gridpilot.gg/apps/website/eslint-rules/template-purity-rules.js

/**
 * ESLint rules for Template Purity Guardrails
 * 
 * Enforces pure template components without business logic
 */

module.exports = {
  // Rule 1: No ViewModels/DisplayObjects in templates
  'no-view-models-in-templates': {
    meta: {
      type: 'problem',
      docs: {
        description: 'Forbid ViewModels/DisplayObjects imports in templates',
        category: 'Template Purity',
      },
      messages: {
        message: 'ViewModels or DisplayObjects import forbidden in templates - see apps/website/lib/contracts/view-data/ViewData.ts',
      },
    },
    create(context) {
      return {
        ImportDeclaration(node) {
          const importPath = node.source.value;
          if ((importPath.includes('@/lib/view-models/') || 
               importPath.includes('@/lib/presenters/') ||
               importPath.includes('@/lib/display-objects/')) &&
              !isInComment(node)) {
            context.report({
              node,
              messageId: 'message',
            });
          }
        },
      };
    },
  },

  // Rule 2: No state hooks in templates
  'no-state-hooks-in-templates': {
    meta: {
      type: 'problem',
      docs: {
        description: 'Forbid state hooks in templates',
        category: 'Template Purity',
      },
      messages: {
        message: 'State hooks forbidden in templates (use *PageClient.tsx) - see apps/website/lib/contracts/view-data/ViewData.ts',
      },
    },
    create(context) {
      return {
        CallExpression(node) {
          if (node.callee.type === 'Identifier' &&
              ['useMemo', 'useEffect', 'useState', 'useReducer'].includes(node.callee.name) &&
              !isInComment(node)) {
            context.report({
              node,
              messageId: 'message',
            });
          }
        },
      };
    },
  },

  // Rule 3: No computations in templates
  'no-computations-in-templates': {
    meta: {
      type: 'problem',
      docs: {
        description: 'Forbid derived computations in templates',
        category: 'Template Purity',
      },
      messages: {
        message: 'Derived computations forbidden in templates - see apps/website/lib/contracts/view-data/ViewData.ts',
      },
    },
    create(context) {
      return {
        CallExpression(node) {
          if (node.callee.type === 'MemberExpression' &&
              ['filter', 'sort', 'reduce'].includes(node.callee.property.name) &&
              !isInComment(node)) {
            context.report({
              node,
              messageId: 'message',
            });
          }
        },
      };
    },
  },

  // Rule 4: No restricted imports in templates
  'no-restricted-imports-in-templates': {
    meta: {
      type: 'problem',
      docs: {
        description: 'Forbid restricted imports in templates',
        category: 'Template Purity',
      },
      messages: {
        message: 'Templates cannot import from page-queries, services, api, di, or contracts - see apps/website/lib/contracts/view-data/ViewData.ts',
      },
    },
    create(context) {
      const restrictedPaths = [
        '@/lib/page-queries/',
        '@/lib/services/',
        '@/lib/api/',
        '@/lib/di/',
        '@/lib/contracts/',
      ];
      
      return {
        ImportDeclaration(node) {
          const importPath = node.source.value;
          if (restrictedPaths.some(path => importPath.includes(path)) &&
              !isInComment(node)) {
            context.report({
              node,
              messageId: 'message',
            });
          }
        },
      };
    },
  },

  // Rule 5: Invalid template signature
  'no-invalid-template-signature': {
    meta: {
      type: 'problem',
      docs: {
        description: 'Enforce correct template component signature',
        category: 'Template Purity',
      },
      messages: {
        message: 'Template component must accept *ViewData type as first parameter - see apps/website/lib/contracts/view-data/ViewData.ts',
      },
    },
    create(context) {
      // Helper to recursively check if type contains ViewData
      function typeContainsViewData(typeNode) {
        if (!typeNode) return false;
        
        // Check direct type name
        if (typeNode.type === 'TSTypeReference' &&
            typeNode.typeName &&
            typeNode.typeName.name &&
            typeNode.typeName.name.includes('ViewData')) {
          return true;
        }
        
        // Check nested in object type
        if (typeNode.type === 'TSTypeLiteral' && typeNode.members) {
          for (const member of typeNode.members) {
            if (member.type === 'TSPropertySignature' &&
                member.typeAnnotation &&
                typeContainsViewData(member.typeAnnotation.typeAnnotation)) {
              return true;
            }
          }
        }
        
        // Check union/intersection types
        if (typeNode.type === 'TSUnionType' || typeNode.type === 'TSIntersectionType') {
          return typeNode.types.some(t => typeContainsViewData(t));
        }
        
        return false;
      }
      
      return {
        FunctionDeclaration(node) {
          if (node.params.length === 0) {
            context.report({
              node,
              messageId: 'message',
            });
            return;
          }
          
          const firstParam = node.params[0];
          if (!firstParam.typeAnnotation || !firstParam.typeAnnotation.typeAnnotation) {
            context.report({
              node,
              messageId: 'message',
            });
            return;
          }
          
          const typeAnnotation = firstParam.typeAnnotation.typeAnnotation;
          
          if (!typeContainsViewData(typeAnnotation)) {
            context.report({
              node,
              messageId: 'message',
            });
          }
        },
      };
    },
  },

  // Rule 6: No template helper exports
  'no-template-helper-exports': {
    meta: {
      type: 'problem',
      docs: {
        description: 'Forbid helper function exports in templates',
        category: 'Template Purity',
      },
      messages: {
        message: 'Templates must not export helper functions - see apps/website/lib/contracts/view-data/ViewData.ts',
      },
    },
    create(context) {
      return {
        ExportNamedDeclaration(node) {
          if (node.declaration &&
              (node.declaration.type === 'FunctionDeclaration' ||
               node.declaration.type === 'VariableDeclaration')) {
            
            // Get the function/variable name
            const name = node.declaration.id?.name;
            
            // Allow the main template component (ends with Template)
            if (name && name.endsWith('Template')) {
              return;
            }
            
            // Allow default exports
            if (node.declaration.type === 'VariableDeclaration' &&
                node.declaration.declarations.some(d => d.id.type === 'Identifier' && d.id.name.endsWith('Template'))) {
              return;
            }
            
            context.report({
              node,
              messageId: 'message',
            });
          }
        },
      };
    },
  },

  // Rule 7: Invalid template filename
  'invalid-template-filename': {
    meta: {
      type: 'problem',
      docs: {
        description: 'Enforce correct template filename',
        category: 'Template Purity',
      },
      messages: {
        message: 'Template files must end with Template.tsx - see apps/website/lib/contracts/view-data/ViewData.ts',
      },
    },
    create(context) {
      const filename = context.getFilename();
      if (filename.includes('/templates/') && !filename.endsWith('Template.tsx')) {
        // Report at the top of the file
        context.report({
          loc: { line: 1, column: 0 },
          messageId: 'message',
        });
      }
      return {};
    },
  },
};

// Helper functions
function isInComment(node) {
  return false;
}