name: AI Code Reviewer

# Reviews are opt-in per PR: add the ai_code_review label to request one
# (the label is auto-removed after the run so re-adding it re-triggers).
# The automatic opened/synchronize/ready_for_review triggers were removed —
# reviewing every push burned reviewer-API spend on PRs nobody asked to have
# reviewed, and a billing outage (HTTP 402) then showed a red check on every
# PR in the repo.
#
# Residual risk accepted: the diff text goes into the LLM prompt, so a
# hostile diff can try to steer the posted comment or labels (prompt
# injection). The maintainer-applied label gate plus the advisory-only
# decision (FAIL_ON_REQUESTED_CHANGES defaults to false) bound that
# blast radius, and it exists for internal PRs too.

on:
  # zizmor: ignore[dangerous-triggers] — pull_request_target is required so
  # the review also works on fork PRs: fork-triggered pull_request runs get
  # no secrets (OPENROUTER_API_KEY) and a read-only token, so the reviewer
  # could neither call the model nor post its comment. This is safe under
  # two invariants — KEEP BOTH when editing this file:
  #   1. Only the ai_code_review label triggers a run, and only users with
  #      triage permission can add labels: every run on fork code is an
  #      explicit maintainer action, never attacker-initiated.
  #   2. Nothing from the PR head is ever executed. The checkout is the
  #      trusted base branch (pull_request_target default), so
  #      .github/scripts/combine-ai-reviews.sh runs from base; the PR head
  #      is fetched as *data only* to compute the diff.
  pull_request_target:
    types: [labeled]

# Per-PR concurrency with cancel-in-progress: re-adding the label while a
# review is still running cancels the now-stale run. Keyed on the PR number
# so runs for *different* PRs never cancel each other — that repo-wide
# cancellation was the problem in the earlier attempt (#3554, reverted
# #3599), not per-PR cancellation.
#
# The labeled trigger fires for *every* label added to the PR, but the job's
# `if` only proceeds when the label is ai_code_review. Without the run_id
# suffix below, a skip-only labeled event would still enter this group,
# cancel a real in-flight review, and then skip itself — leaving the PR with
# no review at all. Routing those into a unique group keyed on run_id means
# they cancel nothing; the `if` discards them quietly.
concurrency:
  group: >-
    ai-code-review-${{ github.event.pull_request.number }}${{
      (github.event.action == 'labeled' && github.event.label.name != 'ai_code_review')
      && format('-skip-{0}', github.run_id) || ''
    }}
  cancel-in-progress: true

permissions: {}  # Minimal top-level for OSSF Scorecard Token-Permissions

jobs:
  comprehensive-review:
    name: AI Code Review
    runs-on: ubuntu-latest
    timeout-minutes: 30
    environment: ci
    # Only the ai_code_review label triggers a review (works on drafts too);
    # every other labeled event is discarded here.
    if: github.event.label.name == 'ai_code_review'
    permissions:
      contents: read
      pull-requests: write
      issues: write
    steps:
      - name: Harden the runner (Audit all outbound calls)
        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
        with:
          egress-policy: audit

      # SECURITY: this checks out the trusted BASE branch (the
      # pull_request_target default), which is what makes running
      # .github/scripts/combine-ai-reviews.sh below safe on fork PRs.
      # Never add `ref: ${{ github.event.pull_request.head.sha }}` here —
      # that would execute fork-controlled scripts with secrets in env.
      - name: Checkout repository
        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
        with:
          persist-credentials: false
          fetch-depth: 0

      - name: Install dependencies
        run: |
          sudo apt-get update
          sudo apt-get install -y jq

      - name: Get PR diff
        env:
          BASE_REF: ${{ github.event.pull_request.base.ref }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
        run: |
          # The PR head — possibly fork code — is fetched as *data only*
          # through the base repo's refs/pull/N/head mirror (present for
          # fork and same-repo PRs alike); it is never checked out and
          # nothing from it is executed. Env vars prevent template
          # injection from malicious branch names.
          git fetch origin "$BASE_REF" "+refs/pull/$PR_NUMBER/head:refs/remotes/origin/pr-head"
          git diff "origin/$BASE_REF...origin/pr-head" --no-color > diff.txt

      - name: Download AI reviewer script
        run: |
          curl -fsSL https://raw.githubusercontent.com/LearningCircuit/Friendly-AI-Reviewer/main/ai-reviewer.sh -o ai-reviewer.sh
          chmod +x ai-reviewer.sh

      - name: AI Code Review
        id: ai-review
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          OPENROUTER_API_KEY: ${{ secrets.OPENROUTER_API_KEY }}
          # Comma-separated list of models. Each model produces one independent
          # review, presented as "Reviewer 1", "Reviewer 2", ... in a single
          # combined comment. Falls back to the shared AI_MODEL (also used by
          # release.yml, which must stay a single model) when unset, so a
          # one-entry list reproduces the original single-review behavior.
          AI_REVIEW_MODELS: ${{ vars.AI_REVIEW_MODELS || vars.AI_MODEL || 'moonshotai/kimi-k2-thinking' }}
          AI_TEMPERATURE: ${{ vars.AI_TEMPERATURE || '0.1' }}
          AI_MAX_TOKENS: ${{ vars.AI_MAX_TOKENS || '64000' }}
          MAX_DIFF_SIZE: ${{ vars.MAX_DIFF_SIZE || '800000' }}
          EXCLUDE_FILE_PATTERNS: ${{ vars.EXCLUDE_FILE_PATTERNS || '*.lock,*.min.js,*.min.css,package-lock.json,yarn.lock' }}
          STRUCTURED_OUTPUT: ${{ vars.STRUCTURED_OUTPUT || 'true' }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          REPO_FULL_NAME: ${{ github.repository }}
          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
          FAIL_ON_REQUESTED_CHANGES: ${{ vars.FAIL_ON_REQUESTED_CHANGES || 'false' }}
          DEBUG_MODE: ${{ vars.DEBUG_MODE || 'false' }}
        run: |
          echo "Running AI code review..."

          # Parse the comma-separated model list. Each entry becomes one
          # independent reviewer ("Reviewer 1", "Reviewer 2", ...). A single
          # entry reproduces the original one-review behavior.
          # `read` returns non-zero at EOF; the here-string always appends a
          # trailing newline so it returns 0 here, but `|| true` keeps a future
          # edge case from tripping `set -e`. An empty/whitespace AI_REVIEW_MODELS
          # yields only empty entries, which the filter below drops, correctly
          # falling through to the "No models configured" error.
          IFS=',' read -ra RAW_MODELS <<< "$AI_REVIEW_MODELS" || true
          MODELS=()
          for m in "${RAW_MODELS[@]}"; do
            # Trim surrounding whitespace with parameter expansion. (xargs would
            # choke on a model id containing a quote and word-collapse internal
            # spaces — model ids shouldn't have either, but this is robust.)
            m="${m#"${m%%[![:space:]]*}"}"   # strip leading whitespace
            m="${m%"${m##*[![:space:]]}"}"   # strip trailing whitespace
            [ -n "$m" ] && MODELS+=("$m")
          done
          if [ "${#MODELS[@]}" -eq 0 ]; then
            echo "❌ No models configured in AI_REVIEW_MODELS"
            exit 1
          fi
          echo "Configured ${#MODELS[@]} reviewer model(s)"

          # Launch every model concurrently so the job's wall-clock is the
          # slowest single review, not the sum of all of them. Each reviewer
          # writes its JSON response and its diagnostics to its own index-keyed
          # files, so the "Reviewer N" numbering stays stable and the parallel
          # output never interleaves. AI_MODEL is overridden per call; all other
          # settings (temperature, token limits, diff size, context fetching)
          # are shared.
          pids=()
          for i in "${!MODELS[@]}"; do
            AI_MODEL="${MODELS[i]}" bash ai-reviewer.sh < diff.txt \
              > "resp_$i.json" 2> "err_$i.log" &
            pids[i]=$!
          done

          # Record each reviewer's exit code to code_<i> (a failing model must
          # not abort the others, so disable errexit around wait).
          for i in "${!MODELS[@]}"; do
            set +e
            wait "${pids[i]}"
            echo $? > "code_$i"
            set -e
          done

          # Assemble the combined comment with the extracted, unit-tested helper
          # (.github/scripts/combine-ai-reviews.sh). It reads resp_<i>.json /
          # code_<i> from the working dir and writes the comment body, label set,
          # decision, and success count back out. Keeping the assembly in a
          # script is what lets tests/ci/test_combine_ai_reviews.py cover the
          # parsing, footer-stripping, label union, and pass/fail logic without
          # any network or GitHub API access.
          bash .github/scripts/combine-ai-reviews.sh "$PWD" "${MODELS[@]}"
          COMMENT_BODY="$(cat comment_body.md)"
          LABELS="$(cat labels.txt)"
          DECISION="$(cat decision.txt)"
          SUCCESS_COUNT="$(cat success_count.txt)"

          # Post (or update) the reviews as a single sticky PR comment. On each
          # push we edit the same comment in place instead of stacking a new one
          # per push. The hidden marker identifies our comment specifically, so
          # we never touch comments from humans or other bots. (Review comments
          # made before this change lack the marker and are left as-is.)
          # A commit-sha line lets reviewers tell which push the (edited-in-place)
          # comment reflects, since GitHub only shows a vague "edited" marker.
          # This literal MUST match the marker the helper script prepends to the
          # comment body.
          STICKY_MARKER="<!-- ai-code-review:sticky -->"
          # STICKY_MARKER is interpolated into the jq program below, so it must
          # stay free of `"` and `\`. gh api's --jq takes no --arg, so we can't
          # pass it as a jq variable; keeping the marker a literal constant is
          # what keeps this safe. The filter yields a single id (we maintain
          # exactly one sticky comment), so no post-filtering is needed.
          EXISTING_COMMENT_ID=$(gh api "repos/$REPO_FULL_NAME/issues/$PR_NUMBER/comments" \
            --paginate \
            --jq "[.[] | select(.body | contains(\"$STICKY_MARKER\"))] | last | .id // empty")
          if [ -n "$EXISTING_COMMENT_ID" ]; then
            echo "Updating existing AI review comment ($EXISTING_COMMENT_ID)"
            printf '%s' "$COMMENT_BODY" | gh api \
              "repos/$REPO_FULL_NAME/issues/comments/$EXISTING_COMMENT_ID" \
              --method PATCH -F body=@- >/dev/null
          else
            echo "Posting new AI review comment"
            printf '%s' "$COMMENT_BODY" | gh pr comment "$PR_NUMBER" --repo "$REPO_FULL_NAME" -F -
          fi

          # Add labels to PR. Iterate line-by-line (labels.txt is one label per
          # line) rather than word-splitting, so a multi-word label such as
          # "good first issue" is treated as a single label, not three.
          echo "Labels to add: $LABELS"
          while IFS= read -r label; do
            [ -n "$label" ] || continue
            echo "Adding label: $label"
            if gh label create "$label" --color "0366d6" --description "Auto-created by AI reviewer" 2>/dev/null; then
              echo "Created new label: $label"
            else
              echo "Label already exists: $label"
            fi
            if gh issue edit "$PR_NUMBER" --add-label "$label" 2>/dev/null; then
              echo "Successfully added label: $label"
            else
              echo "Failed to add label: $label"
            fi
          done <<< "$LABELS"

          # Handle workflow decision (after posting review and labels)
          echo "AI decision: $DECISION"

          # Store the decision as a step output for the downstream
          # "Fail Workflow if Requested" step. $GITHUB_OUTPUT is the modern
          # mechanism — values are scoped to steps.<id>.outputs.<name> and
          # cannot re-enter the runner's process environment, eliminating the
          # $GITHUB_ENV injection class (zizmor github-env audit #8017).
          #
          # Defense-in-depth: an allowlist before the write blocks newline
          # injection. If a manipulated model response put a newline in
          # $DECISION, the bare echo above could write an additional output
          # key. Outputs can't reach the process environment so impact is
          # minimal, but the case statement closes the door cheaply and
          # replaces the lost-on-rework intent of #4985.
          case "$DECISION" in pass|fail) ;; *) DECISION="fail" ;; esac
          echo "DECISION=$DECISION" >> "$GITHUB_OUTPUT"

          # Remove the ai_code_review label so re-adding it re-triggers a review.
          echo "Removing ai_code_review label to allow easy re-triggering"
          if gh issue edit "$PR_NUMBER" --remove-label "ai_code_review" 2>/dev/null; then
            echo "Successfully removed ai_code_review label"
          else
            echo "Failed to remove ai_code_review label (may have been already removed)"
          fi

          # If every reviewer failed, the posted comment carries only failure
          # notes — surface that as a red workflow run rather than a silent pass,
          # matching the original single-review behavior on an unusable response.
          if [ "$SUCCESS_COUNT" -eq 0 ]; then
            echo "❌ All ${#MODELS[@]} reviewer(s) failed to produce a usable review."
            exit 1
          fi

          echo "✅ AI review completed successfully ($SUCCESS_COUNT/${#MODELS[@]} reviewers)"

      - name: Fail Workflow if Requested
        if: env.FAIL_ON_REQUESTED_CHANGES == 'true' && steps.ai-review.outputs.DECISION == 'fail'
        run: |
          echo "❌ AI requested changes and FAIL_ON_REQUESTED_CHANGES is enabled. Failing workflow."
          echo "The review has been posted above. Please address the requested changes."
          exit 1

      - name: Cleanup
        if: always()
        run: |
          rm -f diff.txt
          # Per-reviewer response/log/exit-code files from the parallel fan-out,
          # plus the assembly helper's output files.
          rm -f resp_*.json err_*.log code_* comment_body.md labels.txt decision.txt success_count.txt
          # Only remove ai_response.txt if it exists (only created in debug mode)
          if [ -f "ai_response.txt" ]; then
            rm -f ai_response.txt
          fi