/**
 * Copyright Microsoft Corporation. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

const debug = require('debug');

const registrations = new Map();

class Fixture {
  constructor(pool, name, scope, fn) {
    this.pool = pool;
    this.name = name;
    this.scope = scope;
    this.fn = fn;
    this.deps = fixtureParameterNames(this.fn);
    this.usages = new Set();
    this.value = null;
  }

  async setup() {
    for (const name of this.deps) {
      await this.pool.setupFixture(name);
      this.pool.instances.get(name).usages.add(this.name);
    }

    const params = {};
    for (const n of this.deps)
      params[n] = this.pool.instances.get(n).value;
    let setupFenceFulfill;
    let setupFenceReject;
    const setupFence = new Promise((f, r) => { setupFenceFulfill = f; setupFenceReject = r; });
    const teardownFence = new Promise(f => this._teardownFenceCallback = f);
    debug('pw:test:hook')(`setup "${this.name}"`);
    this._tearDownComplete = this.fn(params, async value => {
      this.value = value;
      setupFenceFulfill();
      await teardownFence;
    }).catch(e => setupFenceReject(e));
    await setupFence;
    this._setup = true;
  }

  async teardown() {
    if (this._teardown)
      return;
    this._teardown = true;
    for (const name of this.usages) {
      const fixture = this.pool.instances.get(name);
      if (!fixture)
        continue;
      await fixture.teardown();
    }
    if (this._setup) {
      debug('pw:test:hook')(`teardown "${this.name}"`);
      this._teardownFenceCallback();
    }
    await this._tearDownComplete;
    this.pool.instances.delete(this.name);
  }
}

class FixturePool {
  constructor() {
    this.instances = new Map();
  }

  async setupFixture(name) {
    let fixture = this.instances.get(name);
    if (fixture)
      return fixture;

    if (!registrations.has(name))
      throw new Error('Unknown fixture: ' + name);
    const { scope, fn } = registrations.get(name);
    fixture = new Fixture(this, name, scope, fn);
    this.instances.set(name, fixture);
    await fixture.setup();
    return fixture;
  }

  async teardownScope(scope) {
    for (const [name, fixture] of this.instances) {
      if (fixture.scope === scope)
        await fixture.teardown();
    }
  }

  async resolveParametersAndRun(fn) {
    const names = fixtureParameterNames(fn);
    for (const name of names)
      await this.setupFixture(name);
    const params = {};
    for (const n of names)
      params[n] = this.instances.get(n).value;
    return fn(params);
  }
}

function fixtureParameterNames(fn) {
  const text = fn.toString();
  const match = text.match(/async(?:\s+function)?\s*\(\s*{\s*([^}]*)\s*}/);
  if (!match || !match[1].trim())
    return [];
  let signature = match[1];
  return signature.split(',').map(t => t.trim());
}

function registerFixture(name, scope, fn) {
  registrations.set(name, { scope, fn });
}

module.exports = { FixturePool, registerFixture };