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Edit File: undo-manager.js

// package-external:@wordpress/is-shallow-equal
  var require_is_shallow_equal = __commonJS({
    "package-external:@wordpress/is-shallow-equal"(exports, module) {
      module.exports = window.wp.isShallowEqual;
    }
  });

// packages/undo-manager/build-module/index.mjs
  var index_exports = {};
  __export(index_exports, {
    createUndoManager: () => createUndoManager
  });
  var import_is_shallow_equal = __toESM(require_is_shallow_equal(), 1);
  function mergeHistoryChanges(changes1, changes2) {
    const newChanges = { ...changes1 };
    Object.entries(changes2).forEach(([key, value]) => {
      if (newChanges[key]) {
        newChanges[key] = { ...newChanges[key], to: value.to };
      } else {
        newChanges[key] = value;
      }
    });
    return newChanges;
  }
  var addHistoryChangesIntoRecord = (record, changes) => {
    const existingChangesIndex = record?.findIndex(
      ({ id: recordIdentifier }) => {
        return typeof recordIdentifier === "string" ? recordIdentifier === changes.id : (0, import_is_shallow_equal.isShallowEqual)(recordIdentifier, changes.id);
      }
    );
    const nextRecord = [...record];
    if (existingChangesIndex !== -1) {
      nextRecord[existingChangesIndex] = {
        id: changes.id,
        changes: mergeHistoryChanges(
          nextRecord[existingChangesIndex].changes,
          changes.changes
        )
      };
    } else {
      nextRecord.push(changes);
    }
    return nextRecord;
  };
  function createUndoManager() {
    let history = [];
    let stagedRecord = [];
    let offset = 0;
    const dropPendingRedos = () => {
      history = history.slice(0, offset || void 0);
      offset = 0;
    };
    const appendStagedRecordToLatestHistoryRecord = () => {
      const index = history.length === 0 ? 0 : history.length - 1;
      let latestRecord = history[index] ?? [];
      stagedRecord.forEach((changes) => {
        latestRecord = addHistoryChangesIntoRecord(latestRecord, changes);
      });
      stagedRecord = [];
      history[index] = latestRecord;
    };
    const isRecordEmpty = (record) => {
      const filteredRecord = record.filter(({ changes }) => {
        return Object.values(changes).some(
          ({ from, to }) => typeof from !== "function" && typeof to !== "function" && !(0, import_is_shallow_equal.isShallowEqual)(from, to)
        );
      });
      return !filteredRecord.length;
    };
    return {
      addRecord(record, isStaged = false) {
        const isEmpty = !record || isRecordEmpty(record);
        if (isStaged) {
          if (isEmpty) {
            return;
          }
          record.forEach((changes) => {
            stagedRecord = addHistoryChangesIntoRecord(
              stagedRecord,
              changes
            );
          });
        } else {
          dropPendingRedos();
          if (stagedRecord.length) {
            appendStagedRecordToLatestHistoryRecord();
          }
          if (isEmpty) {
            return;
          }
          history.push(record);
        }
      },
      undo() {
        if (stagedRecord.length) {
          dropPendingRedos();
          appendStagedRecordToLatestHistoryRecord();
        }
        const undoRecord = history[history.length - 1 + offset];
        if (!undoRecord) {
          return;
        }
        offset -= 1;
        return undoRecord;
      },
      redo() {
        const redoRecord = history[history.length + offset];
        if (!redoRecord) {
          return;
        }
        offset += 1;
        return redoRecord;
      },
      hasUndo() {
        return !!history[history.length - 1 + offset];
      },
      hasRedo() {
        return !!history[history.length + offset];
      }
    };
  }
  return __toCommonJS(index_exports);
})();
(window.wp ||= {}).undoManager = wp.undoManager;
})();