name: Eval

on:
  pull_request_target:
  push:
    # Keep this synced with ci/request-reviews/dev-branches.txt
    branches:
      - master
      - staging
      - release-*
      - staging-*
      - haskell-updates
      - python-updates

permissions:
  contents: read

jobs:
  get-merge-commit:
    uses: ./.github/workflows/get-merge-commit.yml

  attrs:
    name: Attributes
    runs-on: ubuntu-latest
    needs: get-merge-commit
    # Skip this and dependent steps if the PR can't be merged
    if: needs.get-merge-commit.outputs.mergedSha
    outputs:
      baseSha: ${{ steps.baseSha.outputs.baseSha }}
      systems: ${{ steps.systems.outputs.systems }}
    steps:
      - name: Check out the PR at the test merge commit
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          ref: ${{ needs.get-merge-commit.outputs.mergedSha }}
          fetch-depth: 2
          path: nixpkgs

      - name: Determine base commit
        if: github.event_name == 'pull_request_target'
        id: baseSha
        run: |
          baseSha=$(git -C nixpkgs rev-parse HEAD^1)
          echo "baseSha=$baseSha" >> "$GITHUB_OUTPUT"

      - name: Install Nix
        uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30

      - name: Evaluate the list of all attributes and get the systems matrix
        id: systems
        run: |
          nix-build nixpkgs/ci -A eval.attrpathsSuperset
          echo "systems=$(<result/systems.json)" >> "$GITHUB_OUTPUT"

      - name: Upload the list of all attributes
        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
        with:
          name: paths
          path: result/*

  eval-aliases:
    name: Eval nixpkgs with aliases enabled
    runs-on: ubuntu-latest
    needs: [ attrs, get-merge-commit ]
    steps:
      - name: Check out the PR at the test merge commit
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          ref: ${{ needs.get-merge-commit.outputs.mergedSha }}
          path: nixpkgs

      - name: Install Nix
        uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30

      - name: Query nixpkgs with aliases enabled to check for basic syntax errors
        run: |
          time nix-env -I ./nixpkgs -f ./nixpkgs -qa '*' --option restrict-eval true --option allow-import-from-derivation false >/dev/null

  outpaths:
    name: Outpaths
    runs-on: ubuntu-latest
    needs: [ attrs, get-merge-commit ]
    strategy:
      matrix:
        system: ${{ fromJSON(needs.attrs.outputs.systems) }}
    steps:
      - name: Download the list of all attributes
        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
        with:
          name: paths
          path: paths

      - name: Check out the PR at the test merge commit
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          ref: ${{ needs.get-merge-commit.outputs.mergedSha }}
          path: nixpkgs

      - name: Install Nix
        uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30

      - name: Evaluate the ${{ matrix.system }} output paths for all derivation attributes
        env:
          MATRIX_SYSTEM: ${{ matrix.system }}
        run: |
          nix-build nixpkgs/ci -A eval.singleSystem \
            --argstr evalSystem "$MATRIX_SYSTEM" \
            --arg attrpathFile ./paths/paths.json \
            --arg chunkSize 10000
          # If it uses too much memory, slightly decrease chunkSize

      - name: Upload the output paths and eval stats
        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
        with:
          name: intermediate-${{ matrix.system }}
          path: result/*

  process:
    name: Process
    runs-on: ubuntu-latest
    needs: [ outpaths, attrs, get-merge-commit ]
    outputs:
      baseRunId: ${{ steps.baseRunId.outputs.baseRunId }}
    steps:
      - name: Download output paths and eval stats for all systems
        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
        with:
          pattern: intermediate-*
          path: intermediate

      - name: Check out the PR at the test merge commit
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          ref: ${{ needs.get-merge-commit.outputs.mergedSha }}
          path: nixpkgs

      - name: Install Nix
        uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30

      - name: Combine all output paths and eval stats
        run: |
          nix-build nixpkgs/ci -A eval.combine \
            --arg resultsDir ./intermediate \
            -o prResult

      - name: Upload the combined results
        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
        with:
          name: result
          path: prResult/*

      - name: Get base run id
        if: needs.attrs.outputs.baseSha
        id: baseRunId
        run: |
          # Get the latest eval.yml workflow run for the PR's base commit
          if ! run=$(gh api --method GET /repos/"$REPOSITORY"/actions/workflows/eval.yml/runs \
            -f head_sha="$BASE_SHA" -f event=push \
            --jq '.workflow_runs | sort_by(.run_started_at) | .[-1]') \
            || [[ -z "$run" ]]; then
            echo "Could not find an eval.yml workflow run for $BASE_SHA, cannot make comparison"
            exit 0
          fi
          echo "Comparing against $(jq .html_url <<< "$run")"
          runId=$(jq .id <<< "$run")
          conclusion=$(jq -r .conclusion <<< "$run")

          while [[ "$conclusion" == null ]]; do
            echo "Workflow not done, waiting 10 seconds before checking again"
            sleep 10
            conclusion=$(gh api /repos/"$REPOSITORY"/actions/runs/"$runId" --jq '.conclusion')
          done

          if [[ "$conclusion" != "success" ]]; then
            echo "Workflow was not successful (conclusion: $conclusion), cannot make comparison"
            exit 0
          fi

          echo "baseRunId=$runId" >> "$GITHUB_OUTPUT"
        env:
          REPOSITORY: ${{ github.repository }}
          BASE_SHA: ${{ needs.attrs.outputs.baseSha }}
          GH_TOKEN: ${{ github.token }}

      - uses: actions/download-artifact@v4
        if: steps.baseRunId.outputs.baseRunId
        with:
          name: result
          path: baseResult
          github-token: ${{ github.token }}
          run-id: ${{ steps.baseRunId.outputs.baseRunId }}

      - name: Compare against the base branch
        if: steps.baseRunId.outputs.baseRunId
        run: |
          nix-build nixpkgs/ci -A eval.compare \
            --arg beforeResultDir ./baseResult \
            --arg afterResultDir ./prResult \
            -o comparison
          cat comparison/step-summary.md >> "$GITHUB_STEP_SUMMARY"
          # TODO: Request reviews from maintainers for packages whose files are modified in the PR

      - name: Upload the combined results
        if: steps.baseRunId.outputs.baseRunId
        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
        with:
          name: comparison
          path: comparison/*

  # Separate job to have a very tightly scoped PR write token
  tag:
    name: Tag
    runs-on: ubuntu-latest
    needs: process
    if: needs.process.outputs.baseRunId
    permissions:
      pull-requests: write
      statuses: write
    steps:
      - name: Download process result
        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
        with:
          name: comparison
          path: comparison

      - name: Tagging pull request
        run: |
          # Get all currently set rebuild labels
          gh api \
            /repos/"$REPOSITORY"/issues/"$NUMBER"/labels \
            --jq '.[].name | select(startswith("10.rebuild"))' \
            | sort > before

          # And the labels that should be there
          jq -r '.labels[]' comparison/changed-paths.json \
            | sort > after

          # Remove the ones not needed anymore
          while read -r toRemove; do
            echo "Removing label $toRemove"
            gh api \
              --method DELETE \
              /repos/"$REPOSITORY"/issues/"$NUMBER"/labels/"$toRemove"
          done < <(comm -23 before after)

          # And add the ones that aren't set already
          while read -r toAdd; do
            echo "Adding label $toAdd"
            gh api \
              --method POST \
              /repos/"$REPOSITORY"/issues/"$NUMBER"/labels \
              -f "labels[]=$toAdd"
          done < <(comm -13 before after)
        env:
          GH_TOKEN: ${{ github.token }}
          REPOSITORY: ${{ github.repository }}
          NUMBER: ${{ github.event.number }}

      - name: Add eval summary to commit statuses
        if: ${{ github.event_name == 'pull_request_target' }}
        run: |
          description=$(jq -r '
          "Package: added " + (.attrdiff.added | length | tostring) +
          ", removed " + (.attrdiff.removed | length | tostring) +
          ", changed " + (.attrdiff.changed | length | tostring) +
          ", Rebuild: linux " + (.rebuildCountByKernel.linux | tostring) +
          ", darwin " + (.rebuildCountByKernel.darwin | tostring)
          ' <comparison/changed-paths.json)
          target_url="$GITHUB_SERVER_URL/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID?pr=$NUMBER"
          gh api --method POST \
            -H "Accept: application/vnd.github+json" -H "X-GitHub-Api-Version: 2022-11-28" \
            "/repos/$GITHUB_REPOSITORY/statuses/$PR_HEAD_SHA" \
            -f "context=Eval / Summary" -f "state=success" -f "description=$description" -f "target_url=$target_url"
        env:
          GH_TOKEN: ${{ github.token }}
          PR_HEAD_SHA: ${{ github.event.pull_request.head.sha }}
          NUMBER: ${{ github.event.number }}