/*
 * URL shape adapted from OnCo viewParams: `q` for search, repeated facet keys,
 * and `sort` with a leading "-" for descending.
 * https://github.com/judegomila/OnCo @ b594d7433bf4e408b44215e25e5304696d6f840e
 * Copyright (c) 2026 OnCo. MIT License. See ui/NOTICE.
 *
 * The compact `v` parameter, table scopes, and domain value normalisers are not included.
 */

import { cellSortValue, type BrowserRow } from "./browser-row";
import { sortRows } from "./sort-rows";
import type { SortState } from "./types";

export type TableView = {
  q: string;
  facets: Record<string, string[]>;
  sort?: SortState;
};

export type ViewHistory = {
  read: () => string;
  push: (search: string) => void;
  subscribe: (listener: () => void) => () => void;
};

export function browserViewHistory(): ViewHistory {
  return {
    read: () => (typeof window === "undefined" ? "" : window.location.search),
    push: (search) => {
      const path = window.location.pathname;
      window.history.pushState(null, "", search ? `${path}?${search}` : path);
    },
    subscribe: (listener) => {
      window.addEventListener("popstate", listener);
      return () => window.removeEventListener("popstate", listener);
    },
  };
}

export function facetKeysOf(rows: readonly BrowserRow[]): string[] {
  const keys = new Set<string>();
  for (const row of rows) {
    for (const key of Object.keys(row.facets)) keys.add(key);
  }
  return [...keys].sort();
}

export function facetValues(rows: readonly BrowserRow[], key: string): string[] {
  const values = new Set<string>();
  for (const row of rows) {
    for (const value of row.facets[key] ?? []) values.add(value);
  }
  return [...values].sort((a, b) => a.localeCompare(b));
}

function splitValues(params: URLSearchParams, key: string): string[] {
  const values: string[] = [];
  for (const raw of params.getAll(key)) {
    for (const part of raw.split(",")) {
      const trimmed = part.trim();
      if (trimmed && !values.includes(trimmed)) values.push(trimmed);
    }
  }
  return values;
}

export function parseTableView(
  search: string,
  facetKeys: readonly string[],
  sortable: (key: string) => boolean,
): TableView {
  const params = new URLSearchParams(search.startsWith("?") ? search.slice(1) : search);
  const facets: Record<string, string[]> = {};
  for (const key of facetKeys) {
    const values = splitValues(params, key);
    if (values.length > 0) facets[key] = values;
  }
  const rawSort = params.get("sort");
  let sort: SortState | undefined;
  if (rawSort) {
    const key = rawSort.replace(/^-/, "");
    if (sortable(key)) sort = { key, dir: rawSort.startsWith("-") ? -1 : 1 };
  }
  return { q: params.get("q") ?? "", facets, sort };
}

export function serializeTableView(view: TableView, baseSort: SortState): string {
  const params = new URLSearchParams();
  for (const key of Object.keys(view.facets).sort()) {
    for (const value of view.facets[key] ?? []) params.append(key, value);
  }
  const q = view.q.trim();
  if (q) params.set("q", q);
  if (view.sort && (view.sort.key !== baseSort.key || view.sort.dir !== baseSort.dir)) {
    params.set("sort", `${view.sort.dir === -1 ? "-" : ""}${view.sort.key}`);
  }
  return params.toString();
}

export function applyTableView(rows: readonly BrowserRow[], view: TableView): BrowserRow[] {
  const q = view.q.trim().toLowerCase();
  const filtered = rows.filter((row) => {
    for (const [key, selected] of Object.entries(view.facets)) {
      if (selected.length === 0) continue;
      const have = new Set(row.facets[key] ?? []);
      if (!selected.some((value) => have.has(value))) return false;
    }
    if (!q) return true;
    const haystack = [row.name, row.tldr, ...Object.values(row.facets).flat()].join("\n").toLowerCase();
    return haystack.includes(q);
  });
  return sortRows(filtered, view.sort, cellSortValue);
}