#!/usr/bin/env node

/**
 * Run this script (from root directory): npx babel-node scripts/checksum
 *
 * This will check root `package.json` matches each exercise's `package.json`.
 * But the catch is there are some dependencies used for build but not served to end users
 * We skip those dependencies while performing checksum.
 * See `SKIP_PACKAGES_FOR_CHECKSUM` in helpers.js for list of skipped packages.
 */

const path = require('path');
const shell = require('shelljs');
const helpers = require('./helpers');

/**
 * Compares the file of the assignment with some known value
 *
 * @param filename file to check (local to the assignment directory)
 * @param assignment slug with type, eg. practice/two-fer
 * @param baseFile the file path that {filename} must be compared against
 * @param expectedSha known value of {baseFile}
 */
function checksumAssignment(assignment, filename, baseFile, expectedSha) {
  if (!assignment) {
    return;
  }

  const filePath = path.join('exercises', assignment, filename);

  let fileSha;

  if (filename == 'package.json') {
    const packageJson = helpers.prepareExercisePackageJson(filePath, false);

    fileSha = helpers.shaPackageJson(packageJson);
  } else {
    const fileContents = shell.cat(filePath).toString();
    fileSha = helpers.sha(fileContents);
  }

  if (fileSha !== expectedSha) {
    const chalk = require('chalk');
    const diff = require('diff');

    // prettier-ignore
    shell.echo(
      `[Failure] ${filename} did not match for ${assignment} (${chalk.red(expectedSha)} != ${chalk.green(fileSha)})\n`,
      `! Expected ${chalk.red(baseFile)} to match ${chalk.green(filePath)}\n`,
      `! Did you forget to run ${chalk.bold(`npx babel-node scripts/sync`)}?\n`
    );

    if (chalk.supportsColor) {
      const diffParts = diff.diffLines(
        shell.cat(filePath).toString(),
        shell.cat(baseFile).toString(),
        { newlineIsToken: false }
      );

      const output = diffParts
        .map((part) => {
          const color = part.added
            ? chalk.green
            : part.removed
            ? chalk.red
            : chalk.gray;
          return color(part.value);
        })
        .join('');

      shell.echo(output);
    }

    shell.exit(1);
  }
}

/**
 * Check all the exercises, or given, {filename} against {rootFileName}
 *
 * @param filename filename in the exercise directory
 * @param rootFileName filename in the root directory
 */
function checksumAll(filename, rootFileName = filename) {
  const assignments = [shell.env['ASSIGNMENT']].filter(Boolean);

  let expectedSha;

  if (rootFileName == 'exercise-package.json') {
    expectedSha = shell.cat('exercise-package.json.sha').toString();
  } else {
    const fileContents = shell.cat(rootFileName).toString();
    expectedSha = helpers.sha(fileContents);
  }

  if (assignments.length > 0) {
    if (
      !assignments.every((assignment) => helpers.assertAssignment(assignment))
    ) {
      shell.exit();
    }

    return assignments.every((assignment) => {
      shell.echo(`Checking integrity of ${assignment}/${filename}...`);
      return checksumAssignment(
        assignment,
        filename,
        rootFileName,
        expectedSha
      );
    });
  }

  shell.echo(
    `Checking integrity of ${filename} in all ${helpers.assignments.length} exercises`
  );

  helpers.assignments.forEach((assignment) =>
    checksumAssignment(assignment, filename, rootFileName, expectedSha)
  );
}

helpers.registerExitHandler();
helpers.createExercisePackageJson(true);

checksumAll('package.json', 'exercise-package.json');

['.eslintrc', '.npmrc', 'babel.config.js', 'LICENSE'].forEach((fileToCheck) => {
  checksumAll(fileToCheck);
});

shell.echo('All files passed the checksum test');