import { WidgetError } from "./errors.js";
import type {
  StructuredUiRequest,
  SubmitPlaybookFieldsResponse,
} from "./playbook-contracts.js";

const UUID_PATTERN =
  /^[0-9a-f]{8}-[0-9a-f]{4}-[1-8][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/iu;

/** Validates a Playbook UI instruction before it reaches the Shadow DOM. */
export function parseStructuredUiRequest(value: unknown): StructuredUiRequest {
  if (
    !isRecord(value) ||
    !isUuid(value.runId) ||
    typeof value.title !== "string"
  ) {
    throw new WidgetError("invalid_response");
  }
  switch (value.kind) {
    case "stay_context":
      return parseStayContextRequest(value);
    case "contact_details":
      return parseContactDetailsRequest(value);
    case "handoff_choice":
      return parseHandoffChoiceRequest(value);
    case "handoff_result":
      return parseHandoffResultRequest(value);
    default:
      throw new WidgetError("invalid_response");
  }
}

export function parseSubmitPlaybookFieldsResponse(
  value: unknown,
): SubmitPlaybookFieldsResponse {
  if (!isRecord(value)) throw new WidgetError("invalid_response");
  return {
    nextUiRequest:
      value.nextUiRequest === null
        ? null
        : parseStructuredUiRequest(value.nextUiRequest),
  };
}

function parseStayContextRequest(
  value: Record<string, unknown>,
): Extract<StructuredUiRequest, { kind: "stay_context" }> {
  if (typeof value.submitLabel !== "string" || !isRecord(value.initialValues)) {
    throw new WidgetError("invalid_response");
  }
  const initialValues = value.initialValues;
  return {
    kind: "stay_context",
    runId: value.runId as string,
    title: value.title as string,
    submitLabel: value.submitLabel,
    initialValues: {
      ...optionalString(initialValues, "checkIn"),
      ...optionalString(initialValues, "checkOut"),
      ...optionalNumber(initialValues, "adults"),
      ...optionalNumber(initialValues, "children"),
      ...optionalNumber(initialValues, "rooms"),
      ...optionalString(initialValues, "notes"),
    },
  };
}

function parseContactDetailsRequest(
  value: Record<string, unknown>,
): Extract<StructuredUiRequest, { kind: "contact_details" }> {
  if (typeof value.submitLabel !== "string") {
    throw new WidgetError("invalid_response");
  }
  if (typeof value.consentLabel === "string") {
    return {
      kind: "contact_details",
      runId: value.runId as string,
      title: value.title as string,
      submitLabel: value.submitLabel,
      consentLabel: value.consentLabel,
    };
  }
  if (
    typeof value.firstNameLabel !== "string" ||
    typeof value.lastNameLabel !== "string" ||
    typeof value.emailLabel !== "string" ||
    typeof value.phoneLabel !== "string" ||
    typeof value.privacyAcknowledgementLabel !== "string" ||
    typeof value.privacyNoticeLabel !== "string" ||
    !isHttpUrl(value.privacyNoticeUrl) ||
    typeof value.declineLabel !== "string"
  ) {
    throw new WidgetError("invalid_response");
  }
  return {
    kind: "contact_details",
    runId: value.runId as string,
    title: value.title as string,
    submitLabel: value.submitLabel,
    firstNameLabel: value.firstNameLabel,
    lastNameLabel: value.lastNameLabel,
    emailLabel: value.emailLabel,
    phoneLabel: value.phoneLabel,
    privacyAcknowledgementLabel: value.privacyAcknowledgementLabel,
    privacyNoticeLabel: value.privacyNoticeLabel,
    privacyNoticeUrl: value.privacyNoticeUrl,
    declineLabel: value.declineLabel,
  };
}

function parseHandoffChoiceRequest(
  value: Record<string, unknown>,
): Extract<StructuredUiRequest, { kind: "handoff_choice" }> {
  if (!Array.isArray(value.options) || value.options.length === 0) {
    throw new WidgetError("invalid_response");
  }
  const options = value.options.map((option) => {
    if (
      !isRecord(option) ||
      (option.value !== "booking_engine" && option.value !== "staff") ||
      typeof option.label !== "string"
    ) {
      throw new WidgetError("invalid_response");
    }
    if (option.value === "staff") {
      return { value: "staff" as const, label: option.label };
    }
    return { value: "booking_engine" as const, label: option.label };
  });
  return {
    kind: "handoff_choice",
    runId: value.runId as string,
    title: value.title as string,
    options,
  };
}

function parseHandoffResultRequest(
  value: Record<string, unknown>,
): Extract<StructuredUiRequest, { kind: "handoff_result" }> {
  const isDestinationValid =
    value.destinationUrl === null || isHttpUrl(value.destinationUrl);
  if (
    typeof value.message !== "string" ||
    !isDestinationValid ||
    (value.destinationLabel !== null &&
      typeof value.destinationLabel !== "string")
  ) {
    throw new WidgetError("invalid_response");
  }
  return {
    kind: "handoff_result",
    runId: value.runId as string,
    title: value.title as string,
    message: value.message,
    destinationUrl: value.destinationUrl as string | null,
    destinationLabel: value.destinationLabel,
  };
}

function optionalString(
  value: Record<string, unknown>,
  key: string,
): Record<string, string> {
  const field = value[key];
  if (field === undefined) return {};
  if (typeof field !== "string") throw new WidgetError("invalid_response");
  return { [key]: field };
}

function optionalNumber(
  value: Record<string, unknown>,
  key: string,
): Record<string, number> {
  const field = value[key];
  if (field === undefined) return {};
  if (typeof field !== "number" || !Number.isFinite(field)) {
    throw new WidgetError("invalid_response");
  }
  return { [key]: field };
}

function isHttpUrl(value: unknown): value is string {
  if (typeof value !== "string") return false;
  try {
    return ["http:", "https:"].includes(new URL(value).protocol);
  } catch {
    return false;
  }
}

function isUuid(value: unknown): value is string {
  return typeof value === "string" && UUID_PATTERN.test(value);
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}