import { expr2xy } from '@wolf-table/table-renderer';
import { col, row, TableData } from '.';

function scrollTo(
  data: TableData,
  direction: '+' | '-',
  value: number,
  type: 'row' | 'col',
  getValue: (index: number) => number
): boolean {
  const { scroll } = data;
  const scrollIndex = type === 'row' ? 0 : 1;
  const valueIndex = type === 'row' ? 3 : 2;
  let newValue = scroll[valueIndex];
  let changed = false;
  let start = scroll[scrollIndex];
  let freezeOffset = 0;
  const { freeze } = data;
  if (freeze) {
    freezeOffset = expr2xy(freeze)[type === 'row' ? 1 : 0];
  }
  if (value > 0) {
    if (direction === '+') {
      for (let i = start; ; i += 1) {
        if (newValue >= value) break;
        const v = getValue(freezeOffset + i);
        newValue += v;
        data.scroll[scrollIndex] = i + 1;
        changed = true;
      }
    } else {
      for (let i = start; ; i -= 1) {
        if (newValue <= value) break;
        const v = getValue(freezeOffset + i - 1);
        newValue -= v;
        data.scroll[scrollIndex] = i - 1;
        changed = true;
        if (v > 0) break;
      }
    }
  } else {
    data.scroll[scrollIndex] = 0;
    newValue = 0;
    changed = true;
  }
  scroll[valueIndex] = newValue;
  return changed;
}

export function scrollx(data: TableData): number;
export function scrollx(
  data: TableData,
  direction: '+' | '-',
  n: number
): boolean;
export function scrollx(
  data: TableData,
  direction?: '+' | '-',
  n?: number
): any {
  if (direction && n !== undefined) {
    return scrollTo(data, direction, n, 'col', (i) => col(data, i).width);
  }
  return data.scroll[2];
}

export function scrolly(data: TableData): number;
export function scrolly(
  data: TableData,
  direction: '+' | '-',
  n: number
): boolean;
export function scrolly(data: TableData, direction?: '+' | '-', n?: number) {
  if (direction && n !== undefined) {
    return scrollTo(data, direction, n, 'row', (i) => row(data, i).height);
  }
  return data.scroll[3];
}

export function scrollResetRows(data: TableData) {
  data.scroll[0] = 0;
  data.scroll[3] = 0;
}

export function scrollResetCols(data: TableData) {
  data.scroll[1] = 0;
  data.scroll[2] = 0;
}