/**
 * Collabora 自定义页面跳转模块
 *
 * 使用自定义 PostMessage 协议实现页面跳转,不依赖 UNO 命令
 *
 * @encoding UTF-8
 */

/**
 * 页面跳转响应接口
 */
export interface GotoPageResponse {
    pageNumber: number;
    pageIndex: number;
    totalPages: number;
    currentOffset: number;
    targetOffset: number;
    scrollDelta: number;
    timestamp: number;
}

/**
 * Collabora PostMessage 数据类型
 */
interface CollaboraMessageData {
    MessageId?: string;
    msgId?: string;
    Values?: {
        Command?: string;
        Status?: string;
        pageNumber?: number;
        pageIndex?: number;
        totalPages?: number;
        currentOffset?: number;
        targetOffset?: number;
        scrollDelta?: number;
        timestamp?: number;
        Error?: string;
        [key: string]: unknown;
    };
    args?: {
        Command?: string;
        Status?: string;
        pageNumber?: number;
        pageIndex?: number;
        totalPages?: number;
        currentOffset?: number;
        targetOffset?: number;
        scrollDelta?: number;
        timestamp?: number;
        Error?: string;
        [key: string]: unknown;
    };
    [key: string]: unknown;
}

/**
 * 解析 PostMessage 数据
 */
function parseMessageData(data: unknown): CollaboraMessageData {
    if (typeof data === 'string') {
        return JSON.parse(data) as CollaboraMessageData;
    }
    return data as CollaboraMessageData;
}

/**
 * 跳转到指定页面 (自定义实现,不使用 UNO 命令)
 *
 * 使用自定义 custompostMessage 插件实现页面跳转。
 * 注意: Collabora 的页码是从 0 开始的,但此函数接受从 1 开始的页码。
 *
 * @param iframeWindow - iframe 的 contentWindow
 * @param pageNumber - 页码 (从1开始)
 * @returns Promise,解析为跳转响应信息
 *
 * @example
 * ```typescript
 * const response = await customGotoPage(iframeWindow, 5);
 * console.log(`成功跳转到第 ${response.pageNumber} 页`);
 * ```
 */
export async function customGotoPage(
    iframeWindow: Window,
    pageNumber: number
): Promise<GotoPageResponse> {
    return new Promise((resolve, reject) => {
        const timeout = setTimeout(() => {
            cleanup();
            reject(new Error('页面跳转超时'));
        }, 5000);

        const handleMessage = (event: MessageEvent) => {
            try {
                if (event.source !== iframeWindow) {
                    return;
                }

                const data = parseMessageData(event.data);

                // bundle.js 的 _postMessage 会将消息转换为:
                // { MessageId: 'custompostMessage_Resp', Values: { Command: 'GOTO_PAGE', ... } }
                if (
                    data.MessageId === 'custompostMessage_Resp' &&
                    data.Values?.Command === 'GOTO_PAGE'
                ) {
                    clearTimeout(timeout);
                    cleanup();

                    if (data.Values.Status === 'success') {
                        const response: GotoPageResponse = {
                            pageNumber: data.Values.pageNumber || pageNumber,
                            pageIndex: data.Values.pageIndex || pageNumber - 1,
                            totalPages: data.Values.totalPages || 0,
                            currentOffset: data.Values.currentOffset || 0,
                            targetOffset: data.Values.targetOffset || 0,
                            scrollDelta: data.Values.scrollDelta || 0,
                            timestamp: data.Values.timestamp || Date.now(),
                        };
                        resolve(response);
                    } else {
                        reject(new Error(data.Values.Error || '页面跳转失败'));
                    }
                }
            } catch (error) {
                clearTimeout(timeout);
                cleanup();
                reject(error);
            }
        };

        const cleanup = () => {
            window.removeEventListener('message', handleMessage);
        };

        window.addEventListener('message', handleMessage);

        // 发送跳转请求消息
        const message = {
            MessageId: 'custompostMessage',
            Values: {
                Command: 'GOTO_PAGE',
                Args: {
                    pageNumber: pageNumber,
                },
            },
        };

        iframeWindow.postMessage(JSON.stringify(message), '*');
    });
}