating a plugin project
with ease designed as a **GitHub Template Repository** (check the [Creating a repository from a template][gh-template]
article).

The main goal for this Template is to speed up the setup phase of the plugin development for the new as well as existing
developers by preconfiguring the project scaffold, CI and linking to the proper documentation pages and keeping
everything in the most straightforward manner.
<!-- Plugin description end -->

If you're still not sure, what is this about - read our introduction of [What is the IntelliJ Platform?][docs:intro]

We can highlight the following parts of the template project:

- [Gradle Configuration](#gradle-configuration)
- [Plugin Manifest File](#plugin-manifest-file)
- [Sample Code](#sample-code):
  - listeners - project and dynamic plugin lifecycle
  - services - project- and application-related services 
  - actions - basic action with shortcut binding
- [Continuous Integration](#continuous-integration) based on the GitHub Actions
- [Release Flow](#release-flow) using the GitHub Releases
- [Changelog Maintenance](#changelog) with the Gradle Changelog Plugin
- [Publishing Plugin](#publishing-plugin) with the Gradle IntelliJ Plugin

## Getting Started

Before diving into the plugin development and everything that happens around, it is worth mentioning the fundamental
idea behind the GitHub Templates: by creating a new project using the current template, you start with no history
and no reference to this repository - it is the cut corner for creating a new repository with copy-pasting the content
or cloning repositories and clearing the history by your own.

The only thing that you have to do is clicking the <kbd>Use this template</kbd> button.

![Use this template][file:getting-started_use-this-template.png]

After creating your blank project from the template, there will be the [Template Cleanup][file:template_cleanup.yml]
workflow triggered to override or remove the template-specific configuration, like plugin name, current changelog, etc.
When done, project is ready to be cloned on your local environment and opened with the [IntelliJ IDEA][download-ij].

As the last step, you have to manually review the configuration variables described in the
[gradle.properties][file:gradle.properties] file, *optionally* move sources from the *com.github.username.repository*
package to the one that fits you the most and start implementing your ideas.

## Gradle Configuration

The recommended way of the plugin development is using the [Gradle][gradle] setup with
[gradle-intellij-plugin][gradle-intellij-plugin] installed. The gradle-intellij-plugin provides tasks to run the IDE
with your plugin and to publish your plugin to the Marketplace Repository. 

IntelliJ Platform Plugin Template project provides already preconfigured Gradle configuration, however feel free
to follow the [Using Gradle][docs:using-gradle] articles for better understanding and customisation of your build.

The most significant parts of the current configuration are:
- Configuration written with [Gradle Kotlin DSL][gradle-kotlin-dsl]
- Kotlin support with possibility to write Java code
- Integration with [gradle-changelog-plugin][gradle-changelog-plugin] for the automated patching of the change notes and
  description consumed from `CHANGELOG.md` and `README.md` files
- Integration with [gradle-intellij-plugin][gradle-intellij-plugin] for the better development impressions
- Code linting with [detekt][detekt]
- [Plugin publishing][docs:publishing] using token

Project specific configuration file - [gradle.properties][file:gradle.properties] - contains:

```properties
pluginGroup = org.jetbrains.plugins.template
pluginName = Template
pluginVersion = 0.0.2
pluginSinceBuild = 193
pluginUntilBuild = 202

platformType = IC
platformVersion = 2020.1
platformDownloadSources = true
```

| Property name             | Description                                                                           |
| ------------------------- | ------------------------------------------------------------------------------------- |
| `pluginGroup`             | Package name - after *using* the template, will be set to `com.gtihub.username.repo`. |
| `pluginName`              | Name of the plugin displayed in the Marketplace and Plugins Repository.               |
| `pluginVersion`           | Current version of the plugin.                                                        |
| `pluginSinceBuild`        | `since-build` attribute of the <idea-version> tag.                                    |
| `pluginUntilBuild`        | `until-build` attribute of the <idea-version> tag.                                    |
| `platformType`            | The type of IDE distribution.                                                         |
| `platformVersion`         | The version of the IntelliJ Platform IDE that will be used to build the plugin.       |
| `platformDownloadSources` | Download IDE sources while initializing Gradle build.                                 |

Listed properties define the plugin itself or configure the [gradle-intellij-plugin][gradle-intellij-plugin] - check
its documentation for more details. 

## Plugin Template Structure

Generated IntelliJ Template repository contains following content structure:

```
.
├── CHANGELOG.md            Full changes history.
├── LICENSE                 License, MIT by default
├── README.md               README
├── build                   Output build directory
├── build.gradle.kts        Gradle configuration
├── detekt-config.yml       Detekt configuration
├── gradle
│   └── wrapper             Gradle Wrapper
├── gradle.properties       Gradle configuration properties
├── gradlew                 *nix Gradle Wrapper binary
├── gradlew.bat             Windows Gradle Wrapper binary
└── src                     Plugin sources
    └── main
        ├── kotlin          Kotlin source files
        ├── java            Java source files
        └── resources       Resources - plugin.xml, icons, messages
```

Beside of the configuration files, the most important part is the `src` directory containing our implementation
and plugin's manifest - [plugin.xml][file:plugin.xml].

## Plugin Configuration File

Plugin Configuration File is a [plugin.xml][file:plugin.xml] file located in the `src/main/resources/META-INF`
directory. It describes the overall information about the plugin, its dependencies, extensions, and listeners.

```xml
<idea-plugin>
    <id>org.jetbrains.plugins.template</id>
    <name>Template</name>
    <vendor>JetBrains</vendor>
    <depends>com.intellij.modules.platform</depends>

    <extensions defaultExtensionNs="com.intellij">
        <applicationService serviceImplementation="..."/>
        <projectService serviceImplementation="..."/>
    </extensions>

    <projectListeners>
        <listener class="..." topic="..."/>
    </projectListeners>
</idea-plugin>
```

You can read more about that file in [IntelliJ Platform SDK DevGuide][docs:plugin.xml].

## Sample Code

The prepared template is aiming to provide as less code as possible, because it is barely possible to fulfill
the requirements of the various types of the plugins (language support, build tools, VCS related tools) with some
general scaffold. Having that in mind, it contains few following files:

```
.
├── MyBundle.kt                         Bundle class providing access to the resources messages
├── listeners
│   ├── MyDynamicPluginListener.kt      Dynamic Plugin listener - handles plugin lifecycle events
│   └── MyProjectManagerListener.kt     Project Manager listener - handles project lifecycle
└── services
    ├── MyApplicationService.kt         Application level service available for all projects
    └── MyProjectService.kt             Project level service
```

Above files location is `src/main/kotlin`, which indicates the used language - if you will decide to use Java instead,
sources should be located in `src/main/java` directory. 

## Continuous Integration

Continuous Integration depends on the GitHub Actions, which is a set of workflows 

Unit tests
Detekt
verifyPlugin
intellij-plugin-verifier

## Release Flow

### Changelog

When delivering a new release, it is essential to let your audience know what the updated version offering is.
The best way of handling that is to attach the changelog.

The changelog is a curated list containing information of any new features, fixes, deprecations.
If provided, such list would be available in a couple of places: [CHANGELOG.md](./CHANGELOG.md) file,
[Releases page][releases], [What's new][marketplace-plugin-page] section in Marketplace's Plugin page
and inside of the Plugin Manager's item details. 
There are many different methods of handling the project's changelog. One of them, used in the current template project,
is the [Keep a Changelog][keep-a-changelog] approach.

## Publishing Plugin

Cannot find org.jetbrains.plugins.template. Note that you need to upload the plugin to the repository at least once manually (to specify options like the license, repository URL etc.). Follow the instructions: https://www.jetbrains.org/intellij/sdk/docs/basics/getting_started/publishing_plugin.html

## Useful Links

- [IntelliJ Platform SDK DevGuide][docs]
- [IntelliJ Platform UI Guidelines][ij-ui-guidelines]
- [Kotlin UI DSL][docs:kotlin-ui-dsl]
- [IntelliJ SDK Code Samples][code-samples]
- [JetBrains Platform Slack][slack]
- [IntelliJ IDEA Open API and Plugin Development Forum][forum]
- [Keep a Changelog][keep-a-changelog]
- [GitHub Actions][gh-actions]

[gh-template]: https://help.github.com/en/enterprise/2.20/user/github/creating-cloning-and-archiving-repositories/creating-a-repository-from-a-template
[gh-actions]: https://help.github.com/en/actions
[code-samples]: https://github.com/JetBrains/intellij-sdk-code-samples
[gradle-intellij-plugin]: https://github.com/JetBrains/gradle-intellij-plugin
[gradle-changelog-plugin]: https://github.com/JetBrains/gradle-changelog-plugin
[releases]: https://github.com/JetBrains/intellij-platform-plugin-template/releases
[marketplace-plugin-page]: https://plugins.jetbrains.com/plugin/0-TODO
[slack]: https://plugins.jetbrains.com/slack
[forum]: https://intellij-support.jetbrains.com/hc/en-us/community/topics/200366979-IntelliJ-IDEA-Open-API-and-Plugin-Development
[keep-a-changelog]: https://keepachangelog.com
[detekt]: https://detekt.github.io/detekt
[download-ij]: https://www.jetbrains.com/idea/download
[gradle]: https://gradle.org
[gradle-kotlin-dsl]: https://docs.gradle.org/current/userguide/kotlin_dsl.html
[ij-ui-guidelines]: https://jetbrains.github.io/ui

[docs]: https://www.jetbrains.org/intellij/sdk/docs
[docs:intro]: https://www.jetbrains.org/intellij/sdk/docs/intro/intellij_platform.html
[docs:using-gradle]: https://www.jetbrains.org/intellij/sdk/docs/tutorials/build_system.html
[docs:publishing]: https://www.jetbrains.org/intellij/sdk/docs/basics/getting_started/publishing_plugin.html
[docs:kotlin-ui-dsl]: https://www.jetbrains.org/intellij/sdk/docs/user_interface_components/kotlin_ui_dsl.html
[docs:plugin.xml]: https://www.jetbrains.org/intellij/sdk/docs/basics/plugin_structure/plugin_configuration_file.html

[file:getting-started_use-this-template.png]: ./.github/readme/getting-started_use-this-template.png
[file:gradle.properties]: ./gradle.properties
[file:template_cleanup.yml]: ./.github/workflows/template-cleanup.yml
[file:plugin.xml]: ./src/main/resources/META-INF/plugin.xml