name: Database Migration Validation

on:
  pull_request:
    paths:
      - 'src/backend/base/langflow/alembic/**'
      - 'src/backend/base/langflow/services/database/models/**'
      - 'src/backend/base/langflow/services/database/service.py'
      - 'src/backend/tests/unit/alembic/**'
      - '.github/workflows/migration-validation.yml'

jobs:
  model-migration-consistency:
    name: Model/Migration Consistency
    runs-on: ubuntu-latest

    services:
      postgres:
        image: postgres:16
        env:
          POSTGRES_USER: langflow
          POSTGRES_PASSWORD: langflow
          POSTGRES_DB: langflow
        ports:
          - 5432:5432
        options: >-
          --health-cmd="pg_isready -U langflow"
          --health-interval=10s
          --health-timeout=5s
          --health-retries=5

    steps:
      - name: Checkout code
        uses: actions/checkout@v6
        with:
          fetch-depth: 0

      - name: Install uv
        uses: astral-sh/setup-uv@v6

      - name: Setup Python
        uses: actions/setup-python@v6
        with:
          python-version: '3.12'

      - name: Install dependencies
        run: |
          uv sync --extra postgresql

      - name: Check model/migration consistency
        env:
          MIGRATION_VALIDATION_CI: "true"
          LANGFLOW_TEST_DATABASE_URI: "postgresql://langflow:langflow@localhost:5432/langflow"
        run: |
          uv run pytest src/backend/tests/unit/alembic/test_migration_execution.py -x -v

  validate-migration:
    name: Migration Pattern Validation
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v6
        with:
          fetch-depth: 0

      - name: Setup Python
        uses: actions/setup-python@v6
        with:
          python-version: '3.12'

      - name: Get changed migration files
        id: changed-files
        run: |
          set -euo pipefail
          CHANGED_FILES=$(git diff --name-only origin/main...HEAD | grep -E 'src/backend/base/langflow/alembic/versions/.*\.py$' | grep -v 'test_migrations/' || echo "")

          if [ -z "$CHANGED_FILES" ]; then
            echo "No migration files changed"
            echo "files=" >> "$GITHUB_OUTPUT"
          else
            echo "Changed migration files:"
            echo "$CHANGED_FILES"
            echo "files=$(printf '%s' "$CHANGED_FILES" | tr '\n' ' ')" >> "$GITHUB_OUTPUT"
          fi

      - name: Validate migration patterns
        if: steps.changed-files.outputs.files != ''
        env:
          MIGRATION_FILES: ${{ steps.changed-files.outputs.files }}
        run: |
          python src/backend/base/langflow/alembic/migration_validator.py $MIGRATION_FILES

      - name: Generate validation report
        if: always() && steps.changed-files.outputs.files != ''
        env:
          MIGRATION_FILES: ${{ steps.changed-files.outputs.files }}
        run: |
          python src/backend/base/langflow/alembic/migration_validator.py \
            --json $MIGRATION_FILES > validation-report.json 2> validation-stderr.txt || true
          if [ ! -s validation-report.json ]; then
            echo "::error::Validator produced no output. Stderr:"
            cat validation-stderr.txt
          fi

      - name: Post PR comment with results
        if: always() && steps.changed-files.outputs.files != ''
        uses: actions/github-script@v8
        with:
          script: |
            const fs = require('fs');

            let message = '';
            let validationPassed = true;

            try {
              const report = JSON.parse(fs.readFileSync('validation-report.json', 'utf8'));

              for (const result of report) {
                if (!result.valid) {
                  validationPassed = false;
                }
              }

              if (validationPassed) {
                message = `✅ **Migration Validation Passed**\n\n`;
                message += `All migrations follow the Expand-Contract pattern correctly.\n\n`;
              } else {
                message = `❌ **Migration Validation Failed**\n\n`;
                message += `Your migrations don't follow the Expand-Contract pattern.\n\n`;

                for (const result of report) {
                  if (!result.valid || result.warnings.length > 0) {
                    message += `### File: \`${result.file.split('/').pop()}\`\n`;
                    message += `**Phase:** ${result.phase}\n\n`;

                    if (result.violations && result.violations.length > 0) {
                      message += `**Violations:**\n`;
                      for (const v of result.violations) {
                        message += `- Line ${v.line}: ${v.message}\n`;
                      }
                      message += `\n`;
                    }

                    if (result.warnings && result.warnings.length > 0) {
                      message += `**Warnings:**\n`;
                      for (const w of result.warnings) {
                        message += `- Line ${w.line}: ${w.message}\n`;
                      }
                      message += `\n`;
                    }
                  }
                }

                message += `### Resources\n`;
                message += `- Review the [DB Migration Guide](./src/backend/base/langflow/alembic/DB-MIGRATION-GUIDE.MD)\n`;
                message += `- Use \`python scripts/generate_migration.py --help\` to generate compliant migrations\n\n`;

                message += `### Common Issues & Solutions\n`;
                message += `- **New columns must be nullable:** Add \`nullable=True\` or \`server_default\`\n`;
                message += `- **Missing phase marker:** Add \`Phase: EXPAND/MIGRATE/CONTRACT\` to docstring\n`;
                message += `- **Column drops:** Only allowed in CONTRACT phase\n`;
                message += `- **Direct renames:** Use expand-contract pattern instead\n`;
              }
            } catch (error) {
              message = `⚠️ **Migration validation check failed to run properly**\n`;
              message += `Error: ${error.message}\n`;
              validationPassed = false;
            }

            // Post or update comment (non-critical — don't let API errors mask validation results)
            try {
              const { data: comments } = await github.rest.issues.listComments({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
              });

              const botComment = comments.find(comment =>
                comment.user.type === 'Bot' &&
                comment.body.includes('Migration Validation')
              );

              if (botComment) {
                await github.rest.issues.updateComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  comment_id: botComment.id,
                  body: message
                });
              } else {
                await github.rest.issues.createComment({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: context.issue.number,
                  body: message
                });
              }
            } catch (apiError) {
              core.warning(`Failed to post PR comment: ${apiError.message}`);
            }

            // Fail the workflow if validation didn't pass
            if (!validationPassed) {
              core.setFailed('Migration validation failed');
            }