import type { CadError, CadProgress, CadResult, CadUIMessage } from "./cad-types";

type AnyPart = { type?: unknown; text?: unknown; data?: unknown; id?: unknown };
type AnyMessage = { id?: unknown; role?: unknown; parts?: unknown };
type CadPart = CadUIMessage["parts"][number];

export function normalizeCadMessages(input: unknown): CadUIMessage[] {
  if (!Array.isArray(input)) return [];
  return input.flatMap((message): CadUIMessage[] => {
    const candidate = message as AnyMessage;
    if (candidate.role !== "user" && candidate.role !== "assistant") return [];
    const parts = Array.isArray(candidate.parts) ? candidate.parts : [];
    const normalizedParts = parts.flatMap((part): CadPart[] => {
      const item = part as AnyPart;
      if (item.type === "text") {
        return [{ type: "text", text: String(item.text || "") }];
      }
      if (item.type === "data-cad-progress") {
        return [{ type: "data-cad-progress", id: stringId(item.id), data: item.data as CadProgress }];
      }
      if (item.type === "data-cad-result") {
        return [{ type: "data-cad-result", id: stringId(item.id), data: item.data as CadResult }];
      }
      if (item.type === "data-cad-error") {
        return [{ type: "data-cad-error", id: stringId(item.id), data: item.data as CadError }];
      }
      return [];
    });
    return [{
      id: typeof candidate.id === "string" ? candidate.id : crypto.randomUUID(),
      role: candidate.role,
      parts: normalizedParts,
    }];
  });
}

export function messagesForBackend(messages: CadUIMessage[]) {
  return messages
    .filter((message) => message.role === "user" || message.role === "assistant")
    .map((message) => ({
      id: message.id,
      role: message.role,
      parts: message.parts.flatMap((part): { type: string; text?: string; data?: unknown }[] => {
        if (part.type === "text") return [{ type: "text", text: part.text }];
        if (part.type.startsWith("data-cad-") && "data" in part) {
          return [{ type: part.type, data: part.data }];
        }
        return [];
      }),
    }));
}

function stringId(value: unknown) {
  return typeof value === "string" ? value : undefined;
}