#!/usr/bin/env node

// Compares two jsii assemblies and fails if they are different
// Versions in the expected assembly are updated to match this repo
// Usage: diff-test <expected> <actual>

const chalk = require('chalk');
const { structuredPatch } = require('diff');
const { readFile, writeFile } = require('fs').promises;
const { resolve } = require('path');
const process = require('process');

async function main() {
  const [, script, expectedPath, actualPath, ...rest] = process.argv;

  if (rest.length > 0 || actualPath == null || expectedPath == null) {
    console.error(`Error: Illegal arguments.`);
    console.error(`Received:      ${script} ${expectedPath} ${actualPath} ${rest.join(' ')}`)
    console.error(`Correct usage: ${script} <expected> <actual>`);
    return 3;
  }

  const expected = readFile(resolve(expectedPath), { encoding: 'utf-8' });
  const actual = readFile(resolve(actualPath), { encoding: 'utf-8' });

  const patch = structuredPatch(actualPath, expectedPath, await actual, await expected);
  if (patch.hunks.length === 0) {
    // All good, no difference!
    return 0;
  }

  console.log(chalk.grey(`--- ${patch.oldFileName}`));
  console.log(chalk.grey(`+++ ${patch.newFileName}`));
  for (const hunk of patch.hunks) {
    console.log(chalk.grey(`@@ -${hunk.oldStart},${hunk.oldLines} +${hunk.newStart},${hunk.newLines} @@`));
    for (const line of hunk.lines) {
      let color;
      switch (line[0]) {
        case '-':
          color = chalk.redBright;
          break;
        case '+':
          color = chalk.greenBright;
          break;
        default:
          color = chalk.grey;
      }
      console.log(color(line));
    }
  }

  console.error("=========================================================================");
  if (process.env.UPDATE_DIFF) {
    console.error(chalk.yellowBright(`UPDATE_DIFF is set, overwriting ${expectedPath}`));
    await writeFile(expectedPath, await actual, { encoding: 'utf-8' });
    return 0;
  }
  console.error('test failed. to update:');
  console.error(chalk.blueBright(`    cp ${actualPath} ${expectedPath}`));
  console.error();
  console.error('or, execute again with:');
  console.error(chalk.blueBright('    UPDATE_DIFF=1'));
  return 1;
}

main().then(
  (code) => process.exit(code),
  (err) => {
    console.error('Unexpected error:', err);
    process.exit(-1);
  }
)