action.yml

name: "Extremely Linear Merging"
description: '"Merge" GitHub Pull Requests with git-linearize'
author: "Gustav Westling"

inputs:
  token:
    required: true
    description: GitHub token. The standard GITHUB_TOKEN will do just fine.

runs:
  using: "composite"
  steps:
    # 👍
    - name: React to comment
      uses: dkershner6/reaction-action@v1
      with:
        token: ${{ inputs.token }}

    # Installation steps
    - name: Install lucky_commit
      uses: baptiste0928/cargo-install@v1
      with:
        crate: lucky_commit
        args: "--locked --no-default-features"
    - name: Install git-linearize
      shell: bash
      run: |
        mkdir -p ~/.bin
        curl -o ~/.bin/git-linearize https://raw.githubusercontent.com/zegl/extremely-linear/main/git-linearize
        chmod +x ~/.bin/git-linearize

    # Clone and fetch PR metadata
    - name: Get PR SHA
      id: sha
      uses: actions/github-script@v6
      with:
        script: |
          const { owner, repo, number } = context.issue;
          const pr = await github.rest.pulls.get({
            owner,
            repo,
            pull_number: number,
          });
          return {
            pr_number: number,
            pr_head_sha: pr.data.head.sha,
            pr_base_ref: pr.data.base.ref,
            pr_base_sha: pr.data.base.sha
          }
    - uses: actions/checkout@v3
      with:
        fetch-depth: "0"
        ref: ${{ fromJSON(steps.sha.outputs.result).pr_head_sha }}

    # Rebase, linearize, and "merge"!
    - name: "Run git-linearize"
      shell: bash
      run: |
        git fetch origin ${{ fromJSON(steps.sha.outputs.result).pr_base_ref }}
        git config user.name github-actions
        git config user.email github-actions@github.com
        git checkout -b working-branch
        git rebase origin/${{ fromJSON(steps.sha.outputs.result).pr_base_ref }}
        ~/.bin/git-linearize -v
        git push -u origin HEAD:${{ fromJSON(steps.sha.outputs.result).pr_base_ref }}
        echo "PUSHED_REF=$(git rev-parse HEAD)" >> $GITHUB_ENV

    - name: Comment and close PR
      uses: peter-evans/close-pull@v2
      with:
        pull-request-number: ${{ fromJSON(steps.sha.outputs.result).pr_number }}
        comment: Landed as ${{ env.PUSHED_REF }}