import type {
  CalendlyBookingOffer,
  CalendlyEmbeddedBooking,
  ChatHistoryResponse,
  ChatSseEvent,
  WidgetConfigResponse,
  WidgetTheme,
} from "./public-contracts.js";

import { WidgetError } from "./errors.js";
import { parseStructuredUiRequest } from "./playbook-contract-parser.js";

// The widget validates network input by hand so every distribution can enforce
// the public contract without pulling Zod into the browser bundle.
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}$/i;
const DEFAULT_PRIMARY_COLOR = "#111827";

/** Validates the complete fail-closed configuration boundary. */
export function parseWidgetConfig(value: unknown): WidgetConfigResponse {
  if (
    !isRecord(value) ||
    typeof value.embedEnabled !== "boolean" ||
    typeof value.inlineEnabled !== "boolean" ||
    (value.sessionVersion !== undefined &&
      (!Number.isInteger(value.sessionVersion) ||
        (value.sessionVersion as number) < 1)) ||
    !isWidgetTheme(value.theme) ||
    !isRecord(value.accessibility) ||
    typeof value.accessibility.stt !== "boolean" ||
    typeof value.accessibility.tts !== "boolean"
  ) {
    throw new WidgetError("invalid_response");
  }

  return {
    sessionVersion:
      typeof value.sessionVersion === "number" ? value.sessionVersion : 2,
    embedEnabled: value.embedEnabled,
    inlineEnabled: value.inlineEnabled,
    theme: {
      ...value.theme,
      primaryColor: value.theme.primaryColor ?? DEFAULT_PRIMARY_COLOR,
    },
    accessibility: {
      stt: value.accessibility.stt,
      tts: value.accessibility.tts,
    },
  };
}

/**
 * Validates persisted conversation data before it becomes renderable text or
 * internal source state.
 */
export function parseChatHistory(value: unknown): ChatHistoryResponse {
  if (
    !isRecord(value) ||
    typeof value.sessionId !== "string" ||
    !Array.isArray(value.messages)
  ) {
    throw new WidgetError("invalid_response");
  }

  const messages = value.messages.map((message) => {
    if (
      !isRecord(message) ||
      !isUuid(message.id) ||
      typeof message.role !== "string" ||
      typeof message.content !== "string" ||
      !isNullableUuidArray(message.citedChunkIds) ||
      !isNullableString(message.createdAt)
    ) {
      throw new WidgetError("invalid_response");
    }
    return {
      id: message.id,
      role: message.role,
      content: message.content,
      citedChunkIds: message.citedChunkIds,
      createdAt: message.createdAt,
    };
  });
  const structuredUiRequest =
    value.structuredUiRequest === undefined ||
    value.structuredUiRequest === null
      ? null
      : parseStructuredUiRequest(value.structuredUiRequest);
  let externalAction: ChatHistoryResponse["externalAction"] = null;
  if (value.externalAction !== undefined && value.externalAction !== null) {
    if (
      !isRecord(value.externalAction) ||
      !isUuid(value.externalAction.actionId)
    ) {
      throw new WidgetError("invalid_response");
    }
    externalAction = {
      actionId: value.externalAction.actionId,
      ...parseCalendlyEmbeddedBooking(value.externalAction),
    };
  }

  return {
    sessionId: value.sessionId,
    messages,
    externalAction,
    structuredUiRequest,
  };
}

export function parseCalendlyEmbeddedBooking(
  value: unknown,
): CalendlyEmbeddedBooking {
  if (
    !isRecord(value) ||
    value.kind !== "calendly_inline_booking" ||
    typeof value.schedulingUrl !== "string" ||
    typeof value.eventTypeName !== "string" ||
    typeof value.inviteeName !== "string" ||
    typeof value.inviteeEmail !== "string" ||
    typeof value.timezone !== "string" ||
    typeof value.requestedStartTime !== "string" ||
    !isTrustedCalendlyUrl(value.schedulingUrl)
  ) {
    throw new WidgetError("invalid_response");
  }
  return {
    kind: value.kind,
    schedulingUrl: value.schedulingUrl,
    eventTypeName: value.eventTypeName,
    inviteeName: value.inviteeName,
    inviteeEmail: value.inviteeEmail,
    timezone: value.timezone,
    requestedStartTime: value.requestedStartTime,
  };
}

/** Converts one untrusted JSON value into a shared SSE event variant. */
export function parseChatSseEvent(value: unknown): ChatSseEvent {
  if (!isRecord(value) || typeof value.type !== "string") {
    throw new WidgetError("stream_error");
  }

  switch (value.type) {
    case "token":
      if (typeof value.content === "string") {
        return { type: "token", content: value.content };
      }
      break;
    case "sources":
      if (isUuidArray(value.chunkIds)) {
        return { type: "sources", chunkIds: value.chunkIds };
      }
      break;
    case "action_confirmation":
      if (
        isUuid(value.actionId) &&
        typeof value.toolName === "string" &&
        typeof value.summary === "string" &&
        typeof value.confirmationToken === "string" &&
        typeof value.expiresAt === "string"
      ) {
        return {
          type: "action_confirmation",
          actionId: value.actionId,
          toolName: value.toolName,
          summary: value.summary,
          confirmationToken: value.confirmationToken,
          expiresAt: value.expiresAt,
        };
      }
      break;
    case "booking_slots": {
      const offer = parseCalendlyBookingOffer(value.offer);
      return { type: "booking_slots", offer };
    }
    case "structured_ui":
      return {
        type: "structured_ui",
        request: parseStructuredUiRequest(value.request),
      };
    case "done":
      if (isUuid(value.messageId)) {
        return { type: "done", messageId: value.messageId };
      }
      break;
    case "error":
      if (typeof value.error === "string") {
        return { type: "error", error: value.error };
      }
      break;
  }
  throw new WidgetError("stream_error");
}

function parseCalendlyBookingOffer(value: unknown): CalendlyBookingOffer {
  if (
    !isRecord(value) ||
    typeof value.eventTypeName !== "string" ||
    !Array.isArray(value.availableTimes) ||
    value.availableTimes.length === 0 ||
    value.availableTimes.length > 30
  ) {
    throw new WidgetError("stream_error");
  }
  const availableTimes = value.availableTimes.map((slot) => {
    if (
      !isRecord(slot) ||
      typeof slot.startTime !== "string" ||
      (slot.endTime !== undefined && typeof slot.endTime !== "string") ||
      (slot.schedulingUrl !== undefined &&
        (typeof slot.schedulingUrl !== "string" ||
          !isTrustedCalendlyUrl(slot.schedulingUrl)))
    ) {
      throw new WidgetError("stream_error");
    }
    return {
      startTime: slot.startTime,
      ...(typeof slot.endTime === "string" ? { endTime: slot.endTime } : {}),
      ...(typeof slot.schedulingUrl === "string"
        ? { schedulingUrl: slot.schedulingUrl }
        : {}),
    };
  });
  const provider =
    value.provider === "google_calendar" ? "google_calendar" : "calendly";
  return {
    provider,
    eventTypeName: value.eventTypeName,
    availableTimes,
  };
}

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

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

function isUuidArray(value: unknown): value is string[] {
  return Array.isArray(value) && value.every(isUuid);
}

function isNullableUuidArray(value: unknown): value is string[] | null {
  return value === null || isUuidArray(value);
}

function isNullableString(value: unknown): value is string | null {
  return value === null || typeof value === "string";
}

function isWidgetTheme(value: unknown): value is Omit<
  WidgetTheme,
  "primaryColor"
> & {
  primaryColor?: string;
} {
  return (
    isRecord(value) &&
    Array.isArray(value.borderColors) &&
    value.borderColors.length >= 1 &&
    value.borderColors.length <= 3 &&
    value.borderColors.every(isHexColor) &&
    isHexColor(value.buttonColor) &&
    (value.primaryColor === undefined || isHexColor(value.primaryColor)) &&
    typeof value.placeholder === "string" &&
    value.placeholder.trim().length >= 1 &&
    value.placeholder.length <= 120
  );
}

function isHexColor(value: unknown): value is string {
  return typeof value === "string" && /^#[0-9a-f]{6}$/i.test(value);
}

function isTrustedCalendlyUrl(value: string): boolean {
  try {
    const url = new URL(value);
    return (
      url.protocol === "https:" &&
      url.username.length === 0 &&
      url.password.length === 0 &&
      (url.hostname === "calendly.com" ||
        url.hostname.endsWith(".calendly.com"))
    );
  } catch {
    return false;
  }
}