refactor: move es-mapping-generator to monorepo

packages/es-mapping-generator/src/mapping.ts

@@ -0,0 +1,921 @@
+/*
+ * Copyright (C) 2019-2021 StApps
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+import {
+  MappingDynamicTemplate,
+  MappingObjectProperty,
+  MappingProperty,
+} from '@elastic/elasticsearch/lib/api/types';
+import {Logger} from '@openstapps/logger';
+import merge from 'deepmerge';
+import {stringify} from 'flatted';
+import {DeclarationReflection, ProjectReflection, SignatureReflection} from 'typedoc';
+import {
+  ArrayType,
+  Comment,
+  CommentTag,
+  IntrinsicType,
+  ReferenceType,
+  ReflectionType,
+  StringLiteralType,
+  Type,
+  TypeParameterType,
+  UnionType,
+} from 'typedoc/dist/lib/models';
+import {fieldmap, filterableMap, filterableTagName} from './config/fieldmap';
+import {premaps} from './config/premap';
+import {settings} from './config/settings';
+import {dynamicTypes, isTagType, MISSING_PREMAP, PARSE_ERROR, TYPE_CONFLICT, typemap} from './config/typemap';
+import {AggregationSchema, ESNestedAggregation} from './types/aggregation';
+import {ElasticsearchTemplateCollection, MappingGenTemplate} from './types/mapping';
+
+let dynamicTemplates: Record<string, MappingDynamicTemplate>[] = [];
+let errors: string[] = [];
+let showErrors = true;
+
+let aggregations: AggregationSchema = {};
+
+const indexableTag = 'indexable';
+const aggregatableTag = 'aggregatable';
+const aggregatableTagParameterGlobal = 'global';
+const inheritTagsName = 'inherittags';
+
+// clamp printed object to 1000 chars to keep error messages readable
+const maxErrorObjectChars = 1000;
+
+let ignoredTagsList = ['indexable', 'validatable', inheritTagsName];
+let inheritTagsMap: {[path: string]: CommentTag[]} = {};
+
+/**
+ * Gets all interfaces that have an @indexable tag
+ *
+ * @param projectReflection the project reflection from which to extract the indexable interfaces
+ */
+export function getAllIndexableInterfaces(projectReflection: ProjectReflection): DeclarationReflection[] {
+  let indexableInterfaces: DeclarationReflection[] = [];
+
+  if (!Array.isArray(projectReflection.children) || projectReflection.children.length === 0) {
+    throw new Error('No DeclarationReflections found. Please check your input path');
+  }
+
+  // push all declaration reflections into one array
+  for (const declarationReflection of projectReflection.children) {
+    if (Array.isArray(declarationReflection.children)) {
+      indexableInterfaces = [...indexableInterfaces, ...declarationReflection.children];
+    }
+  }
+
+  // filter all declaration reflections with an @indexable tag
+  indexableInterfaces = indexableInterfaces.filter(declarationReflection => {
+    if (
+      typeof declarationReflection.comment === 'undefined' ||
+      typeof declarationReflection.comment.tags === 'undefined'
+    ) {
+      return false;
+    }
+
+    return (
+      typeof declarationReflection.comment.tags.find(commentTag => {
+        return commentTag.tagName === indexableTag;
+      }) !== 'undefined'
+    );
+  });
+
+  return indexableInterfaces;
+}
+
+/**
+ * Composes error messages, that are readable and contain a certain minimum of information
+ *
+ * @param path the path where the error took place
+ * @param topTypeName the name of the SCThingType
+ * @param typeName the name of the object, with which something went wrong
+ * @param object the object or name
+ * @param message the error message
+ */
+function composeErrorMessage(
+  path: string,
+  topTypeName: string,
+  typeName: string,
+  object: string,
+  message: string,
+) {
+  const error = `At "${topTypeName}::${path.slice(
+    0,
+    Math.max(0, path.length - 1),
+  )}" for ${typeName} "${trimString(object, maxErrorObjectChars)}": ${message}`;
+  errors.push(error);
+  if (showErrors) {
+    // tslint:disable-next-line:no-floating-promises
+    void Logger.error(error);
+  }
+}
+
+/**
+ * Trims a string to a readable size and appends "..."
+ *
+ * @param value the string to trim
+ * @param maxLength the maximum allowed length before it is clamped
+ */
+function trimString(value: string, maxLength: number): string {
+  return value.length > maxLength ? `${value.slice(0, Math.max(0, maxLength))}...` : value;
+}
+
+/**
+ * Gets the Reflections and names for Generics in a ReferenceType of a DeclarationReflection
+ *
+ * Warning to future maintainers: The code for generics doesn't account for depth. when there is a new generic, it will
+ * override the previous one, if there isn't, it will just continue passing it down.
+ *
+ * @param type the ReferenceType of a DeclarationReflection
+ * @param out the previous reflection, it then overrides all parameters or keeps old ones
+ * @param topTypeName the name of the object, with which something went wrong
+ * @param path the current path to the object we are in
+ * @param tags any tags attached to the type
+ */
+function getReflectionGeneric(
+  type: ReferenceType,
+  out: Map<string, MappingProperty>,
+  topTypeName: string,
+  path: string,
+  tags: CommentTag[],
+): Map<string, MappingProperty> {
+  if (
+    typeof type.typeArguments !== 'undefined' &&
+    type.reflection instanceof DeclarationReflection &&
+    typeof type.reflection.typeParameters !== 'undefined'
+  ) {
+    for (let i = 0; i < type.reflection.typeParameters.length; i++) {
+      if (i < type.typeArguments.length) {
+        out.set(
+          type.reflection.typeParameters[i].name,
+          handleType(type.typeArguments[i], out, topTypeName, path, tags),
+        );
+      } else {
+        // this can happen due to a bug in TypeDoc https://github.com/TypeStrong/typedoc/issues/1061
+        // we have no way to know the type here, so we have to use this.
+        out.set(type.reflection.typeParameters[i].name, {
+          dynamic: true,
+          properties: {},
+        });
+
+        Logger.warn(
+          `Type "${type.name}": Defaults of generics (Foo<T = any>) currently don't work due to a bug` +
+            ` in TypeDoc. It has been replaced by a dynamic type.`,
+        );
+      }
+    }
+  }
+
+  return out;
+}
+
+/**
+ * Handles a ReferenceType that has no value
+ *
+ * Most of the times that is an external type.
+ *
+ * @param ref the ReferenceType
+ * @param generics the generics from levels above, so we can use them without having access to the parent
+ * @param path the current path to the object we are in
+ * @param topTypeName the name of the SCThingType
+ * @param tags any tags attached to the type
+ */
+function handleExternalType(
+  ref: ReferenceType,
+  generics: Map<string, MappingProperty>,
+  path: string,
+  topTypeName: string,
+  tags: CommentTag[],
+): MappingProperty {
+  for (const premap of Object.keys(premaps)) {
+    if (premap === ref.name) {
+      return readFieldTags(premaps[premap], path, topTypeName, tags);
+    }
+  }
+
+  if (ref.name === 'Array') {
+    // basically an external type, but Array is quite common, especially with generics
+    if (typeof ref.typeArguments === 'undefined' || typeof ref.typeArguments[0] === 'undefined') {
+      composeErrorMessage(path, topTypeName, 'Array with generics', 'array', 'Failed to parse');
+
+      return {type: PARSE_ERROR};
+    }
+
+    return readFieldTags(
+      handleType(
+        ref.typeArguments[0],
+        getReflectionGeneric(ref, new Map(generics), path, topTypeName, tags),
+        path,
+        topTypeName,
+        tags,
+      ),
+      path,
+      topTypeName,
+      tags,
+    );
+  }
+  if (ref.name === '__type') {
+    // empty object
+    return {
+      dynamic: 'strict',
+      properties: {},
+    };
+  }
+
+  composeErrorMessage(path, topTypeName, 'external type', ref.name, 'Missing pre-map');
+
+  return readFieldTags({type: MISSING_PREMAP}, path, topTypeName, tags);
+}
+
+/**
+ * Handles an object
+ *
+ * @param decl the DeclarationReflection of the object
+ * @param generics the generics from levels above, so we can use them without having access to the parent
+ * @param path the current path to the object we are in
+ * @param topTypeName the name of the SCThingType
+ * @param inheritedTags the inherited tags
+ */
+function handleDeclarationReflection(
+  decl: DeclarationReflection,
+  generics: Map<string, MappingProperty>,
+  path: string,
+  topTypeName: string,
+  inheritedTags?: CommentTag[],
+): MappingProperty {
+  // check if we have an object referencing a generic
+  if (generics.has(decl.name)) {
+    // if the object name is the same as the generic name
+    return readFieldTags(generics.get(decl.name)!, path, topTypeName, decl.comment?.tags ?? []);
+    // use the value defined by the generic
+  }
+
+  // start the actual handling process
+  const out: MappingProperty = {
+    dynamic: 'strict',
+    properties: {},
+  };
+
+  let empty = true;
+  // first check if there are any index signatures, so for example `[name: string]: Foo`
+  if (typeof decl.indexSignature !== 'undefined') {
+    out.dynamic = true;
+
+    if (typeof decl.indexSignature.type !== 'undefined') {
+      empty = false;
+      const template: Record<string, MappingDynamicTemplate> = {};
+      template[decl.name] = {
+        mapping: handleType(
+          decl.indexSignature.type,
+          new Map(generics),
+          path,
+          topTypeName,
+          getCommentTags(decl.indexSignature, path, topTypeName),
+        ),
+        match: '*',
+        match_mapping_type: '*',
+        path_match: `${path}*`,
+      };
+      dynamicTemplates.push(template);
+    }
+  }
+
+  if (decl.kindString === 'Enumeration') {
+    return readTypeTags('string', path, topTypeName, getCommentTags(decl, path, topTypeName, inheritedTags));
+  }
+
+  // check all the children, so in this case we are dealing with an OBJECT
+  if (typeof decl.children !== 'undefined' && decl.children.length > 0) {
+    for (const child of decl.children) {
+      empty = false;
+      out.properties![child.name] = handleDeclarationReflection(
+        child,
+        new Map(generics),
+        `${path}${child.name}.`,
+        topTypeName,
+      );
+    }
+  } else if (decl.type instanceof Type) {
+    // if the object is a type, so we are dealing with a PROPERTY
+    // get inherited tags
+    const tags =
+      (inheritedTags ?? []).length > 0
+        ? typeof inheritedTags!.find(it => isTagType(it.tagName)) !== 'undefined'
+          ? inheritedTags!
+          : [...(inheritedTags ?? []), ...getCommentTags(decl, path, topTypeName)]
+        : getCommentTags(decl, path, topTypeName);
+
+    return handleType(decl.type, new Map(generics), path, topTypeName, tags);
+  } else if (decl.kindString === 'Enumeration member') {
+    return readTypeTags(
+      typeof decl.defaultValue,
+      path,
+      topTypeName,
+      getCommentTags(decl, path, topTypeName, inheritedTags),
+    );
+  }
+
+  if (empty) {
+    composeErrorMessage(path, topTypeName, 'object', decl.name, 'Empty object');
+  }
+
+  return readFieldTags(out, path, topTypeName, getCommentTags(decl, path, topTypeName));
+}
+
+/**
+ * Reads all comment tags, including inherited ones
+ *
+ * @param decl the DeclarationReflection to read the tags from
+ * @param path the path on which the comments lie
+ * @param topTypeName the name of the SCThingType
+ * @param inheritedTags any tags that might have been inherited by a parent
+ * @param breakId the id of the previous reflection to prevent infinite recursion in some cases
+ */
+function getCommentTags(
+  decl: DeclarationReflection | SignatureReflection,
+  path: string,
+  topTypeName: string,
+  inheritedTags: CommentTag[] = [],
+  // tslint:disable-next-line:no-unnecessary-initializer
+  breakId: number | undefined = undefined,
+): CommentTag[] {
+  if (decl.id === breakId) {
+    return [];
+  }
+
+  let out: CommentTag[] =
+    decl.comment instanceof Comment
+      ? typeof decl.comment.tags !== 'undefined'
+        ? decl.comment.tags
+        : inheritedTags
+      : inheritedTags;
+  if (
+    decl.overwrites instanceof ReferenceType &&
+    decl.overwrites.reflection instanceof DeclarationReflection
+  ) {
+    out = arrayPriorityJoin(
+      getCommentTags(decl.overwrites.reflection, path, topTypeName, inheritedTags, decl.id),
+      out,
+    );
+  }
+  if (
+    decl.inheritedFrom instanceof ReferenceType &&
+    decl.inheritedFrom.reflection instanceof DeclarationReflection
+  ) {
+    out = arrayPriorityJoin(
+      getCommentTags(decl.inheritedFrom.reflection, path, topTypeName, inheritedTags, decl.id),
+      out,
+    );
+  }
+
+  saveCommentTags(out, path, topTypeName);
+  const inheritTag = out.find(value => value.tagName === inheritTagsName);
+  if (typeof inheritTag !== 'undefined') {
+    out = arrayPriorityJoin(out, retrieveCommentTags(inheritTag.text.trim(), path, topTypeName));
+  }
+
+  return out;
+}
+
+/**
+ * Saves all comment tags to the map
+ *
+ * @param tags all tags to be saved (@see and @[inheritTags] will be stripped)
+ * @param path the path of field
+ * @param topTypeName the name of the SCThingType
+ */
+function saveCommentTags(tags: CommentTag[], path: string, topTypeName: string) {
+  inheritTagsMap[`${topTypeName}::${path.slice(0, Math.max(0, path.length - 1))}`] = tags.filter(
+    value => value.tagName !== 'see' && value.tagName !== inheritTagsName,
+  );
+}
+
+/**
+ * Retrieves any saved tags
+ *
+ * @param path the path to the original field
+ * @param currentPath the current path to the object we are in
+ * @param topTypeName the name of the SCThingType
+ */
+function retrieveCommentTags(path: string, currentPath: string, topTypeName: string): CommentTag[] {
+  if (!(path in inheritTagsMap)) {
+    composeErrorMessage(currentPath, topTypeName, path, 'Comment', 'Referenced path to tags does not exist!');
+
+    return [];
+  }
+
+  return inheritTagsMap[path];
+}
+
+/**
+ * Joins two arrays of CommentTags, but overrides all original CommentTags with the same tagName
+ *
+ * @param originals the original array
+ * @param overrider the array that should be appended and provide the override values
+ */
+function arrayPriorityJoin(originals: CommentTag[], overrider: CommentTag[]): CommentTag[] {
+  const out: CommentTag[] = overrider;
+
+  for (const original of originals) {
+    const result = overrider.find(element => original.tagName === element.tagName);
+
+    // no support for multiple tags with the same name
+    if (!(result instanceof CommentTag)) {
+      out.push(original);
+    }
+  }
+
+  return out;
+}
+
+/**
+ * Handles UnionTypes
+ *
+ * Put into a separate function as it is a little bit more complex
+ * Works fairly reliable, although there are issues with primitive union types, which don't work at all (And never will)
+ *
+ * @param type the type object
+ * @param generics the generics from levels above, so we can use them without having access to the parent
+ * @param path the current path to the object we are in
+ * @param topTypeName the name of the SCThingType
+ * @param tags any tags attached to the type
+ */
+function handleUnionType(
+  type: UnionType,
+  generics: Map<string, MappingProperty>,
+  path: string,
+  topTypeName: string,
+  tags: CommentTag[],
+): MappingProperty {
+  const list: MappingProperty[] = [];
+
+  for (const subType of type.types) {
+    if (subType instanceof IntrinsicType && subType.name === 'undefined') {
+      continue;
+    }
+    list.push(handleType(subType, new Map(generics), path, topTypeName, tags));
+  }
+
+  if (list.length > 0) {
+    let out = list[0];
+
+    for (const item of list) {
+      out = merge<MappingProperty>(out, item);
+    }
+
+    return out;
+  }
+
+  composeErrorMessage(
+    path,
+    topTypeName,
+    'Union Type',
+    stringify(list),
+    'Empty union type. This is likely not a user error.',
+  );
+
+  return {type: PARSE_ERROR};
+}
+
+/**
+ * Serves as a kind of distributor for the different types, should not contain any specific code
+ *
+ * @param type the type object
+ * @param generics the generics from levels above, so we can use them without having access to the parent
+ * @param path the current path to the object we are in
+ * @param topTypeName the name of the SCThingType
+ * @param tags any tags attached to the type
+ */
+function handleType(
+  type: Type,
+  generics: Map<string, MappingProperty>,
+  path: string,
+  topTypeName: string,
+  tags: CommentTag[],
+): MappingProperty {
+  // logger.log((type as any).name);
+  if (type instanceof ArrayType) {
+    // array is irrelevant in Elasticsearch, so just go with the element type
+    const esType = handleType(type.elementType, new Map(generics), path, topTypeName, tags);
+    // also merge tags of the array to the element type
+    // filter out the type tags lazily, this can lead to double messages for "Not implemented tag"
+    let newTags = tags;
+    if ('type' in esType) {
+      newTags = tags.filter(tag => {
+        return !(tag.tagName === esType.type);
+      });
+    }
+
+    return readFieldTags(esType, path, topTypeName, newTags);
+  }
+  if (type.type === 'stringLiteral') {
+    // a string literal, usually for type
+    return readTypeTags(type.type, path, topTypeName, tags);
+  }
+  if (type instanceof IntrinsicType) {
+    // the absolute default type, like strings
+    return readTypeTags(type.name, path, topTypeName, tags);
+  }
+  if (type instanceof UnionType) {
+    // the union type...
+    return handleUnionType(type, new Map(generics), path, topTypeName, tags);
+  }
+  if (type instanceof ReferenceType) {
+    if (typeof premaps[type.name] === 'undefined' && typeof type.reflection !== 'undefined') {
+      // there is really no way to make this typesafe, every element in DeclarationReflection is optional.
+      return handleDeclarationReflection(
+        type.reflection as DeclarationReflection,
+        getReflectionGeneric(type, new Map(generics), path, topTypeName, tags),
+        path,
+        topTypeName,
+        tags,
+      );
+    }
+
+    return handleExternalType(type, new Map(generics), path, topTypeName, tags);
+  }
+  if (type instanceof TypeParameterType) {
+    // check if we have an object referencing a generic
+    if (generics.has(type.name)) {
+      return generics.get(type.name)!;
+    }
+    composeErrorMessage(path, topTypeName, 'Generic', type.name, 'Missing reflection, please report!');
+
+    return {type: PARSE_ERROR};
+  }
+  if (type instanceof ReflectionType) {
+    return readFieldTags(
+      handleDeclarationReflection(type.declaration, new Map(generics), path, topTypeName),
+      path,
+      topTypeName,
+      tags,
+    );
+  }
+
+  composeErrorMessage(path, topTypeName, 'type', stringify(type), 'Not implemented type');
+
+  return {type: PARSE_ERROR};
+}
+
+/**
+ * Adds an aggregatable to the aggregations list
+ *
+ * @param path the current path
+ * @param topTypeName the name of the top type
+ * @param global whether the topTypeName will be used
+ */
+function addAggregatable(path: string, topTypeName: string, global: boolean) {
+  // push type.path and remove the '.' at the end of the path
+
+  if (global) {
+    const property_ = path.slice(0, -1).split('.').pop() as string; // cannot be undefined
+
+    return ((aggregations['@all'] as ESNestedAggregation).aggs[property_.split('.').pop() as string] = {
+      terms: {
+        field: `${property_}.raw`,
+        size: 1000,
+      },
+    });
+  }
+
+  const property = path.slice(0, -1);
+
+  return ((aggregations[topTypeName] as ESNestedAggregation).aggs[property] = {
+    terms: {
+      field: `${property}.raw`,
+      size: 1000,
+    },
+  });
+}
+
+/**
+ * Reads all tags related to Elasticsearch fields from the fieldMap
+ *
+ * @param previous the previous ElasticsearchValue, for example and object
+ * @param path the current path to the object we are in
+ * @param topTypeName the name of the SCThingType
+ * @param tags tags attached to the value
+ * @param dataType the ElasticsearchDataType, for checking if a tag is a type tag
+ */
+function readFieldTags(
+  previous: MappingProperty,
+  path: string,
+  topTypeName: string,
+  tags: CommentTag[],
+  dataType?: string,
+): MappingProperty {
+  for (const tag of tags) {
+    if (tag.tagName === aggregatableTag) {
+      addAggregatable(path, topTypeName, tag.text.trim() === aggregatableTagParameterGlobal);
+    }
+
+    if (!ignoredTagsList.includes(tag.tagName)) {
+      if (typeof fieldmap[tag.tagName] !== 'undefined') {
+        if (typeof previous.fields === 'undefined') {
+          // create in case it doesn't exist
+          previous.fields = {};
+        }
+        if (tag.text.trim() === '') {
+          // merge fields
+          previous.fields = {...previous.fields, ...fieldmap[tag.tagName].default};
+        } else if (typeof fieldmap[tag.tagName][tag.text.trim()] !== 'undefined') {
+          // merge fields
+          previous.fields = {...previous.fields, ...fieldmap[tag.tagName][tag.text.trim()]};
+        } else if (!fieldmap[tag.tagName].ignore.includes(tag.text.trim())) {
+          // when there is an unidentified tag
+          composeErrorMessage(
+            path,
+            topTypeName,
+            'tag',
+            tag.tagName,
+            `Not implemented tag param "${tag.text.trim()}"`,
+          );
+        }
+      } else if (tag.tagName === filterableTagName) {
+        if (typeof previous.fields === 'undefined') {
+          previous.fields = {};
+        }
+        if ('type' in previous) {
+          const type = filterableMap[previous.type!];
+          if (typeof type !== 'undefined') {
+            // merge fields
+            previous.fields = {...previous.fields, raw: {type: type}};
+          } else {
+            composeErrorMessage(
+              path,
+              topTypeName,
+              'tag',
+              tag.tagName,
+              `Not implemented for ${previous.type}`,
+            );
+          }
+        } else {
+          composeErrorMessage(path, topTypeName, 'tag', tag.tagName, 'Not applicable for object types');
+        }
+      } else if (typeof dataType === 'undefined' || typeof typemap[dataType][tag.tagName] === 'undefined') {
+        composeErrorMessage(path, topTypeName, 'tag', tag.tagName, `Not implemented tag`);
+      }
+    }
+  }
+
+  return previous;
+}
+
+/**
+ * Reads all types related to Elasticsearch fields from the fieldMap
+ *
+ * @param type the type of the value
+ * @param path the current path to the object we are in
+ * @param topTypeName the name of the SCThingType
+ * @param tags tags attached to the value
+ */
+function readTypeTags(type: string, path: string, topTypeName: string, tags: CommentTag[]): MappingProperty {
+  let out: MappingProperty = {type: PARSE_ERROR};
+
+  if (typeof typemap[type] !== 'undefined') {
+    // first look if the value has a definition in the typemap
+    for (let i = tags.length - 1; i >= 0; i--) {
+      if (
+        !ignoredTagsList.includes(tags[i].tagName) &&
+        typeof typemap[type][tags[i].tagName] !== 'undefined'
+      ) {
+        // if we have a tag that indicates a type
+        if (out.type !== PARSE_ERROR) {
+          composeErrorMessage(
+            path,
+            topTypeName,
+            'type',
+            type,
+            `Type conflict; "${typemap[type][tags[i].tagName]}" would override "${
+              (out as MappingProperty).type
+            }"`,
+          );
+          (out as MappingProperty).type = TYPE_CONFLICT;
+          continue;
+        }
+        (out as MappingProperty).type = typemap[type][tags[i].tagName];
+      }
+    }
+
+    if (out.type === PARSE_ERROR) {
+      (out as MappingProperty).type = typemap[type].default;
+    }
+
+    out = readFieldTags(out, path, topTypeName, tags, type);
+
+    return out;
+  }
+  if (dynamicTypes.includes(type)) {
+    // Elasticsearch dynamic type TODO: doesn't work for direct types
+    return {
+      dynamic: true,
+      properties: {},
+    };
+  }
+
+  composeErrorMessage(path, topTypeName, 'type', type, 'Not implemented type');
+
+  return out;
+}
+
+/**
+ * Reset the state
+ *
+ * This is kind of a suboptimal solution and should be changed in the future.
+ * https://gitlab.com/openstapps/core-tools/-/issues/49
+ *
+ * @param resetInheritTags whether inherited tags should be reset as well
+ */
+function reset(resetInheritTags = true) {
+  errors = [];
+  dynamicTemplates = [];
+  aggregations = {
+    '@all': {
+      aggs: {},
+      filter: {
+        match_all: {},
+      },
+    },
+  };
+
+  if (resetInheritTags) {
+    inheritTagsMap = {};
+  }
+}
+
+/**
+ * Takes a project reflection and generates an ElasticsearchTemplate from it
+ *
+ * Serves as the entry point for getting the mapping, so if you just want to get the mapping files for Elasticsearch,
+ * you can do so by calling this function, `RETURNED_VALUE.template` contains the mapping in a fashion that is directly
+ * readable by Elasticsearch.
+ *
+ * @param projectReflection a reflection of the project you want to get the ES Mappings from
+ * @param ignoredTags the tag names for which the error output should be suppressed
+ * @param showErrorOutput whether to print all errors in the command line or not
+ * @param interfaceFilter only parse specific interfaces, this is for testing purposes
+ */
+export function generateTemplate(
+  projectReflection: ProjectReflection,
+  ignoredTags: string[],
+  showErrorOutput = true,
+  interfaceFilter: string[] = [],
+): MappingGenTemplate {
+  reset();
+
+  showErrors = showErrorOutput;
+
+  ignoredTagsList = ['indexable', 'validatable', inheritTagsName];
+  // eslint-disable-next-line prefer-spread
+  ignoredTagsList.push.apply(ignoredTagsList, ignoredTags);
+
+  const indexableInterfaces = getAllIndexableInterfaces(projectReflection);
+
+  const out: ElasticsearchTemplateCollection = {};
+
+  for (const _interface of indexableInterfaces) {
+    // TODO: lots of duplicate code, this all needs to be changed https://gitlab.com/openstapps/core-tools/-/issues/49
+    if (!Array.isArray(_interface.children) || _interface.children.length === 0) {
+      throw new Error('Interface needs at least some properties to be indexable');
+    }
+
+    const typeObject = _interface.children.find(declarationReflection => {
+      return declarationReflection.name === 'type';
+    });
+
+    if (typeof typeObject === 'undefined' || typeof typeObject.type === 'undefined') {
+      throw new TypeError('Interface needs a type to be indexable');
+    }
+
+    let typeName = 'INVALID_TYPE';
+    if (typeObject.type instanceof ReferenceType) {
+      if (
+        typeObject.type.reflection instanceof DeclarationReflection &&
+        typeof typeObject.type.reflection.defaultValue === 'string'
+      ) {
+        typeName = typeObject.type.reflection.defaultValue.replace('"', '').replace('"', '');
+      } else {
+        // tslint:disable-next-line:no-floating-promises
+        void Logger.error(
+          'Your input files seem to be incorrect, or there is a major bug in the mapping generator.',
+        );
+      }
+    } else if (typeObject.type instanceof StringLiteralType) {
+      Logger.warn(`The interface ${_interface.name} uses a string literal as type, please use SCThingType.`);
+      typeName = typeObject.type.value;
+    } else {
+      // tslint:disable-next-line:no-floating-promises
+      void Logger.error(
+        `The interface ${_interface.name} is required to use an SCThingType as a type, please do so.`,
+      );
+    }
+    // init aggregation schema for type
+    aggregations[typeName] = {
+      aggs: {},
+      filter: {
+        term: {
+          type: typeName,
+        },
+      },
+    };
+    handleDeclarationReflection(_interface, new Map(), '', typeName);
+  }
+
+  // second traversal
+  reset(false);
+
+  for (const _interface of indexableInterfaces) {
+    if (!Array.isArray(_interface.children) || _interface.children.length === 0) {
+      throw new Error('Interface needs at least some properties to be indexable');
+    }
+
+    const typeObject = _interface.children.find(declarationReflection => {
+      return declarationReflection.name === 'type';
+    });
+
+    if (typeof typeObject === 'undefined' || typeof typeObject.type === 'undefined') {
+      throw new TypeError('Interface needs a type to be indexable');
+    }
+
+    let typeName = 'INVALID_TYPE';
+    if (typeObject.type instanceof ReferenceType) {
+      if (
+        typeObject.type.reflection instanceof DeclarationReflection &&
+        typeof typeObject.type.reflection.defaultValue === 'string'
+      ) {
+        typeName = typeObject.type.reflection.defaultValue.replace('"', '').replace('"', '');
+      } else {
+        // tslint:disable-next-line:no-floating-promises
+        void Logger.error(
+          'Your input files seem to be incorrect, or there is a major bug in the mapping generator.',
+        );
+      }
+    } else if (typeObject.type instanceof StringLiteralType) {
+      Logger.warn(`The interface ${_interface.name} uses a string literal as type, please use SCThingType.`);
+      typeName = typeObject.type.value;
+    } else {
+      // tslint:disable-next-line:no-floating-promises
+      void Logger.error(
+        `The interface ${_interface.name} is required to use an SCThingType as a type, please do so.`,
+      );
+    }
+
+    // filter out
+    if (interfaceFilter.length > 0 && typeof interfaceFilter.find(it => it === typeName) === 'undefined') {
+      continue;
+    }
+
+    // init aggregation schema for type
+    aggregations[typeName] = {
+      aggs: {},
+      filter: {
+        term: {
+          type: typeName,
+        },
+      },
+    };
+
+    let typeNameWithoutSpaces = typeName.toLowerCase();
+    while (typeNameWithoutSpaces.includes(' ')) {
+      typeNameWithoutSpaces = typeNameWithoutSpaces.replace(' ', '_');
+    }
+    const templateName = `template_${typeNameWithoutSpaces}`;
+
+    out[templateName] = {
+      mappings: handleDeclarationReflection(_interface, new Map(), '', typeName) as MappingObjectProperty,
+      settings: settings,
+      index_patterns: [`stapps_${typeNameWithoutSpaces}*`],
+    };
+    out[templateName].mappings!.properties!.creation_date = {
+      type: 'date',
+    };
+
+    out[templateName].mappings!.dynamic_templates = dynamicTemplates;
+
+    // Set some properties
+    out[templateName].mappings!._source = {
+      excludes: ['creation_date'],
+    };
+    out[templateName].mappings!.date_detection = false;
+
+    dynamicTemplates = [];
+
+    if (Object.keys((aggregations[typeName] as ESNestedAggregation).aggs).length === 0) {
+      delete aggregations[typeName];
+    }
+  }
+
+  return {aggregations, mappings: out, errors};
+}