require-default-props.js

/**
 * @fileOverview Enforce a defaultProps definition for every prop that is not a required prop.
 * @author Vitor Balocco
 */
'use strict';

var find = require('array.prototype.find');
var Components = require('../util/Components');
var variableUtil = require('../util/variable');
var annotations = require('../util/annotations');

// ------------------------------------------------------------------------------
// Rule Definition
// ------------------------------------------------------------------------------

module.exports = {
  meta: {
    docs: {
      description: 'Enforce a defaultProps definition for every prop that is not a required prop.',
      category: 'Best Practices'
    },

    schema: []
  },

  create: Components.detect(function(context, components, utils) {
    /**
     * Checks if the Identifier node passed in looks like a propTypes declaration.
     * @param   {ASTNode}  node The node to check. Must be an Identifier node.
     * @returns {Boolean}       `true` if the node is a propTypes declaration, `false` if not
     */
    function isPropTypesDeclaration(node) {
      return node.type === 'Identifier' && node.name === 'propTypes';
    }

    /**
     * Checks if the Identifier node passed in looks like a defaultProps declaration.
     * @param   {ASTNode}  node The node to check. Must be an Identifier node.
     * @returns {Boolean}       `true` if the node is a defaultProps declaration, `false` if not
     */
    function isDefaultPropsDeclaration(node) {
      return node.type === 'Identifier' &&
            (node.name === 'defaultProps' || node.name === 'getDefaultProps');
    }

    /**
     * Checks if the PropTypes MemberExpression node passed in declares a required propType.
     * @param   {ASTNode} propTypeExpression node to check. Must be a `PropTypes` MemberExpression.
     * @returns {Boolean}                    `true` if this PropType is required, `false` if not.
     */
    function isRequiredPropType(propTypeExpression) {
      return propTypeExpression.type === 'MemberExpression' && propTypeExpression.property.name === 'isRequired';
    }

    /**
     * Find a variable by name in the current scope.
     * @param  {string} name Name of the variable to look for.
     * @returns {ASTNode|null} Return null if the variable could not be found, ASTNode otherwise.
     */
    function findVariableByName(name) {
      var variable = find(variableUtil.variablesInScope(context), function(item) {
        return item.name === name;
      });

      if (!variable || !variable.defs[0] || !variable.defs[0].node) {
        return null;
      }

      if (variable.defs[0].node.type === 'TypeAlias') {
        return variable.defs[0].node.right;
      }

      return variable.defs[0].node.init;
    }

    /**
     * Try to resolve the node passed in to a variable in the current scope. If the node passed in is not
     * an Identifier, then the node is simply returned.
     * @param   {ASTNode} node The node to resolve.
     * @returns {ASTNode|null} Return null if the value could not be resolved, ASTNode otherwise.
     */
    function resolveNodeValue(node) {
      if (node.type === 'Identifier') {
        return findVariableByName(node.name);
      }

      return node;
    }

    /**
     * Tries to find the definition of a GenericTypeAnnotation in the current scope.
     * @param  {ASTNode}      node The node GenericTypeAnnotation node to resolve.
     * @return {ASTNode|null}      Return null if definition cannot be found, ASTNode otherwise.
     */
    function resolveGenericTypeAnnotation(node) {
      if (node.type !== 'GenericTypeAnnotation' || node.id.type !== 'Identifier') {
        return null;
      }

      return findVariableByName(node.id.name);
    }

    function resolveUnionTypeAnnotation(node) {
      // Go through all the union and resolve any generic types.
      return node.types.map(function(annotation) {
        if (annotation.type === 'GenericTypeAnnotation') {
          return resolveGenericTypeAnnotation(annotation);
        }

        return annotation;
      });
    }

    /**
     * Extracts a PropType from an ObjectExpression node.
     * @param   {ASTNode} objectExpression ObjectExpression node.
     * @returns {Object[]}        Array of PropType object representations, to be consumed by `addPropTypesToComponent`.
     */
    function getPropTypesFromObjectExpression(objectExpression) {
      var props = objectExpression.properties.filter(function(property) {
        return property.type !== 'ExperimentalSpreadProperty';
      });

      return props.map(function(property) {
        return {
          name: property.key.name,
          isRequired: isRequiredPropType(property.value),
          node: property
        };
      });
    }

    /**
     * Extracts a PropType from a TypeAnnotation node.
     * @param   {ASTNode} node TypeAnnotation node.
     * @returns {Object[]}     Array of PropType object representations, to be consumed by `addPropTypesToComponent`.
     */
    function getPropTypesFromTypeAnnotation(node) {
      var properties;

      switch (node.typeAnnotation.type) {
        case 'GenericTypeAnnotation':
          var annotation = resolveGenericTypeAnnotation(node.typeAnnotation);

          if (annotation && annotation.id) {
            annotation = findVariableByName(annotation.id.name);
          }

          properties = annotation ? (annotation.properties || []) : [];
          break;

        case 'UnionTypeAnnotation':
          var union = resolveUnionTypeAnnotation(node.typeAnnotation);
          properties = union.reduce(function(acc, curr) {
            if (!curr) {
              return acc;
            }

            return acc.concat(curr.properties);
          }, []);
          break;

        case 'ObjectTypeAnnotation':
          properties = node.typeAnnotation.properties;
          break;

        default:
          properties = [];
          break;
      }

      var props = properties.filter(function(property) {
        return property.type === 'ObjectTypeProperty';
      });

      return props.map(function(property) {
        // the `key` property is not present in ObjectTypeProperty nodes, so we need to get the key name manually.
        var tokens = context.getFirstTokens(property, 1);
        var name = tokens[0].value;

        return {
          name: name,
          isRequired: !property.optional,
          node: property
        };
      });
    }

    /**
     * Extracts a DefaultProp from an ObjectExpression node.
     * @param   {ASTNode} objectExpression ObjectExpression node.
     * @returns {Object|string}            Object representation of a defaultProp, to be consumed by
     *                                     `addDefaultPropsToComponent`, or string "unresolved", if the defaultProps
     *                                     from this ObjectExpression can't be resolved.
     */
    function getDefaultPropsFromObjectExpression(objectExpression) {
      var hasSpread = find(objectExpression.properties, function(property) {
        return property.type === 'ExperimentalSpreadProperty';
      });

      if (hasSpread) {
        return 'unresolved';
      }

      return objectExpression.properties.map(function(property) {
        return property.key.name;
      });
    }

    /**
     * Marks a component's DefaultProps declaration as "unresolved". A component's DefaultProps is
     * marked as "unresolved" if we cannot safely infer the values of its defaultProps declarations
     * without risking false negatives.
     * @param   {Object} component The component to mark.
     * @returns {void}
     */
    function markDefaultPropsAsUnresolved(component) {
      components.set(component.node, {
        defaultProps: 'unresolved'
      });
    }

    /**
     * Adds propTypes to the component passed in.
     * @param   {ASTNode}  component The component to add the propTypes to.
     * @param   {Object[]} propTypes propTypes to add to the component.
     * @returns {void}
     */
    function addPropTypesToComponent(component, propTypes) {
      var props = component.propTypes || [];

      components.set(component.node, {
        propTypes: props.concat(propTypes)
      });
    }

    /**
     * Adds defaultProps to the component passed in.
     * @param   {ASTNode}         component    The component to add the defaultProps to.
     * @param   {String[]|String} defaultProps defaultProps to add to the component or the string "unresolved"
     *                                         if this component has defaultProps that can't be resolved.
     * @returns {void}
     */
    function addDefaultPropsToComponent(component, defaultProps) {
      // Early return if this component's defaultProps is already marked as "unresolved".
      if (component.defaultProps === 'unresolved') {
        return;
      }

      if (defaultProps === 'unresolved') {
        markDefaultPropsAsUnresolved(component);
        return;
      }

      var defaults = component.defaultProps || {};

      defaultProps.forEach(function(defaultProp) {
        defaults[defaultProp] = true;
      });

      components.set(component.node, {
        defaultProps: defaults
      });
    }

    /**
     * Tries to find a props type annotation in a stateless component.
     * @param  {ASTNode} node The AST node to look for a props type annotation.
     * @return {void}
     */
    function handleStatelessComponent(node) {
      if (!node.params || !node.params.length || !annotations.isAnnotatedFunctionPropsDeclaration(node, context)) {
        return;
      }

      // find component this props annotation belongs to
      var component = components.get(utils.getParentStatelessComponent());
      if (!component) {
        return;
      }

      addPropTypesToComponent(component, getPropTypesFromTypeAnnotation(node.params[0].typeAnnotation, context));
    }

    function handlePropTypeAnnotationClassProperty(node) {
      // find component this props annotation belongs to
      var component = components.get(utils.getParentES6Component());
      if (!component) {
        return;
      }

      addPropTypesToComponent(component, getPropTypesFromTypeAnnotation(node.typeAnnotation, context));
    }

    function isPropTypeAnnotation(node) {
      return (node.key.name === 'props' && !!node.typeAnnotation);
    }

    /**
     * Reports all propTypes passed in that don't have a defaultProp counterpart.
     * @param  {Object[]} propTypes    List of propTypes to check.
     * @param  {Object}   defaultProps Object of defaultProps to check. Keys are the props names.
     * @return {void}
     */
    function reportPropTypesWithoutDefault(propTypes, defaultProps) {
      // If this defaultProps is "unresolved", then we should ignore this component and not report
      // any errors for it, to avoid false-positives with e.g. external defaultProps declarations or spread operators.
      if (defaultProps === 'unresolved') {
        return;
      }

      propTypes.forEach(function(prop) {
        if (prop.isRequired) {
          return;
        }

        if (defaultProps[prop.name]) {
          return;
        }

        context.report(
          prop.node,
          'propType "{{name}}" is not required, but has no corresponding defaultProp declaration.',
          {name: prop.name}
        );
      });
    }

    // --------------------------------------------------------------------------
    // Public API
    // --------------------------------------------------------------------------

    return {
      MemberExpression: function(node) {
        var isPropType = isPropTypesDeclaration(node.property);
        var isDefaultProp = isDefaultPropsDeclaration(node.property);

        if (!isPropType && !isDefaultProp) {
          return;
        }

        // find component this propTypes/defaultProps belongs to
        var component = utils.getRelatedComponent(node);
        if (!component) {
          return;
        }

        // e.g.:
        // MyComponent.propTypes = {
        //   foo: React.PropTypes.string.isRequired,
        //   bar: React.PropTypes.string
        // };
        //
        // or:
        //
        // MyComponent.propTypes = myPropTypes;
        if (node.parent.type === 'AssignmentExpression') {

          var expression = resolveNodeValue(node.parent.right);
          if (!expression || expression.type !== 'ObjectExpression') {
            // If a value can't be found, we mark the defaultProps declaration as "unresolved", because
            // we should ignore this component and not report any errors for it, to avoid false-positives
            // with e.g. external defaultProps declarations.
            if (isDefaultProp) {
              markDefaultPropsAsUnresolved(component);
            }

            return;
          }

          if (isPropType) {
            addPropTypesToComponent(component, getPropTypesFromObjectExpression(expression));
          } else {
            addDefaultPropsToComponent(component, getDefaultPropsFromObjectExpression(expression));
          }

          return;
        }

        // e.g.:
        // MyComponent.propTypes.baz = React.PropTypes.string;
        if (node.parent.type === 'MemberExpression' && node.parent.parent.type === 'AssignmentExpression') {

          if (isPropType) {
            addPropTypesToComponent(component, [{
              name: node.parent.property.name,
              isRequired: isRequiredPropType(node.parent.parent.right),
              node: node.parent.parent
            }]);
          } else {
            addDefaultPropsToComponent(component, [node.parent.property.name]);
          }

          return;
        }
      },

      // e.g.:
      // class Hello extends React.Component {
      //   static get propTypes() {
      //     return {
      //       name: React.PropTypes.string
      //     };
      //   }
      //   static get defaultProps() {
      //     return {
      //       name: 'Dean'
      //     };
      //   }
      //   render() {
      //     return <div>Hello {this.props.name}</div>;
      //   }
      // }
      MethodDefinition: function(node) {
        if (!node.static || node.kind !== 'get') {
          return;
        }

        var isPropType = isPropTypesDeclaration(node.key);
        var isDefaultProp = isDefaultPropsDeclaration(node.key);

        if (!isPropType && !isDefaultProp) {
          return;
        }

        // find component this propTypes/defaultProps belongs to
        var component = components.get(utils.getParentES6Component());
        if (!component) {
          return;
        }

        var returnStatement = utils.findReturnStatement(node);
        if (!returnStatement) {
          return;
        }

        var expression = resolveNodeValue(returnStatement.argument);
        if (!expression || expression.type !== 'ObjectExpression') {
          return;
        }

        if (isPropType) {
          addPropTypesToComponent(component, getPropTypesFromObjectExpression(expression));
        } else {
          addDefaultPropsToComponent(component, getDefaultPropsFromObjectExpression(expression));
        }
      },

      // e.g.:
      // class Greeting extends React.Component {
      //   render() {
      //     return (
      //       <h1>Hello, {this.props.foo} {this.props.bar}</h1>
      //     );
      //   }
      //   static propTypes = {
      //     foo: React.PropTypes.string,
      //     bar: React.PropTypes.string.isRequired
      //   };
      // }
      ClassProperty: function(node) {
        if (isPropTypeAnnotation(node)) {
          handlePropTypeAnnotationClassProperty(node);
          return;
        }

        if (!node.static) {
          return;
        }

        if (!node.value) {
          return;
        }

        var isPropType = isPropTypesDeclaration(node.key);
        var isDefaultProp = isDefaultPropsDeclaration(node.key);

        if (!isPropType && !isDefaultProp) {
          return;
        }

        // find component this propTypes/defaultProps belongs to
        var component = components.get(utils.getParentES6Component());
        if (!component) {
          return;
        }

        var expression = resolveNodeValue(node.value);
        if (!expression || expression.type !== 'ObjectExpression') {
          return;
        }

        if (isPropType) {
          addPropTypesToComponent(component, getPropTypesFromObjectExpression(expression));
        } else {
          addDefaultPropsToComponent(component, getDefaultPropsFromObjectExpression(expression));
        }
      },

      // e.g.:
      // React.createClass({
      //   render: function() {
      //     return <div>{this.props.foo}</div>;
      //   },
      //   propTypes: {
      //     foo: React.PropTypes.string.isRequired,
      //   },
      //   getDefaultProps: function() {
      //     return {
      //       foo: 'default'
      //     };
      //   }
      // });
      ObjectExpression: function(node) {
        // find component this propTypes/defaultProps belongs to
        var component = utils.isES5Component(node) && components.get(node);
        if (!component) {
          return;
        }

        // Search for the proptypes declaration
        node.properties.forEach(function(property) {
          if (property.type === 'ExperimentalSpreadProperty') {
            return;
          }

          var isPropType = isPropTypesDeclaration(property.key);
          var isDefaultProp = isDefaultPropsDeclaration(property.key);

          if (!isPropType && !isDefaultProp) {
            return;
          }

          if (isPropType && property.value.type === 'ObjectExpression') {
            addPropTypesToComponent(component, getPropTypesFromObjectExpression(property.value));
            return;
          }

          if (isDefaultProp && property.value.type === 'FunctionExpression') {
            var returnStatement = utils.findReturnStatement(property);
            if (!returnStatement || returnStatement.argument.type !== 'ObjectExpression') {
              return;
            }

            addDefaultPropsToComponent(component, getDefaultPropsFromObjectExpression(returnStatement.argument));
          }
        });
      },

      // Check for type annotations in stateless components
      FunctionDeclaration: handleStatelessComponent,
      ArrowFunctionExpression: handleStatelessComponent,
      FunctionExpression: handleStatelessComponent,

      'Program:exit': function() {
        var list = components.list();

        for (var component in list) {
          if (!list.hasOwnProperty(component)) {
            continue;
          }

          // If no propTypes could be found, we don't report anything.
          if (!list[component].propTypes) {
            return;
          }

          reportPropTypesWithoutDefault(
            list[component].propTypes,
            list[component].defaultProps || {}
          );
        }
      }
    };
  })
};