# Assign Reviewers — Smart team assignment based on diff weight
#
# Triggers on PR open and ready_for_review events. Checks out the coordinator
# repo (zed-industries/codeowner-coordinator) to access the assignment script and rules,
# then assigns the 1-2 most relevant teams as reviewers.
#
# NOTE: This file is stored in the codeowner-coordinator repo but must be deployed to
# the zed repo at .github/workflows/assign-reviewers.yml. See INSTALL.md.
#
# AUTH NOTE: Uses a GitHub App (COORDINATOR_APP_ID + COORDINATOR_APP_PRIVATE_KEY)
# for all API operations: cloning the private coordinator repo, requesting team
# reviewers, and setting PR assignees. GITHUB_TOKEN is not used.
#
# SECURITY INVARIANTS (pull_request_target):
# This workflow runs with access to secrets for ALL PRs including forks.
# It is safe ONLY because:
#   1. The checkout is the coordinator repo at ref: main — NEVER the PR head/branch
#   2. No ${{ }} interpolation of event fields in run: blocks — all routed via env:
#   3. The script never executes, sources, or reads files from the PR branch
# Violating any of these enables remote code execution with secret access.

name: Assign Reviewers

on:
  # zizmor: ignore[dangerous-triggers] reviewed — no PR code checkout, only coordinator repo at ref: main
  pull_request_target:
    types: [opened, ready_for_review]

# GITHUB_TOKEN is not used — all operations use the GitHub App token.
# Declare minimal permissions so the default token has no write access.
permissions: {}

# Prevent duplicate runs for the same PR (e.g., rapid push + ready_for_review).
concurrency:
  group: assign-reviewers-${{ github.event.pull_request.number }}
  cancel-in-progress: true

# NOTE: For ready_for_review events, the webhook payload may still carry
# draft: true due to a GitHub race condition (payload serialized before DB
# update). We trust the event type instead — the script rechecks draft status
# via a live API call as defense-in-depth.
#
# No author_association filter — external and fork PRs also get reviewer
# assignments. Assigned reviewers are inherently scoped to org team members
# by the GitHub Teams API.
jobs:
  assign-reviewers:
    if: >-
      github.event.action == 'ready_for_review' || github.event.pull_request.draft == false
    runs-on: ubuntu-latest
    steps:
      - name: Generate app token
        id: app-token
        uses: actions/create-github-app-token@f8d387b68d61c58ab83c6c016672934102569859 # v3.0.0
        with:
          app-id: ${{ vars.COORDINATOR_APP_ID }}
          private-key: ${{ secrets.COORDINATOR_APP_PRIVATE_KEY }}
          repositories: codeowner-coordinator,zed

      # SECURITY: checks out the coordinator repo at ref: main, NOT the PR branch.
      # persist-credentials: false prevents the token from leaking into .git/config.
      - name: Checkout coordinator repo
        uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
        with:
          repository: zed-industries/codeowner-coordinator
          ref: main
          path: codeowner-coordinator
          token: ${{ steps.app-token.outputs.token }}
          persist-credentials: false

      - name: Setup Python
        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
        with:
          python-version: "3.11"

      - name: Install dependencies
        run: |
          pip install --no-deps -q --only-binary ':all:' \
            -r /dev/stdin <<< "pyyaml==6.0.3 --hash=sha256:b8bb0864c5a28024fac8a632c443c87c5aa6f215c0b126c449ae1a150412f31d"

      - name: Assign reviewers
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}
          PR_URL: ${{ github.event.pull_request.html_url }}
          TARGET_REPO: ${{ github.repository }}
          ASSIGN_INTERNAL: ${{ vars.ASSIGN_INTERNAL || 'false' }}
          ASSIGN_EXTERNAL: ${{ vars.ASSIGN_EXTERNAL || 'true' }}
        run: |
          cd codeowner-coordinator
          python .github/scripts/assign-reviewers.py \
            --pr "$PR_URL" \
            --apply \
            --rules-file team-membership-rules.yml \
            --repo "$TARGET_REPO" \
            --org zed-industries \
            2>&1 | tee /tmp/assign-reviewers-output.txt

      - name: Upload output
        if: always()
        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
        with:
          name: assign-reviewers-output
          path: /tmp/assign-reviewers-output.txt
          retention-days: 30