1 files changed, 96 insertions, 0 deletions
diff --git a/src/console/completion/reducer.ts b/src/console/completion/reducer.ts
new file mode 100644
index 0000000..905451f
--- /dev/null
+++ b/src/console/completion/reducer.ts
@@ -0,0 +1,96 @@
+import Completions from "../Completions";
+import CompletionType from "../../shared/CompletionType";
+import {
+  INIT_COMPLETIONS,
+  SET_COMPLETION_SOURCE,
+  SET_COMPLETIONS,
+  COMPLETION_NEXT,
+  COMPLETION_PREV,
+  CompletionAction,
+} from "./actions";
+
+export interface State {
+  completionTypes?: CompletionType[];
+  completionSource: string;
+  completions: Completions;
+  select: number;
+}
+
+export const defaultState = {
+  completionTypes: undefined,
+  completionSource: "",
+  completions: [],
+  select: -1,
+};
+
+const nextSelection = (state: State): number => {
+  const length = state.completions
+    .map((g) => g.items.length)
+    .reduce((x, y) => x + y, 0);
+  if (length === 0) {
+    return -1;
+  }
+  if (state.select < 0) {
+    return 0;
+  }
+  if (state.select + 1 < length) {
+    return state.select + 1;
+  }
+  return -1;
+};
+
+const prevSelection = (state: State): number => {
+  if (state.completions.length === 0) {
+    return -1;
+  }
+  const length = state.completions
+    .map((g) => g.items.length)
+    .reduce((x, y) => x + y);
+  if (state.select < 0) {
+    return length - 1;
+  }
+  return state.select - 1;
+};
+
+// eslint-disable-next-line max-lines-per-function
+export default function reducer(
+  state: State = defaultState,
+  action: CompletionAction
+): State {
+  switch (action.type) {
+    case INIT_COMPLETIONS:
+      return {
+        ...state,
+        completionTypes: action.completionTypes,
+        completions: [],
+        select: -1,
+      };
+    case SET_COMPLETION_SOURCE:
+      return {
+        ...state,
+        completionSource: action.completionSource,
+        select: -1,
+      };
+    case SET_COMPLETIONS:
+      return {
+        ...state,
+        completions: action.completions,
+      };
+    case COMPLETION_NEXT: {
+      const select = nextSelection(state);
+      return {
+        ...state,
+        select: select,
+      };
+    }
+    case COMPLETION_PREV: {
+      const select = prevSelection(state);
+      return {
+        ...state,
+        select: select,
+      };
+    }
+    default:
+      return state;
+  }
+}