/**
 * @license
 * Copyright 2021 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import {IParameterModel} from '../interfaces/i_parameter_model.js';
import {IProcedureModel} from '../interfaces/i_procedure_model.js';
import type {ISerializer} from '../interfaces/i_serializer.js';
import {ObservableProcedureModel} from '../procedures/observable_procedure_model.js';
import {ObservableParameterModel} from '../procedures/observable_parameter_model.js';
import * as priorities from './priorities.js';
// import * as serializationRegistry from './registry.js';
import type {Workspace} from '../workspace.js';


/**
 * Representation of a procedure data model.
 */
export interface State {
  id: string, name: string, returnTypes: string[]|null,
      parameters?: ParameterState[],
}

/**
 * Representation of a parameter data model.
 */
export interface ParameterState {
  id: string, name: string, types?: string[],
}

/**
 * A newable signature for an IProcedureModel.
 *
 * Refer to
 * https://www.typescriptlang.org/docs/handbook/2/generics.html#using-class-types-in-generics
 * for what is going on with this.
 */
type ProcedureModelConstructor<ProcedureModel extends IProcedureModel> =
    new (workspace: Workspace, name: string, id: string) => ProcedureModel;

/**
 * A newable signature for an IParameterModel.
 *
 * Refer to
 * https://www.typescriptlang.org/docs/handbook/2/generics.html#using-class-types-in-generics
 * for what is going on with this.
 */
type ParameterModelConstructor<ParameterModel extends IParameterModel> =
    new (workspace: Workspace, name: string, id: string) => ParameterModel;


/** Serializes the given IProcedureModel to JSON. */
function saveProcedure(proc: IProcedureModel): State {
  const state: State = {
    id: proc.getId(),
    name: proc.getName(),
    returnTypes: proc.getReturnTypes(),
  };
  if (!proc.getParameters().length) return state;
  state.parameters = proc.getParameters().map((param) => saveParameter(param));
  return state;
}

/** Serializes the given IParameterModel to JSON. */
function saveParameter(param: IParameterModel): ParameterState {
  const state: ParameterState = {
    id: param.getId(),
    name: param.getName(),
  };
  if (!param.getTypes().length) return state;
  state.types = param.getTypes();
  return state;
}

/** Deserializes the given procedure model State from JSON. */
function
loadProcedure<ProcedureModel extends IProcedureModel,
                                     ParameterModel extends IParameterModel>(
    procedureModelClass: ProcedureModelConstructor<ProcedureModel>,
    parameterModelClass: ParameterModelConstructor<ParameterModel>,
    state: State, workspace: Workspace): ProcedureModel {
  const proc = new procedureModelClass(workspace, state.name, state.id)
                   .setReturnTypes(state.returnTypes);
  if (!state.parameters) return proc;
  for (const [index, param] of state.parameters.entries()) {
    proc.insertParameter(
        loadParameter(parameterModelClass, param, workspace), index);
  }
  return proc;
}

/** Deserializes the given ParameterState from JSON. */
function loadParameter<ParameterModel extends IParameterModel>(
    parameterModelClass: ParameterModelConstructor<ParameterModel>,
    state: ParameterState, workspace: Workspace): ParameterModel {
  return new parameterModelClass(workspace, state.name, state.id)
      .setTypes(state.types || []);
}

/** Serializer for saving and loading procedure state. */
export class ProcedureSerializer<ProcedureModel extends IProcedureModel,
                                                        ParameterModel extends
                                     IParameterModel> implements ISerializer {
  public priority = priorities.PROCEDURES;

  /**
   * Constructs the procedure serializer.
   *
   * Example usage:
   *   new ProcedureSerializer(MyProcedureModelClass, MyParameterModelClass)
   *
   * @param procedureModelClass The class (implementing IProcedureModel) that
   *     you want this serializer to deserialize.
   * @param parameterModelClass The class (implementing IParameterModel) that
   *     you want this serializer to deserialize.
   */
  constructor(
      private readonly procedureModelClass:
          ProcedureModelConstructor<ProcedureModel>,
      private readonly parameterModelClass:
          ParameterModelConstructor<ParameterModel>) {}

  /** Serializes the procedure models of the given workspace. */
  save(workspace: Workspace): State[]|null {
    return workspace.getProcedureMap().getProcedures().map(
        (proc) => saveProcedure(proc));
  }

  /**
   * Deserializes the procedures models defined by the given state into the
   * workspace.
   */
  load(state: State[], workspace: Workspace) {
    const map = workspace.getProcedureMap();
    for (const procState of state) {
      map.add(loadProcedure(
          this.procedureModelClass, this.parameterModelClass, procState,
          workspace));
    }
  }

  /** Disposes of any procedure models that exist on the workspace. */
  clear(workspace: Workspace) {
    workspace.getProcedureMap().clear();
  }
}

/**
 * A ProcedureSerializer that deserializes to create the built-in
 * ObservableProcedureModels and ObservableParameterModels.
 */
export const observableProcedureSerializer =
    new ProcedureSerializer(ObservableProcedureModel, ObservableParameterModel);

// serializationRegistry.register('procedures', observableProcedureSerializer);