Components.js

/**
 * @fileoverview Utility class and functions for React components detection
 * @author Yannick Croissant
 */

'use strict';

const doctrine = require('doctrine');
const arrayIncludes = require('array-includes');
const values = require('object.values');

const variableUtil = require('./variable');
const pragmaUtil = require('./pragma');
const astUtil = require('./ast');
const propTypesUtil = require('./propTypes');
const jsxUtil = require('./jsx');
const usedPropTypesUtil = require('./usedPropTypes');
const defaultPropsUtil = require('./defaultProps');
const isFirstLetterCapitalized = require('./isFirstLetterCapitalized');
const isCreateElement = require('./isCreateElement');
const isDestructuredFromPragmaImport = require('./isDestructuredFromPragmaImport');

function getId(node) {
  return node && node.range.join(':');
}

function usedPropTypesAreEquivalent(propA, propB) {
  if (propA.name === propB.name) {
    if (!propA.allNames && !propB.allNames) {
      return true;
    }
    if (Array.isArray(propA.allNames) && Array.isArray(propB.allNames) && propA.allNames.join('') === propB.allNames.join('')) {
      return true;
    }
    return false;
  }
  return false;
}

function mergeUsedPropTypes(propsList, newPropsList) {
  const propsToAdd = newPropsList.filter((newProp) => {
    const newPropIsAlreadyInTheList = propsList.some((prop) => usedPropTypesAreEquivalent(prop, newProp));
    return !newPropIsAlreadyInTheList;
  });

  return propsList.concat(propsToAdd);
}

const Lists = new WeakMap();

/**
 * Components
 */
class Components {
  constructor() {
    Lists.set(this, {});
  }

  /**
   * Add a node to the components list, or update it if it's already in the list
   *
   * @param {ASTNode} node The AST node being added.
   * @param {Number} confidence Confidence in the component detection (0=banned, 1=maybe, 2=yes)
   * @returns {Object} Added component object
   */
  add(node, confidence) {
    const id = getId(node);
    const list = Lists.get(this);
    if (list[id]) {
      if (confidence === 0 || list[id].confidence === 0) {
        list[id].confidence = 0;
      } else {
        list[id].confidence = Math.max(list[id].confidence, confidence);
      }
      return list[id];
    }
    list[id] = {
      node,
      confidence
    };
    return list[id];
  }

  /**
   * Find a component in the list using its node
   *
   * @param {ASTNode} node The AST node being searched.
   * @returns {Object} Component object, undefined if the component is not found or has confidence value of 0.
   */
  get(node) {
    const id = getId(node);
    const item = Lists.get(this)[id];
    if (item && item.confidence >= 1) {
      return item;
    }
    return null;
  }

  /**
   * Update a component in the list
   *
   * @param {ASTNode} node The AST node being updated.
   * @param {Object} props Additional properties to add to the component.
   */
  set(node, props) {
    const list = Lists.get(this);
    let component = list[getId(node)];
    while (!component) {
      node = node.parent;
      if (!node) {
        return;
      }
      component = list[getId(node)];
    }

    Object.assign(
      component,
      props,
      {
        usedPropTypes: mergeUsedPropTypes(
          component.usedPropTypes || [],
          props.usedPropTypes || []
        )
      }
    );
  }

  /**
   * Return the components list
   * Components for which we are not confident are not returned
   *
   * @returns {Object} Components list
   */
  list() {
    const thisList = Lists.get(this);
    const list = {};
    const usedPropTypes = {};

    // Find props used in components for which we are not confident
    Object.keys(thisList).filter((i) => thisList[i].confidence < 2).forEach((i) => {
      let component = null;
      let node = null;
      node = thisList[i].node;
      while (!component && node.parent) {
        node = node.parent;
        // Stop moving up if we reach a decorator
        if (node.type === 'Decorator') {
          break;
        }
        component = this.get(node);
      }
      if (component) {
        const newUsedProps = (thisList[i].usedPropTypes || []).filter((propType) => !propType.node || propType.node.kind !== 'init');

        const componentId = getId(component.node);

        usedPropTypes[componentId] = mergeUsedPropTypes(usedPropTypes[componentId] || [], newUsedProps);
      }
    });

    // Assign used props in not confident components to the parent component
    Object.keys(thisList).filter((j) => thisList[j].confidence >= 2).forEach((j) => {
      const id = getId(thisList[j].node);
      list[j] = thisList[j];
      if (usedPropTypes[id]) {
        list[j].usedPropTypes = mergeUsedPropTypes(list[j].usedPropTypes || [], usedPropTypes[id]);
      }
    });
    return list;
  }

  /**
   * Return the length of the components list
   * Components for which we are not confident are not counted
   *
   * @returns {Number} Components list length
   */
  length() {
    const list = Lists.get(this);
    return Object.keys(list).filter((i) => list[i].confidence >= 2).length;
  }
}

function getWrapperFunctions(context, pragma) {
  const componentWrapperFunctions = context.settings.componentWrapperFunctions || [];

  // eslint-disable-next-line arrow-body-style
  return componentWrapperFunctions.map((wrapperFunction) => {
    return typeof wrapperFunction === 'string'
      ? {property: wrapperFunction}
      : Object.assign({}, wrapperFunction, {
        object: wrapperFunction.object === '<pragma>' ? pragma : wrapperFunction.object
      });
  }).concat([
    {property: 'forwardRef', object: pragma},
    {property: 'memo', object: pragma}
  ]);
}

function componentRule(rule, context) {
  const createClass = pragmaUtil.getCreateClassFromContext(context);
  const pragma = pragmaUtil.getFromContext(context);
  const sourceCode = context.getSourceCode();
  const components = new Components();
  const wrapperFunctions = getWrapperFunctions(context, pragma);

  // Utilities for component detection
  const utils = {

    /**
     * Check if the node is a React ES5 component
     *
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if the node is a React ES5 component, false if not
     */
    isES5Component(node) {
      if (!node.parent) {
        return false;
      }
      return new RegExp(`^(${pragma}\\.)?${createClass}$`).test(sourceCode.getText(node.parent.callee));
    },

    /**
     * Check if the node is a React ES6 component
     *
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if the node is a React ES6 component, false if not
     */
    isES6Component(node) {
      if (utils.isExplicitComponent(node)) {
        return true;
      }

      if (!node.superClass) {
        return false;
      }
      return new RegExp(`^(${pragma}\\.)?(Pure)?Component$`).test(sourceCode.getText(node.superClass));
    },

    /**
     * Check if the node is explicitly declared as a descendant of a React Component
     *
     * @param {ASTNode} node The AST node being checked (can be a ReturnStatement or an ArrowFunctionExpression).
     * @returns {Boolean} True if the node is explicitly declared as a descendant of a React Component, false if not
     */
    isExplicitComponent(node) {
      let comment;
      // Sometimes the passed node may not have been parsed yet by eslint, and this function call crashes.
      // Can be removed when eslint sets "parent" property for all nodes on initial AST traversal: https://github.com/eslint/eslint-scope/issues/27
      // eslint-disable-next-line no-warning-comments
      // FIXME: Remove try/catch when https://github.com/eslint/eslint-scope/issues/27 is implemented.
      try {
        comment = sourceCode.getJSDocComment(node);
      } catch (e) {
        comment = null;
      }

      if (comment === null) {
        return false;
      }

      const commentAst = doctrine.parse(comment.value, {
        unwrap: true,
        tags: ['extends', 'augments']
      });

      const relevantTags = commentAst.tags.filter((tag) => tag.name === 'React.Component' || tag.name === 'React.PureComponent');

      return relevantTags.length > 0;
    },

    /**
     * Checks to see if our component extends React.PureComponent
     *
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if node extends React.PureComponent, false if not
     */
    isPureComponent(node) {
      if (node.superClass) {
        return new RegExp(`^(${pragma}\\.)?PureComponent$`).test(sourceCode.getText(node.superClass));
      }
      return false;
    },

    /**
     * Check if variable is destructured from pragma import
     *
     * @param {string} variable The variable name to check
     * @returns {Boolean} True if createElement is destructured from the pragma
     */
    isDestructuredFromPragmaImport(variable) {
      return isDestructuredFromPragmaImport(variable, context);
    },

    /**
     * Checks to see if node is called within createElement from pragma
     *
     * @param {ASTNode} node The AST node being checked.
     * @returns {Boolean} True if createElement called from pragma
     */
    isCreateElement(node) {
      return isCreateElement(node, context);
    },

    /**
     * Check if we are in a class constructor
     * @return {boolean} true if we are in a class constructor, false if not
     */
    inConstructor() {
      let scope = context.getScope();
      while (scope) {
        if (scope.block && scope.block.parent && scope.block.parent.kind === 'constructor') {
          return true;
        }
        scope = scope.upper;
      }
      return false;
    },

    /**
     * Determine if the node is MemberExpression of `this.state`
     * @param {Object} node The node to process
     * @returns {Boolean}
     */
    isStateMemberExpression(node) {
      return node.type === 'MemberExpression' && node.object.type === 'ThisExpression' && node.property.name === 'state';
    },

    isReturningJSX(ASTNode, strict) {
      return jsxUtil.isReturningJSX(this.isCreateElement.bind(this), ASTNode, context, strict, true);
    },

    isReturningJSXOrNull(ASTNode, strict) {
      return jsxUtil.isReturningJSX(this.isCreateElement.bind(this), ASTNode, context, strict);
    },

    getPragmaComponentWrapper(node) {
      let isPragmaComponentWrapper;
      let currentNode = node;
      let prevNode;
      do {
        currentNode = currentNode.parent;
        isPragmaComponentWrapper = this.isPragmaComponentWrapper(currentNode);
        if (isPragmaComponentWrapper) {
          prevNode = currentNode;
        }
      } while (isPragmaComponentWrapper);

      return prevNode;
    },

    getComponentNameFromJSXElement(node) {
      if (node.type !== 'JSXElement') {
        return null;
      }
      if (node.openingElement && node.openingElement.name && node.openingElement.name.name) {
        return node.openingElement.name.name;
      }
      return null;
    },

    /**
     * Getting the first JSX element's name.
     * @param {object} node
     * @returns {string | null}
     */
    getNameOfWrappedComponent(node) {
      if (node.length < 1) {
        return null;
      }
      const body = node[0].body;
      if (!body) {
        return null;
      }
      if (body.type === 'JSXElement') {
        return this.getComponentNameFromJSXElement(body);
      }
      if (body.type === 'BlockStatement') {
        const jsxElement = body.body.find((item) => item.type === 'ReturnStatement');
        return jsxElement
          && jsxElement.argument
          && this.getComponentNameFromJSXElement(jsxElement.argument);
      }
      return null;
    },

    /**
     * Get the list of names of components created till now
     * @returns {string | boolean}
     */
    getDetectedComponents() {
      const list = components.list();
      return values(list).filter((val) => {
        if (val.node.type === 'ClassDeclaration') {
          return true;
        }
        if (
          val.node.type === 'ArrowFunctionExpression'
          && val.node.parent
          && val.node.parent.type === 'VariableDeclarator'
          && val.node.parent.id
        ) {
          return true;
        }
        return false;
      }).map((val) => {
        if (val.node.type === 'ArrowFunctionExpression') return val.node.parent.id.name;
        return val.node.id && val.node.id.name;
      });
    },

    /**
     * It will check wheater memo/forwardRef is wrapping existing component or
     * creating a new one.
     * @param {object} node
     * @returns {boolean}
     */
    nodeWrapsComponent(node) {
      const childComponent = this.getNameOfWrappedComponent(node.arguments);
      const componentList = this.getDetectedComponents();
      return !!childComponent && arrayIncludes(componentList, childComponent);
    },

    isPragmaComponentWrapper(node) {
      if (!node || node.type !== 'CallExpression') {
        return false;
      }

      return wrapperFunctions.some((wrapperFunction) => {
        if (node.callee.type === 'MemberExpression') {
          return wrapperFunction.object
            && wrapperFunction.object === node.callee.object.name
            && wrapperFunction.property === node.callee.property.name
            && !this.nodeWrapsComponent(node);
        }
        return wrapperFunction.property === node.callee.name
          && (!wrapperFunction.object
            // Functions coming from the current pragma need special handling
            || (wrapperFunction.object === pragma && this.isDestructuredFromPragmaImport(node.callee.name))
          );
      });
    },

    /**
     * Find a return statement in the current node
     *
     * @param {ASTNode} node The AST node being checked
     */
    findReturnStatement: astUtil.findReturnStatement,

    /**
     * Get the parent component node from the current scope
     *
     * @returns {ASTNode} component node, null if we are not in a component
     */
    getParentComponent() {
      return (
        utils.getParentES6Component()
        || utils.getParentES5Component()
        || utils.getParentStatelessComponent()
      );
    },

    /**
     * Get the parent ES5 component node from the current scope
     *
     * @returns {ASTNode} component node, null if we are not in a component
     */
    getParentES5Component() {
      let scope = context.getScope();
      while (scope) {
        const node = scope.block && scope.block.parent && scope.block.parent.parent;
        if (node && utils.isES5Component(node)) {
          return node;
        }
        scope = scope.upper;
      }
      return null;
    },

    /**
     * Get the parent ES6 component node from the current scope
     *
     * @returns {ASTNode} component node, null if we are not in a component
     */
    getParentES6Component() {
      let scope = context.getScope();
      while (scope && scope.type !== 'class') {
        scope = scope.upper;
      }
      const node = scope && scope.block;
      if (!node || !utils.isES6Component(node)) {
        return null;
      }
      return node;
    },

    /**
     * @param {ASTNode} node
     * @returns {boolean}
     */
    isInAllowedPositionForComponent(node) {
      switch (node.parent.type) {
        case 'VariableDeclarator':
        case 'AssignmentExpression':
        case 'Property':
        case 'ReturnStatement':
        case 'ExportDefaultDeclaration':
        case 'ArrowFunctionExpression': {
          return true;
        }
        case 'SequenceExpression': {
          return utils.isInAllowedPositionForComponent(node.parent)
            && node === node.parent.expressions[node.parent.expressions.length - 1];
        }
        default:
          return false;
      }
    },

    /**
     * Get node if node is a stateless component, or node.parent in cases like
     * `React.memo` or `React.forwardRef`. Otherwise returns `undefined`.
     * @param {ASTNode} node
     * @returns {ASTNode | undefined}
     */
    getStatelessComponent(node) {
      const parent = node.parent;
      if (
        node.type === 'FunctionDeclaration'
        && (!node.id || isFirstLetterCapitalized(node.id.name))
        && utils.isReturningJSXOrNull(node)
      ) {
        return node;
      }

      if (node.type === 'FunctionExpression' || node.type === 'ArrowFunctionExpression') {
        const isMethod = parent.type === 'Property' && parent.method;
        const isPropertyAssignment = parent.type === 'AssignmentExpression'
          && parent.left.type === 'MemberExpression';
        const isModuleExportsAssignment = isPropertyAssignment
          && parent.left.object.name === 'module'
          && parent.left.property.name === 'exports';

        if (node.parent.type === 'ExportDefaultDeclaration') {
          if (utils.isReturningJSX(node)) {
            return node;
          }
          return undefined;
        }

        if (node.parent.type === 'VariableDeclarator' && utils.isReturningJSXOrNull(node)) {
          if (isFirstLetterCapitalized(node.parent.id.name)) {
            return node;
          }
          return undefined;
        }

        // Case like `React.memo(() => <></>)` or `React.forwardRef(...)`
        const pragmaComponentWrapper = utils.getPragmaComponentWrapper(node);
        if (pragmaComponentWrapper) {
          return pragmaComponentWrapper;
        }

        if (!(utils.isInAllowedPositionForComponent(node) && utils.isReturningJSXOrNull(node))) {
          return undefined;
        }

        if (utils.isParentComponentNotStatelessComponent(node)) {
          return undefined;
        }

        if (isMethod && !isFirstLetterCapitalized(node.parent.key.name)) {
          return utils.isReturningJSX(node) ? node : undefined;
        }

        if (node.id) {
          return isFirstLetterCapitalized(node.id.name) ? node : undefined;
        }

        if (
          isPropertyAssignment
          && !isModuleExportsAssignment
          && !isFirstLetterCapitalized(parent.left.property.name)
        ) {
          return undefined;
        }

        return node;
      }

      return undefined;
    },

    /**
     * Get the parent stateless component node from the current scope
     *
     * @returns {ASTNode} component node, null if we are not in a component
     */
    getParentStatelessComponent() {
      let scope = context.getScope();
      while (scope) {
        const node = scope.block;
        const statelessComponent = utils.getStatelessComponent(node);
        if (statelessComponent) {
          return statelessComponent;
        }
        scope = scope.upper;
      }
      return null;
    },

    /**
     * Get the related component from a node
     *
     * @param {ASTNode} node The AST node being checked (must be a MemberExpression).
     * @returns {ASTNode} component node, null if we cannot find the component
     */
    getRelatedComponent(node) {
      let i;
      let j;
      let k;
      let l;
      let componentNode;
      // Get the component path
      const componentPath = [];
      while (node) {
        if (node.property && node.property.type === 'Identifier') {
          componentPath.push(node.property.name);
        }
        if (node.object && node.object.type === 'Identifier') {
          componentPath.push(node.object.name);
        }
        node = node.object;
      }
      componentPath.reverse();
      const componentName = componentPath.slice(0, componentPath.length - 1).join('.');

      // Find the variable in the current scope
      const variableName = componentPath.shift();
      if (!variableName) {
        return null;
      }
      let variableInScope;
      const variables = variableUtil.variablesInScope(context);
      for (i = 0, j = variables.length; i < j; i++) {
        if (variables[i].name === variableName) {
          variableInScope = variables[i];
          break;
        }
      }
      if (!variableInScope) {
        return null;
      }

      // Try to find the component using variable references
      const refs = variableInScope.references;
      refs.some((ref) => {
        let refId = ref.identifier;
        if (refId.parent && refId.parent.type === 'MemberExpression') {
          refId = refId.parent;
        }
        if (sourceCode.getText(refId) !== componentName) {
          return false;
        }
        if (refId.type === 'MemberExpression') {
          componentNode = refId.parent.right;
        } else if (
          refId.parent
          && refId.parent.type === 'VariableDeclarator'
          && refId.parent.init
          && refId.parent.init.type !== 'Identifier'
        ) {
          componentNode = refId.parent.init;
        }
        return true;
      });

      if (componentNode) {
        // Return the component
        return components.add(componentNode, 1);
      }

      // Try to find the component using variable declarations
      const defs = variableInScope.defs;
      const defInScope = defs.find((def) => (
        def.type === 'ClassName'
        || def.type === 'FunctionName'
        || def.type === 'Variable'
      ));
      if (!defInScope || !defInScope.node) {
        return null;
      }
      componentNode = defInScope.node.init || defInScope.node;

      // Traverse the node properties to the component declaration
      for (i = 0, j = componentPath.length; i < j; i++) {
        if (!componentNode.properties) {
          continue; // eslint-disable-line no-continue
        }
        for (k = 0, l = componentNode.properties.length; k < l; k++) {
          if (componentNode.properties[k].key && componentNode.properties[k].key.name === componentPath[i]) {
            componentNode = componentNode.properties[k];
            break;
          }
        }
        if (!componentNode || !componentNode.value) {
          return null;
        }
        componentNode = componentNode.value;
      }

      // Return the component
      return components.add(componentNode, 1);
    },

    isParentComponentNotStatelessComponent(node) {
      return !!(
        node.parent
        && node.parent.key
        && node.parent.key.type === 'Identifier'
        // custom component functions must start with a capital letter (returns false otherwise)
        && node.parent.key.name.charAt(0) === node.parent.key.name.charAt(0).toLowerCase()
        // react render function cannot have params
        && !!(node.params || []).length
      );
    }
  };

  // Component detection instructions
  const detectionInstructions = {
    CallExpression(node) {
      if (!utils.isPragmaComponentWrapper(node)) {
        return;
      }
      if (node.arguments.length > 0 && astUtil.isFunctionLikeExpression(node.arguments[0])) {
        components.add(node, 2);
      }
    },

    ClassExpression(node) {
      if (!utils.isES6Component(node)) {
        return;
      }
      components.add(node, 2);
    },

    ClassDeclaration(node) {
      if (!utils.isES6Component(node)) {
        return;
      }
      components.add(node, 2);
    },

    ClassProperty(node) {
      node = utils.getParentComponent();
      if (!node) {
        return;
      }
      components.add(node, 2);
    },

    ObjectExpression(node) {
      if (!utils.isES5Component(node)) {
        return;
      }
      components.add(node, 2);
    },

    FunctionExpression(node) {
      if (node.async) {
        components.add(node, 0);
        return;
      }

      const component = utils.getParentComponent();
      if (
        !component
        || (component.parent && component.parent.type === 'JSXExpressionContainer')
      ) {
        // Ban the node if we cannot find a parent component
        components.add(node, 0);
        return;
      }
      components.add(component, 1);
    },

    FunctionDeclaration(node) {
      if (node.async) {
        components.add(node, 0);
        return;
      }

      node = utils.getParentComponent();
      if (!node) {
        return;
      }
      components.add(node, 1);
    },

    ArrowFunctionExpression(node) {
      if (node.async) {
        components.add(node, 0);
        return;
      }

      const component = utils.getParentComponent();

      if (
        !component
        || (component.parent && component.parent.type === 'JSXExpressionContainer')
      ) {
        // Ban the node if we cannot find a parent component
        components.add(node, 0);
        return;
      }
      if (component.expression && utils.isReturningJSX(component)) {
        components.add(component, 2);
      } else {
        components.add(component, 1);
      }
    },

    ThisExpression(node) {
      const component = utils.getParentComponent();
      if (!component || !/Function/.test(component.type) || !node.parent.property) {
        return;
      }
      // Ban functions accessing a property on a ThisExpression
      components.add(node, 0);
    },

    ReturnStatement(node) {
      if (!utils.isReturningJSX(node)) {
        return;
      }
      node = utils.getParentComponent();
      if (!node) {
        const scope = context.getScope();
        components.add(scope.block, 1);
        return;
      }
      components.add(node, 2);
    }
  };

  // Update the provided rule instructions to add the component detection
  const ruleInstructions = rule(context, components, utils);
  const updatedRuleInstructions = Object.assign({}, ruleInstructions);
  const propTypesInstructions = propTypesUtil(context, components, utils);
  const usedPropTypesInstructions = usedPropTypesUtil(context, components, utils);
  const defaultPropsInstructions = defaultPropsUtil(context, components, utils);
  const allKeys = new Set(Object.keys(detectionInstructions).concat(
    Object.keys(propTypesInstructions),
    Object.keys(usedPropTypesInstructions),
    Object.keys(defaultPropsInstructions)
  ));

  allKeys.forEach((instruction) => {
    updatedRuleInstructions[instruction] = (node) => {
      if (instruction in detectionInstructions) {
        detectionInstructions[instruction](node);
      }
      if (instruction in propTypesInstructions) {
        propTypesInstructions[instruction](node);
      }
      if (instruction in usedPropTypesInstructions) {
        usedPropTypesInstructions[instruction](node);
      }
      if (instruction in defaultPropsInstructions) {
        defaultPropsInstructions[instruction](node);
      }
      if (ruleInstructions[instruction]) {
        return ruleInstructions[instruction](node);
      }
    };
  });

  // Return the updated rule instructions
  return updatedRuleInstructions;
}

module.exports = Object.assign(Components, {
  detect(rule) {
    return componentRule.bind(this, rule);
  }
});