"use client";

/**
 * Chat types shared by the chat UI, the context builder and the streaming
 * client. The API key rule applies here too: nothing in a chat request may
 * carry the key anywhere except the `x-ollama-key` header of our own route.
 */

export type ChatRole = "user" | "assistant";

/** A context chunk that actually travelled with a request. */
export type ChatSource = {
  deckId: string;
  deckTitle: string;
  section: string;
};

export type ChatAttachment = {
  name: string;
  kind: "photo" | "document" | "text";
  chars: number;
};

export type ChatError = { message: string; kind?: string };

export type ChatMessage = {
  id: string;
  role: ChatRole;
  content: string;
  /** Reasoning streamed separately; hidden behind the Thinking row. */
  thinking?: string;
  /** Model that produced an assistant turn. */
  model?: string;
  /** Context chunks sent with this turn (assistant turns display them). */
  sources?: ChatSource[];
  attachments?: ChatAttachment[];
  at: number;
  /** Set when an assistant turn failed; content may hold a partial answer. */
  error?: ChatError;
};

/**
 * What the chat is allowed to ground on. `all` = every deck with notes,
 * `none` = general chat, `decks` = a chosen set.
 */
export type ChatScope =
  | { kind: "all" }
  | { kind: "none" }
  | { kind: "decks"; deckIds: string[] };

export type ChatModelChoice = {
  name: string;
  badge: "text" | "vision" | "both";
  available: boolean | null;
};

/** Last model choice, remembered across visits. */
const MODEL_KEY = "freezmo.chat.model.v1";

export function readStoredChatModel(): string | null {
  try {
    const value = window.localStorage.getItem(MODEL_KEY);
    return value && value.trim() ? value : null;
  } catch {
    return null;
  }
}

export function storeChatModel(model: string): void {
  try {
    window.localStorage.setItem(MODEL_KEY, model);
  } catch {
    /* private mode */
  }
}

export function chatMessageId(prefix: string): string {
  const rand =
    typeof crypto !== "undefined" && "randomUUID" in crypto
      ? crypto.randomUUID().slice(0, 8)
      : Math.random().toString(36).slice(2, 10);
  return `${prefix}_${Date.now().toString(36)}_${rand}`;
}