/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {
  Rule,
  SchematicsException,
  Tree,
  apply,
  applyTemplates,
  chain,
  filter,
  mergeWith,
  move,
  noop,
  strings,
  url,
} from '@angular-devkit/schematics';
import * as ts from '../third_party/github.com/Microsoft/TypeScript/lib/typescript';
import { addDeclarationToModule, addExportToModule } from '../utility/ast-utils';
import { InsertChange } from '../utility/change';
import { buildRelativePath, findModuleFromOptions } from '../utility/find-module';
import { parseName } from '../utility/parse-name';
import { validateHtmlSelector } from '../utility/validation';
import { buildDefaultPath, getWorkspace } from '../utility/workspace';
import { Schema as DirectiveOptions } from './schema';

function addDeclarationToNgModule(options: DirectiveOptions): Rule {
  return (host: Tree) => {
    if (options.skipImport || !options.module) {
      return host;
    }

    const modulePath = options.module;
    const text = host.read(modulePath);
    if (text === null) {
      throw new SchematicsException(`File ${modulePath} does not exist.`);
    }
    const sourceText = text.toString('utf-8');
    const source = ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);

    const directivePath =
      `/${options.path}/` +
      (options.flat ? '' : strings.dasherize(options.name) + '/') +
      strings.dasherize(options.name) +
      '.directive';
    const relativePath = buildRelativePath(modulePath, directivePath);
    const classifiedName = strings.classify(`${options.name}Directive`);
    const declarationChanges = addDeclarationToModule(
      source,
      modulePath,
      classifiedName,
      relativePath,
    );
    const declarationRecorder = host.beginUpdate(modulePath);
    for (const change of declarationChanges) {
      if (change instanceof InsertChange) {
        declarationRecorder.insertLeft(change.pos, change.toAdd);
      }
    }
    host.commitUpdate(declarationRecorder);

    if (options.export) {
      // Need to refresh the AST because we overwrote the file in the host.
      const text = host.read(modulePath);
      if (text === null) {
        throw new SchematicsException(`File ${modulePath} does not exist.`);
      }
      const sourceText = text.toString('utf-8');
      const source = ts.createSourceFile(modulePath, sourceText, ts.ScriptTarget.Latest, true);

      const exportRecorder = host.beginUpdate(modulePath);
      const exportChanges = addExportToModule(
        source,
        modulePath,
        strings.classify(`${options.name}Directive`),
        relativePath,
      );

      for (const change of exportChanges) {
        if (change instanceof InsertChange) {
          exportRecorder.insertLeft(change.pos, change.toAdd);
        }
      }
      host.commitUpdate(exportRecorder);
    }

    return host;
  };
}

function buildSelector(options: DirectiveOptions, projectPrefix: string) {
  let selector = options.name;
  if (options.prefix) {
    selector = `${options.prefix}-${selector}`;
  } else if (options.prefix === undefined && projectPrefix) {
    selector = `${projectPrefix}-${selector}`;
  }

  return strings.camelize(selector);
}

export default function (options: DirectiveOptions): Rule {
  return async (host: Tree) => {
    const workspace = await getWorkspace(host);
    const project = workspace.projects.get(options.project as string);
    if (!project) {
      throw new SchematicsException(`Project "${options.project}" does not exist.`);
    }

    if (options.path === undefined) {
      options.path = buildDefaultPath(project);
    }

    options.module = findModuleFromOptions(host, options);

    const parsedPath = parseName(options.path, options.name);
    options.name = parsedPath.name;
    options.path = parsedPath.path;
    options.selector = options.selector || buildSelector(options, project.prefix || '');

    validateHtmlSelector(options.selector);

    const templateSource = apply(url('./files'), [
      options.skipTests ? filter((path) => !path.endsWith('.spec.ts.template')) : noop(),
      applyTemplates({
        ...strings,
        'if-flat': (s: string) => (options.flat ? '' : s),
        ...options,
      }),
      move(parsedPath.path),
    ]);

    return chain([addDeclarationToNgModule(options), mergeWith(templateSource)]);
  };
}