chore: import upstream snapshot with attribution

tools/challenge-parser/parser/plugins/add-seed.js

@@ -0,0 +1,129 @@
+const { isEmpty } = require('lodash');
+const { root } = require('mdast-builder');
+const visitChildren = require('unist-util-visit-children');
+const { getSection } = require('./utils/get-section');
+const { getFileVisitor } = require('./utils/get-file-visitor');
+
+const path = require('path');
+
+const editableRegionMarker = '--fcc-editable-region--';
+
+function isWorkshop(file) {
+  return file.path && file.path.includes(path.sep + 'workshop-');
+}
+
+function findRegionMarkers(challengeFile) {
+  const lines = challengeFile.contents.split('\n');
+  const editableLines = lines
+    .map((line, id) => (line.trim() === editableRegionMarker ? id : -1))
+    .filter(id => id >= 0);
+
+  if (editableLines.length > 2) {
+    throw Error('Editable region has too many markers: ' + editableLines);
+  }
+
+  if (editableLines.length === 0) {
+    return null;
+  } else if (editableLines.length === 1) {
+    throw Error(`Editable region not closed`);
+  } else {
+    return editableLines;
+  }
+}
+
+function removeLines(contents, toRemove) {
+  const lines = contents.split('\n');
+  return lines.filter((_, id) => !toRemove.includes(id)).join('\n');
+}
+
+// TODO: DRY this.  Start with an array of markers and go from there.
+function addSeeds() {
+  function transformer(tree, file) {
+    const seedTree = root(getSection(tree, `--seed--`));
+    // Not all challenges have seeds (video challenges, for example), so we stop
+    // processing in these cases.
+    if (isEmpty(seedTree.children)) return;
+    const contentsTree = root(getSection(seedTree, `--seed-contents--`));
+    const seeds = {};
+
+    // Seed contents are required.
+    if (isEmpty(contentsTree.children))
+      throw Error('## --seed-contents-- must appear in # --seed-- sections');
+
+    const visitForContents = visitChildren(
+      getFileVisitor(seeds, 'contents', validateEditableMarkers)
+    );
+    visitForContents(contentsTree);
+
+    const seedVals = Object.values(seeds);
+    file.data = {
+      ...file.data,
+      challengeFiles: seedVals
+    };
+
+    // process region markers - remove them from content and add them to data
+    let totalEditableRegionMarkers = 0;
+
+    const challengeFiles = Object.values(seeds).map(data => {
+      const seed = { ...data };
+      // Per-file check: ensures no single seed file has more than 2 markers.
+      // This is distinct from the workshop-level check below, which enforces
+      // exactly 2 total markers across all seed files combined.
+      const editRegionMarkers = findRegionMarkers(seed);
+      if (editRegionMarkers) {
+        seed.contents = removeLines(seed.contents, editRegionMarkers);
+
+        if (editRegionMarkers[1] <= editRegionMarkers[0]) {
+          throw Error('Editable region must be non zero');
+        }
+        seed.editableRegionBoundaries = editRegionMarkers;
+        totalEditableRegionMarkers += editRegionMarkers.length;
+      } else {
+        seed.editableRegionBoundaries = [];
+      }
+      return seed;
+    });
+
+    if (isWorkshop(file) && totalEditableRegionMarkers !== 2) {
+      throw Error(
+        `Workshop challenge ${file.path} must have exactly 2 editable region markers`
+      );
+    }
+
+    file.data = {
+      ...file.data,
+      challengeFiles
+    };
+  }
+
+  return transformer;
+}
+
+function validateEditableMarkers({ value, position }) {
+  const twoMarkersRE = RegExp(
+    editableRegionMarker + '.*' + editableRegionMarker
+  );
+  const formattedMarkerRE = /--fcc - editable - region--/;
+  const lines = value.split('\n');
+  const baseLineNumber = position.start.line + 1;
+  lines.forEach((line, index) => {
+    if (line.match(twoMarkersRE)) {
+      throw Error(
+        `Line ${
+          baseLineNumber + index
+        } has two markers. Each line should only have one.`
+      );
+    }
+    if (line.match(formattedMarkerRE)) {
+      throw Error(
+        `Line ${
+          baseLineNumber + index
+        } has a malformed marker. It should be --fcc-editable-region--`
+      );
+    }
+  });
+}
+
+module.exports = addSeeds;
+module.exports.editableRegionMarker = editableRegionMarker;
+module.exports.isWorkshop = isWorkshop;