export type RybbitEvent = {
  type?: string;
  timestamp?: string;
  pathname?: string;
  path?: string;
  url?: string;
  event_name?: string;
  name?: string;
  properties?: Record<string, unknown>;
};

export type AuditRybbitSummary = {
  opened: boolean;
  viewCount: number;
  lastView: string | null;
  ctaClicks: number;
  websiteLinkClicks: number;
  deviceTypes: string[];
};

type FetchLike = (
  input: string | URL,
  init?: RequestInit,
) => Promise<Pick<Response, "ok" | "status" | "json" | "text">>;

export function buildRybbitEventsUrl(input: {
  apiUrl: string;
  siteId: string;
  startDate?: string;
  endDate?: string;
}) {
  const base = input.apiUrl.endsWith("/") ? input.apiUrl : `${input.apiUrl}/`;
  const url = new URL(`api/sites/${encodeURIComponent(input.siteId)}/events`, base);

  if (input.startDate) {
    url.searchParams.set("start_date", input.startDate);
  }
  if (input.endDate) {
    url.searchParams.set("end_date", input.endDate);
  }

  return url;
}

function eventPath(event: RybbitEvent) {
  const propertyPath =
    typeof event.properties?.pathname === "string"
      ? event.properties.pathname
      : typeof event.properties?.path === "string"
        ? event.properties.path
        : undefined;

  return event.pathname ?? event.path ?? propertyPath ?? event.url ?? "";
}

function eventName(event: RybbitEvent) {
  const propertyName =
    typeof event.properties?.event_name === "string"
      ? event.properties.event_name
      : typeof event.properties?.name === "string"
        ? event.properties.name
        : undefined;

  return event.event_name ?? event.name ?? propertyName ?? "";
}

function eventDevice(event: RybbitEvent) {
  const value =
    event.properties?.deviceType ??
    event.properties?.device_type ??
    event.properties?.device;

  return typeof value === "string" && value.trim().length > 0
    ? value.trim()
    : null;
}

function isAuditEvent(event: RybbitEvent, auditPath: string) {
  const path = eventPath(event);
  return path === auditPath || path.endsWith(auditPath);
}

export function summarizeAuditRybbitEvents(
  events: RybbitEvent[],
  auditPath: string,
): AuditRybbitSummary {
  const matchingEvents = events.filter((event) => isAuditEvent(event, auditPath));
  const pageviews = matchingEvents.filter((event) => event.type === "pageview");
  const ctaClicks = matchingEvents.filter((event) => {
    const name = eventName(event);
    return event.type === "custom_event" && name === "audit_cta_click";
  });
  const websiteLinkClicks = matchingEvents.filter((event) => {
    const name = eventName(event);
    return event.type === "outbound_link" || name === "audit_website_link_click";
  });
  const lastView = pageviews
    .map((event) => event.timestamp)
    .filter((timestamp): timestamp is string => Boolean(timestamp))
    .sort()
    .at(-1) ?? null;
  const deviceTypes = [
    ...new Set(
      matchingEvents
        .map(eventDevice)
        .filter((device): device is string => device !== null),
    ),
  ].sort();

  return {
    opened: pageviews.length > 0,
    viewCount: pageviews.length,
    lastView,
    ctaClicks: ctaClicks.length,
    websiteLinkClicks: websiteLinkClicks.length,
    deviceTypes,
  };
}

function normalizeEventsPayload(payload: unknown): RybbitEvent[] {
  if (Array.isArray(payload)) {
    return payload.filter((event): event is RybbitEvent => typeof event === "object" && event !== null);
  }

  if (
    typeof payload === "object" &&
    payload !== null &&
    "data" in payload &&
    Array.isArray((payload as { data?: unknown }).data)
  ) {
    return (payload as { data: unknown[] }).data.filter(
      (event): event is RybbitEvent => typeof event === "object" && event !== null,
    );
  }

  return [];
}

export async function fetchRybbitAuditAnalytics(input: {
  apiUrl?: string;
  apiKey?: string;
  siteId?: string;
  auditPath: string;
  startDate?: string;
  endDate?: string;
  fetchImpl?: FetchLike;
}) {
  if (!input.apiUrl || !input.apiKey || !input.siteId) {
    return {
      ok: false as const,
      error: "Rybbit ist nicht vollständig konfiguriert.",
      data: summarizeAuditRybbitEvents([], input.auditPath),
    };
  }

  try {
    const response = await (input.fetchImpl ?? fetch)(
      buildRybbitEventsUrl({
        apiUrl: input.apiUrl,
        siteId: input.siteId,
        startDate: input.startDate,
        endDate: input.endDate,
      }),
      {
        headers: {
          Authorization: `Bearer ${input.apiKey}`,
        },
      },
    );

    if (!response.ok) {
      const body = await response.text();
      return {
        ok: false as const,
        error: `Rybbit API Fehler ${response.status}: ${body.slice(0, 160)}`,
        data: summarizeAuditRybbitEvents([], input.auditPath),
      };
    }

    const payload = await response.json();
    return {
      ok: true as const,
      data: summarizeAuditRybbitEvents(
        normalizeEventsPayload(payload),
        input.auditPath,
      ),
    };
  } catch (error) {
    return {
      ok: false as const,
      error: error instanceof Error ? error.message : String(error),
      data: summarizeAuditRybbitEvents([], input.auditPath),
    };
  }
}