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hsmusic-wiki - HSMusic - static wiki software cataloguing collaborative creation
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-rw-r--r--src/data/yaml.js692
1 files changed, 642 insertions, 50 deletions
diff --git a/src/data/yaml.js b/src/data/yaml.js
index a1eb73fb..9a0295b8 100644
--- a/src/data/yaml.js
+++ b/src/data/yaml.js
@@ -8,11 +8,14 @@ import {inspect as nodeInspect} from 'node:util';
 import yaml from 'js-yaml';
 
 import {colors, ENABLE_COLOR, logInfo, logWarn} from '#cli';
+import {parseContentNodes, splitContentNodesAround} from '#replacer';
 import {sortByName} from '#sort';
 import Thing from '#thing';
 import thingConstructors from '#things';
+import {matchContentEntries, multipleLyricsDetectionRegex} from '#wiki-data';
 
 import {
+  aggregateThrows,
   annotateErrorWithFile,
   decorateErrorWithIndex,
   decorateErrorWithAnnotation,
@@ -30,8 +33,10 @@ import {
   atOffset,
   empty,
   filterProperties,
+  getNestedProp,
   stitchArrays,
   typeAppearance,
+  unique,
   withEntries,
 } from '#sugar';
 
@@ -86,6 +91,10 @@ function makeProcessDocument(thingConstructor, {
   // A or B.
   //
   invalidFieldCombinations = [],
+
+  // Bouncing function used to process subdocuments: this is a function which
+  // in turn calls the appropriate *result of* makeProcessDocument.
+  processDocument: bouncer,
 }) {
   if (!thingConstructor) {
     throw new Error(`Missing Thing class`);
@@ -95,6 +104,10 @@ function makeProcessDocument(thingConstructor, {
     throw new Error(`Expected fields to be provided`);
   }
 
+  if (!bouncer) {
+    throw new Error(`Missing processDocument bouncer`);
+  }
+
   const knownFields = Object.keys(fieldSpecs);
 
   const ignoredFields =
@@ -142,9 +155,12 @@ function makeProcessDocument(thingConstructor, {
         : `document`);
 
     const aggregate = openAggregate({
+      ...aggregateThrows(ProcessDocumentError),
       message: `Errors processing ${constructorPart}` + namePart,
     });
 
+    const thing = Reflect.construct(thingConstructor, []);
+
     const documentEntries = Object.entries(document)
       .filter(([field]) => !ignoredFields.includes(field));
 
@@ -192,13 +208,50 @@ function makeProcessDocument(thingConstructor, {
 
     const fieldValues = {};
 
+    const subdocSymbol = Symbol('subdoc');
+    const subdocLayouts = {};
+
+    const isSubdocToken = value =>
+      typeof value === 'object' &&
+      value !== null &&
+      Object.hasOwn(value, subdocSymbol);
+
+    const transformUtilities = {
+      ...thingConstructors,
+
+      subdoc(documentType, data, {
+        bindInto = null,
+        provide = null,
+      } = {}) {
+        if (!documentType)
+          throw new Error(`Expected document type, got ${typeAppearance(documentType)}`);
+        if (!data)
+          throw new Error(`Expected data, got ${typeAppearance(data)}`);
+        if (typeof data !== 'object' || data === null)
+          throw new Error(`Expected data to be an object, got ${typeAppearance(data)}`);
+        if (typeof bindInto !== 'string' && bindInto !== null)
+          throw new Error(`Expected bindInto to be a string, got ${typeAppearance(bindInto)}`);
+        if (typeof provide !== 'object' && provide !== null)
+          throw new Error(`Expected provide to be an object, got ${typeAppearance(provide)}`);
+
+        return {
+          [subdocSymbol]: {
+            documentType,
+            data,
+            bindInto,
+            provide,
+          },
+        };
+      },
+    };
+
     for (const [field, documentValue] of documentEntries) {
       if (skippedFields.has(field)) continue;
 
       // This variable would like to certify itself as "not into capitalism".
       let propertyValue =
         (fieldSpecs[field].transform
-          ? fieldSpecs[field].transform(documentValue)
+          ? fieldSpecs[field].transform(documentValue, transformUtilities)
           : documentValue);
 
       // Completely blank items in a YAML list are read as null.
@@ -221,10 +274,99 @@ function makeProcessDocument(thingConstructor, {
         }
       }
 
+      if (isSubdocToken(propertyValue)) {
+        subdocLayouts[field] = propertyValue[subdocSymbol];
+        continue;
+      }
+
+      if (Array.isArray(propertyValue) && propertyValue.every(isSubdocToken)) {
+        subdocLayouts[field] =
+          propertyValue
+            .map(token => token[subdocSymbol]);
+        continue;
+      }
+
       fieldValues[field] = propertyValue;
     }
 
-    const thing = Reflect.construct(thingConstructor, []);
+    const subdocErrors = [];
+
+    const followSubdocSetup = setup => {
+      let error = null;
+
+      let subthing;
+      try {
+        const result = bouncer(setup.data, setup.documentType);
+        subthing = result.thing;
+        result.aggregate.close();
+      } catch (caughtError) {
+        error = caughtError;
+      }
+
+      if (subthing) {
+        if (setup.bindInto) {
+          subthing[setup.bindInto] = thing;
+        }
+
+        if (setup.provide) {
+          Object.assign(subthing, setup.provide);
+        }
+      }
+
+      return {error, subthing};
+    };
+
+    for (const [field, layout] of Object.entries(subdocLayouts)) {
+      if (Array.isArray(layout)) {
+        const subthings = [];
+        let anySucceeded = false;
+        let anyFailed = false;
+
+        for (const [index, setup] of layout.entries()) {
+          const {subthing, error} = followSubdocSetup(setup);
+          if (error) {
+            subdocErrors.push(new SubdocError(
+              {field, index},
+              setup,
+              {cause: error}));
+          }
+
+          if (subthing) {
+            subthings.push(subthing);
+            anySucceeded = true;
+          } else {
+            anyFailed = true;
+          }
+        }
+
+        if (anySucceeded) {
+          fieldValues[field] = subthings;
+        } else if (anyFailed) {
+          skippedFields.add(field);
+        }
+      } else {
+        const setup = layout;
+        const {subthing, error} = followSubdocSetup(setup);
+
+        if (error) {
+          subdocErrors.push(new SubdocError(
+            {field},
+            setup,
+            {cause: error}));
+        }
+
+        if (subthing) {
+          fieldValues[field] = subthing;
+        } else {
+          skippedFields.add(field);
+        }
+      }
+    }
+
+    if (!empty(subdocErrors)) {
+      aggregate.push(new SubdocAggregateError(
+        subdocErrors, thingConstructor));
+    }
 
     const fieldValueErrors = [];
 
@@ -258,6 +400,8 @@ function makeProcessDocument(thingConstructor, {
   });
 }
 
+export class ProcessDocumentError extends AggregateError {}
+
 export class UnknownFieldsError extends Error {
   constructor(fields) {
     super(`Unknown fields ignored: ${fields.map(field => colors.red(field)).join(', ')}`);
@@ -345,12 +489,46 @@ export class SkippedFieldsSummaryError extends Error {
         : `${entries.length} fields`);
 
     super(
-      colors.bright(colors.yellow(`Altogether, skipped ${numFieldsText}:\n`)) +
+      colors.bright(colors.yellow(`Altogether, skipped ${numFieldsText}:`)) + '\n' +
       lines.join('\n') + '\n' +
       colors.bright(colors.yellow(`See above errors for details.`)));
   }
 }
 
+export class SubdocError extends Error {
+  constructor({field, index = null}, setup, options) {
+    const fieldText =
+      (index === null
+        ? colors.green(`"${field}"`)
+        : colors.yellow(`#${index + 1}`) + ' in ' +
+          colors.green(`"${field}"`));
+
+    const constructorText =
+      setup.documentType.name;
+
+    if (options.cause instanceof ProcessDocumentError) {
+      options.cause[Symbol.for('hsmusic.aggregate.translucent')] = true;
+    }
+
+    super(
+      `Errors processing ${constructorText} for ${fieldText} field`,
+      options);
+  }
+}
+
+export class SubdocAggregateError extends AggregateError {
+  [Symbol.for('hsmusic.aggregate.translucent')] = true;
+
+  constructor(errors, thingConstructor) {
+    const constructorText =
+      colors.green(thingConstructor.name);
+
+    super(
+      errors,
+      `Errors processing subdocuments for ${constructorText}`);
+  }
+}
+
 export function parseDate(date) {
   return new Date(date);
 }
@@ -433,49 +611,39 @@ export function parseContributors(entries) {
   });
 }
 
-export function parseAdditionalFiles(entries) {
+export function parseAdditionalFiles(entries, {subdoc, AdditionalFile}) {
   return parseArrayEntries(entries, item => {
     if (typeof item !== 'object') return item;
 
-    return {
-      title: item['Title'],
-      description: item['Description'] ?? null,
-      files: item['Files'],
-    };
+    return subdoc(AdditionalFile, item, {bindInto: 'thing'});
   });
 }
 
-export function parseAdditionalNames(entries) {
+export function parseAdditionalNames(entries, {subdoc, AdditionalName}) {
   return parseArrayEntries(entries, item => {
-    if (typeof item === 'object' && typeof item['Name'] === 'string')
-      return {
-        name: item['Name'],
-        annotation: item['Annotation'] ?? null,
-      };
+    if (typeof item === 'object') {
+      return subdoc(AdditionalName, item, {bindInto: 'thing'});
+    }
 
     if (typeof item !== 'string') return item;
 
     const match = item.match(extractAccentRegex);
     if (!match) return item;
 
-    return {
-      name: match.groups.main,
-      annotation: match.groups.accent ?? null,
+    const document = {
+      ['Name']: match.groups.main,
+      ['Annotation']: match.groups.accent ?? null,
     };
+
+    return subdoc(AdditionalName, document, {bindInto: 'thing'});
   });
 }
 
-export function parseSerieses(entries) {
+export function parseSerieses(entries, {subdoc, Series}) {
   return parseArrayEntries(entries, item => {
     if (typeof item !== 'object') return item;
 
-    return {
-      name: item['Name'],
-      description: item['Description'] ?? null,
-      albums: item['Albums'] ?? null,
-
-      showAlbumArtists: item['Show Album Artists'] ?? null,
-    };
+    return subdoc(Series, item, {bindInto: 'group'});
   });
 }
 
@@ -613,6 +781,172 @@ export function parseAnnotatedReferences(entries, {
   });
 }
 
+export function parseArtwork({
+  single = false,
+  thingProperty = null,
+  dimensionsFromThingProperty = null,
+  fileExtensionFromThingProperty = null,
+  dateFromThingProperty = null,
+  artistContribsFromThingProperty = null,
+  artistContribsArtistProperty = null,
+  artTagsFromThingProperty = null,
+  referencedArtworksFromThingProperty = null,
+}) {
+  const provide = {
+    thingProperty,
+    dimensionsFromThingProperty,
+    fileExtensionFromThingProperty,
+    dateFromThingProperty,
+    artistContribsFromThingProperty,
+    artistContribsArtistProperty,
+    artTagsFromThingProperty,
+    referencedArtworksFromThingProperty,
+  };
+
+  const parseSingleEntry = (entry, {subdoc, Artwork}) =>
+    subdoc(Artwork, entry, {bindInto: 'thing', provide});
+
+  const transform = (value, ...args) =>
+    (Array.isArray(value)
+      ? value.map(entry => parseSingleEntry(entry, ...args))
+   : single
+      ? parseSingleEntry(value, ...args)
+      : [parseSingleEntry(value, ...args)]);
+
+  transform.provide = provide;
+
+  return transform;
+}
+
+export function parseContentEntriesFromSourceText(thingClass, sourceText, {subdoc}) {
+  function map(matchEntry) {
+    let artistText = null, artistReferences = null;
+
+    const artistTextNodes =
+      Array.from(
+        splitContentNodesAround(
+          parseContentNodes(matchEntry.artistText),
+          /\|/g));
+
+    const separatorIndices =
+      artistTextNodes
+        .filter(node => node.type === 'separator')
+        .map(node => artistTextNodes.indexOf(node));
+
+    if (empty(separatorIndices)) {
+      if (artistTextNodes.length === 1 && artistTextNodes[0].type === 'text') {
+        artistReferences = matchEntry.artistText;
+      } else {
+        artistText = matchEntry.artistText;
+      }
+    } else {
+      const firstSeparatorIndex =
+        separatorIndices.at(0);
+
+      const secondSeparatorIndex =
+        separatorIndices.at(1) ??
+        artistTextNodes.length;
+
+      artistReferences =
+        matchEntry.artistText.slice(
+          artistTextNodes.at(0).i,
+          artistTextNodes.at(firstSeparatorIndex - 1).iEnd);
+
+      artistText =
+        matchEntry.artistText.slice(
+          artistTextNodes.at(firstSeparatorIndex).iEnd,
+          artistTextNodes.at(secondSeparatorIndex - 1).iEnd);
+    }
+
+    if (artistReferences) {
+      artistReferences =
+        artistReferences
+          .split(',')
+          .map(ref => ref.trim());
+    }
+
+    return {
+      'Artists':
+        artistReferences,
+
+      'Artist Text':
+        artistText,
+
+      'Annotation':
+        matchEntry.annotation,
+
+      'Date':
+        matchEntry.date,
+
+      'Second Date':
+        matchEntry.secondDate,
+
+      'Date Kind':
+        matchEntry.dateKind,
+
+      'Access Date':
+        matchEntry.accessDate,
+
+      'Access Kind':
+        matchEntry.accessKind,
+
+      'Body':
+        matchEntry.body,
+    };
+  }
+
+  const documents =
+    matchContentEntries(sourceText)
+      .map(matchEntry =>
+        withEntries(
+          map(matchEntry),
+          entries => entries
+            .filter(([key, value]) =>
+              value !== undefined &&
+              value !== null)));
+
+  const subdocs =
+    documents.map(document =>
+      subdoc(thingClass, document, {bindInto: 'thing'}));
+
+  return subdocs;
+}
+
+export function parseContentEntries(thingClass, value, {subdoc}) {
+  if (typeof value === 'string') {
+    return parseContentEntriesFromSourceText(thingClass, value, {subdoc});
+  } else if (Array.isArray(value)) {
+    return value.map(doc => subdoc(thingClass, doc, {bindInto: 'thing'}));
+  } else {
+    return value;
+  }
+}
+
+export function parseCommentary(value, {subdoc, CommentaryEntry}) {
+  return parseContentEntries(CommentaryEntry, value, {subdoc});
+}
+
+export function parseCreditingSources(value, {subdoc, CreditingSourcesEntry}) {
+  return parseContentEntries(CreditingSourcesEntry, value, {subdoc});
+}
+
+export function parseReferencingSources(value, {subdoc, ReferencingSourcesEntry}) {
+  return parseContentEntries(ReferencingSourcesEntry, value, {subdoc});
+}
+
+export function parseLyrics(value, {subdoc, LyricsEntry}) {
+  if (
+    typeof value === 'string' &&
+    !multipleLyricsDetectionRegex.test(value)
+  ) {
+    const document = {'Body': value};
+
+    return [subdoc(LyricsEntry, document, {bindInto: 'thing'})];
+  }
+
+  return parseContentEntries(LyricsEntry, value, {subdoc});
+}
+
 // documentModes: Symbols indicating sets of behavior for loading and processing
 // data files.
 export const documentModes = {
@@ -688,16 +1022,23 @@ export const documentModes = {
 export function getAllDataSteps() {
   try {
     thingConstructors;
-  } catch (error) {
+  } catch {
     throw new Error(`Thing constructors aren't ready yet, can't get all data steps`);
   }
 
   const steps = [];
 
+  const seenLoadingFns = new Set();
+
   for (const thingConstructor of Object.values(thingConstructors)) {
     const getSpecFn = thingConstructor[Thing.getYamlLoadingSpec];
     if (!getSpecFn) continue;
 
+    // Subclasses can expose literally the same static properties
+    // by inheritence. We don't want to double-count those!
+    if (seenLoadingFns.has(getSpecFn)) continue;
+    seenLoadingFns.add(getSpecFn);
+
     steps.push(getSpecFn({
       documentModes,
       thingConstructors,
@@ -890,7 +1231,7 @@ export function processThingsFromDataStep(documents, dataStep) {
         throw new Error(`Class "${thingClass.name}" doesn't specify Thing.yamlDocumentSpec`);
       }
 
-      fn = makeProcessDocument(thingClass, spec);
+      fn = makeProcessDocument(thingClass, {...spec, processDocument});
       submap.set(thingClass, fn);
     }
 
@@ -905,15 +1246,23 @@ export function processThingsFromDataStep(documents, dataStep) {
       const aggregate = openAggregate({message: `Errors processing documents`});
 
       documents.forEach(
-        decorateErrorWithIndex(document => {
+        decorateErrorWithIndex((document, index) => {
           const {thing, aggregate: subAggregate} =
             processDocument(document, dataStep.documentThing);
 
+          thing[Thing.yamlSourceDocument] = document;
+          thing[Thing.yamlSourceDocumentPlacement] =
+            [documentModes.allInOne, index];
+
           result.push(thing);
           aggregate.call(subAggregate.close);
         }));
 
-      return {aggregate, result};
+      return {
+        aggregate,
+        result,
+        things: result,
+      };
     }
 
     case documentModes.oneDocumentTotal: {
@@ -923,7 +1272,15 @@ export function processThingsFromDataStep(documents, dataStep) {
       const {thing, aggregate} =
         processDocument(documents[0], dataStep.documentThing);
 
-      return {aggregate, result: thing};
+      thing[Thing.yamlSourceDocument] = documents[0];
+      thing[Thing.yamlSourceDocumentPlacement] =
+        [documentModes.oneDocumentTotal];
+
+      return {
+        aggregate,
+        result: thing,
+        things: [thing],
+      };
     }
 
     case documentModes.headerAndEntries: {
@@ -938,6 +1295,10 @@ export function processThingsFromDataStep(documents, dataStep) {
       const {thing: headerThing, aggregate: headerAggregate} =
         processDocument(headerDocument, dataStep.headerDocumentThing);
 
+      headerThing[Thing.yamlSourceDocument] = headerDocument;
+      headerThing[Thing.yamlSourceDocumentPlacement] =
+        [documentModes.headerAndEntries, 'header'];
+
       try {
         headerAggregate.close();
       } catch (caughtError) {
@@ -951,6 +1312,10 @@ export function processThingsFromDataStep(documents, dataStep) {
         const {thing: entryThing, aggregate: entryAggregate} =
           processDocument(entryDocument, dataStep.entryDocumentThing);
 
+        entryThing[Thing.yamlSourceDocument] = entryDocument;
+        entryThing[Thing.yamlSourceDocumentPlacement] =
+          [documentModes.headerAndEntries, 'entry', index];
+
         entryThings.push(entryThing);
 
         try {
@@ -967,6 +1332,7 @@ export function processThingsFromDataStep(documents, dataStep) {
           header: headerThing,
           entries: entryThings,
         },
+        things: [headerThing, ...entryThings],
       };
     }
 
@@ -980,7 +1346,15 @@ export function processThingsFromDataStep(documents, dataStep) {
       const {thing, aggregate} =
         processDocument(documents[0], dataStep.documentThing);
 
-      return {aggregate, result: thing};
+      thing[Thing.yamlSourceDocument] = documents[0];
+      thing[Thing.yamlSourceDocumentPlacement] =
+        [documentModes.onePerFile];
+
+      return {
+        aggregate,
+        result: thing,
+        things: [thing],
+      };
     }
 
     default:
@@ -1080,9 +1454,16 @@ export async function processThingsFromDataSteps(documentLists, fileLists, dataS
           file: files,
           documents: documentLists,
         }).map(({file, documents}) => {
-            const {result, aggregate} =
+            const {result, aggregate, things} =
               processThingsFromDataStep(documents, dataStep);
 
+            for (const thing of things) {
+              thing[Thing.yamlSourceFilename] =
+                path.relative(dataPath, file)
+                  .split(path.sep)
+                  .join(path.posix.sep);
+            }
+
             const close = decorateErrorWithFileFromDataPath(aggregate.close, {dataPath});
             aggregate.close = () => close({file});
 
@@ -1230,39 +1611,50 @@ export function linkWikiDataArrays(wikiData, {bindFind, bindReverse}) {
     // entries must be present here even without any properties to explicitly
     // link if the 'find' or 'reverse' properties will be implicitly linked
 
-    [wikiData.albumData, [
-      'albumData',
-      'trackData',
+    ['albumData', [
+      'artworkData',
       'wikiInfo',
     ]],
 
-    [wikiData.artTagData, [/* reverse */]],
+    ['artTagData', [/* reverse */]],
+
+    ['artistData', [/* find, reverse */]],
+
+    ['artworkData', ['artworkData']],
 
-    [wikiData.artistData, [/* find, reverse */]],
+    ['commentaryData', [/* find */]],
 
-    [wikiData.flashData, [
+    ['creditingSourceData', [/* find */]],
+
+    ['flashData', [
       'wikiInfo',
     ]],
 
-    [wikiData.flashActData, [/* find, reverse */]],
+    ['flashActData', [/* find, reverse */]],
+
+    ['flashSideData', [/* find */]],
+
+    ['groupData', [/* find, reverse */]],
 
-    [wikiData.flashSideData, [/* find */]],
+    ['groupCategoryData', [/* find */]],
 
-    [wikiData.groupData, [/* find, reverse */]],
+    ['homepageLayout.sections.rows', [/* find */]],
 
-    [wikiData.groupCategoryData, [/* find */]],
+    ['lyricsData', [/* find */]],
 
-    [wikiData.homepageLayout.rows, [/* find */]],
+    ['referencingSourceData', [/* find */]],
 
-    [wikiData.trackData, [
-      'albumData',
+    ['seriesData', [/* find */]],
+
+    ['trackData', [
+      'artworkData',
       'trackData',
       'wikiInfo',
     ]],
 
-    [wikiData.trackSectionData, [/* reverse */]],
+    ['trackSectionData', [/* reverse */]],
 
-    [[wikiData.wikiInfo], [/* find */]],
+    ['wikiInfo', [/* find */]],
   ]);
 
   const constructorHasFindMap = new Map();
@@ -1271,8 +1663,12 @@ export function linkWikiDataArrays(wikiData, {bindFind, bindReverse}) {
   const boundFind = bindFind(wikiData);
   const boundReverse = bindReverse(wikiData);
 
-  for (const [things, keys] of linkWikiDataSpec.entries()) {
-    if (things === undefined) continue;
+  for (const [thingDataProp, keys] of linkWikiDataSpec.entries()) {
+    const thingData = getNestedProp(wikiData, thingDataProp);
+    const things =
+      (Array.isArray(thingData)
+        ? thingData.flat(Infinity)
+        : [thingData]);
 
     for (const thing of things) {
       if (thing === undefined) continue;
@@ -1393,3 +1789,199 @@ export async function quickLoadAllFromYAML(dataPath, {
 
   return wikiData;
 }
+
+export function cruddilyGetAllThings(wikiData) {
+  const allThings = [];
+
+  for (const v of Object.values(wikiData)) {
+    if (Array.isArray(v)) {
+      allThings.push(...v);
+    } else {
+      allThings.push(v);
+    }
+  }
+
+  return allThings;
+}
+
+export function getThingLayoutForFilename(filename, wikiData) {
+  const things =
+    cruddilyGetAllThings(wikiData)
+      .filter(thing =>
+        thing[Thing.yamlSourceFilename] === filename);
+
+  if (empty(things)) {
+    return null;
+  }
+
+  const allDocumentModes =
+    unique(things.map(thing =>
+      thing[Thing.yamlSourceDocumentPlacement][0]));
+
+  if (allDocumentModes.length > 1) {
+    throw new Error(`More than one document mode for documents from ${filename}`);
+  }
+
+  const documentMode = allDocumentModes[0];
+
+  switch (documentMode) {
+    case documentModes.allInOne: {
+      return {
+        documentMode,
+        things:
+          things.sort((a, b) =>
+            a[Thing.yamlSourceDocumentPlacement][1] -
+            b[Thing.yamlSourceDocumentPlacement][1]),
+      };
+    }
+
+    case documentModes.oneDocumentTotal:
+    case documentModes.onePerFile: {
+      if (things.length > 1) {
+        throw new Error(`More than one document for ${filename}`);
+      }
+
+      return {
+        documentMode,
+        thing: things[0],
+      };
+    }
+
+    case documentModes.headerAndEntries: {
+      const headerThings =
+        things.filter(thing =>
+          thing[Thing.yamlSourceDocumentPlacement][1] === 'header');
+
+      if (headerThings.length > 1) {
+        throw new Error(`More than one header document for ${filename}`);
+      }
+
+      return {
+        documentMode,
+        headerThing: headerThings[0] ?? null,
+        entryThings:
+          things
+            .filter(thing =>
+              thing[Thing.yamlSourceDocumentPlacement][1] === 'entry')
+            .sort((a, b) =>
+              a[Thing.yamlSourceDocumentPlacement][2] -
+              b[Thing.yamlSourceDocumentPlacement][2]),
+      };
+    }
+
+    default: {
+      return {documentMode};
+    }
+  }
+}
+
+export function flattenThingLayoutToDocumentOrder(layout) {
+  switch (layout.documentMode) {
+    case documentModes.oneDocumentTotal:
+    case documentModes.onePerFile: {
+      if (layout.thing) {
+        return [0];
+      } else {
+        return [];
+      }
+    }
+
+    case documentModes.allInOne: {
+      const indices =
+        layout.things
+          .map(thing => thing[Thing.yamlSourceDocumentPlacement][1]);
+
+      return indices;
+    }
+
+    case documentModes.headerAndEntries: {
+      const entryIndices =
+        layout.entryThings
+          .map(thing => thing[Thing.yamlSourceDocumentPlacement][2])
+          .map(index => index + 1);
+
+      if (layout.headerThing) {
+        return [0, ...entryIndices];
+      } else {
+        return entryIndices;
+      }
+    }
+
+    default: {
+      throw new Error(`Unknown document mode`);
+    }
+  }
+}
+
+export function* splitDocumentsInYAMLSourceText(sourceText) {
+  // Not multiline!
+  const dividerRegex = /(?:\r\n|\n|^)-{3,}(?:\r\n|\n|$)/g;
+
+  let previousDivider = '';
+
+  while (true) {
+    const {lastIndex} = dividerRegex;
+    const match = dividerRegex.exec(sourceText);
+    if (match) {
+      const nextDivider = match[0];
+
+      yield {
+        previousDivider,
+        nextDivider,
+        text: sourceText.slice(lastIndex, match.index),
+      };
+
+      previousDivider = nextDivider;
+    } else {
+      const nextDivider = '';
+      const lineBreak = previousDivider.match(/\r?\n/)?.[0] ?? '';
+
+      yield {
+        previousDivider,
+        nextDivider,
+        text: sourceText.slice(lastIndex).replace(/(?<!\n)$/, lineBreak),
+      };
+
+      return;
+    }
+  }
+}
+
+export function recombineDocumentsIntoYAMLSourceText(documents) {
+  const dividers =
+    unique(
+      documents
+        .flatMap(d => [d.previousDivider, d.nextDivider])
+        .filter(Boolean));
+
+  const divider = dividers[0];
+
+  if (dividers.length > 1) {
+    // TODO: Accommodate mixed dividers as best as we can lol
+    logWarn`Found multiple dividers in this file, using only ${divider}`;
+  }
+
+  let sourceText = '';
+
+  for (const document of documents) {
+    if (sourceText) {
+      sourceText += divider;
+    }
+
+    sourceText += document.text;
+  }
+
+  return sourceText;
+}
+
+export function reorderDocumentsInYAMLSourceText(sourceText, order) {
+  const sourceDocuments =
+    Array.from(splitDocumentsInYAMLSourceText(sourceText));
+
+  const sortedDocuments =
+    Array.from(
+      order,
+      sourceIndex => sourceDocuments[sourceIndex]);
+
+  return recombineDocumentsIntoYAMLSourceText(sortedDocuments);
+}