import { existsSync, readFileSync } from "fs";
import { join } from "path";

export const HOME_CHAT_ANIMATION_CONFIG_KEY = "home_chat_animation_config";
export const HOME_CHAT_ANIMATION_MAX_BYTES = 1024 * 1024;

export type HomeChatAnimationConfig = {
  enabled: boolean;
  fileName: string;
  htmlContent: string;
  updatedAt: string | null;
};

export function normalizeHomeChatAnimationHtml(value: unknown): string {
  if (typeof value !== "string") {
    return "";
  }

  return value
    .replace(/^\uFEFF/, "")
    .replace(/\u0000/g, "")
    .replace(/\u2028|\u2029/g, "\n");
}

export function getHomeChatAnimationHtmlBytes(htmlContent: string): number {
  return Buffer.byteLength(htmlContent, "utf8");
}

export function normalizeHomeChatAnimationConfig(
  value: unknown,
): HomeChatAnimationConfig {
  const raw =
    value && typeof value === "object" && !Array.isArray(value)
      ? (value as Record<string, unknown>)
      : {};

  const enabled = raw.enabled === true;
  const fileName = String(raw.fileName || "").trim().slice(0, 255);
  const htmlContent = normalizeHomeChatAnimationHtml(raw.htmlContent);
  const updatedAt = String(raw.updatedAt || "").trim() || null;

  return {
    enabled,
    fileName,
    htmlContent,
    updatedAt,
  };
}

let cachedDefaultHomeAnimationHtml: string | null | undefined;

export function getDefaultHomeChatAnimationHtml(): string {
  if (cachedDefaultHomeAnimationHtml !== undefined) {
    return cachedDefaultHomeAnimationHtml || "";
  }

  const candidatePaths = [join(process.cwd(), "动画效果.html")];

  for (const candidatePath of candidatePaths) {
    if (!existsSync(candidatePath)) {
      continue;
    }

    cachedDefaultHomeAnimationHtml = normalizeHomeChatAnimationHtml(
      readFileSync(candidatePath, "utf8"),
    );
    return cachedDefaultHomeAnimationHtml;
  }

  cachedDefaultHomeAnimationHtml = "";
  return "";
}

export function resolvePublicHomeChatAnimationConfig(
  value: unknown,
): HomeChatAnimationConfig & { usesDefaultFallback: boolean } {
  const normalized = normalizeHomeChatAnimationConfig(value);
  const fallbackHtml = getDefaultHomeChatAnimationHtml();
  const htmlContent = normalized.htmlContent || fallbackHtml;
  const usesDefaultFallback =
    !normalized.htmlContent && Boolean(fallbackHtml);

  if (!normalized.enabled || !htmlContent) {
    return {
      enabled: false,
      fileName: normalized.fileName,
      htmlContent: "",
      updatedAt: normalized.updatedAt,
      usesDefaultFallback,
    };
  }

  return {
    enabled: true,
    fileName:
      normalized.fileName || (usesDefaultFallback ? "动画效果.html" : ""),
    htmlContent,
    updatedAt: normalized.updatedAt,
    usesDefaultFallback,
  };
}