/**
 * Request-log filters shared by the Requests page, its pagination links and the CSV export route.
 * Pure helpers: no database or framework imports so they can be used anywhere.
 */

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

export const REQUEST_RANGES = ["24h", "7d", "30d", "custom"] as const;
export type RequestRange = (typeof REQUEST_RANGES)[number];

export const REQUEST_STATUSES = ["success", "failed", "pending"] as const;
export type RequestStatus = (typeof REQUEST_STATUSES)[number];

export const REQUEST_SOURCES = ["api", "playground", "sdk"] as const;
export type RequestSource = (typeof REQUEST_SOURCES)[number];

export const REQUEST_NETWORKS = ["datacenter", "residential", "isp", "mobile"] as const;

export const REQUESTS_PAGE_SIZE = 50;
export const REQUESTS_EXPORT_MAX = 10_000;

export interface RequestFilters {
  range: RequestRange;
  /** ISO date (YYYY-MM-DD), only used when range = custom. */
  from?: string;
  to?: string;
  status?: RequestStatus;
  domain?: string;
  network?: (typeof REQUEST_NETWORKS)[number];
  country?: string;
  httpStatus?: number;
  requestId?: string;
  source?: RequestSource;
  page: number;
}

function first(v: string | string[] | undefined): string | undefined {
  const s = Array.isArray(v) ? v[0] : v;
  const t = s?.trim();
  return t ? t : undefined;
}

function oneOf<T extends readonly string[]>(v: string | undefined, allowed: T): T[number] | undefined {
  return v && (allowed as readonly string[]).includes(v) ? (v as T[number]) : undefined;
}

const ISO_DATE = /^\d{4}-\d{2}-\d{2}$/;

export function parseRequestFilters(sp: SearchParams): RequestFilters {
  const from = first(sp.from);
  const to = first(sp.to);
  const hasCustomDates = Boolean((from && ISO_DATE.test(from)) || (to && ISO_DATE.test(to)));
  const rangeRaw = oneOf(first(sp.range), REQUEST_RANGES);
  const range: RequestRange = hasCustomDates && (!rangeRaw || rangeRaw === "custom") ? "custom" : rangeRaw && rangeRaw !== "custom" ? rangeRaw : hasCustomDates ? "custom" : "7d";
  const httpRaw = first(sp.http);
  const httpStatus = httpRaw && /^\d{3}$/.test(httpRaw) ? Number(httpRaw) : undefined;
  const pageRaw = Number(first(sp.page) ?? "1");
  const country = first(sp.country)?.toUpperCase();
  return {
    range,
    from: range === "custom" && from && ISO_DATE.test(from) ? from : undefined,
    to: range === "custom" && to && ISO_DATE.test(to) ? to : undefined,
    status: oneOf(first(sp.status), REQUEST_STATUSES),
    domain: first(sp.domain)?.toLowerCase().slice(0, 253),
    network: oneOf(first(sp.network), REQUEST_NETWORKS),
    country: country && /^[A-Z]{2}$/.test(country) ? country : undefined,
    httpStatus,
    requestId: first(sp.id)?.slice(0, 64),
    source: oneOf(first(sp.source), REQUEST_SOURCES),
    page: Number.isFinite(pageRaw) && pageRaw >= 1 ? Math.floor(pageRaw) : 1,
  };
}

/** Absolute time window for a filter set. `to` is exclusive; null means "now". */
export function filterWindow(f: RequestFilters, now = new Date()): { from: Date; to: Date | null } {
  if (f.range === "custom") {
    const from = f.from ? new Date(`${f.from}T00:00:00.000Z`) : new Date(now.getTime() - 30 * 86_400_000);
    const to = f.to ? new Date(new Date(`${f.to}T00:00:00.000Z`).getTime() + 86_400_000) : null;
    return { from, to };
  }
  const hours = f.range === "24h" ? 24 : f.range === "7d" ? 24 * 7 : 24 * 30;
  return { from: new Date(now.getTime() - hours * 3_600_000), to: null };
}

/** Serialize filters back to a query string. `overrides` lets callers change a page or drop a key (pass undefined). */
export function filtersToSearchParams(f: RequestFilters, overrides: Partial<Record<keyof RequestFilters, string | number | undefined>> = {}): URLSearchParams {
  const merged: Record<string, string | number | undefined> = {
    range: f.range,
    from: f.from,
    to: f.to,
    status: f.status,
    domain: f.domain,
    network: f.network,
    country: f.country,
    http: f.httpStatus,
    id: f.requestId,
    source: f.source,
    page: f.page > 1 ? f.page : undefined,
  };
  for (const [k, v] of Object.entries(overrides)) {
    const key = k === "httpStatus" ? "http" : k === "requestId" ? "id" : k;
    merged[key] = v;
  }
  if (merged.range === "7d" && !merged.from && !merged.to) delete merged.range;
  if (merged.range !== "custom") {
    delete merged.from;
    delete merged.to;
  }
  const sp = new URLSearchParams();
  for (const [k, v] of Object.entries(merged)) if (v !== undefined && v !== "" && v !== null) sp.set(k, String(v));
  return sp;
}

export function requestsHref(f: RequestFilters, overrides?: Partial<Record<keyof RequestFilters, string | number | undefined>>): string {
  const qs = filtersToSearchParams(f, overrides).toString();
  return `/dashboard/requests${qs ? `?${qs}` : ""}`;
}

export interface FilterChip {
  key: keyof RequestFilters;
  label: string;
  value: string;
}

export function activeFilterChips(f: RequestFilters): FilterChip[] {
  const chips: FilterChip[] = [];
  if (f.range === "custom") chips.push({ key: "range", label: "Dates", value: `${f.from ?? "…"} → ${f.to ?? "now"}` });
  else if (f.range !== "7d") chips.push({ key: "range", label: "Range", value: f.range === "24h" ? "Last 24 hours" : "Last 30 days" });
  if (f.status) chips.push({ key: "status", label: "Status", value: f.status });
  if (f.domain) chips.push({ key: "domain", label: "Domain", value: f.domain });
  if (f.network) chips.push({ key: "network", label: "Network", value: f.network });
  if (f.country) chips.push({ key: "country", label: "Country", value: f.country });
  if (f.httpStatus) chips.push({ key: "httpStatus", label: "HTTP", value: String(f.httpStatus) });
  if (f.requestId) chips.push({ key: "requestId", label: "Request", value: f.requestId });
  if (f.source) chips.push({ key: "source", label: "Source", value: f.source });
  return chips;
}

/** Remove one chip: custom ranges drop both dates and fall back to the default window. */
export function hrefWithoutChip(f: RequestFilters, key: keyof RequestFilters): string {
  if (key === "range") return requestsHref({ ...f, range: "7d", from: undefined, to: undefined, page: 1 });
  return requestsHref({ ...f, [key]: undefined, page: 1 });
}