name: Codex Auto Review

on:
  pull_request:
    types: [ready_for_review, opened]

concurrency:
  group: codex-review-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  codex-review:
    runs-on: ubicloud-standard-2
    timeout-minutes: 30
    if: github.event.pull_request.draft == false && github.event.pull_request.head.repo.fork == false
    permissions:
      contents: read
      issues: write
    steps:
      - name: Check Codex configuration
        id: codex_config
        env:
          CODEX_AUTH_JSON: ${{ secrets.CODEX_AUTH_JSON }}
        run: |
          if [ -n "$CODEX_AUTH_JSON" ]; then
            echo "enabled=true" >> "$GITHUB_OUTPUT"
          else
            echo "enabled=false" >> "$GITHUB_OUTPUT"
            echo "CODEX_AUTH_JSON is not configured; skipping Codex review."
          fi

      - name: Checkout repository
        if: steps.codex_config.outputs.enabled == 'true'
        uses: actions/checkout@v5
        with:
          ref: refs/pull/${{ github.event.pull_request.number }}/merge
          fetch-depth: 1

      - name: Set up Node.js
        if: steps.codex_config.outputs.enabled == 'true'
        uses: actions/setup-node@v4
        with:
          node-version: 22

      - name: Install Codex CLI
        if: steps.codex_config.outputs.enabled == 'true'
        run: npm install --global @openai/codex@0.117.0

      - name: Configure file-backed Codex auth
        if: steps.codex_config.outputs.enabled == 'true'
        env:
          CODEX_AUTH_JSON: ${{ secrets.CODEX_AUTH_JSON }}
        run: |
          CODEX_HOME="$HOME/.codex"
          echo "CODEX_HOME=$CODEX_HOME" >> "$GITHUB_ENV"
          mkdir -p "$CODEX_HOME"
          chmod 700 "$CODEX_HOME"
          cat > "$CODEX_HOME/config.toml" <<'EOF'
          cli_auth_credentials_store = "file"
          EOF
          printf '%s' "$CODEX_AUTH_JSON" > "$CODEX_HOME/auth.json"
          chmod 600 "$CODEX_HOME/auth.json"
          node -e 'JSON.parse(require("fs").readFileSync(process.argv[1], "utf8"))' "$CODEX_HOME/auth.json"

      - name: Pre-fetch base and head refs for the PR
        if: steps.codex_config.outputs.enabled == 'true'
        env:
          PR_BASE_REF: ${{ github.event.pull_request.base.ref }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
        run: |
          git fetch --no-tags origin \
            "$PR_BASE_REF" \
            "+refs/pull/$PR_NUMBER/head"

      - name: Write Codex review context
        if: steps.codex_config.outputs.enabled == 'true'
        env:
          PR_REPOSITORY: ${{ github.repository }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          PR_BASE_SHA: ${{ github.event.pull_request.base.sha }}
          PR_HEAD_SHA: ${{ github.event.pull_request.head.sha }}
          PR_TITLE: ${{ github.event.pull_request.title }}
          PR_BODY: ${{ github.event.pull_request.body || '' }}
        run: |
          mkdir -p .github/codex
          node <<'NODE'
          const fs = require('fs');
          const lines = [
            `Repository: ${process.env.PR_REPOSITORY}`,
            `PR number: ${process.env.PR_NUMBER}`,
            `Base SHA: ${process.env.PR_BASE_SHA}`,
            `Head SHA: ${process.env.PR_HEAD_SHA}`,
            '',
            'PR title:',
            process.env.PR_TITLE || '(empty)',
            '',
            'PR body:',
            process.env.PR_BODY || '(empty)',
            '',
            'Changed commits command:',
            `git log --oneline ${process.env.PR_BASE_SHA}...${process.env.PR_HEAD_SHA}`,
            '',
            'Changed files command:',
            `git diff --stat ${process.env.PR_BASE_SHA}...${process.env.PR_HEAD_SHA}`,
            '',
            'Full review diff command:',
            `git diff --unified=0 ${process.env.PR_BASE_SHA}...${process.env.PR_HEAD_SHA}`
          ];
          fs.writeFileSync('.github/codex/pr-review-context.md', `${lines.join('\n')}\n`);
          NODE

      - name: Run Codex review
        if: steps.codex_config.outputs.enabled == 'true'
        run: |
          codex exec \
            -C "$GITHUB_WORKSPACE" \
            -m gpt-5.4 \
            -c 'model_reasoning_effort="xhigh"' \
            -s read-only \
            -o codex-final-message.md \
            - < .github/codex/pr-review.prompt.md

      - name: Post Codex review comment
        if: steps.codex_config.outputs.enabled == 'true'
        uses: actions/github-script@v7
        with:
          github-token: ${{ github.token }}
          script: |
            const fs = require('fs');
            const path = `${process.env.GITHUB_WORKSPACE}/codex-final-message.md`;
            if (!fs.existsSync(path)) {
              core.info('Codex did not produce a final message; skipping PR comment.');
              return;
            }
            const body = fs.readFileSync(path, 'utf8').trim();
            if (!body) {
              core.info('Codex final message was empty; skipping PR comment.');
              return;
            }
            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.payload.pull_request.number,
              body,
            });