import { omit } from 'lodash'

import {
    PanelState,
    PanelAction,
    PanelInitAction,
    PanelDestroyAction,
    PanelResizeStartAction,
    PanelResizeAction,
    PanelResizeStopAction,
} from './interfaces'

import {
    PANEL_INIT,
    PANEL_DESTROY,
    PANEL_RESIZE_START,
    PANEL_RESIZE,
    PANEL_RESIZE_STOP,
} from './actions'

interface PanelsState {
    [key: string]: PanelState
}

const initialState: PanelsState = {}

export const panelReducer
    = (state: PanelsState = initialState, action: PanelAction): PanelsState => {
        switch (action.type) {
            case PANEL_INIT: {
                return panelInit(state, action)
            }
            case PANEL_DESTROY: {
                return panelDestroy(state, action)
            }
            case PANEL_RESIZE_START: {
                return panelResizeStart(state, action)
            }
            case PANEL_RESIZE: {
                return panelResize(state, action)
            }
            case PANEL_RESIZE_STOP: {
                return panelResizeStop(state, action)
            }
        }
        return state
    }

const panelUpdate
    = (state: PanelsState, id: string, fn: (a: Partial<PanelState>) => Partial<PanelState>):
        PanelsState =>
            ({
                ...state,
                [id]: {
                    ...state[id],
                    ...fn(state[id]),
                },
            })

const panelInit = (state: PanelsState, action: PanelInitAction) =>
    panelUpdate(state, action.id, (panel: PanelState) => panel
        ? panel
        : {
            intervals: action.intervals,
            dragging: false,
            idx: -1,
        })

const panelDestroy = (state: PanelsState, action: PanelDestroyAction): PanelsState =>
    omit(state, action.id) as PanelsState

const panelResizeStart = (state: PanelsState, action: PanelResizeStartAction): PanelsState =>
    panelUpdate(state, action.id, () => ({
        dragging: true,
        idx: action.idx,
    }))

const panelResize = (state: PanelsState, action: PanelResizeAction): PanelsState =>
    panelUpdate(state, action.id, () => ({
        intervals: action.intervals,
    }))

const panelResizeStop = (state: PanelsState, action: PanelResizeStopAction): PanelsState =>
    panelUpdate(state, action.id, () => ({
        dragging: false,
    }))