import { ActionReducer, StateAction } from "../StateManager.js";
import { UnitMetadata, FieldDescriptor } from "../../metadata/UnitMetadata.js";
import { Action } from "../action/DataUnitAction.js";
import StateManager from "../StateManager.js";


class UnitMetadataReducerImpl implements ActionReducer{
    
    public sliceName: string = "unitMetadata";
        
    public reduce(_stateManager:StateManager, currentState: UnitMetadata, action: StateAction): UnitMetadata {
        if(action.type === Action.METADATA_LOADED){
            return action.payload;
        }
        return currentState;
    }

}

export const UnitMetadataReducer = new UnitMetadataReducerImpl();

export const getMetadata = (stateManager: StateManager): UnitMetadata => {
    return stateManager.select(UnitMetadataReducer.sliceName, (state: UnitMetadata) => state);
};

export const getField = (stateManager: StateManager, fieldName: string): FieldDescriptor|undefined => {
    const md: UnitMetadata = getMetadata(stateManager);
    return md ? md.fields.find(fmd => fmd.name === fieldName) : undefined;
}