/**
 * @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 {AST, TmplAstBoundEvent, TmplAstNode} from '@angular/compiler';
import {CompilerOptions, ConfigurationHost, readConfiguration} from '@angular/compiler-cli';
import {absoluteFromSourceFile, AbsoluteFsPath} from '@angular/compiler-cli/src/ngtsc/file_system';
import {TypeCheckShimGenerator} from '@angular/compiler-cli/src/ngtsc/typecheck';
import {OptimizeFor, TypeCheckingProgramStrategy} from '@angular/compiler-cli/src/ngtsc/typecheck/api';
import * as ts from 'typescript/lib/tsserverlibrary';

import {LanguageServiceAdapter, LSParseConfigHost} from './adapters';
import {CompilerFactory} from './compiler_factory';
import {CompletionBuilder, CompletionNodeContext} from './completions';
import {DefinitionBuilder} from './definitions';
import {QuickInfoBuilder} from './quick_info';
import {ReferenceBuilder} from './references';
import {getTargetAtPosition, TargetNode, TargetNodeKind} from './template_target';
import {getTemplateInfoAtPosition, isTypeScriptFile} from './utils';

export class LanguageService {
  private options: CompilerOptions;
  readonly compilerFactory: CompilerFactory;
  private readonly strategy: TypeCheckingProgramStrategy;
  private readonly adapter: LanguageServiceAdapter;
  private readonly parseConfigHost: LSParseConfigHost;

  constructor(project: ts.server.Project, private readonly tsLS: ts.LanguageService) {
    this.parseConfigHost = new LSParseConfigHost(project.projectService.host);
    this.options = parseNgCompilerOptions(project, this.parseConfigHost);

    // Projects loaded into the Language Service often include test files which are not part of the
    // app's main compilation unit, and these test files often include inline NgModules that declare
    // components from the app. These declarations conflict with the main declarations of such
    // components in the app's NgModules. This conflict is not normally present during regular
    // compilation because the app and the tests are part of separate compilation units.
    //
    // As a temporary mitigation of this problem, we instruct the compiler to ignore classes which
    // are not exported. In many cases, this ensures the test NgModules are ignored by the compiler
    // and only the real component declaration is used.
    this.options.compileNonExportedClasses = false;

    this.strategy = createTypeCheckingProgramStrategy(project);
    this.adapter = new LanguageServiceAdapter(project);
    this.compilerFactory = new CompilerFactory(this.adapter, this.strategy, this.options);
    this.watchConfigFile(project);
  }

  getCompilerOptions(): CompilerOptions {
    return this.options;
  }

  getSemanticDiagnostics(fileName: string): ts.Diagnostic[] {
    const compiler = this.compilerFactory.getOrCreateWithChangedFile(fileName);
    const ttc = compiler.getTemplateTypeChecker();
    const diagnostics: ts.Diagnostic[] = [];
    if (isTypeScriptFile(fileName)) {
      const program = compiler.getNextProgram();
      const sourceFile = program.getSourceFile(fileName);
      if (sourceFile) {
        diagnostics.push(...ttc.getDiagnosticsForFile(sourceFile, OptimizeFor.SingleFile));
      }
    } else {
      const components = compiler.getComponentsWithTemplateFile(fileName);
      for (const component of components) {
        if (ts.isClassDeclaration(component)) {
          diagnostics.push(...ttc.getDiagnosticsForComponent(component));
        }
      }
    }
    this.compilerFactory.registerLastKnownProgram();
    return diagnostics;
  }

  getDefinitionAndBoundSpan(fileName: string, position: number): ts.DefinitionInfoAndBoundSpan
      |undefined {
    const compiler = this.compilerFactory.getOrCreateWithChangedFile(fileName);
    const results =
        new DefinitionBuilder(this.tsLS, compiler).getDefinitionAndBoundSpan(fileName, position);
    this.compilerFactory.registerLastKnownProgram();
    return results;
  }

  getTypeDefinitionAtPosition(fileName: string, position: number):
      readonly ts.DefinitionInfo[]|undefined {
    const compiler = this.compilerFactory.getOrCreateWithChangedFile(fileName);
    const results =
        new DefinitionBuilder(this.tsLS, compiler).getTypeDefinitionsAtPosition(fileName, position);
    this.compilerFactory.registerLastKnownProgram();
    return results;
  }

  getQuickInfoAtPosition(fileName: string, position: number): ts.QuickInfo|undefined {
    const compiler = this.compilerFactory.getOrCreateWithChangedFile(fileName);
    const templateInfo = getTemplateInfoAtPosition(fileName, position, compiler);
    if (templateInfo === undefined) {
      return undefined;
    }
    const positionDetails = getTargetAtPosition(templateInfo.template, position);
    if (positionDetails === null) {
      return undefined;
    }
    const results =
        new QuickInfoBuilder(
            this.tsLS, compiler, templateInfo.component, positionDetails.nodeInContext.node)
            .get();
    this.compilerFactory.registerLastKnownProgram();
    return results;
  }

  getReferencesAtPosition(fileName: string, position: number): ts.ReferenceEntry[]|undefined {
    const compiler = this.compilerFactory.getOrCreateWithChangedFile(fileName);
    const results =
        new ReferenceBuilder(this.strategy, this.tsLS, compiler).get(fileName, position);
    this.compilerFactory.registerLastKnownProgram();
    return results;
  }

  private getCompletionBuilder(fileName: string, position: number):
      CompletionBuilder<TmplAstNode|AST>|null {
    const compiler = this.compilerFactory.getOrCreateWithChangedFile(fileName);
    const templateInfo = getTemplateInfoAtPosition(fileName, position, compiler);
    if (templateInfo === undefined) {
      return null;
    }
    const positionDetails = getTargetAtPosition(templateInfo.template, position);
    if (positionDetails === null) {
      return null;
    }
    return new CompletionBuilder(
        this.tsLS, compiler, templateInfo.component, positionDetails.nodeInContext.node,
        nodeContextFromTarget(positionDetails.nodeInContext), positionDetails.parent,
        positionDetails.template);
  }

  getCompletionsAtPosition(
      fileName: string, position: number, options: ts.GetCompletionsAtPositionOptions|undefined):
      ts.WithMetadata<ts.CompletionInfo>|undefined {
    const builder = this.getCompletionBuilder(fileName, position);
    if (builder === null) {
      return undefined;
    }
    const result = builder.getCompletionsAtPosition(options);
    this.compilerFactory.registerLastKnownProgram();
    return result;
  }

  getCompletionEntryDetails(
      fileName: string, position: number, entryName: string,
      formatOptions: ts.FormatCodeOptions|ts.FormatCodeSettings|undefined,
      preferences: ts.UserPreferences|undefined): ts.CompletionEntryDetails|undefined {
    const builder = this.getCompletionBuilder(fileName, position);
    if (builder === null) {
      return undefined;
    }
    const result = builder.getCompletionEntryDetails(entryName, formatOptions, preferences);
    this.compilerFactory.registerLastKnownProgram();
    return result;
  }

  getCompletionEntrySymbol(fileName: string, position: number, entryName: string): ts.Symbol
      |undefined {
    const builder = this.getCompletionBuilder(fileName, position);
    if (builder === null) {
      return undefined;
    }
    const result = builder.getCompletionEntrySymbol(entryName);
    this.compilerFactory.registerLastKnownProgram();
    return result;
  }

  private watchConfigFile(project: ts.server.Project) {
    // TODO: Check the case when the project is disposed. An InferredProject
    // could be disposed when a tsconfig.json is added to the workspace,
    // in which case it becomes a ConfiguredProject (or vice-versa).
    // We need to make sure that the FileWatcher is closed.
    if (!(project instanceof ts.server.ConfiguredProject)) {
      return;
    }
    const {host} = project.projectService;
    host.watchFile(
        project.getConfigFilePath(), (fileName: string, eventKind: ts.FileWatcherEventKind) => {
          project.log(`Config file changed: ${fileName}`);
          if (eventKind === ts.FileWatcherEventKind.Changed) {
            this.options = parseNgCompilerOptions(project, this.parseConfigHost);
          }
        });
  }
}

function parseNgCompilerOptions(
    project: ts.server.Project, host: ConfigurationHost): CompilerOptions {
  if (!(project instanceof ts.server.ConfiguredProject)) {
    return {};
  }
  const {options, errors} =
      readConfiguration(project.getConfigFilePath(), /* existingOptions */ undefined, host);
  if (errors.length > 0) {
    project.setProjectErrors(errors);
  }

  return options;
}

function createTypeCheckingProgramStrategy(project: ts.server.Project):
    TypeCheckingProgramStrategy {
  return {
    supportsInlineOperations: false,
    shimPathForComponent(component: ts.ClassDeclaration): AbsoluteFsPath {
      return TypeCheckShimGenerator.shimFor(absoluteFromSourceFile(component.getSourceFile()));
    },
    getProgram(): ts.Program {
      const program = project.getLanguageService().getProgram();
      if (!program) {
        throw new Error('Language service does not have a program!');
      }
      return program;
    },
    updateFiles(contents: Map<AbsoluteFsPath, string>) {
      for (const [fileName, newText] of contents) {
        const scriptInfo = getOrCreateTypeCheckScriptInfo(project, fileName);
        const snapshot = scriptInfo.getSnapshot();
        const length = snapshot.getLength();
        scriptInfo.editContent(0, length, newText);
      }
    },
  };
}

function getOrCreateTypeCheckScriptInfo(
    project: ts.server.Project, tcf: string): ts.server.ScriptInfo {
  // First check if there is already a ScriptInfo for the tcf
  const {projectService} = project;
  let scriptInfo = projectService.getScriptInfo(tcf);
  if (!scriptInfo) {
    // ScriptInfo needs to be opened by client to be able to set its user-defined
    // content. We must also provide file content, otherwise the service will
    // attempt to fetch the content from disk and fail.
    scriptInfo = projectService.getOrCreateScriptInfoForNormalizedPath(
        ts.server.toNormalizedPath(tcf),
        true,              // openedByClient
        '',                // fileContent
        ts.ScriptKind.TS,  // scriptKind
    );
    if (!scriptInfo) {
      throw new Error(`Failed to create script info for ${tcf}`);
    }
  }
  // Add ScriptInfo to project if it's missing. A ScriptInfo needs to be part of
  // the project so that it becomes part of the program.
  if (!project.containsScriptInfo(scriptInfo)) {
    project.addRoot(scriptInfo);
  }
  return scriptInfo;
}

function nodeContextFromTarget(target: TargetNode): CompletionNodeContext {
  switch (target.kind) {
    case TargetNodeKind.ElementInTagContext:
      return CompletionNodeContext.ElementTag;
    case TargetNodeKind.ElementInBodyContext:
      // Completions in element bodies are for new attributes.
      return CompletionNodeContext.ElementAttributeKey;
    case TargetNodeKind.AttributeInKeyContext:
      return CompletionNodeContext.ElementAttributeKey;
    case TargetNodeKind.AttributeInValueContext:
      if (target.node instanceof TmplAstBoundEvent) {
        return CompletionNodeContext.EventValue;
      } else {
        return CompletionNodeContext.None;
      }
    default:
      // No special context is available.
      return CompletionNodeContext.None;
  }
}