/**
 * @file chatDraft.ts — a Chat pane's unsent prompt (`PaneChat`): its text and
 * attachments, kept per SESSION in this browser's localStorage
 * (`agenthub.chat.draft.<sessionId>`), so it survives the pane switching to
 * its terminal (which unmounts the chat) and a page reload — as the terminal's
 * own half-typed line survives in tmux. An image's preview (a blob URL) does
 * not outlive the page, so a restored attachment keeps only its path and name.
 * Cleared once the prompt is sent (an empty draft removes the key).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import type { PromptImage } from "../components/run/RunSetup";

const key = (sessionId: string) => `agenthub.chat.draft.${sessionId}`;

export interface ChatDraft {
  prompt: string;
  images: PromptImage[];
}

export function readChatDraft(sessionId: string): ChatDraft {
  try {
    const v = JSON.parse(
      localStorage.getItem(key(sessionId)) || "null"
    ) as Partial<ChatDraft> | null;
    return {
      prompt: typeof v?.prompt === "string" ? v.prompt : "",
      images: Array.isArray(v?.images)
        ? v.images
            .filter((i) => typeof i?.path === "string" && typeof i.name === "string")
            .map((i) => ({ path: i.path, name: i.name }))
        : [],
    };
  } catch {
    return { prompt: "", images: [] };
  }
}

export function writeChatDraft(sessionId: string, prompt: string, images: PromptImage[]) {
  try {
    if (!prompt && !images.length) localStorage.removeItem(key(sessionId));
    else
      localStorage.setItem(
        key(sessionId),
        JSON.stringify({ prompt, images: images.map(({ path, name }) => ({ path, name })) })
      );
  } catch {
    /* storage full or blocked: the draft lives for this page only */
  }
}