namespace.js

import declaredScope from 'eslint-module-utils/declaredScope'
import Exports from '../ExportMap'
import importDeclaration from '../importDeclaration'
import docsUrl from '../docsUrl'

module.exports = {
  meta: {
    type: 'problem',
    docs: {
      url: docsUrl('namespace'),
    },

    schema: [
      {
        'type': 'object',
        'properties': {
          'allowComputed': {
            'description':
              'If `false`, will report computed (and thus, un-lintable) references ' +
              'to namespace members.',
            'type': 'boolean',
            'default': false,
          },
        },
        'additionalProperties': false,
      },
    ],
  },

  create: function namespaceRule(context) {

    // read options
    const {
      allowComputed = false,
    } = context.options[0] || {}

    const namespaces = new Map()

    function makeMessage(last, namepath) {
       return `'${last.name}' not found in` +
              (namepath.length > 1 ? ' deeply ' : ' ') +
              `imported namespace '${namepath.join('.')}'.`
    }

    return {

      // pick up all imports at body entry time, to properly respect hoisting
      Program: function ({ body }) {
        function processBodyStatement(declaration) {
          if (declaration.type !== 'ImportDeclaration') return

          if (declaration.specifiers.length === 0) return

          const imports = Exports.get(declaration.source.value, context)
          if (imports == null) return null

          if (imports.errors.length) {
            imports.reportErrors(context, declaration)
            return
          }

          for (const specifier of declaration.specifiers) {
            switch (specifier.type) {
              case 'ImportNamespaceSpecifier':
                if (!imports.size) {
                  context.report(specifier,
                    `No exported names found in module '${declaration.source.value}'.`)
                }
                namespaces.set(specifier.local.name, imports)
                break
              case 'ImportDefaultSpecifier':
              case 'ImportSpecifier': {
                const meta = imports.get(
                  // default to 'default' for default http://i.imgur.com/nj6qAWy.jpg
                  specifier.imported ? specifier.imported.name : 'default')
                if (!meta || !meta.namespace) break
                namespaces.set(specifier.local.name, meta.namespace)
                break
              }
            }
          }
        }
        body.forEach(processBodyStatement)
      },

      // same as above, but does not add names to local map
      ExportNamespaceSpecifier: function (namespace) {
        var declaration = importDeclaration(context)

        var imports = Exports.get(declaration.source.value, context)
        if (imports == null) return null

        if (imports.errors.length) {
          imports.reportErrors(context, declaration)
          return
        }

        if (!imports.size) {
          context.report(namespace,
            `No exported names found in module '${declaration.source.value}'.`)
        }
      },

      // todo: check for possible redefinition

      MemberExpression: function (dereference) {
        if (dereference.object.type !== 'Identifier') return
        if (!namespaces.has(dereference.object.name)) return

        if (dereference.parent.type === 'AssignmentExpression' &&
            dereference.parent.left === dereference) {
            context.report(dereference.parent,
                `Assignment to member of namespace '${dereference.object.name}'.`)
        }

        // go deep
        var namespace = namespaces.get(dereference.object.name)
        var namepath = [dereference.object.name]
        // while property is namespace and parent is member expression, keep validating
        while (namespace instanceof Exports &&
               dereference.type === 'MemberExpression') {

          if (dereference.computed) {
            if (!allowComputed) {
              context.report(dereference.property,
                'Unable to validate computed reference to imported namespace \'' +
                dereference.object.name + '\'.')
            }
            return
          }

          if (!namespace.has(dereference.property.name)) {
            context.report(
              dereference.property,
              makeMessage(dereference.property, namepath))
            break
          }

          const exported = namespace.get(dereference.property.name)
          if (exported == null) return

          // stash and pop
          namepath.push(dereference.property.name)
          namespace = exported.namespace
          dereference = dereference.parent
        }

      },

      VariableDeclarator: function ({ id, init }) {
        if (init == null) return
        if (init.type !== 'Identifier') return
        if (!namespaces.has(init.name)) return

        // check for redefinition in intermediate scopes
        if (declaredScope(context, init.name) !== 'module') return

        // DFS traverse child namespaces
        function testKey(pattern, namespace, path = [init.name]) {
          if (!(namespace instanceof Exports)) return

          if (pattern.type !== 'ObjectPattern') return

          for (const property of pattern.properties) {
            if (
              property.type === 'ExperimentalRestProperty'
              || property.type === 'RestElement'
              || !property.key
            ) {
              continue
            }

            if (property.key.type !== 'Identifier') {
              context.report({
                node: property,
                message: 'Only destructure top-level names.',
              })
              continue
            }

            if (!namespace.has(property.key.name)) {
              context.report({
                node: property,
                message: makeMessage(property.key, path),
              })
              continue
            }

            path.push(property.key.name)
            const dependencyExportMap = namespace.get(property.key.name)
            // could be null when ignored or ambiguous
            if (dependencyExportMap !== null) {
              testKey(property.value, dependencyExportMap.namespace, path)
            }
            path.pop()
          }
        }

        testKey(id, namespaces.get(init.name))
      },

      JSXMemberExpression: function({object, property}) {
         if (!namespaces.has(object.name)) return
         var namespace = namespaces.get(object.name)
         if (!namespace.has(property.name)) {
           context.report({
             node: property,
             message: makeMessage(property, [object.name]),
           })
         }
      },
    }
  },
}