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;
  // …and `cardRow` gives the value a line of its own: a row's lone "…" flowed in after the facts,
  // at the end of one card's line and on the next line of another — never in the same place twice.
  cardRow?: boolean;
  // A column a table WITHOUT the card fallback (the playlist's drag-reorderable hybrid) leaves out
  // while the TABLE is narrower than 42rem: its fixed widths alone overran the box and left the title
  // no width. The table's own width, not the viewport's (an `@container` round it): beside the
  // playlist rail a desktop window gave the table 432 px, and the title column was 0 px wide.
  narrowHidden?: boolean;
  // …and one a table leaves out while it is narrower than 64rem — a 1024 tablet window, or a desktop
  // one beside a panel: a secondary column that gives its room back to the name (the owner,
  // 2026-09-27: at 1024 the channel name had 60 px while About took as much). Same `@container` rule.
  tabletHidden?: boolean;
}

// The classes that hide a column below its width (`narrowHidden` / `tabletHidden`), for its cells and,
// in a fixed layout, for its <col> too: a hidden cell under a <col> that keeps its width would leave an
// empty stripe. The table's OWN width decides, so the caller wraps the table in an `@container`.
// `cue` is the inverse: shown ONLY while the column is hidden — the hidden-filter cue names a
// filter whose funnel went off screen, and by the same container query, so it cannot disagree with
// the table about which columns are gone (not at any text size: both are rem).
// Whole literals, because Tailwind only generates a class it can read in one piece.
const HIDE_BELOW = {
  narrow: {
    cell: " hidden @2xl:table-cell",
    col: " hidden @2xl:table-column",
    cue: " @2xl:hidden",
  },
  tablet: {
    cell: " hidden @5xl:table-cell",
    col: " hidden @5xl:table-column",
    cue: " @5xl:hidden",
  },
} as const;

export function columnHideClass(
  col: { narrowHidden?: boolean; tabletHidden?: boolean },
  part: "cell" | "col" | "cue" = "cell",
): string {
  if (col.narrowHidden) return HIDE_BELOW.narrow[part];
  if (col.tabletHidden) return HIDE_BELOW.tablet[part];
  return "";
}

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[]);
    }),
  );
}

/** What a set filter says, in the words its funnel uses: an option's label, not its value. */
export function filterValueLabel<T>(col: Column<T>, value: string | string[]): string {
  const f = col.filter;
  if (!f || f.kind === "text") return String(value);
  const label = (v: string) => f.options.find((o) => o.value === v)?.label ?? v;
  return Array.isArray(value) ? value.map(label).join(", ") : label(value);
}