name: PR Template Suggester

on:
  pull_request:
    types: [opened, edited, synchronize]

permissions:
  pull-requests: write
  contents: read

jobs:
  suggest-template:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v4

      - name: Analyze PR files and suggest template
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const { data: files } = await github.rest.pulls.listFiles({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number,
            });

            let goFiles = 0;
            let jsFiles = 0;
            let tsFiles = 0;
            let mdFiles = 0;
            let otherFiles = 0;

            for (const file of files) {
              const filename = file.filename.toLowerCase();
              if (filename.endsWith('.go')) {
                goFiles++;
              } else if (filename.endsWith('.js') || filename.endsWith('.jsx')) {
                jsFiles++;
              } else if (filename.endsWith('.ts') || filename.endsWith('.tsx') || filename.endsWith('.vue')) {
                tsFiles++;
              } else if (filename.endsWith('.md')) {
                mdFiles++;
              } else {
                otherFiles++;
              }
            }

            const totalFiles = goFiles + jsFiles + tsFiles + mdFiles + otherFiles;
            if (totalFiles === 0) {
              console.log('No files changed');
              return;
            }

            let suggestedTemplate = null;
            let templateEmoji = '';
            let templateLabel = '';

            if (goFiles / totalFiles > 0.5) {
              suggestedTemplate = 'backend';
              templateEmoji = '🔧';
              templateLabel = 'backend';
            } else if ((jsFiles + tsFiles) / totalFiles > 0.5) {
              suggestedTemplate = 'frontend';
              templateEmoji = '🎨';
              templateLabel = 'frontend';
            } else if (mdFiles / totalFiles > 0.7) {
              suggestedTemplate = 'docs';
              templateEmoji = '📝';
              templateLabel = 'documentation';
            }

            const { data: pr } = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number,
            });

            const prBody = pr.body || '';
            const usesBackendTemplate = prBody.includes('Pull Request - Backend');
            const usesFrontendTemplate = prBody.includes('Pull Request - Frontend');
            const usesDocsTemplate = prBody.includes('Pull Request - Documentation');
            const usesGeneralTemplate = prBody.includes('Pull Request - General');
            const usingDefaultTemplate = !usesBackendTemplate && !usesFrontendTemplate && !usesDocsTemplate && !usesGeneralTemplate;

            if (templateLabel) {
              try {
                await github.rest.issues.addLabels({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: context.issue.number,
                  labels: [templateLabel]
                });
                console.log(`Added label: ${templateLabel}`);
              } catch (error) {
                console.log(`Label might not exist, skipping...`);
              }
            }

            if (suggestedTemplate && usingDefaultTemplate) {
              const templateUrl = `https://raw.githubusercontent.com/${context.repo.owner}/${context.repo.repo}/dev/.github/PULL_REQUEST_TEMPLATE/${suggestedTemplate}.md`;

              let fileStats = [];
              if (goFiles > 0) fileStats.push(`🔧 Go files: ${goFiles}`);
              if (jsFiles > 0) fileStats.push(`🎨 JavaScript files: ${jsFiles}`);
              if (tsFiles > 0) fileStats.push(`🎨 TypeScript files: ${tsFiles}`);
              if (mdFiles > 0) fileStats.push(`📝 Markdown files: ${mdFiles}`);
              if (otherFiles > 0) fileStats.push(`📦 Other files: ${otherFiles}`);

              const fileStatsText = fileStats.map(s => `- ${s}`).join('\n');

              const comment = `## ${templateEmoji} 建议使用专用模板 | Suggested Template

            您的PR主要包含 **${suggestedTemplate}** 相关的变更。我们建议使用更适合的模板以简化填写。

            Your PR primarily contains **${suggestedTemplate}** changes. We suggest using a more suitable template to simplify filling.

            **文件统计 | File Statistics**
            ${fileStatsText}

            **推荐模板 | Recommended Template**
            \`\`\`
            .github/PULL_REQUEST_TEMPLATE/${suggestedTemplate}.md
            \`\`\`

            **如何使用 | How to use**
            1. 编辑PR描述 | Edit PR description
            2. 复制 [${suggestedTemplate} 模板内容](${templateUrl}) | Copy [${suggestedTemplate} template content](${templateUrl})
            3. 或在创建PR时使用URL参数 | Or use URL parameter when creating PR
               \`?template=${suggestedTemplate}.md\`

            _这是一个自动建议，您可以继续使用当前模板。_

            _This is an automated suggestion. You may continue using the current template._`;

              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body: comment
              });

              console.log(`Suggested ${suggestedTemplate} template`);
            } else if (suggestedTemplate && !usingDefaultTemplate) {
              console.log(`PR already uses a specific template`);
            } else {
              console.log('No specific template suggestion needed - mixed changes');
            }