import { z } from "zod/v4";
import { colineUiNodeSchema, type ColineUiNode } from "./tree";

/**
 * The chat-card tree subset (plan §10.4, open question #4 resolved).
 *
 * Tool result cards render inside chat bubbles on every platform, so the
 * card vocabulary is a strict subset of the tree: presentational nodes,
 * references, and buttons (which dispatch ordinary app actions). Form
 * inputs, tabs, menus, and other stateful chrome are excluded — a card is
 * a result, not an app surface.
 *
 * Bounds keep cards cheap to render and impossible to abuse as a layout
 * engine: max 120 nodes, depth 6, 20 table rows.
 */

export const CHAT_CARD_ALLOWED_NODE_TYPES = new Set<string>([
  "Text",
  "Heading",
  "Badge",
  "Divider",
  "FileCard",
  "UserChip",
  "Image",
  "Link",
  "CodeBlock",
  "Table",
  "Avatar",
  "Alert",
  "Progress",
  "Stack",
  "Card",
  "Button",
  "Reference",
]);

export const CHAT_CARD_MAX_NODES = 120;
export const CHAT_CARD_MAX_DEPTH = 6;
export const CHAT_CARD_MAX_TABLE_ROWS = 20;

export type ChatCardValidation =
  | { ok: true; nodeCount: number }
  | { ok: false; reason: string };

interface WalkState {
  count: number;
}

function childrenOf(node: ColineUiNode): ColineUiNode[] {
  switch (node.type) {
    case "Stack":
      return node.props.children;
    case "Card":
      return [...(node.props.children ?? []), ...(node.props.footer ?? [])];
    default:
      return [];
  }
}

function walk(node: ColineUiNode, depth: number, state: WalkState): string | null {
  if (depth > CHAT_CARD_MAX_DEPTH) {
    return `Card exceeds the maximum depth of ${CHAT_CARD_MAX_DEPTH}.`;
  }
  state.count += 1;
  if (state.count > CHAT_CARD_MAX_NODES) {
    return `Card exceeds the maximum of ${CHAT_CARD_MAX_NODES} nodes.`;
  }
  if (!CHAT_CARD_ALLOWED_NODE_TYPES.has(node.type)) {
    return `"${node.type}" nodes are not allowed in tool result cards.`;
  }
  if (node.type === "Table" && node.props.rows.length > CHAT_CARD_MAX_TABLE_ROWS) {
    return `Card tables are limited to ${CHAT_CARD_MAX_TABLE_ROWS} rows.`;
  }
  for (const child of childrenOf(node)) {
    const issue = walk(child, depth + 1, state);
    if (issue) return issue;
  }
  return null;
}

export function validateChatCardTree(node: unknown): ChatCardValidation {
  const parsed = colineUiNodeSchema.safeParse(node);
  if (!parsed.success) {
    return { ok: false, reason: "Card is not a valid Coline UI tree." };
  }
  const state: WalkState = { count: 0 };
  const issue = walk(parsed.data, 1, state);
  if (issue) {
    return { ok: false, reason: issue };
  }
  return { ok: true, nodeCount: state.count };
}

/** Schema wrapper: parses a tree AND enforces the chat-card subset. */
export const chatCardTreeSchema = colineUiNodeSchema.superRefine((node, ctx) => {
  const state: WalkState = { count: 0 };
  const issue = walk(node, 1, state);
  if (issue) {
    ctx.addIssue({ code: "custom", message: issue });
  }
});

export type ChatCardTree = z.infer<typeof chatCardTreeSchema>;