/**
 * @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 {R3PartialDeclaration} from '@angular/compiler';
import {AstObject} from '../ast/ast_value';
import {DeclarationScope} from './declaration_scope';
import {EmitScope} from './emit_scopes/emit_scope';
import {IifeEmitScope} from './emit_scopes/iife_emit_scope';
import {LinkerEnvironment} from './linker_environment';
import {PartialLinkerSelector} from './partial_linkers/partial_linker_selector';

export const NO_STATEMENTS: Readonly<any[]> = [] as const;

/**
 * This class is responsible for linking all the partial declarations found in a single file.
 */
export class FileLinker<TConstantScope, TStatement, TExpression> {
  private linkerSelector = new PartialLinkerSelector<TExpression>(this.linkerEnvironment.options);
  private emitScopes = new Map<TConstantScope, EmitScope<TStatement, TExpression>>();

  constructor(
      private linkerEnvironment: LinkerEnvironment<TStatement, TExpression>,
      private sourceUrl: string, readonly code: string) {}

  /**
   * Return true if the given callee name matches a partial declaration that can be linked.
   */
  isPartialDeclaration(calleeName: string): boolean {
    return this.linkerSelector.supportsDeclaration(calleeName);
  }

  /**
   * Link the metadata extracted from the args of a call to a partial declaration function.
   *
   * The `declarationScope` is used to determine the scope and strategy of emission of the linked
   * definition and any shared constant statements.
   *
   * @param declarationFn the name of the function used to declare the partial declaration - e.g.
   *     `ɵɵngDeclareDirective`.
   * @param args the arguments passed to the declaration function, should be a single object that
   *     corresponds to the `R3DeclareDirectiveMetadata` or `R3DeclareComponentMetadata` interfaces.
   * @param declarationScope the scope that contains this call to the declaration function.
   */
  linkPartialDeclaration(
      declarationFn: string, args: TExpression[],
      declarationScope: DeclarationScope<TConstantScope, TExpression>): TExpression {
    if (args.length !== 1) {
      throw new Error(
          `Invalid function call: It should have only a single object literal argument, but contained ${
              args.length}.`);
    }

    const metaObj =
        AstObject.parse<R3PartialDeclaration, TExpression>(args[0], this.linkerEnvironment.host);
    const ngImport = metaObj.getNode('ngImport');
    const emitScope = this.getEmitScope(ngImport, declarationScope);

    const version = metaObj.getString('version');
    const linker = this.linkerSelector.getLinker(declarationFn, version);
    const definition =
        linker.linkPartialDeclaration(this.sourceUrl, this.code, emitScope.constantPool, metaObj);

    return emitScope.translateDefinition(definition);
  }

  /**
   * Return all the shared constant statements and their associated constant scope references, so
   * that they can be inserted into the source code.
   */
  getConstantStatements(): {constantScope: TConstantScope, statements: TStatement[]}[] {
    const results: {constantScope: TConstantScope, statements: TStatement[]}[] = [];
    for (const [constantScope, emitScope] of this.emitScopes.entries()) {
      const statements = emitScope.getConstantStatements();
      results.push({constantScope, statements});
    }
    return results;
  }

  private getEmitScope(
      ngImport: TExpression, declarationScope: DeclarationScope<TConstantScope, TExpression>):
      EmitScope<TStatement, TExpression> {
    const constantScope = declarationScope.getConstantScopeRef(ngImport);
    if (constantScope === null) {
      // There is no constant scope so we will emit extra statements into the definition IIFE.
      return new IifeEmitScope(ngImport, this.linkerEnvironment);
    }

    if (!this.emitScopes.has(constantScope)) {
      this.emitScopes.set(constantScope, new EmitScope(ngImport, this.linkerEnvironment));
    }
    return this.emitScopes.get(constantScope)!;
  }
}
