/**
 * @license
 * Copyright Google Inc. 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 {AbstractType, Type} from '../interface/type';
import {stringify} from '../util/stringify';

import {resolveForwardRef} from './forward_ref';
import {InjectionToken} from './injection_token';
import {catchInjectorError, formatError, INJECTOR, NG_TEMP_TOKEN_PATH, NullInjector, setCurrentInjector, THROW_IF_NOT_FOUND, USE_VALUE, ɵɵinject} from './injector_compatibility';
import {getInjectableDef, ɵɵdefineInjectable} from './interface/defs';
import {InjectFlags} from './interface/injector';
import {ConstructorProvider, ExistingProvider, FactoryProvider, StaticClassProvider, StaticProvider, ValueProvider} from './interface/provider';
import {Inject, Optional, Self, SkipSelf} from './metadata';
import {createInjector} from './r3_injector';
import {INJECTOR_SCOPE} from './scope';

export function INJECTOR_IMPL__PRE_R3__(
    providers: StaticProvider[], parent: Injector|undefined, name: string) {
  return new StaticInjector(providers, parent, name);
}

export function INJECTOR_IMPL__POST_R3__(
    providers: StaticProvider[], parent: Injector|undefined, name: string) {
  return createInjector({name: name}, parent, providers, name);
}

export const INJECTOR_IMPL = INJECTOR_IMPL__PRE_R3__;

/**
 * Concrete injectors implement this interface. Injectors are configured
 * with [providers](guide/glossary#provider) that associate
 * dependencies of various types with [injection tokens](guide/glossary#di-token).
 *
 * @see ["DI Providers"](guide/dependency-injection-providers).
 * @see `StaticProvider`
 *
 * @usageNotes
 *
 *  The following example creates a service injector instance.
 *
 * {@example core/di/ts/provider_spec.ts region='ConstructorProvider'}
 *
 * ### Usage example
 *
 * {@example core/di/ts/injector_spec.ts region='Injector'}
 *
 * `Injector` returns itself when given `Injector` as a token:
 *
 * {@example core/di/ts/injector_spec.ts region='injectInjector'}
 *
 * @publicApi
 */
export abstract class Injector {
  static THROW_IF_NOT_FOUND = THROW_IF_NOT_FOUND;
  static NULL: Injector = new NullInjector();

  /**
   * Retrieves an instance from the injector based on the provided token.
   * @returns The instance from the injector if defined, otherwise the `notFoundValue`.
   * @throws When the `notFoundValue` is `undefined` or `Injector.THROW_IF_NOT_FOUND`.
   */
  abstract get<T>(
      token: Type<T>|InjectionToken<T>|AbstractType<T>, notFoundValue?: T, flags?: InjectFlags): T;
  /**
   * @deprecated from v4.0.0 use Type<T> or InjectionToken<T>
   * @suppress {duplicate}
   */
  abstract get(token: any, notFoundValue?: any): any;

  /**
   * @deprecated from v5 use the new signature Injector.create(options)
   */
  static create(providers: StaticProvider[], parent?: Injector): Injector;

  /**
   * Creates a new injector instance that provides one or more dependencies,
   * according to a given type or types of `StaticProvider`.
   *
   * @param options An object with the following properties:
   * * `providers`: An array of providers of the [StaticProvider type](api/core/StaticProvider).
   * * `parent`: (optional) A parent injector.
   * * `name`: (optional) A developer-defined identifying name for the new injector.
   *
   * @returns The new injector instance.
   *
   */
  static create(options: {providers: StaticProvider[], parent?: Injector, name?: string}): Injector;


  static create(
      options: StaticProvider[]|{providers: StaticProvider[], parent?: Injector, name?: string},
      parent?: Injector): Injector {
    if (Array.isArray(options)) {
      return INJECTOR_IMPL(options, parent, '');
    } else {
      return INJECTOR_IMPL(options.providers, options.parent, options.name || '');
    }
  }

  /** @nocollapse */
  static ɵprov = ɵɵdefineInjectable({
    token: Injector,
    providedIn: 'any' as any,
    factory: () => ɵɵinject(INJECTOR),
  });

  /**
   * @internal
   * @nocollapse
   */
  static __NG_ELEMENT_ID__ = -1;
}



const IDENT = function<T>(value: T): T {
  return value;
};
const EMPTY = <any[]>[];
const CIRCULAR = IDENT;
const MULTI_PROVIDER_FN = function(): any[] {
  return Array.prototype.slice.call(arguments);
};

const enum OptionFlags {
  Optional = 1 << 0,
  CheckSelf = 1 << 1,
  CheckParent = 1 << 2,
  Default = CheckSelf | CheckParent
}
const NO_NEW_LINE = 'ɵ';

export class StaticInjector implements Injector {
  readonly parent: Injector;
  readonly source: string|null;
  readonly scope: string|null;

  private _records: Map<any, Record|null>;

  constructor(
      providers: StaticProvider[], parent: Injector = Injector.NULL, source: string|null = null) {
    this.parent = parent;
    this.source = source;
    const records = this._records = new Map<any, Record>();
    records.set(
        Injector, <Record>{token: Injector, fn: IDENT, deps: EMPTY, value: this, useNew: false});
    records.set(
        INJECTOR, <Record>{token: INJECTOR, fn: IDENT, deps: EMPTY, value: this, useNew: false});
    this.scope = recursivelyProcessProviders(records, providers);
  }

  get<T>(token: Type<T>|InjectionToken<T>, notFoundValue?: T, flags?: InjectFlags): T;
  get(token: any, notFoundValue?: any): any;
  get(token: any, notFoundValue?: any, flags: InjectFlags = InjectFlags.Default): any {
    const records = this._records;
    let record = records.get(token);
    if (record === undefined) {
      // This means we have never seen this record, see if it is tree shakable provider.
      const injectableDef = getInjectableDef(token);
      if (injectableDef) {
        const providedIn = injectableDef && injectableDef.providedIn;
        if (providedIn === 'any' || providedIn != null && providedIn === this.scope) {
          records.set(
              token,
              record = resolveProvider(
                  {provide: token, useFactory: injectableDef.factory, deps: EMPTY}));
        }
      }
      if (record === undefined) {
        // Set record to null to make sure that we don't go through expensive lookup above again.
        records.set(token, null);
      }
    }
    let lastInjector = setCurrentInjector(this);
    try {
      return tryResolveToken(token, record, records, this.parent, notFoundValue, flags);
    } catch (e) {
      return catchInjectorError(e, token, 'StaticInjectorError', this.source);
    } finally {
      setCurrentInjector(lastInjector);
    }
  }

  toString() {
    const tokens = <string[]>[], records = this._records;
    records.forEach((v, token) => tokens.push(stringify(token)));
    return `StaticInjector[${tokens.join(', ')}]`;
  }
}

type SupportedProvider =
    ValueProvider|ExistingProvider|StaticClassProvider|ConstructorProvider|FactoryProvider;

interface Record {
  fn: Function;
  useNew: boolean;
  deps: DependencyRecord[];
  value: any;
}

interface DependencyRecord {
  token: any;
  options: number;
}

function resolveProvider(provider: SupportedProvider): Record {
  const deps = computeDeps(provider);
  let fn: Function = IDENT;
  let value: any = EMPTY;
  let useNew: boolean = false;
  let provide = resolveForwardRef(provider.provide);
  if (USE_VALUE in provider) {
    // We need to use USE_VALUE in provider since provider.useValue could be defined as undefined.
    value = (provider as ValueProvider).useValue;
  } else if ((provider as FactoryProvider).useFactory) {
    fn = (provider as FactoryProvider).useFactory;
  } else if ((provider as ExistingProvider).useExisting) {
    // Just use IDENT
  } else if ((provider as StaticClassProvider).useClass) {
    useNew = true;
    fn = resolveForwardRef((provider as StaticClassProvider).useClass);
  } else if (typeof provide == 'function') {
    useNew = true;
    fn = provide;
  } else {
    throw staticError(
        'StaticProvider does not have [useValue|useFactory|useExisting|useClass] or [provide] is not newable',
        provider);
  }
  return {deps, fn, useNew, value};
}

function multiProviderMixError(token: any) {
  return staticError('Cannot mix multi providers and regular providers', token);
}

function recursivelyProcessProviders(records: Map<any, Record>, provider: StaticProvider): string|
    null {
  let scope: string|null = null;
  if (provider) {
    provider = resolveForwardRef(provider);
    if (Array.isArray(provider)) {
      // if we have an array recurse into the array
      for (let i = 0; i < provider.length; i++) {
        scope = recursivelyProcessProviders(records, provider[i]) || scope;
      }
    } else if (typeof provider === 'function') {
      // Functions were supported in ReflectiveInjector, but are not here. For safety give useful
      // error messages
      throw staticError('Function/Class not supported', provider);
    } else if (provider && typeof provider === 'object' && provider.provide) {
      // At this point we have what looks like a provider: {provide: ?, ....}
      let token = resolveForwardRef(provider.provide);
      const resolvedProvider = resolveProvider(provider);
      if (provider.multi === true) {
        // This is a multi provider.
        let multiProvider: Record|undefined = records.get(token);
        if (multiProvider) {
          if (multiProvider.fn !== MULTI_PROVIDER_FN) {
            throw multiProviderMixError(token);
          }
        } else {
          // Create a placeholder factory which will look up the constituents of the multi provider.
          records.set(token, multiProvider = <Record>{
            token: provider.provide,
            deps: [],
            useNew: false,
            fn: MULTI_PROVIDER_FN,
            value: EMPTY
          });
        }
        // Treat the provider as the token.
        token = provider;
        multiProvider.deps.push({token, options: OptionFlags.Default});
      }
      const record = records.get(token);
      if (record && record.fn == MULTI_PROVIDER_FN) {
        throw multiProviderMixError(token);
      }
      if (token === INJECTOR_SCOPE) {
        scope = resolvedProvider.value;
      }
      records.set(token, resolvedProvider);
    } else {
      throw staticError('Unexpected provider', provider);
    }
  }
  return scope;
}

function tryResolveToken(
    token: any, record: Record|undefined|null, records: Map<any, Record|null>, parent: Injector,
    notFoundValue: any, flags: InjectFlags): any {
  try {
    return resolveToken(token, record, records, parent, notFoundValue, flags);
  } catch (e) {
    // ensure that 'e' is of type Error.
    if (!(e instanceof Error)) {
      e = new Error(e);
    }
    const path: any[] = e[NG_TEMP_TOKEN_PATH] = e[NG_TEMP_TOKEN_PATH] || [];
    path.unshift(token);
    if (record && record.value == CIRCULAR) {
      // Reset the Circular flag.
      record.value = EMPTY;
    }
    throw e;
  }
}

function resolveToken(
    token: any, record: Record|undefined|null, records: Map<any, Record|null>, parent: Injector,
    notFoundValue: any, flags: InjectFlags): any {
  let value;
  if (record && !(flags & InjectFlags.SkipSelf)) {
    // If we don't have a record, this implies that we don't own the provider hence don't know how
    // to resolve it.
    value = record.value;
    if (value == CIRCULAR) {
      throw Error(NO_NEW_LINE + 'Circular dependency');
    } else if (value === EMPTY) {
      record.value = CIRCULAR;
      let obj = undefined;
      let useNew = record.useNew;
      let fn = record.fn;
      let depRecords = record.deps;
      let deps = EMPTY;
      if (depRecords.length) {
        deps = [];
        for (let i = 0; i < depRecords.length; i++) {
          const depRecord: DependencyRecord = depRecords[i];
          const options = depRecord.options;
          const childRecord =
              options & OptionFlags.CheckSelf ? records.get(depRecord.token) : undefined;
          deps.push(tryResolveToken(
              // Current Token to resolve
              depRecord.token,
              // A record which describes how to resolve the token.
              // If undefined, this means we don't have such a record
              childRecord,
              // Other records we know about.
              records,
              // If we don't know how to resolve dependency and we should not check parent for it,
              // than pass in Null injector.
              !childRecord && !(options & OptionFlags.CheckParent) ? Injector.NULL : parent,
              options & OptionFlags.Optional ? null : Injector.THROW_IF_NOT_FOUND,
              InjectFlags.Default));
        }
      }
      record.value = value = useNew ? new (fn as any)(...deps) : fn.apply(obj, deps);
    }
  } else if (!(flags & InjectFlags.Self)) {
    value = parent.get(token, notFoundValue, InjectFlags.Default);
  } else if (!(flags & InjectFlags.Optional)) {
    value = Injector.NULL.get(token, notFoundValue);
  } else {
    value = Injector.NULL.get(token, typeof notFoundValue !== 'undefined' ? notFoundValue : null);
  }
  return value;
}

function computeDeps(provider: StaticProvider): DependencyRecord[] {
  let deps: DependencyRecord[] = EMPTY;
  const providerDeps: any[] =
      (provider as ExistingProvider & StaticClassProvider & ConstructorProvider).deps;
  if (providerDeps && providerDeps.length) {
    deps = [];
    for (let i = 0; i < providerDeps.length; i++) {
      let options = OptionFlags.Default;
      let token = resolveForwardRef(providerDeps[i]);
      if (Array.isArray(token)) {
        for (let j = 0, annotations = token; j < annotations.length; j++) {
          const annotation = annotations[j];
          if (annotation instanceof Optional || annotation == Optional) {
            options = options | OptionFlags.Optional;
          } else if (annotation instanceof SkipSelf || annotation == SkipSelf) {
            options = options & ~OptionFlags.CheckSelf;
          } else if (annotation instanceof Self || annotation == Self) {
            options = options & ~OptionFlags.CheckParent;
          } else if (annotation instanceof Inject) {
            token = (annotation as Inject).token;
          } else {
            token = resolveForwardRef(annotation);
          }
        }
      }
      deps.push({token, options});
    }
  } else if ((provider as ExistingProvider).useExisting) {
    const token = resolveForwardRef((provider as ExistingProvider).useExisting);
    deps = [{token, options: OptionFlags.Default}];
  } else if (!providerDeps && !(USE_VALUE in provider)) {
    // useValue & useExisting are the only ones which are exempt from deps all others need it.
    throw staticError('\'deps\' required', provider);
  }
  return deps;
}

function staticError(text: string, obj: any): Error {
  return new Error(formatError(text, obj, 'StaticInjectorError'));
}