// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.

import { green, red } from "../colors/mod.ts";

interface Constructor {
  new (...args: any[]): any;
}

const assertions = {
  /** Make an assertion, if not `true`, then throw. */
  assert(expr: boolean, msg = ""): void {
    if (!expr) {
      throw new Error(msg);
    }
  },

  /** Make an assertion that `actual` and `expected` are equal, deeply. If not
   * deeply equal, then throw.
   */
  equal(actual: unknown, expected: unknown, msg?: string): void {
    if (!equal(actual, expected)) {
      let actualString: string;
      let expectedString: string;
      try {
        actualString = String(actual);
      } catch (e) {
        actualString = "[Cannot display]";
      }
      try {
        expectedString = String(expected);
      } catch (e) {
        expectedString = "[Cannot display]";
      }
      console.error(
        "assertEqual failed. actual =",
        actualString,
        "expected =",
        expectedString
      );
      if (!msg) {
        msg = `actual: ${actualString} expected: ${expectedString}`;
      }
      throw new Error(msg);
    }
  },

  /** Make an assertion that `actual` and `expected` are strictly equal.  If
   * not then throw.
   */
  strictEqual(actual: unknown, expected: unknown, msg = ""): void {
    if (actual !== expected) {
      let actualString: string;
      let expectedString: string;
      try {
        actualString = String(actual);
      } catch (e) {
        actualString = "[Cannot display]";
      }
      try {
        expectedString = String(expected);
      } catch (e) {
        expectedString = "[Cannot display]";
      }
      console.error(
        "strictEqual failed. actual =",
        actualString,
        "expected =",
        expectedString
      );
      if (!msg) {
        msg = `actual: ${actualString} expected: ${expectedString}`;
      }
      throw new Error(msg);
    }
  },

  /**
   * Forcefully throws a failed assertion
   */
  fail(msg?: string): void {
    assert(false, `Failed assertion${msg ? `: ${msg}` : "."}`);
  },

  /** Executes a function, expecting it to throw.  If it does not, then it
   * throws.  An error class and a string that should be included in the
   * error message can also be asserted.
   */
  throws(
    fn: () => void,
    ErrorClass?: Constructor,
    msgIncludes = "",
    msg = ""
  ): void {
    let doesThrow = false;
    try {
      fn();
    } catch (e) {
      if (ErrorClass && !(Object.getPrototypeOf(e) === ErrorClass.prototype)) {
        msg = `Expected error to be instance of "${ErrorClass.name}"${
          msg ? `: ${msg}` : "."
        }`;
        throw new Error(msg);
      }
      if (msgIncludes) {
        if (!e.message.includes(msgIncludes)) {
          msg = `Expected error message to include "${msgIncludes}", but got "${
            e.message
          }"${msg ? `: ${msg}` : "."}`;
          throw new Error(msg);
        }
      }
      doesThrow = true;
    }
    if (!doesThrow) {
      msg = `Expected function to throw${msg ? `: ${msg}` : "."}`;
      throw new Error(msg);
    }
  },

  async throwsAsync(
    fn: () => Promise<void>,
    ErrorClass?: Constructor,
    msgIncludes = "",
    msg = ""
  ): Promise<void> {
    let doesThrow = false;
    try {
      await fn();
    } catch (e) {
      if (ErrorClass && !(Object.getPrototypeOf(e) === ErrorClass.prototype)) {
        msg = `Expected error to be instance of "${ErrorClass.name}"${
          msg ? `: ${msg}` : "."
        }`;
        throw new Error(msg);
      }
      if (msgIncludes) {
        if (!e.message.includes(msgIncludes)) {
          msg = `Expected error message to include "${msgIncludes}", but got "${
            e.message
          }"${msg ? `: ${msg}` : "."}`;
          throw new Error(msg);
        }
      }
      doesThrow = true;
    }
    if (!doesThrow) {
      msg = `Expected function to throw${msg ? `: ${msg}` : "."}`;
      throw new Error(msg);
    }
  }
};

type Assert = typeof assertions.assert & typeof assertions;

// Decorate assertions.assert with all the assertions
Object.assign(assertions.assert, assertions);

export const assert = assertions.assert as Assert;

/**
 * An alias to assert.equal
 * @deprecated
 */
export const assertEqual = assert.equal;

export function equal(c: unknown, d: unknown): boolean {
  const seen = new Map();
  return (function compare(a: unknown, b: unknown) {
    if (Object.is(a, b)) {
      return true;
    }
    if (a && typeof a === "object" && b && typeof b === "object") {
      if (seen.get(a) === b) {
        return true;
      }
      if (Object.keys(a || {}).length !== Object.keys(b || {}).length) {
        return false;
      }
      const merged = { ...a, ...b };
      for (const key in merged) {
        type Key = keyof typeof merged;
        if (!compare(a && a[key as Key], b && b[key as Key])) {
          return false;
        }
      }
      seen.set(a, b);
      return true;
    }
    return false;
  })(c, d);
}

export type TestFunction = () => void | Promise<void>;

export interface TestDefinition {
  fn: TestFunction;
  name: string;
}

export const exitOnFail = true;

let filterRegExp: RegExp | null;
const tests: TestDefinition[] = [];

let filtered = 0;
const ignored = 0;
const measured = 0;

// Must be called before any test() that needs to be filtered.
export function setFilter(s: string): void {
  filterRegExp = new RegExp(s, "i");
}

export function test(t: TestDefinition | TestFunction): void {
  const fn: TestFunction = typeof t === "function" ? t : t.fn;
  const name: string = t.name;

  if (!name) {
    throw new Error("Test function may not be anonymous");
  }
  if (filter(name)) {
    tests.push({ fn, name });
  } else {
    filtered++;
  }
}

function filter(name: string): boolean {
  if (filterRegExp) {
    return filterRegExp.test(name);
  } else {
    return true;
  }
}

function red_failed() {
  return red("FAILED");
}

function green_ok() {
  return green("ok");
}

interface TestStats {
  filtered: number;
  ignored: number;
  measured: number;
  passed: number;
  failed: number;
}

interface TestResult {
  name: string;
  error: Error;
  ok: boolean;
  printed: boolean;
}

interface TestResults {
  keys: Map<string, number>;
  cases: Map<number, TestResult>;
}

function createTestResults(tests: Array<TestDefinition>): TestResults {
  return tests.reduce(
    (acc: TestResults, { name }: TestDefinition, i: number): TestResults => {
      acc.keys.set(name, i);
      acc.cases.set(i, { name, printed: false, ok: false, error: null });
      return acc;
    },
    { cases: new Map(), keys: new Map() }
  );
}

function report(result: TestResult): void {
  if (result.ok) {
    console.log(`test ${result.name} ... ${green_ok()}`);
  } else if (result.error) {
    console.error(
      `test ${result.name} ... ${red_failed()}\n${result.error.stack}`
    );
  } else {
    console.log(`test ${result.name} ... unresolved`);
  }
  result.printed = true;
}

function printResults(
  stats: TestStats,
  results: TestResults,
  flush: boolean
): void {
  if (flush) {
    for (const result of results.cases.values()) {
      if (!result.printed) {
        report(result);
        if (result.error && exitOnFail) {
          break;
        }
      }
    }
  }
  // Attempting to match the output of Rust's test runner.
  console.log(
    `\ntest result: ${stats.failed ? red_failed() : green_ok()}. ` +
      `${stats.passed} passed; ${stats.failed} failed; ` +
      `${stats.ignored} ignored; ${stats.measured} measured; ` +
      `${stats.filtered} filtered out\n`
  );
}

function previousPrinted(name: string, results: TestResults): boolean {
  const curIndex: number = results.keys.get(name);
  if (curIndex === 0) {
    return true;
  }
  return results.cases.get(curIndex - 1).printed;
}

async function createTestCase(
  stats: TestStats,
  results: TestResults,
  { fn, name }: TestDefinition
): Promise<void> {
  const result: TestResult = results.cases.get(results.keys.get(name));
  try {
    await fn();
    stats.passed++;
    result.ok = true;
  } catch (err) {
    stats.failed++;
    result.error = err;
    if (exitOnFail) {
      throw err;
    }
  }
  if (previousPrinted(name, results)) {
    report(result);
  }
}

function initTestCases(
  stats: TestStats,
  results: TestResults,
  tests: Array<TestDefinition>
): Array<Promise<void>> {
  return tests.map(createTestCase.bind(null, stats, results));
}

async function runTestsParallel(
  stats: TestStats,
  results: TestResults,
  tests: Array<TestDefinition>
): Promise<void> {
  try {
    await Promise.all(initTestCases(stats, results, tests));
  } catch (_) {
    // The error was thrown to stop awaiting all promises if exitOnFail === true
    // stats.failed has been incremented and the error stored in results
  }
}

async function runTestsSerial(
  stats: TestStats,
  tests: Array<TestDefinition>
): Promise<void> {
  for (const { fn, name } of tests) {
    // See https://github.com/denoland/deno/pull/1452
    // about this usage of groupCollapsed
    console.groupCollapsed(`test ${name} `);
    try {
      await fn();
      stats.passed++;
      console.log("...", green_ok());
      console.groupEnd();
    } catch (err) {
      console.log("...", red_failed());
      console.groupEnd();
      console.error(err.stack);
      stats.failed++;
      if (exitOnFail) {
        break;
      }
    }
  }
}

/** Defines options for controlling execution details of a test suite. */
export interface RunOptions {
  parallel?: boolean;
}

/**
 * Runs specified test cases.
 * Parallel execution can be enabled via the boolean option; default: serial.
 */
export async function runTests({ parallel = false }: RunOptions = {}): Promise<
  void
> {
  const stats: TestStats = {
    measured: 0,
    ignored: 0,
    filtered: filtered,
    passed: 0,
    failed: 0
  };
  const results: TestResults = createTestResults(tests);
  console.log(`running ${tests.length} tests`);
  if (parallel) {
    await runTestsParallel(stats, results, tests);
  } else {
    await runTestsSerial(stats, tests);
  }
  printResults(stats, results, parallel);
  if (stats.failed) {
    // Use setTimeout to avoid the error being ignored due to unhandled
    // promise rejections being swallowed.
    setTimeout(() => {
      console.error(`There were ${stats.failed} test failures.`);
      Deno.exit(1);
    }, 0);
  }
}

/**
 * Runs specified test cases if the enclosing script is main.
 * Execution mode is toggleable via opts.parallel, defaults to false.
 */
export async function runIfMain(
  meta: ImportMeta,
  opts?: RunOptions
): Promise<void> {
  if (meta.main) {
    return runTests(opts);
  }
}