const Emittery = require('emittery');
const Task = require('../../../lib/task');

const ARGUMENT_ERROR = 'ArgumentError';

describe('@jsdoc/task-runner/lib/task', () => {
  it('is a function', () => {
    expect(Task).toBeFunction();
  });

  it('inherits from emittery', () => {
    expect(new Task() instanceof Emittery).toBeTrue();
  });

  it('can be constructed with no arguments', () => {
    function factory() {
      return new Task();
    }

    expect(factory).not.toThrow();
  });

  it('uses the provided name', () => {
    const task = new Task({ name: 'foo' });

    expect(task.name).toBe('foo');
  });

  it('uses the provided function', () => {
    const func = () => Promise.resolve();
    const task = new Task({ func });

    expect(task.func).toBe(func);
  });

  describe('dependsOn', () => {
    it('accepts an array of task names as dependencies', () => {
      const dependsOn = ['bar', 'baz'];
      const task = new Task({
        name: 'foo',
        func: () => Promise.resolve(),
        dependsOn,
      });

      expect(task.dependsOn).toEqual(dependsOn);
    });

    it('accepts a single task name as a dependency', () => {
      const task = new Task({
        name: 'foo',
        func: () => Promise.resolve(),
        dependsOn: 'bar',
      });

      expect(task.dependsOn).toEqual(['bar']);
    });

    it('fails with non-string, non-array dependencies', () => {
      function factory() {
        return new Task({
          name: 'foo',
          func: () => Promise.resolve(),
          dependsOn: 7,
        });
      }

      expect(factory).toThrowErrorOfType(ARGUMENT_ERROR);
    });

    it('fails with non-string arrays of dependencies', () => {
      function factory() {
        return new Task({
          name: 'foo',
          func: () => Promise.resolve(),
          dependsOn: [7],
        });
      }

      expect(factory).toThrowErrorOfType(ARGUMENT_ERROR);
    });
  });

  it('uses the provided dependencies', () => {
    const dependsOn = ['foo', 'bar'];
    const task = new Task({ dependsOn });

    expect(task.dependsOn).toEqual(dependsOn);
  });

  describe('run', () => {
    it('requires a name', async () => {
      let error;

      async function start() {
        const task = new Task({
          func: () => Promise.resolve(),
        });

        await task.run();
      }

      try {
        await start();
      } catch (e) {
        error = e;
      }

      expect(error).toBeDefined();
    });

    it('requires a function', async () => {
      let error;

      async function run() {
        const task = new Task({
          name: 'foo',
        });

        await task.run();
      }

      try {
        await run();
      } catch (e) {
        error = e;
      }

      expect(error).toBeDefined();
    });

    it('accepts a context object', async () => {
      const context = {};
      const task = new Task({
        name: 'foo',
        func: (c) => {
          c.foo = 'bar';

          return Promise.resolve();
        },
      });

      await task.run(context);

      expect(context.foo).toBe('bar');
    });

    describe('events', () => {
      it('emits a `start` event', async () => {
        let event;
        const task = new Task({
          name: 'foo',
          func: () => Promise.resolve(),
        });

        task.on('start', (e) => {
          event = e;
        });

        await task.run();

        expect(event).toBe(task);
      });

      it('emits an `end` event', async () => {
        let event;
        const task = new Task({
          name: 'foo',
          func: () => Promise.resolve(),
        });

        task.on('end', (e) => {
          event = e;
        });

        await task.run();

        expect(event).toBe(task);
      });

      it('emits an `error` event if necessary', async () => {
        let error = new Error('oh no!');
        let event;
        const task = new Task({
          name: 'foo',
          func: () => Promise.reject(error),
        });

        task.on('error', (e) => {
          event = e;
        });

        try {
          await task.run();
        } catch (e) {
          // Expected behavior.
        }

        expect(event.error).toBe(error);
        expect(event.task).toBe(task);
      });
    });
  });
});