/**
 * @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 * as ts from 'typescript';

/**
 * Return the node that most tightly encompass the specified `position`.
 * @param node
 * @param position
 */
export function findTightestNode(node: ts.Node, position: number): ts.Node|undefined {
  if (node.getStart() <= position && position < node.getEnd()) {
    return node.forEachChild(c => findTightestNode(c, position)) || node;
  }
}

/**
 * Returns a property assignment from the assignment value if the property name
 * matches the specified `key`, or `undefined` if there is no match.
 */
export function getPropertyAssignmentFromValue(value: ts.Node, key: string): ts.PropertyAssignment|
    undefined {
  const propAssignment = value.parent;
  if (!propAssignment || !ts.isPropertyAssignment(propAssignment) ||
      propAssignment.name.getText() !== key) {
    return;
  }
  return propAssignment;
}

/**
 * Given a decorator property assignment, return the ClassDeclaration node that corresponds to the
 * directive class the property applies to.
 * If the property assignment is not on a class decorator, no declaration is returned.
 *
 * For example,
 *
 * @Component({
 *   template: '<div></div>'
 *   ^^^^^^^^^^^^^^^^^^^^^^^---- property assignment
 * })
 * class AppComponent {}
 *           ^---- class declaration node
 *
 * @param propAsgnNode property assignment
 */
export function getClassDeclFromDecoratorProp(propAsgnNode: ts.PropertyAssignment):
    ts.ClassDeclaration|undefined {
  if (!propAsgnNode.parent || !ts.isObjectLiteralExpression(propAsgnNode.parent)) {
    return;
  }
  const objLitExprNode = propAsgnNode.parent;
  if (!objLitExprNode.parent || !ts.isCallExpression(objLitExprNode.parent)) {
    return;
  }
  const callExprNode = objLitExprNode.parent;
  if (!callExprNode.parent || !ts.isDecorator(callExprNode.parent)) {
    return;
  }
  const decorator = callExprNode.parent;
  if (!decorator.parent || !ts.isClassDeclaration(decorator.parent)) {
    return;
  }
  const classDeclNode = decorator.parent;
  return classDeclNode;
}

/**
 * Given the node which is the string of the inline template for a component, returns the
 * `ts.ClassDeclaration` for the component.
 */
export function getClassDeclOfInlineTemplateNode(templateStringNode: ts.Node): ts.ClassDeclaration|
    undefined {
  if (!ts.isStringLiteralLike(templateStringNode)) {
    return;
  }
  const tmplAsgn = getPropertyAssignmentFromValue(templateStringNode, 'template');
  if (!tmplAsgn) {
    return;
  }
  return getClassDeclFromDecoratorProp(tmplAsgn);
}