/**
 * @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 {CompileDirectiveSummary} from '../../compile_metadata';
import {BindingForm, convertPropertyBinding} from '../../compiler_util/expression_converter';
import {ConstantPool} from '../../constant_pool';
import * as core from '../../core';
import {AST, ParsedEvent, ParsedEventType, ParsedProperty} from '../../expression_parser/ast';
import * as o from '../../output/output_ast';
import {ParseError, ParseSourceSpan, sanitizeIdentifier} from '../../parse_util';
import {CssSelector, SelectorMatcher} from '../../selector';
import {ShadowCss} from '../../shadow_css';
import {CONTENT_ATTR, HOST_ATTR} from '../../style_compiler';
import {BindingParser} from '../../template_parser/binding_parser';
import {error} from '../../util';
import {BoundEvent} from '../r3_ast';
import {Identifiers as R3} from '../r3_identifiers';
import {prepareSyntheticListenerFunctionName, prepareSyntheticPropertyName, R3CompiledExpression, typeWithParameters} from '../util';

import {DeclarationListEmitMode, R3ComponentMetadata, R3DirectiveMetadata, R3HostMetadata, R3QueryMetadata} from './api';
import {MIN_STYLING_BINDING_SLOTS_REQUIRED, StylingBuilder, StylingInstructionCall} from './styling_builder';
import {BindingScope, makeBindingParser, prepareEventListenerParameters, renderFlagCheckIfStmt, resolveSanitizationFn, TemplateDefinitionBuilder, ValueConverter} from './template';
import {asLiteral, chainedInstruction, conditionallyCreateMapObjectLiteral, CONTEXT_NAME, DefinitionMap, getQueryPredicate, RENDER_FLAGS, TEMPORARY_NAME, temporaryAllocator} from './util';


// This regex matches any binding names that contain the "attr." prefix, e.g. "attr.required"
// If there is a match, the first matching group will contain the attribute name to bind.
const ATTR_REGEX = /attr\.([^\]]+)/;

function baseDirectiveFields(
    meta: R3DirectiveMetadata, constantPool: ConstantPool,
    bindingParser: BindingParser): DefinitionMap {
  const definitionMap = new DefinitionMap();
  const selectors = core.parseSelectorToR3Selector(meta.selector);

  // e.g. `type: MyDirective`
  definitionMap.set('type', meta.internalType);

  // e.g. `selectors: [['', 'someDir', '']]`
  if (selectors.length > 0) {
    definitionMap.set('selectors', asLiteral(selectors));
  }

  if (meta.queries.length > 0) {
    // e.g. `contentQueries: (rf, ctx, dirIndex) => { ... }
    definitionMap.set(
        'contentQueries', createContentQueriesFunction(meta.queries, constantPool, meta.name));
  }

  if (meta.viewQueries.length) {
    definitionMap.set(
        'viewQuery', createViewQueriesFunction(meta.viewQueries, constantPool, meta.name));
  }

  // e.g. `hostBindings: (rf, ctx) => { ... }
  definitionMap.set(
      'hostBindings',
      createHostBindingsFunction(
          meta.host, meta.typeSourceSpan, bindingParser, constantPool, meta.selector || '',
          meta.name, definitionMap));

  // e.g 'inputs: {a: 'a'}`
  definitionMap.set('inputs', conditionallyCreateMapObjectLiteral(meta.inputs, true));

  // e.g 'outputs: {a: 'a'}`
  definitionMap.set('outputs', conditionallyCreateMapObjectLiteral(meta.outputs));

  if (meta.exportAs !== null) {
    definitionMap.set('exportAs', o.literalArr(meta.exportAs.map(e => o.literal(e))));
  }

  return definitionMap;
}

/**
 * Add features to the definition map.
 */
function addFeatures(definitionMap: DefinitionMap, meta: R3DirectiveMetadata|R3ComponentMetadata) {
  // e.g. `features: [NgOnChangesFeature]`
  const features: o.Expression[] = [];

  const providers = meta.providers;
  const viewProviders = (meta as R3ComponentMetadata).viewProviders;
  if (providers || viewProviders) {
    const args = [providers || new o.LiteralArrayExpr([])];
    if (viewProviders) {
      args.push(viewProviders);
    }
    features.push(o.importExpr(R3.ProvidersFeature).callFn(args));
  }

  if (meta.usesInheritance) {
    features.push(o.importExpr(R3.InheritDefinitionFeature));
  }
  if (meta.fullInheritance) {
    features.push(o.importExpr(R3.CopyDefinitionFeature));
  }
  if (meta.lifecycle.usesOnChanges) {
    features.push(o.importExpr(R3.NgOnChangesFeature));
  }
  if (features.length) {
    definitionMap.set('features', o.literalArr(features));
  }
}

/**
 * Compile a directive for the render3 runtime as defined by the `R3DirectiveMetadata`.
 */
export function compileDirectiveFromMetadata(
    meta: R3DirectiveMetadata, constantPool: ConstantPool,
    bindingParser: BindingParser): R3CompiledExpression {
  const definitionMap = baseDirectiveFields(meta, constantPool, bindingParser);
  addFeatures(definitionMap, meta);
  const expression =
      o.importExpr(R3.defineDirective).callFn([definitionMap.toLiteralMap()], undefined, true);
  const type = createDirectiveType(meta);

  return {expression, type, statements: []};
}

/**
 * Compile a component for the render3 runtime as defined by the `R3ComponentMetadata`.
 */
export function compileComponentFromMetadata(
    meta: R3ComponentMetadata, constantPool: ConstantPool,
    bindingParser: BindingParser): R3CompiledExpression {
  const definitionMap = baseDirectiveFields(meta, constantPool, bindingParser);
  addFeatures(definitionMap, meta);

  const selector = meta.selector && CssSelector.parse(meta.selector);
  const firstSelector = selector && selector[0];

  // e.g. `attr: ["class", ".my.app"]`
  // This is optional an only included if the first selector of a component specifies attributes.
  if (firstSelector) {
    const selectorAttributes = firstSelector.getAttrs();
    if (selectorAttributes.length) {
      definitionMap.set(
          'attrs',
          constantPool.getConstLiteral(
              o.literalArr(selectorAttributes.map(
                  value => value != null ? o.literal(value) : o.literal(undefined))),
              /* forceShared */ true));
    }
  }

  // Generate the CSS matcher that recognize directive
  let directiveMatcher: SelectorMatcher|null = null;

  if (meta.directives.length > 0) {
    const matcher = new SelectorMatcher();
    for (const {selector, type} of meta.directives) {
      matcher.addSelectables(CssSelector.parse(selector), type);
    }
    directiveMatcher = matcher;
  }

  // e.g. `template: function MyComponent_Template(_ctx, _cm) {...}`
  const templateTypeName = meta.name;
  const templateName = templateTypeName ? `${templateTypeName}_Template` : null;

  const directivesUsed = new Set<o.Expression>();
  const pipesUsed = new Set<o.Expression>();
  const changeDetection = meta.changeDetection;

  const template = meta.template;
  const templateBuilder = new TemplateDefinitionBuilder(
      constantPool, BindingScope.createRootScope(), 0, templateTypeName, null, null, templateName,
      directiveMatcher, directivesUsed, meta.pipes, pipesUsed, R3.namespaceHTML,
      meta.relativeContextFilePath, meta.i18nUseExternalIds);

  const templateFunctionExpression = templateBuilder.buildTemplateFunction(template.nodes, []);

  // We need to provide this so that dynamically generated components know what
  // projected content blocks to pass through to the component when it is instantiated.
  const ngContentSelectors = templateBuilder.getNgContentSelectors();
  if (ngContentSelectors) {
    definitionMap.set('ngContentSelectors', ngContentSelectors);
  }

  // e.g. `decls: 2`
  definitionMap.set('decls', o.literal(templateBuilder.getConstCount()));

  // e.g. `vars: 2`
  definitionMap.set('vars', o.literal(templateBuilder.getVarCount()));

  // Generate `consts` section of ComponentDef:
  // - either as an array:
  //   `consts: [['one', 'two'], ['three', 'four']]`
  // - or as a factory function in case additional statements are present (to support i18n):
  //   `consts: function() { var i18n_0; if (ngI18nClosureMode) {...} else {...} return [i18n_0]; }`
  const {constExpressions, prepareStatements} = templateBuilder.getConsts();
  if (constExpressions.length > 0) {
    let constsExpr: o.LiteralArrayExpr|o.FunctionExpr = o.literalArr(constExpressions);
    // Prepare statements are present - turn `consts` into a function.
    if (prepareStatements.length > 0) {
      constsExpr = o.fn([], [...prepareStatements, new o.ReturnStatement(constsExpr)]);
    }
    definitionMap.set('consts', constsExpr);
  }

  definitionMap.set('template', templateFunctionExpression);

  // e.g. `directives: [MyDirective]`
  if (directivesUsed.size) {
    const directivesList = o.literalArr(Array.from(directivesUsed));
    const directivesExpr = compileDeclarationList(directivesList, meta.declarationListEmitMode);
    definitionMap.set('directives', directivesExpr);
  }

  // e.g. `pipes: [MyPipe]`
  if (pipesUsed.size) {
    const pipesList = o.literalArr(Array.from(pipesUsed));
    const pipesExpr = compileDeclarationList(pipesList, meta.declarationListEmitMode);
    definitionMap.set('pipes', pipesExpr);
  }

  if (meta.encapsulation === null) {
    meta.encapsulation = core.ViewEncapsulation.Emulated;
  }

  // e.g. `styles: [str1, str2]`
  if (meta.styles && meta.styles.length) {
    const styleValues = meta.encapsulation == core.ViewEncapsulation.Emulated ?
        compileStyles(meta.styles, CONTENT_ATTR, HOST_ATTR) :
        meta.styles;
    const strings = styleValues.map(str => constantPool.getConstLiteral(o.literal(str)));
    definitionMap.set('styles', o.literalArr(strings));
  } else if (meta.encapsulation === core.ViewEncapsulation.Emulated) {
    // If there is no style, don't generate css selectors on elements
    meta.encapsulation = core.ViewEncapsulation.None;
  }

  // Only set view encapsulation if it's not the default value
  if (meta.encapsulation !== core.ViewEncapsulation.Emulated) {
    definitionMap.set('encapsulation', o.literal(meta.encapsulation));
  }

  // e.g. `animation: [trigger('123', [])]`
  if (meta.animations !== null) {
    definitionMap.set(
        'data', o.literalMap([{key: 'animation', value: meta.animations, quoted: false}]));
  }

  // Only set the change detection flag if it's defined and it's not the default.
  if (changeDetection != null && changeDetection !== core.ChangeDetectionStrategy.Default) {
    definitionMap.set('changeDetection', o.literal(changeDetection));
  }

  const expression =
      o.importExpr(R3.defineComponent).callFn([definitionMap.toLiteralMap()], undefined, true);
  const type = createComponentType(meta);

  return {expression, type, statements: []};
}

/**
 * Creates the type specification from the component meta. This type is inserted into .d.ts files
 * to be consumed by upstream compilations.
 */
export function createComponentType(meta: R3ComponentMetadata): o.Type {
  const typeParams = createDirectiveTypeParams(meta);
  typeParams.push(stringArrayAsType(meta.template.ngContentSelectors));
  return o.expressionType(o.importExpr(R3.ComponentDeclaration, typeParams));
}

/**
 * Compiles the array literal of declarations into an expression according to the provided emit
 * mode.
 */
function compileDeclarationList(
    list: o.LiteralArrayExpr, mode: DeclarationListEmitMode): o.Expression {
  switch (mode) {
    case DeclarationListEmitMode.Direct:
      // directives: [MyDir],
      return list;
    case DeclarationListEmitMode.Closure:
      // directives: function () { return [MyDir]; }
      return o.fn([], [new o.ReturnStatement(list)]);
    case DeclarationListEmitMode.ClosureResolved:
      // directives: function () { return [MyDir].map(ng.resolveForwardRef); }
      const resolvedList = list.prop('map').callFn([o.importExpr(R3.resolveForwardRef)]);
      return o.fn([], [new o.ReturnStatement(resolvedList)]);
  }
}

function prepareQueryParams(query: R3QueryMetadata, constantPool: ConstantPool): o.Expression[] {
  const parameters = [getQueryPredicate(query, constantPool), o.literal(toQueryFlags(query))];
  if (query.read) {
    parameters.push(query.read);
  }
  return parameters;
}

/**
 * A set of flags to be used with Queries.
 *
 * NOTE: Ensure changes here are in sync with `packages/core/src/render3/interfaces/query.ts`
 */
export const enum QueryFlags {
  /**
   * No flags
   */
  none = 0b0000,

  /**
   * Whether or not the query should descend into children.
   */
  descendants = 0b0001,

  /**
   * The query can be computed statically and hence can be assigned eagerly.
   *
   * NOTE: Backwards compatibility with ViewEngine.
   */
  isStatic = 0b0010,

  /**
   * If the `QueryList` should fire change event only if actual change to query was computed (vs old
   * behavior where the change was fired whenever the query was recomputed, even if the recomputed
   * query resulted in the same list.)
   */
  emitDistinctChangesOnly = 0b0100,
}

/**
 * Translates query flags into `TQueryFlags` type in packages/core/src/render3/interfaces/query.ts
 * @param query
 */
function toQueryFlags(query: R3QueryMetadata): number {
  return (query.descendants ? QueryFlags.descendants : QueryFlags.none) |
      (query.static ? QueryFlags.isStatic : QueryFlags.none) |
      (query.emitDistinctChangesOnly ? QueryFlags.emitDistinctChangesOnly : QueryFlags.none);
}

function convertAttributesToExpressions(attributes: {[name: string]: o.Expression}):
    o.Expression[] {
  const values: o.Expression[] = [];
  for (let key of Object.getOwnPropertyNames(attributes)) {
    const value = attributes[key];
    values.push(o.literal(key), value);
  }
  return values;
}

// Define and update any content queries
function createContentQueriesFunction(
    queries: R3QueryMetadata[], constantPool: ConstantPool, name?: string): o.Expression {
  const createStatements: o.Statement[] = [];
  const updateStatements: o.Statement[] = [];
  const tempAllocator = temporaryAllocator(updateStatements, TEMPORARY_NAME);

  for (const query of queries) {
    // creation, e.g. r3.contentQuery(dirIndex, somePredicate, true, null);
    createStatements.push(
        o.importExpr(R3.contentQuery)
            .callFn([o.variable('dirIndex'), ...prepareQueryParams(query, constantPool) as any])
            .toStmt());

    // update, e.g. (r3.queryRefresh(tmp = r3.loadQuery()) && (ctx.someDir = tmp));
    const temporary = tempAllocator();
    const getQueryList = o.importExpr(R3.loadQuery).callFn([]);
    const refresh = o.importExpr(R3.queryRefresh).callFn([temporary.set(getQueryList)]);
    const updateDirective = o.variable(CONTEXT_NAME)
                                .prop(query.propertyName)
                                .set(query.first ? temporary.prop('first') : temporary);
    updateStatements.push(refresh.and(updateDirective).toStmt());
  }

  const contentQueriesFnName = name ? `${name}_ContentQueries` : null;
  return o.fn(
      [
        new o.FnParam(RENDER_FLAGS, o.NUMBER_TYPE), new o.FnParam(CONTEXT_NAME, null),
        new o.FnParam('dirIndex', null)
      ],
      [
        renderFlagCheckIfStmt(core.RenderFlags.Create, createStatements),
        renderFlagCheckIfStmt(core.RenderFlags.Update, updateStatements)
      ],
      o.INFERRED_TYPE, null, contentQueriesFnName);
}

function stringAsType(str: string): o.Type {
  return o.expressionType(o.literal(str));
}

function stringMapAsType(map: {[key: string]: string|string[]}): o.Type {
  const mapValues = Object.keys(map).map(key => {
    const value = Array.isArray(map[key]) ? map[key][0] : map[key];
    return {
      key,
      value: o.literal(value),
      quoted: true,
    };
  });
  return o.expressionType(o.literalMap(mapValues));
}

function stringArrayAsType(arr: ReadonlyArray<string|null>): o.Type {
  return arr.length > 0 ? o.expressionType(o.literalArr(arr.map(value => o.literal(value)))) :
                          o.NONE_TYPE;
}

export function createDirectiveTypeParams(meta: R3DirectiveMetadata): o.Type[] {
  // On the type side, remove newlines from the selector as it will need to fit into a TypeScript
  // string literal, which must be on one line.
  const selectorForType = meta.selector !== null ? meta.selector.replace(/\n/g, '') : null;

  return [
    typeWithParameters(meta.type.type, meta.typeArgumentCount),
    selectorForType !== null ? stringAsType(selectorForType) : o.NONE_TYPE,
    meta.exportAs !== null ? stringArrayAsType(meta.exportAs) : o.NONE_TYPE,
    stringMapAsType(meta.inputs),
    stringMapAsType(meta.outputs),
    stringArrayAsType(meta.queries.map(q => q.propertyName)),
  ];
}

/**
 * Creates the type specification from the directive meta. This type is inserted into .d.ts files
 * to be consumed by upstream compilations.
 */
export function createDirectiveType(meta: R3DirectiveMetadata): o.Type {
  const typeParams = createDirectiveTypeParams(meta);
  return o.expressionType(o.importExpr(R3.DirectiveDeclaration, typeParams));
}

// Define and update any view queries
function createViewQueriesFunction(
    viewQueries: R3QueryMetadata[], constantPool: ConstantPool, name?: string): o.Expression {
  const createStatements: o.Statement[] = [];
  const updateStatements: o.Statement[] = [];
  const tempAllocator = temporaryAllocator(updateStatements, TEMPORARY_NAME);

  viewQueries.forEach((query: R3QueryMetadata) => {
    // creation, e.g. r3.viewQuery(somePredicate, true);
    const queryDefinition =
        o.importExpr(R3.viewQuery).callFn(prepareQueryParams(query, constantPool));
    createStatements.push(queryDefinition.toStmt());

    // update, e.g. (r3.queryRefresh(tmp = r3.loadQuery()) && (ctx.someDir = tmp));
    const temporary = tempAllocator();
    const getQueryList = o.importExpr(R3.loadQuery).callFn([]);
    const refresh = o.importExpr(R3.queryRefresh).callFn([temporary.set(getQueryList)]);
    const updateDirective = o.variable(CONTEXT_NAME)
                                .prop(query.propertyName)
                                .set(query.first ? temporary.prop('first') : temporary);
    updateStatements.push(refresh.and(updateDirective).toStmt());
  });

  const viewQueryFnName = name ? `${name}_Query` : null;
  return o.fn(
      [new o.FnParam(RENDER_FLAGS, o.NUMBER_TYPE), new o.FnParam(CONTEXT_NAME, null)],
      [
        renderFlagCheckIfStmt(core.RenderFlags.Create, createStatements),
        renderFlagCheckIfStmt(core.RenderFlags.Update, updateStatements)
      ],
      o.INFERRED_TYPE, null, viewQueryFnName);
}

// Return a host binding function or null if one is not necessary.
function createHostBindingsFunction(
    hostBindingsMetadata: R3HostMetadata, typeSourceSpan: ParseSourceSpan,
    bindingParser: BindingParser, constantPool: ConstantPool, selector: string, name: string,
    definitionMap: DefinitionMap): o.Expression|null {
  const bindingContext = o.variable(CONTEXT_NAME);
  const styleBuilder = new StylingBuilder(bindingContext);

  const {styleAttr, classAttr} = hostBindingsMetadata.specialAttributes;
  if (styleAttr !== undefined) {
    styleBuilder.registerStyleAttr(styleAttr);
  }
  if (classAttr !== undefined) {
    styleBuilder.registerClassAttr(classAttr);
  }

  const createStatements: o.Statement[] = [];
  const updateStatements: o.Statement[] = [];

  const hostBindingSourceSpan = typeSourceSpan;
  const directiveSummary = metadataAsSummary(hostBindingsMetadata);

  // Calculate host event bindings
  const eventBindings =
      bindingParser.createDirectiveHostEventAsts(directiveSummary, hostBindingSourceSpan);
  if (eventBindings && eventBindings.length) {
    const listeners = createHostListeners(eventBindings, name);
    createStatements.push(...listeners);
  }

  // Calculate the host property bindings
  const bindings = bindingParser.createBoundHostProperties(directiveSummary, hostBindingSourceSpan);
  const allOtherBindings: ParsedProperty[] = [];

  // We need to calculate the total amount of binding slots required by
  // all the instructions together before any value conversions happen.
  // Value conversions may require additional slots for interpolation and
  // bindings with pipes. These calculates happen after this block.
  let totalHostVarsCount = 0;
  bindings && bindings.forEach((binding: ParsedProperty) => {
    const stylingInputWasSet = styleBuilder.registerInputBasedOnName(
        binding.name, binding.expression, hostBindingSourceSpan);
    if (stylingInputWasSet) {
      totalHostVarsCount += MIN_STYLING_BINDING_SLOTS_REQUIRED;
    } else {
      allOtherBindings.push(binding);
      totalHostVarsCount++;
    }
  });

  let valueConverter: ValueConverter;
  const getValueConverter = () => {
    if (!valueConverter) {
      const hostVarsCountFn = (numSlots: number): number => {
        const originalVarsCount = totalHostVarsCount;
        totalHostVarsCount += numSlots;
        return originalVarsCount;
      };
      valueConverter = new ValueConverter(
          constantPool,
          () => error('Unexpected node'),  // new nodes are illegal here
          hostVarsCountFn,
          () => error('Unexpected pipe'));  // pipes are illegal here
    }
    return valueConverter;
  };

  const propertyBindings: o.Expression[][] = [];
  const attributeBindings: o.Expression[][] = [];
  const syntheticHostBindings: o.Expression[][] = [];
  allOtherBindings.forEach((binding: ParsedProperty) => {
    // resolve literal arrays and literal objects
    const value = binding.expression.visit(getValueConverter());
    const bindingExpr = bindingFn(bindingContext, value);

    const {bindingName, instruction, isAttribute} = getBindingNameAndInstruction(binding);

    const securityContexts =
        bindingParser.calcPossibleSecurityContexts(selector, bindingName, isAttribute)
            .filter(context => context !== core.SecurityContext.NONE);

    let sanitizerFn: o.ExternalExpr|null = null;
    if (securityContexts.length) {
      if (securityContexts.length === 2 &&
          securityContexts.indexOf(core.SecurityContext.URL) > -1 &&
          securityContexts.indexOf(core.SecurityContext.RESOURCE_URL) > -1) {
        // Special case for some URL attributes (such as "src" and "href") that may be a part
        // of different security contexts. In this case we use special sanitization function and
        // select the actual sanitizer at runtime based on a tag name that is provided while
        // invoking sanitization function.
        sanitizerFn = o.importExpr(R3.sanitizeUrlOrResourceUrl);
      } else {
        sanitizerFn = resolveSanitizationFn(securityContexts[0], isAttribute);
      }
    }
    const instructionParams = [o.literal(bindingName), bindingExpr.currValExpr];
    if (sanitizerFn) {
      instructionParams.push(sanitizerFn);
    }

    updateStatements.push(...bindingExpr.stmts);

    if (instruction === R3.hostProperty) {
      propertyBindings.push(instructionParams);
    } else if (instruction === R3.attribute) {
      attributeBindings.push(instructionParams);
    } else if (instruction === R3.syntheticHostProperty) {
      syntheticHostBindings.push(instructionParams);
    } else {
      updateStatements.push(o.importExpr(instruction).callFn(instructionParams).toStmt());
    }
  });

  if (propertyBindings.length > 0) {
    updateStatements.push(chainedInstruction(R3.hostProperty, propertyBindings).toStmt());
  }

  if (attributeBindings.length > 0) {
    updateStatements.push(chainedInstruction(R3.attribute, attributeBindings).toStmt());
  }

  if (syntheticHostBindings.length > 0) {
    updateStatements.push(
        chainedInstruction(R3.syntheticHostProperty, syntheticHostBindings).toStmt());
  }

  // since we're dealing with directives/components and both have hostBinding
  // functions, we need to generate a special hostAttrs instruction that deals
  // with both the assignment of styling as well as static attributes to the host
  // element. The instruction below will instruct all initial styling (styling
  // that is inside of a host binding within a directive/component) to be attached
  // to the host element alongside any of the provided host attributes that were
  // collected earlier.
  const hostAttrs = convertAttributesToExpressions(hostBindingsMetadata.attributes);
  styleBuilder.assignHostAttrs(hostAttrs, definitionMap);

  if (styleBuilder.hasBindings) {
    // finally each binding that was registered in the statement above will need to be added to
    // the update block of a component/directive templateFn/hostBindingsFn so that the bindings
    // are evaluated and updated for the element.
    styleBuilder.buildUpdateLevelInstructions(getValueConverter()).forEach(instruction => {
      if (instruction.calls.length > 0) {
        const calls: o.Expression[][] = [];

        instruction.calls.forEach(call => {
          // we subtract a value of `1` here because the binding slot was already allocated
          // at the top of this method when all the input bindings were counted.
          totalHostVarsCount +=
              Math.max(call.allocateBindingSlots - MIN_STYLING_BINDING_SLOTS_REQUIRED, 0);
          calls.push(convertStylingCall(call, bindingContext, bindingFn));
        });

        updateStatements.push(chainedInstruction(instruction.reference, calls).toStmt());
      }
    });
  }

  if (totalHostVarsCount) {
    definitionMap.set('hostVars', o.literal(totalHostVarsCount));
  }

  if (createStatements.length > 0 || updateStatements.length > 0) {
    const hostBindingsFnName = name ? `${name}_HostBindings` : null;
    const statements: o.Statement[] = [];
    if (createStatements.length > 0) {
      statements.push(renderFlagCheckIfStmt(core.RenderFlags.Create, createStatements));
    }
    if (updateStatements.length > 0) {
      statements.push(renderFlagCheckIfStmt(core.RenderFlags.Update, updateStatements));
    }
    return o.fn(
        [new o.FnParam(RENDER_FLAGS, o.NUMBER_TYPE), new o.FnParam(CONTEXT_NAME, null)], statements,
        o.INFERRED_TYPE, null, hostBindingsFnName);
  }

  return null;
}

function bindingFn(implicit: any, value: AST) {
  return convertPropertyBinding(
      null, implicit, value, 'b', BindingForm.Expression, () => error('Unexpected interpolation'));
}

function convertStylingCall(
    call: StylingInstructionCall, bindingContext: any, bindingFn: Function) {
  return call.params(value => bindingFn(bindingContext, value).currValExpr);
}

function getBindingNameAndInstruction(binding: ParsedProperty):
    {bindingName: string, instruction: o.ExternalReference, isAttribute: boolean} {
  let bindingName = binding.name;
  let instruction!: o.ExternalReference;

  // Check to see if this is an attr binding or a property binding
  const attrMatches = bindingName.match(ATTR_REGEX);
  if (attrMatches) {
    bindingName = attrMatches[1];
    instruction = R3.attribute;
  } else {
    if (binding.isAnimation) {
      bindingName = prepareSyntheticPropertyName(bindingName);
      // host bindings that have a synthetic property (e.g. @foo) should always be rendered
      // in the context of the component and not the parent. Therefore there is a special
      // compatibility instruction available for this purpose.
      instruction = R3.syntheticHostProperty;
    } else {
      instruction = R3.hostProperty;
    }
  }

  return {bindingName, instruction, isAttribute: !!attrMatches};
}

function createHostListeners(eventBindings: ParsedEvent[], name?: string): o.Statement[] {
  const listeners: o.Expression[][] = [];
  const syntheticListeners: o.Expression[][] = [];
  const instructions: o.Statement[] = [];

  eventBindings.forEach(binding => {
    let bindingName = binding.name && sanitizeIdentifier(binding.name);
    const bindingFnName = binding.type === ParsedEventType.Animation ?
        prepareSyntheticListenerFunctionName(bindingName, binding.targetOrPhase) :
        bindingName;
    const handlerName = name && bindingName ? `${name}_${bindingFnName}_HostBindingHandler` : null;
    const params = prepareEventListenerParameters(BoundEvent.fromParsedEvent(binding), handlerName);

    if (binding.type == ParsedEventType.Animation) {
      syntheticListeners.push(params);
    } else {
      listeners.push(params);
    }
  });

  if (syntheticListeners.length > 0) {
    instructions.push(chainedInstruction(R3.syntheticHostListener, syntheticListeners).toStmt());
  }

  if (listeners.length > 0) {
    instructions.push(chainedInstruction(R3.listener, listeners).toStmt());
  }

  return instructions;
}

function metadataAsSummary(meta: R3HostMetadata): CompileDirectiveSummary {
  // clang-format off
  return {
    // This is used by the BindingParser, which only deals with listeners and properties. There's no
    // need to pass attributes to it.
    hostAttributes: {},
    hostListeners: meta.listeners,
    hostProperties: meta.properties,
  } as CompileDirectiveSummary;
  // clang-format on
}



const HOST_REG_EXP = /^(?:\[([^\]]+)\])|(?:\(([^\)]+)\))$/;
// Represents the groups in the above regex.
const enum HostBindingGroup {
  // group 1: "prop" from "[prop]", or "attr.role" from "[attr.role]", or @anim from [@anim]
  Binding = 1,

  // group 2: "event" from "(event)"
  Event = 2,
}

// Defines Host Bindings structure that contains attributes, listeners, and properties,
// parsed from the `host` object defined for a Type.
export interface ParsedHostBindings {
  attributes: {[key: string]: o.Expression};
  listeners: {[key: string]: string};
  properties: {[key: string]: string};
  specialAttributes: {styleAttr?: string; classAttr?: string;};
}

export function parseHostBindings(host: {[key: string]: string|o.Expression}): ParsedHostBindings {
  const attributes: {[key: string]: o.Expression} = {};
  const listeners: {[key: string]: string} = {};
  const properties: {[key: string]: string} = {};
  const specialAttributes: {styleAttr?: string; classAttr?: string;} = {};

  for (const key of Object.keys(host)) {
    const value = host[key];
    const matches = key.match(HOST_REG_EXP);

    if (matches === null) {
      switch (key) {
        case 'class':
          if (typeof value !== 'string') {
            // TODO(alxhub): make this a diagnostic.
            throw new Error(`Class binding must be string`);
          }
          specialAttributes.classAttr = value;
          break;
        case 'style':
          if (typeof value !== 'string') {
            // TODO(alxhub): make this a diagnostic.
            throw new Error(`Style binding must be string`);
          }
          specialAttributes.styleAttr = value;
          break;
        default:
          if (typeof value === 'string') {
            attributes[key] = o.literal(value);
          } else {
            attributes[key] = value;
          }
      }
    } else if (matches[HostBindingGroup.Binding] != null) {
      if (typeof value !== 'string') {
        // TODO(alxhub): make this a diagnostic.
        throw new Error(`Property binding must be string`);
      }
      // synthetic properties (the ones that have a `@` as a prefix)
      // are still treated the same as regular properties. Therefore
      // there is no point in storing them in a separate map.
      properties[matches[HostBindingGroup.Binding]] = value;
    } else if (matches[HostBindingGroup.Event] != null) {
      if (typeof value !== 'string') {
        // TODO(alxhub): make this a diagnostic.
        throw new Error(`Event binding must be string`);
      }
      listeners[matches[HostBindingGroup.Event]] = value;
    }
  }

  return {attributes, listeners, properties, specialAttributes};
}

/**
 * Verifies host bindings and returns the list of errors (if any). Empty array indicates that a
 * given set of host bindings has no errors.
 *
 * @param bindings set of host bindings to verify.
 * @param sourceSpan source span where host bindings were defined.
 * @returns array of errors associated with a given set of host bindings.
 */
export function verifyHostBindings(
    bindings: ParsedHostBindings, sourceSpan: ParseSourceSpan): ParseError[] {
  const summary = metadataAsSummary(bindings);
  // TODO: abstract out host bindings verification logic and use it instead of
  // creating events and properties ASTs to detect errors (FW-996)
  const bindingParser = makeBindingParser();
  bindingParser.createDirectiveHostEventAsts(summary, sourceSpan);
  bindingParser.createBoundHostProperties(summary, sourceSpan);
  return bindingParser.errors;
}

function compileStyles(styles: string[], selector: string, hostSelector: string): string[] {
  const shadowCss = new ShadowCss();
  return styles.map(style => {
    return shadowCss!.shimCssText(style, selector, hostSelector);
  });
}