Added FileListStateReducer

src/FileListStateReducer.mjs

@@ -0,0 +1,178 @@
+/**
+ * @typedef {import("./api/FileListDir").FileListDir} FileListDir
+ * @typedef {import("./api/FileListItem").FileListItem} FileListItem
+ * @typedef {import("./sort/FileListSort").FileListSort} FileListSort
+ * @typedef {import("./FileListActions").FileListAction} FileListAction
+ * @typedef {import("./FileListState").FileListState} FileListState
+ */
+import FileListItem from "./api/FileListItem.mjs";
+import FileListSort from "./sort/FileListSort.mjs";
+import FileListState from "./FileListState.mjs";
+
+/**
+ * @param {FileListState} state
+ * @param {any} action
+ * @returns {FileListState}
+ */
+function FileListStateReducer(state, action) {
+  /** @type {FileListAction} */
+  const a = action;
+  switch (a.action) {
+    case "FileListParamsChangedAction":
+      return {
+        ...state,
+        offset: a.offset,
+        index: a.index,
+        selectedNames: a.selectedNames,
+      };
+
+    case "FileListDirChangedAction": {
+      const processed = processDir(a.currDir, state.sort);
+      const newIndex = () => {
+        if (a.dir === FileListItem.up.name) {
+          let focusedDir = stripPrefix(state.currDir.path, a.currDir.path);
+          focusedDir = stripPrefix(focusedDir, "/");
+          focusedDir = stripPrefix(focusedDir, "\\");
+
+          return Math.max(
+            processed.items.findIndex((i) => i.name === focusedDir),
+            0
+          );
+        }
+        return 0;
+      };
+
+      return {
+        ...state,
+        offset: 0,
+        index: newIndex(),
+        currDir: processed,
+        selectedNames: new Set(),
+      };
+    }
+    case "FileListDirUpdatedAction": {
+      const processed = processDir(a.currDir, state.sort);
+      const currIndex = state.offset + state.index;
+      const newIndex = (() => {
+        const currItem = FileListState.currentItem(state);
+        if (currItem) {
+          const index = processed.items.findIndex(
+            (i) => i.name === currItem.name
+          );
+          return index < 0
+            ? Math.min(currIndex, a.currDir.items.length)
+            : index;
+        }
+        return 0;
+      })();
+      const [offset, index] =
+        newIndex === currIndex ? [state.offset, state.index] : [0, newIndex];
+
+      const newSelected = () => {
+        const names = new Set();
+        processed.items.forEach((i) => {
+          if (state.selectedNames.has(i.name)) {
+            names.add(i.name);
+          }
+        });
+        return names;
+      };
+
+      return {
+        ...state,
+        offset,
+        index,
+        currDir: processed,
+        selectedNames:
+          state.selectedNames.size > 0 ? newSelected() : state.selectedNames,
+      };
+    }
+    case "FileListItemCreatedAction": {
+      const processed = processDir(a.currDir, state.sort);
+      const newIndex = processed.items.findIndex((i) => i.name === a.name);
+      const [offset, index] =
+        newIndex < 0 ? [state.offset, state.index] : [0, newIndex];
+
+      return {
+        ...state,
+        offset,
+        index,
+        currDir: processed,
+      };
+    }
+    case "FileListSortAction": {
+      const nextSort = FileListSort.nextSort(state.sort, a.mode);
+      const processed = processDir(state.currDir, nextSort);
+      const currItem = FileListState.currentItem(state);
+      const newIndex = currItem
+        ? processed.items.findIndex((i) => i.name === currItem.name)
+        : -1;
+      const [offset, index] =
+        newIndex < 0 ? [state.offset, state.index] : [0, newIndex];
+
+      return {
+        ...state,
+        offset,
+        index,
+        currDir: processed,
+        sort: nextSort,
+      };
+    }
+    case "FileListDiskSpaceUpdatedAction":
+      return {
+        ...state,
+        diskSpace: a.diskSpace,
+      };
+
+    default:
+      return state;
+  }
+}
+
+/**
+ * @param {string} s
+ * @param {string} prefix
+ * @returns {string}
+ */
+function stripPrefix(s, prefix) {
+  return s.startsWith(prefix) ? s.substring(prefix.length) : s;
+}
+
+/**
+ * @param {FileListDir} currDir
+ * @param {FileListSort} sort
+ * @returns {FileListDir}
+ */
+function processDir(currDir, sort) {
+  /**
+   * @returns {FileListItem[]}
+   */
+  function sortCurrItems() {
+    const dirs = currDir.items.filter(
+      (i) => i.name !== FileListItem.up.name && i.isDir
+    );
+    const files = currDir.items.filter(
+      (i) => i.name !== FileListItem.up.name && !i.isDir
+    );
+    const sortedDirs = sortItems(dirs, sort);
+    const sortedFiles = sortItems(files, sort);
+
+    return currDir.isRoot
+      ? [...sortedDirs, ...sortedFiles]
+      : [FileListItem.up, ...sortedDirs, ...sortedFiles];
+  }
+
+  return { ...currDir, items: sortCurrItems() };
+}
+
+/**
+ * @param {FileListItem[]} items
+ * @param {FileListSort} sort
+ * @returns {FileListItem[]}
+ */
+function sortItems(items, sort) {
+  const sorted = FileListSort.sortItems(items, sort.mode);
+  return sort.asc ? sorted : sorted.reverse();
+}
+
+export default FileListStateReducer;