spiegel-keyman/web/tools/sourcemap-root/index.ts

var fs = require("fs");

function displayHelp() {
  console.log("KeymanWeb's sourcemap-cleansing tool.  This tool is designed to produce clean filepaths");
  console.log("in the sourcemaps for ease of reference in browser and Sentry, copying the clean paths TS");
  console.log("is able to provide, whereas Closure's minification is not.");
  console.log("");
  console.log("Usage:  node sourcemap-root <source.map> <dest.map> [-s|--suffix <path>]");
  console.log("        -s|--suffix <path> Appends <path> to the input sourcemap's 'sourceRoot'.")
}

// By default, any node-based process has two command-line args:
// [0] - node installation root
// [1] - path to the script being run.

// Basic help-request check
if(process.argv.length < 4) {  // [2] and [3] - <source.map> and <dest.map> respectively.
  displayHelp();
  process.exit(1);
} else {
  switch(process.argv[2]) {
    case '--help':
    case '-h':
    case '-?':
      displayHelp();
      process.exit();
    default:
      // program continues as normal.
  }
}

function assert_is_map(filename: string) {
  if(filename.lastIndexOf(".map") != (filename.length - 4)) {
    console.error("Error:  sourcemap .map file was not provided as first argument.");
    console.log();
    displayHelp();
    process.exit(1);
  }
}
// Verify the first parameter is a sourcemap filepath.
let sourceFile = process.argv[2];
let destFile = process.argv[3];

assert_is_map(sourceFile);
assert_is_map(destFile);

// Now to process any additional flags.
var sourceRootSuffix = "";

// Starting at [5] - optional command-line arguments
for(let procArgIndex = 4; procArgIndex < process.argv.length; procArgIndex++) {
  let flag = process.argv[procArgIndex];
  
  if(flag.indexOf('-') != 0) {
    console.error("Error:  Unexpected command-line argument provided: \"" + flag + "\" is not an argument flag")
    process.exit(1);
  }

  switch(flag) {
    case "-s":
    case "--suffix":
      procArgIndex++;
      sourceRootSuffix = process.argv[procArgIndex];
      break;
    default:
      console.warn("Unrecognized flag found in argument list: \"" + flag + "\"");
  }
}

let sourceContent: string;
let destContent: string;
try {
  sourceContent = fs.readFileSync(sourceFile) as string;
  destContent = fs.readFileSync(destFile) as string;
} catch(err) {
  console.error("Could not read specified input files");
  console.error("");
  console.error(err);
  process.exit(1);
}

let sourceJSON = JSON.parse(sourceContent) as {[key: string]: any};
let destJSON = JSON.parse(destContent) as {[key: string]: any};

// We now have the root JSON contents.  Time to go to work!  First, the easy parts.
destJSON["file"] = sourceJSON["file"];
destJSON["sourceRoot"] = sourceJSON["sourceRoot"] + sourceRootSuffix;

// The hard part:  mapping the source file arrays correctly.
// A raw copy of the arrays will not work properly.
let sourceSources = sourceJSON["sources"] as string[];
let destSources = destJSON["sources"] as string[];
let finalDestSources: string[] = [];

/**
 * Closure's minification always uses the TS paths as a suffix, prepending relative minification-path info to reuse them.
 * So, if we can find the TS path complete within a path in the minified sourcemap, it's a match.
 *
 * It's key that we preserve the original ordering of the source files from Closure's output sourcemaps, as is done here.
 * Otherwise, browsers will incorrectly match the inlined source to any given file, causing a fair bit of confusion.  
 * This is why we iterate over the destination's defined array; this way ensures identical ordering for the finalized version.
 */
for(let destPath of destSources) {
  let matched = false;

  for(let sourcePath of sourceSources) {
    if(destPath.indexOf(sourcePath) != -1) {
      matched = true;
      finalDestSources.push(sourcePath);
      break;
    }
  }

  if(!matched) {
    finalDestSources.push(destPath);
  }
}

destJSON["sources"] = finalDestSources;

let destOutput = JSON.stringify(destJSON);
fs.writeFileSync(destFile, destOutput);