import { produce } from 'immer'
import type {
    ApplyPropsAction,
    SetSelectionAnchor,
    UpdateSelectionAction,
} from '../actions'
import type { GridRowId } from '../../types'

import { createReducer } from '../utils/createReducer'

export type GridSelectionState = {
    controlled: boolean
    mode: 'single' | 'multi' | 'none'
    selection: Set<GridRowId>
    anchor: GridRowId | null
}

const initialState: GridSelectionState = {
    controlled: false,
    mode: 'single',
    selection: new Set(),
    anchor: null,
}

export default createReducer<GridSelectionState>({
    initialState,
    reducers: {
        applyProps(state, action: ApplyPropsAction) {
            return produce(state, (draft) => {
                draft.controlled = !!action.payload.selection
                if (action.payload.selection !== undefined) {
                    draft.selection = action.payload.selection
                }
                if (action.payload.selectionMode !== undefined) {
                    draft.mode = action.payload.selectionMode
                    if (!draft.controlled) {
                        if (draft.mode === 'none') {
                            draft.selection = new Set()
                        } else if (
                            draft.mode === 'single' &&
                            draft.selection.size > 1
                        ) {
                            /* Reduce selection to last one chosen */
                            draft.selection = new Set(
                                [...draft.selection].slice(-1)
                            )
                        }
                    }
                }
            })
        },
        updateSelection(state, action: UpdateSelectionAction) {
            return {
                ...state,
                selection: action.payload,
            }
        },
        setSelectionAnchor(state, action: SetSelectionAnchor) {
            return {
                ...state,
                anchor: action.payload,
            }
        },
    },
})

export const selectSelection = (state: GridSelectionState) => state.selection

export const selectSelectionMode = (state: GridSelectionState) => state.mode

export const selectSelectionAnchor = (
    state: GridSelectionState
): GridRowId | null => state.anchor