useMetaState hook implemented

src/routes/Detail/useMetaState.js

@@ -0,0 +1,80 @@
+const React = require('react');
+
+const metaStateReducer = (state, action) => {
+    switch (action.type) {
+        case 'groups-changed': {
+            if (state.selectedGroup !== null) {
+                const selectedGroupIncluded = action.groups.some((group) => {
+                    return group.req.base === state.selectedGroup.req.base &&
+                        group.content.type === 'Ready';
+                });
+                if (selectedGroupIncluded) {
+                    return {
+                        ...state,
+                        resourceRef: action.resourceRef,
+                        groups: action.groups
+                    };
+                }
+            }
+
+            const readyGroup = action.groups.find((group) => group.content.type === 'Ready');
+            const selectedGroup = readyGroup ? readyGroup : null;
+            return {
+                ...state,
+                resourceRef: action.resourceRef,
+                groups: action.groups,
+                selectedGroup
+            };
+        }
+        case 'group-selected': {
+            const selectedGroup = state.groups.find((group) => {
+                return group.req.base === action.base &&
+                    group.content.type === 'Ready';
+            });
+            if (selectedGroup) {
+                return {
+                    ...state,
+                    selectedGroup
+                };
+            }
+
+            return state;
+        }
+        default: {
+            return state;
+        }
+    }
+};
+
+const metaStateInitializer = ([metaResourceRef, metaGroups]) => {
+    const initialState = {
+        resourceRef: null,
+        groups: [],
+        selectedGroup: null
+    };
+    const initAction = {
+        type: 'groups-changed',
+        resourceRef: metaResourceRef,
+        groups: metaGroups
+    };
+
+    return metaStateReducer(initialState, initAction);
+};
+
+const useMetaState = (metaResourceRef, metaGroups) => {
+    const [{ resourceRef, groups, selectedGroup }, metaStateDispatch] = React.useReducer(
+        metaStateReducer,
+        [metaResourceRef, metaGroups],
+        metaStateInitializer
+    );
+    React.useEffect(() => {
+        metaStateDispatch({
+            type: 'groups-changed',
+            resourceRef: metaResourceRef,
+            groups: metaGroups
+        });
+    }, [metaGroups]);
+    return [resourceRef, groups, selectedGroup];
+};
+
+module.exports = useMetaState;