import type { GridRowId } from '../types'
import type { ApiSection } from './types'

export type GridScrollApi = {
    /**
     * Scroll grid to row and column.
     *
     * @param rowId : id of row to scroll to. Passing null will not scroll the grid vertically.
     * @param columnId : id of column to scroll to. Passing null or omitting will not scroll the grid horizontally. Defaults to first column if the provided column id is not valid.
     * @param mode : scroll-mode. 'always' means it will always scroll. 'auto' will only scroll if not in viewport.
     */
    scrollTo: (
        rowId: GridRowId | null,
        columnId?: string | null,
        mode?: 'always' | 'auto'
    ) => void
    /**
     * Scroll to first row in grid.
     * @param columnId : id of column to scroll to. Passing null or omitting will not scroll the grid horizontally. Defaults to first column if the provided column id is not valid.
     */
    scrollToTop: (columnId?: string | null) => void
    /**
     * Scroll to last row in grid.
     * @param columnId : id of column to scroll to. Passing null or omitting will not scroll the grid horizontally. Defaults to first column if the provided column id is not valid.
     */
    scrollToBottom: (columnId?: string | null) => void
}

export const createScrollApi: ApiSection<GridScrollApi> = (store, events) => {
    const api: GridScrollApi = {
        scrollTo(rowId, columnId, mode = 'always') {
            const state = store.getState()

            const targetRowIndex =
                rowId === null
                    ? null
                    : store.selectors.selectRowIds(state).indexOf(rowId)
            let targetColumnIndex: number | null = null
            let targetColumnId = columnId
            if (columnId != null) {
                const columnIds = store.selectors.selectColumnIds(state)
                targetColumnId =
                    columnId && columnIds.includes(columnId)
                        ? columnId
                        : columnIds[0]
                targetColumnIndex = columnIds.indexOf(targetColumnId)
            }

            if (
                (targetColumnIndex !== null && targetColumnIndex >= 0) ||
                (targetRowIndex !== null && targetRowIndex >= 0)
            ) {
                events.emit(
                    'scrollToIndex',
                    targetRowIndex,
                    targetColumnIndex,
                    mode
                )
            }
        },
        scrollToBottom(columnId) {
            const rowIds = store.selectors.selectRowIds(store.getState())
            const rowId = rowIds[rowIds.length - 1]
            api.scrollTo(rowId, columnId)
        },
        scrollToTop(columnId) {
            const rowId = store.selectors.selectRowIds(store.getState())[0]
            api.scrollTo(rowId, columnId)
        },
    }
    return api
}