import type { TableColumnsType } from 'antd'

type Column<RecordType extends object> = TableColumnsType<RecordType>[number]

type WidthContext<RecordType extends object> = {
  leafPercent: WeakMap<Column<RecordType>, number>
  firstLeaf: Column<RecordType> | undefined
}

/**
 * 把业务列宽（px 数值）按相对权重归一化为百分比。
 * rowSelection / expandable 等内置列由调用方传入需要预留的百分比。
 */
export function normalizePercentColumns<RecordType extends object>(
  columns: TableColumnsType<RecordType>,
  options: { reservedPercent?: number } = {},
): TableColumnsType<RecordType> {
  const leaves: Column<RecordType>[] = []
  collectLeaves(columns, leaves)

  const explicitWeights = leaves
    .map((column) => columnWeight(column))
    .filter((width): width is number => width !== null)
  const fallbackWeight =
    explicitWeights.length > 0
      ? explicitWeights.reduce((sum, width) => sum + width, 0) / explicitWeights.length
      : 100
  const totalWeight = leaves.reduce(
    (sum, column) => sum + (columnWeight(column) ?? fallbackWeight),
    0,
  )
  const budgetPercent = Math.max(60, 100 - Math.max(0, options.reservedPercent ?? 0))

  const leafPercent = new WeakMap<Column<RecordType>, number>()
  for (const column of leaves) {
    const weight = columnWeight(column) ?? fallbackWeight
    leafPercent.set(column, (weight / totalWeight) * budgetPercent)
  }

  return applyPercentWidths(columns, { leafPercent, firstLeaf: leaves[0] })
}

function applyPercentWidths<RecordType extends object>(
  columns: TableColumnsType<RecordType>,
  context: WidthContext<RecordType>,
): TableColumnsType<RecordType> {
  return columns.map((column) => {
    const children = 'children' in column ? column.children : undefined
    if (Array.isArray(children) && children.length > 0) {
      const normalizedChildren = applyPercentWidths(children, context)
      const width = normalizedChildren.reduce((sum, child) => sum + percentOf(child.width), 0)
      return {
        ...withoutMinWidth(column),
        width: `${width.toFixed(4)}%`,
        align: 'center',
        children: normalizedChildren,
      }
    }

    return {
      ...withoutMinWidth(column),
      width: `${(context.leafPercent.get(column) ?? 0).toFixed(4)}%`,
      align: column === context.firstLeaf ? 'left' : 'center',
      ...(column === context.firstLeaf
        ? { className: appendClassName(column.className, 'percent-table-first-column') }
        : {}),
    }
  })
}

function collectLeaves<RecordType extends object>(
  columns: TableColumnsType<RecordType>,
  leaves: Column<RecordType>[],
) {
  for (const column of columns) {
    const children = 'children' in column ? column.children : undefined
    if (Array.isArray(children) && children.length > 0) {
      collectLeaves(children, leaves)
    } else {
      leaves.push(column)
    }
  }
}

function columnWeight<RecordType extends object>(column: Column<RecordType>) {
  return numericWidth(column.width) ?? numericWidth(column.minWidth)
}

function withoutMinWidth<RecordType extends object>(column: Column<RecordType>) {
  const { minWidth: _minWidth, ...rest } = column
  return rest
}

function appendClassName(className: string | undefined, next: string) {
  return [className, next].filter(Boolean).join(' ')
}

function numericWidth(width: unknown) {
  if (typeof width === 'number' && Number.isFinite(width) && width > 0) return width
  if (typeof width === 'string') {
    const parsed = Number.parseFloat(width)
    if (Number.isFinite(parsed) && parsed > 0) return parsed
  }
  return null
}

function percentOf(width: unknown) {
  if (typeof width !== 'string' || !width.endsWith('%')) return 0
  const parsed = Number.parseFloat(width)
  return Number.isFinite(parsed) ? parsed : 0
}