"use strict";

/*
 * LINE WORKS 共有ドライブAPIのラッパー。
 * 仕様書:
 *   https://developers.worksmobile.com/jp/docs/sharedrive-list
 *   https://developers.worksmobile.com/jp/docs/sharedrive-file-folder-create
 *   https://developers.worksmobile.com/jp/docs/sharedrive-file-create
 *   https://developers.worksmobile.com/en/docs/file-upload (アップロード段階2の詳細)
 *
 * 必要スコープ: file (読み書き全般)
 */

const fs = require("fs");
const path = require("path");

const { updateEnvValue } = require("./env");
const defaultLogger = require("./logger");

const LW_API_BASE_URL = "https://www.worksapis.com/v1.0";

// 各API呼び出しの間隔(ミリ秒)とレート制限時の最大リトライ回数。
// lineworks-anythingllm.js の lwFetch と同じスロットリング方式。
const LW_REQUEST_DELAY_MS = Number(process.env.LW_REQUEST_DELAY_MS || 250);
const LW_MAX_RETRIES = Number(process.env.LW_MAX_RETRIES || 5);

function sleep(ms) {
    return new Promise((resolve) => setTimeout(resolve, ms));
}

async function lwFetch(url, options = {}, logger = defaultLogger) {
    for (let attempt = 0; attempt <= LW_MAX_RETRIES; attempt++) {
        await sleep(LW_REQUEST_DELAY_MS);

        const response = await fetch(url, options);

        if (response.status !== 429) {
            return response;
        }
        if (attempt === LW_MAX_RETRIES) {
            return response;
        }

        const retryAfterHeader = response.headers.get("retry-after");
        const retryAfterMs = retryAfterHeader
            ? Number(retryAfterHeader) * 1000
            : LW_REQUEST_DELAY_MS * Math.pow(2, attempt + 1);

        logger.warn(
            `[Rate Limit] 429を検知。${Math.round(retryAfterMs / 1000)}秒待機してリトライします... ` +
                `(${attempt + 1}/${LW_MAX_RETRIES}) url=${url}`
        );
        await sleep(retryAfterMs);
    }
}

async function parseJsonResponse(response, errorLabel) {
    const raw = await response.text();
    let data;
    try {
        data = raw ? JSON.parse(raw) : {};
    } catch (_err) {
        throw new Error(`${errorLabel}のレスポンスがJSONではありません: ${raw}`);
    }
    if (!response.ok) {
        throw new Error(`${errorLabel}失敗: ${response.status} ${JSON.stringify(data)}`);
    }
    return data;
}

// ====================================================================
// 共有ドライブID解決
// ====================================================================

// GET /sharedrives にはページング用パラメータ(count/cursor)が存在しない
// (/files 系のようなresponseMetaData.nextCursorは返らない)ため、1回のみ呼び出す。
async function listSharedDrives(token, logger = defaultLogger) {
    const res = await lwFetch(
        `${LW_API_BASE_URL}/sharedrives`,
        { headers: { Authorization: `Bearer ${token}` } },
        logger
    );
    const data = await parseJsonResponse(res, "共有ドライブ一覧取得");

    return Array.isArray(data.sharedrives) ? data.sharedrives : [];
}

// .env の LW_SHAREDRIVE_ID があればそれを使用(APIを呼ばない)。無ければ
// LW_SHAREDRIVE_NAME と一致する共有ドライブを検索し、.env に書き戻して次回以降キャッシュする。
async function resolveSharedDriveId(token, logger = defaultLogger) {
    const cached = process.env.LW_SHAREDRIVE_ID;
    if (cached) {
        logger.info(`共有ドライブID: キャッシュ値を使用 (${cached})`);
        return cached;
    }

    const targetName = process.env.LW_SHAREDRIVE_NAME || "システムバックアップ";
    logger.info(`共有ドライブID未キャッシュ。名前で検索します: ${targetName}`);

    const drives = await listSharedDrives(token, logger);
    const found = drives.find((d) => d.name === targetName);
    if (!found) {
        throw new Error(`共有ドライブが見つかりません: ${targetName}`);
    }

    updateEnvValue("LW_SHAREDRIVE_ID", found.sharedriveId);
    logger.info(`共有ドライブID解決: name=${targetName} id=${found.sharedriveId} (.envへ保存)`);

    return found.sharedriveId;
}

// ====================================================================
// フォルダ一覧・作成
// ====================================================================

// parentFileId が falsy の場合はルート直下を対象にする。
async function listChildren(token, sharedriveId, parentFileId, logger = defaultLogger) {
    const files = [];
    let cursor = "";
    const basePath = parentFileId
        ? `${LW_API_BASE_URL}/sharedrives/${encodeURIComponent(sharedriveId)}/files/${encodeURIComponent(parentFileId)}/children`
        : `${LW_API_BASE_URL}/sharedrives/${encodeURIComponent(sharedriveId)}/files`;

    while (true) {
        const params = new URLSearchParams();
        params.set("count", "200");
        if (cursor) params.set("cursor", cursor);

        const res = await lwFetch(
            `${basePath}?${params.toString()}`,
            { headers: { Authorization: `Bearer ${token}` } },
            logger
        );
        const data = await parseJsonResponse(res, "ファイル一覧取得");

        const page = Array.isArray(data.files) ? data.files : [];
        files.push(...page);

        const nextCursor = data?.responseMetaData?.nextCursor || "";
        if (!nextCursor || nextCursor === cursor) break;
        cursor = nextCursor;
    }

    return files;
}

async function createFolder(token, sharedriveId, parentFileId, folderName, logger = defaultLogger) {
    const url = parentFileId
        ? `${LW_API_BASE_URL}/sharedrives/${encodeURIComponent(sharedriveId)}/files/${encodeURIComponent(parentFileId)}/createfolder`
        : `${LW_API_BASE_URL}/sharedrives/${encodeURIComponent(sharedriveId)}/files/createfolder`;

    const res = await lwFetch(
        url,
        {
            method: "POST",
            headers: {
                Authorization: `Bearer ${token}`,
                "Content-Type": "application/json",
            },
            body: JSON.stringify({ fileName: folderName }),
        },
        logger
    );

    return parseJsonResponse(res, `フォルダ作成 (${folderName})`);
}

// 同名フォルダが既にあれば再利用し、無ければ作成する。
async function ensureFolder(token, sharedriveId, parentFileId, folderName, logger = defaultLogger) {
    const children = await listChildren(token, sharedriveId, parentFileId, logger);
    const existing = children.find((f) => f.fileType === "FOLDER" && f.fileName === folderName);
    if (existing) {
        logger.info(`フォルダ確認: 既存を使用 name=${folderName} id=${existing.fileId}`);
        return existing;
    }

    const created = await createFolder(token, sharedriveId, parentFileId, folderName, logger);
    logger.info(`フォルダ確認: 新規作成 name=${folderName} id=${created.fileId}`);
    return created;
}

// ====================================================================
// アップロード (段階1: uploadUrl発行 → 段階2: multipart/form-dataで実バイト送信)
// ====================================================================

async function fileToBlob(filePath, mimeType) {
    if (typeof fs.openAsBlob === "function") {
        // Node 18.13+: ファイル全体をメモリに載せずBlobとして扱える
        return fs.openAsBlob(filePath, { type: mimeType });
    }
    const buffer = fs.readFileSync(filePath);
    return new Blob([buffer], { type: mimeType });
}

async function uploadFile(token, sharedriveId, parentFileId, filePath, options = {}, logger = defaultLogger) {
    const overwrite = options.overwrite === true;
    const stat = fs.statSync(filePath);
    const fileName = path.basename(filePath);

    logger.info(`アップロード開始: ファイル名=${fileName} サイズ=${stat.size}bytes`);
    const startedAt = Date.now();

    const stage1Res = await lwFetch(
        `${LW_API_BASE_URL}/sharedrives/${encodeURIComponent(sharedriveId)}/files/${encodeURIComponent(parentFileId)}`,
        {
            method: "POST",
            headers: {
                Authorization: `Bearer ${token}`,
                "Content-Type": "application/json",
            },
            body: JSON.stringify({
                fileName,
                modifiedTime: new Date(stat.mtimeMs).toISOString(),
                fileSize: stat.size,
                overwrite,
                resume: false,
                suffixOnDuplicate: false,
            }),
        },
        logger
    );
    const stage1Data = await parseJsonResponse(stage1Res, `アップロードURL発行 (${fileName})`);
    if (!stage1Data.uploadUrl) {
        throw new Error(`アップロードURL発行失敗 (${fileName}): uploadUrlが返却されませんでした`);
    }

    const blob = await fileToBlob(filePath, "application/octet-stream");
    const form = new FormData();
    form.append("Filedata", blob, fileName);

    const stage2Res = await lwFetch(
        stage1Data.uploadUrl,
        {
            method: "POST",
            headers: { Authorization: `Bearer ${token}` },
            body: form,
        },
        logger
    );
    const stage2Data = await parseJsonResponse(stage2Res, `アップロード (${fileName})`);

    const elapsedSec = ((Date.now() - startedAt) / 1000).toFixed(1);
    logger.info(`アップロード成功: ファイル名=${fileName} fileId=${stage2Data.fileId} 所要時間=${elapsedSec}秒`);

    return stage2Data;
}

// ====================================================================
// 削除
// ====================================================================

async function deleteFile(token, sharedriveId, fileId, logger = defaultLogger) {
    const res = await lwFetch(
        `${LW_API_BASE_URL}/sharedrives/${encodeURIComponent(sharedriveId)}/files/${encodeURIComponent(fileId)}`,
        {
            method: "DELETE",
            headers: { Authorization: `Bearer ${token}` },
        },
        logger
    );

    if (res.status !== 204 && !res.ok) {
        const raw = await res.text();
        throw new Error(`削除失敗 (${fileId}): ${res.status} ${raw}`);
    }
}

module.exports = {
    LW_API_BASE_URL,
    listSharedDrives,
    resolveSharedDriveId,
    listChildren,
    ensureFolder,
    uploadFile,
    deleteFile,
};