import {describe, it, expect, vi, Mock, beforeAll, beforeEach} from 'vitest';
import { readFile, writeFile } from 'fs/promises';
import { JsonLinesDataSource } from '../src';
import { resource, validation as v } from '@modal-sh/yasumi';
import {DataSource} from '@modal-sh/yasumi/dist/types/backend';

vi.mock('fs/promises');

const toJsonl = (dummyItems: unknown[]) => dummyItems.map((i) => JSON.stringify(i)).join('\n');

const ID_ATTR = 'id' as const;

describe('prepareResource', () => {
  beforeAll(() => {
    const mockWriteFile = writeFile as Mock;
    mockWriteFile.mockImplementation(() => { /* noop */ })
  });

  it('works', () => {
    const schema = v.object({});
    const r = resource(schema);
    const ds = new JsonLinesDataSource<typeof schema>();
    expect(() => ds.prepareResource(r)).not.toThrow();
  });
});

describe('methods', () => {
  const dummyItems = [
    {
      id: 1,
      name: 'foo',
    },
    {
      id: 2,
      name: 'bar',
    },
    {
      id: 3,
      name: 'baz',
    },
  ];
  const schema = v.object({
    name: v.string(),
  });
  let ds: DataSource<v.Output<typeof schema>>;
  let mockGenerationStrategy: Mock;
  beforeEach(() => {
    mockGenerationStrategy = vi.fn();
    const r = resource(schema)
      .id(ID_ATTR, {
        generationStrategy: mockGenerationStrategy,
        schema: v.any(),
        serialize: (id) => id.toString(),
        deserialize: (id) => Number(id.toString()),
      });
    ds = new JsonLinesDataSource<typeof schema>();
    ds.prepareResource(r);
  });

  beforeEach(() => {
    const mockReadFile = readFile as Mock;
    mockReadFile.mockReturnValueOnce(toJsonl(dummyItems));
  });

  let mockWriteFile: Mock;
  beforeEach(() => {
    mockWriteFile = writeFile as Mock;
    mockWriteFile.mockImplementationOnce(() => { /* noop */ });
  });

  describe('initialize', () => {
    it('works', async () => {
      try {
        await ds.initialize();
      } catch {
        expect.fail('Could not initialize data source.');
      }
    });
  });

  describe('operations', () => {
    beforeEach(async () => {
      await ds.initialize();
    });

    describe('getTotalCount', () => {
      it('works', async () => {
        if (typeof ds.getTotalCount !== 'function') {
          return;
        }
        const totalCount = await ds.getTotalCount();
        expect(totalCount).toBe(dummyItems.length);
      });
    });

    describe('getMultiple', () => {
      it('works', async () => {
        const items = await ds.getMultiple();
        expect(items).toEqual(dummyItems);
      });
    });

    describe('getById', () => {
      it('works', async () => {
        const id = 2;
        const item = await ds.getById(id.toString()); // ID is always a string because it originates from URLs
        const expected = dummyItems.find((i) => i[ID_ATTR] === id);
        expect(item).toEqual(expected);
      });
    });

    describe('getSingle', () => {
      it('works', async () => {
        if (typeof ds.getSingle !== 'function') {
          // skip if data source doesn't offer this
          return;
        }
        const item = await ds.getSingle();
        const expected = dummyItems[0];
        expect(item).toEqual(expected);
      });
    });

    describe('create', () => {
      it('works', async () => {
        const data = {
          // notice we don't have IDs here, as it is expected to be generated by newId()
          name: 'foo'
        };
        const newItem = await ds.create(data);

        expect(mockWriteFile).toBeCalledWith(
          expect.any(String),
          toJsonl([
            ...dummyItems,
            data
          ])
        );
        expect(newItem).toEqual(data);
      });
    });

    describe('delete', () => {
      it('works', async () => {
        await ds.delete('1');
        expect(mockWriteFile).toBeCalledWith(
          expect.any(String),
          toJsonl(dummyItems.filter((d) => d[ID_ATTR] !== 1)),
        );
      });
    });

    describe('emplace', () => {
      it('replaces existing data', async () => {
        const data = {
          [ID_ATTR]: 2,
          name: 'foo',
        };
        const { id, ...etcData } = data;
        const newItem = await ds.emplace(
          id.toString(),
          etcData,
        );

        expect(mockWriteFile).toBeCalledWith(
          expect.any(String),
          toJsonl(dummyItems.map((d) =>
            d[ID_ATTR] === data[ID_ATTR]
              // ID will be defined first, since we are just writing to file, we need strict ordering
              ? { [ID_ATTR]: id, ...etcData }
              : d
          )),
        );
        expect(newItem).toEqual([data, false]);
      });

      it('creates new data', async () => {
        const data = {
          [ID_ATTR]: 4,
          name: 'quux',
        };
        const { [ID_ATTR]: id, ...etcData } = data;
        const newItem = await ds.emplace(
          id.toString(),
          etcData,
        );

        expect(mockWriteFile).toBeCalledWith(
          expect.any(String),
          toJsonl([
            ...dummyItems,
            data
          ]),
        );
        expect(newItem).toEqual([data, true]);
      });
    });

    describe('patch', () => {
      it('works', async () => {
        const data = {
          [ID_ATTR]: 2,
          name: 'foo',
        };
        const { id, ...etcData } = data;
        const newItem = await ds.emplace(
          id.toString(),
          etcData,
        );

        expect(mockWriteFile).toBeCalledWith(
          expect.any(String),
          toJsonl(dummyItems.map((d) =>
            d[ID_ATTR] === data[ID_ATTR]
              // ID will be defined first, since we are just writing to file, we need strict ordering
              ? { [ID_ATTR]: id, ...etcData }
              : d
          )),
        );
        expect(newItem).toBeDefined();
      });
    });

    describe('newId', () => {
      it('works', async () => {
        const v = Math.floor(Math.random() * Number.MAX_SAFE_INTEGER);
        mockGenerationStrategy.mockResolvedValueOnce(v);
        const id = await ds.newId();
        expect(id).toBe(v);
      });
    });
  });
});