import type { ReactNode } from "react";

// The column contract every table-shaped view shares — `DataTable`, the playlist manager's hybrid
// table, the channel card grid — plus the filter predicate that reads it.
//
// It lives in `lib/`, not beside the header component in `components/ui/tableHeader`, because `lib/`
// helpers need it too (`sortOptions`, `useFilterState`, `channelsUrlState`) and the dependency
// direction is one-way: `lib/` may not import from `components/` (lint-enforced, see
// eslint.config.js). The contract is data + closures; nothing in it renders.

type ColumnFilter<T> =
  | { kind: "text"; get: (row: T) => string }
  | {
      kind: "select";
      options: { value: string; label: string }[];
      test: (row: T, value: string) => boolean;
    }
  | {
      kind: "multi";
      options: { value: string; label: string }[];
      test: (row: T, values: string[]) => boolean;
    };

export interface Column<T> {
  key: string;
  header: string;
  render: (row: T) => ReactNode;
  align?: "left" | "right" | "center";
  width?: string;
  sortable?: boolean;
  sortValue?: (row: T) => string | number;
  filter?: ColumnFilter<T>;
  // Keep the cell on one line so the column auto-sizes to its content (table-layout: auto).
  nowrap?: boolean;
  // Card fallback (below md): `cardPrimary` renders as the card heading (no label); `hideInCard`
  // omits the column; `cardLabel:false` shows the value without its header label.
  cardPrimary?: boolean;
  hideInCard?: boolean;
  cardLabel?: boolean;
}

export type FilterMap = Record<string, string | string[]>;

export function isActive(value: string | string[] | undefined): boolean {
  return Array.isArray(value) ? value.length > 0 : !!value;
}

/** Apply every column's own filter predicate. A column with no filter, or an empty value, passes. */
export function filterRows<T>(rows: T[], columns: Column<T>[], filters: FilterMap): T[] {
  return rows.filter((row) =>
    columns.every((col) => {
      const f = col.filter;
      if (!f) return true;
      const val = filters[col.key];
      if (!isActive(val)) return true;
      if (f.kind === "text") return f.get(row).toLowerCase().includes(String(val).toLowerCase());
      if (f.kind === "select") return f.test(row, String(val));
      return f.test(row, val as string[]);
    }),
  );
}