import { useState } from "react";
import { Button } from "@/components/ui/button";
import { useFileConnections } from "@/store/file-connection";
import { toast } from "sonner";
import { upsertLanguageTranslations } from "@/lib/db";
import { flattenValues } from "@/lib/i18n-structure";
import { RefreshCw } from "lucide-react";

type Props = {
  projectId: string;
  onSynced: () => void | Promise<void>;
  disabled?: boolean;
};

async function ensureReadPermission(handle: FileSystemFileHandle): Promise<boolean> {
  try {
    // @ts-expect-error - queryPermission/requestPermission exist in supporting browsers
    const q = await handle.queryPermission?.({ mode: "read" });
    if (q === "granted") return true;
    // @ts-expect-error - requestPermission exist in supporting browsers
    const r = await handle.requestPermission?.({ mode: "read" });
    return r === "granted";
  } catch {
    try {
      // Fallback: try to read once; if it throws, we treat as no permission
      const f = await handle.getFile();
      // Touch the file object so TS doesn't complain about unused variable
      if (!f) return false;
      return true;
    } catch {
      return false;
    }
  }
}

export function SyncFromFilesButton({ projectId, onSynced, disabled }: Props) {
  const [syncing, setSyncing] = useState(false);
  const connSnap = useFileConnections(projectId);

  const hasConnections = Object.keys(connSnap.connections).length > 0;

  async function handleSync() {
    if (!projectId) return;
    if (!hasConnections) {
      toast.info("没有已连接的语言");
      return;
    }

    setSyncing(true);

    try {
      const entries = Object.entries(connSnap.connections);
      const results = await Promise.allSettled(
        entries.map(async ([lang, conn]) => {
          const canRead = await ensureReadPermission(conn.handle);
          if (!canRead) throw new Error(`${lang}: 无读取权限`);

          const file = await conn.handle.getFile();
          const text = await file.text();

          let json: unknown;
          try {
            json = JSON.parse(text);
          } catch {
            throw new Error(`${lang}: JSON 解析失败`);
          }

          const values = flattenValues(json);
          await upsertLanguageTranslations(projectId, lang, values);
          return lang;
        })
      );

      const failed: string[] = [];
      let success = 0;

      for (const r of results) {
        if (r.status === "fulfilled") success += 1;
        else failed.push((r.reason as Error)?.message || "未知语言");
      }

      if (failed.length === 0) {
        toast.success(`同步完成（${success}）`);
      } else if (success === 0) {
        toast.error(`全部失败（${failed.length}）：${failed.join("，")}`);
      } else {
        toast.warning(`部分成功（成功 ${success}，失败 ${failed.length}）：${failed.join("，")}`);
      }
    } finally {
      setSyncing(false);
      await onSynced?.();
    }
  }

  return (
    <Button
      variant="outline"
      onClick={handleSync}
      disabled={syncing || disabled || !hasConnections}
      title={!hasConnections ? "暂无已连接的语言" : "读取已连接文件并导入翻译"}
    >
      <RefreshCw />
      {syncing ? "读取中..." : "一键读取"}
    </Button>
  );
}