const path = require('path');
const { v4 } = require('uuid');
const { logger } = require('@librechat/data-schemas');
const { getCodeBaseURL } = require('@librechat/agents');
const {
  getBasePath,
  logAxiosError,
  sanitizeArtifactPath,
  flattenArtifactPath,
  createAxiosInstance,
  classifyCodeArtifact,
  codeServerHttpAgent,
  codeServerHttpsAgent,
  extractCodeArtifactText,
} = require('@librechat/api');
const {
  Tools,
  megabyte,
  fileConfig,
  FileContext,
  FileSources,
  imageExtRegex,
  inferMimeType,
  EToolResources,
  EModelEndpoint,
  mergeFileConfig,
  getEndpointFileConfig,
} = require('librechat-data-provider');
const { filterFilesByAgentAccess } = require('~/server/services/Files/permissions');
const { createFile, getFiles, updateFile, claimCodeFile } = require('~/models');
const { getStrategyFunctions } = require('~/server/services/Files/strategies');
const { convertImage } = require('~/server/services/Files/images/convert');
const { determineFileType } = require('~/server/utils');

const axios = createAxiosInstance();

/**
 * Creates a fallback download URL response when file cannot be processed locally.
 * Used when: file exceeds size limit, storage strategy unavailable, or download error occurs.
 * @param {Object} params - The parameters.
 * @param {string} params.name - The filename.
 * @param {string} params.session_id - The code execution session ID.
 * @param {string} params.id - The file ID from the code environment.
 * @param {string} params.conversationId - The current conversation ID.
 * @param {string} params.toolCallId - The tool call ID that generated the file.
 * @param {string} params.messageId - The current message ID.
 * @param {number} params.expiresAt - Expiration timestamp (24 hours from creation).
 * @returns {Object} Fallback response with download URL.
 */
const createDownloadFallback = ({
  id,
  name,
  messageId,
  expiresAt,
  session_id,
  toolCallId,
  conversationId,
}) => {
  const basePath = getBasePath();
  return {
    filename: name,
    filepath: `${basePath}/api/files/code/download/${session_id}/${id}`,
    expiresAt,
    conversationId,
    toolCallId,
    messageId,
  };
};

/**
 * Process code execution output files - downloads and saves both images and non-image files.
 * All files are saved to local storage with fileIdentifier metadata for code env re-upload.
 * @param {ServerRequest} params.req - The Express request object.
 * @param {string} params.id - The file ID from the code environment.
 * @param {string} params.name - The filename.
 * @param {string} params.toolCallId - The tool call ID that generated the file.
 * @param {string} params.session_id - The code execution session ID.
 * @param {string} params.conversationId - The current conversation ID.
 * @param {string} params.messageId - The current message ID.
 * @returns {Promise<MongoFile & { messageId: string, toolCallId: string } | undefined>} The file metadata or undefined if an error occurs.
 */
const processCodeOutput = async ({
  req,
  id,
  name,
  toolCallId,
  conversationId,
  messageId,
  session_id,
}) => {
  const appConfig = req.config;
  const currentDate = new Date();
  const baseURL = getCodeBaseURL();
  const fileExt = path.extname(name).toLowerCase();
  const isImage = fileExt && imageExtRegex.test(name);

  const mergedFileConfig = mergeFileConfig(appConfig.fileConfig);
  const endpointFileConfig = getEndpointFileConfig({
    fileConfig: mergedFileConfig,
    endpoint: EModelEndpoint.agents,
  });
  const fileSizeLimit = endpointFileConfig.fileSizeLimit ?? mergedFileConfig.serverFileSizeLimit;

  try {
    const formattedDate = currentDate.toISOString();
    const response = await axios({
      method: 'get',
      url: `${baseURL}/download/${session_id}/${id}`,
      responseType: 'arraybuffer',
      headers: {
        'User-Agent': 'LibreChat/1.0',
      },
      httpAgent: codeServerHttpAgent,
      httpsAgent: codeServerHttpsAgent,
      timeout: 15000,
    });

    const buffer = Buffer.from(response.data, 'binary');

    // Enforce file size limit
    if (buffer.length > fileSizeLimit) {
      logger.warn(
        `[processCodeOutput] File "${name}" (${(buffer.length / megabyte).toFixed(2)} MB) exceeds size limit of ${(fileSizeLimit / megabyte).toFixed(2)} MB, falling back to download URL`,
      );
      return createDownloadFallback({
        id,
        name,
        messageId,
        toolCallId,
        session_id,
        conversationId,
        expiresAt: currentDate.getTime() + 86400000,
      });
    }

    const fileIdentifier = `${session_id}/${id}`;

    /* `safeName` keeps the directory structure (`a/b/file.txt` -> `a/b/file.txt`)
     * so the next prime() can place the file at the same nested path in the
     * sandbox; flattening would re-create the bug where every nested artifact
     * collapsed into the root and read_file calls 404'd. The flat-form
     * storage key is composed below once `file_id` is known so we can cap
     * the total length at filesystem NAME_MAX. */
    const safeName = sanitizeArtifactPath(name);
    if (safeName !== name) {
      logger.warn(
        `[processCodeOutput] Filename sanitized: "${name}" -> "${safeName}" | conv=${conversationId}`,
      );
    }

    /**
     * Atomically claim a file_id for this (filename, conversationId, context) tuple.
     * Uses $setOnInsert so concurrent calls for the same filename converge on
     * a single record instead of creating duplicates (TOCTOU race fix).
     *
     * Claim by `safeName` (not raw `name`) so the claim and the eventual
     * `createFile` agree on the filename column — otherwise weird inputs
     * (e.g. `"proj name/file@v1.txt"`) would claim under the raw name and
     * then write under the sanitized one, leaving the claim row orphaned.
     */
    const newFileId = v4();
    const claimed = await claimCodeFile({
      filename: safeName,
      conversationId,
      file_id: newFileId,
      user: req.user.id,
    });
    const file_id = claimed.file_id;
    const isUpdate = file_id !== newFileId;

    if (isUpdate) {
      logger.debug(
        `[processCodeOutput] Updating existing file "${safeName}" (${file_id}) instead of creating duplicate`,
      );
    }

    /**
     * Preserve the original `messageId` on update. Each `processCodeOutput`
     * call would otherwise overwrite it with the current run's run id, which
     * decouples the file from the assistant message that originally created
     * it. `getCodeGeneratedFiles` filters by `messageId IN <thread>`, so a
     * stale id (e.g. from a later regeneration / failed re-read attempt)
     * silently excludes the file from priming on subsequent turns.
     */
    const persistedMessageId = isUpdate ? (claimed.messageId ?? messageId) : messageId;

    if (isImage) {
      const usage = isUpdate ? (claimed.usage ?? 0) + 1 : 1;
      const _file = await convertImage(req, buffer, 'high', `${file_id}${fileExt}`);
      const filepath = usage > 1 ? `${_file.filepath}?v=${Date.now()}` : _file.filepath;
      const file = {
        ..._file,
        filepath,
        file_id,
        messageId: persistedMessageId,
        usage,
        filename: safeName,
        conversationId,
        user: req.user.id,
        type: `image/${appConfig.imageOutputType}`,
        createdAt: isUpdate ? claimed.createdAt : formattedDate,
        updatedAt: formattedDate,
        source: appConfig.fileStrategy,
        context: FileContext.execute_code,
        metadata: { fileIdentifier },
      };
      await createFile(file, true);
      return Object.assign(file, { messageId, toolCallId });
    }

    const { saveBuffer } = getStrategyFunctions(appConfig.fileStrategy);
    if (!saveBuffer) {
      logger.warn(
        `[processCodeOutput] saveBuffer not available for strategy ${appConfig.fileStrategy}, falling back to download URL`,
      );
      return createDownloadFallback({
        id,
        name,
        messageId,
        toolCallId,
        session_id,
        conversationId,
        expiresAt: currentDate.getTime() + 86400000,
      });
    }

    const detectedType = await determineFileType(buffer, true);
    const mimeType = detectedType?.mime || inferMimeType(name, '') || 'application/octet-stream';

    /** Check MIME type support - for code-generated files, we're lenient but log unsupported types */
    const isSupportedMimeType = fileConfig.checkType(
      mimeType,
      endpointFileConfig.supportedMimeTypes,
    );
    if (!isSupportedMimeType) {
      logger.warn(
        `[processCodeOutput] File "${name}" has unsupported MIME type "${mimeType}", proceeding with storage but may not be usable as tool resource`,
      );
    }

    /* Compose the storage key here, after `file_id` is known, so the
     * `flattenArtifactPath` cap budget can be calculated against the
     * actual prefix length. The full key has to fit in one filesystem
     * path component (NAME_MAX = 255 on most filesystems); without this
     * cap, deeply-nested artifact paths whose individual segments were
     * within bounds can still produce a flat form that overflows once
     * `${file_id}__` is prepended, causing `ENAMETOOLONG` inside
     * saveBuffer and falling back to a download URL. The 255 figure is
     * the conservative cross-platform NAME_MAX (Linux ext4, NTFS, APFS).
     */
    const NAME_MAX = 255;
    const flatName = flattenArtifactPath(safeName, NAME_MAX - file_id.length - 2);
    const fileName = `${file_id}__${flatName}`;
    const filepath = await saveBuffer({
      userId: req.user.id,
      buffer,
      fileName,
      basePath: 'uploads',
    });

    /* `classifyCodeArtifact` and `extractCodeArtifactText` make
     * extension/bare-name decisions on the input string. With the
     * path-preserving sanitizer they can now receive a nested path like
     * `reports.v1/Makefile`, which the classifier's `extensionOf` reads
     * as `v1/Makefile` (the slice after the dot in the directory name)
     * and the bare-name branch rejects because it sees a `.` anywhere in
     * the string. Result: extensionless artifacts under dotted folders
     * (Makefile, Dockerfile, etc.) get misclassified as `other` and
     * skip text extraction. Pass the basename so classification matches
     * what it would have gotten with the old flat-name flow. */
    const leafName = path.basename(safeName);
    const category = classifyCodeArtifact(leafName, mimeType);
    const text = await extractCodeArtifactText(buffer, leafName, mimeType, category);

    const file = {
      file_id,
      filepath,
      messageId: persistedMessageId,
      object: 'file',
      filename: safeName,
      type: mimeType,
      conversationId,
      user: req.user.id,
      bytes: buffer.length,
      updatedAt: formattedDate,
      metadata: { fileIdentifier },
      source: appConfig.fileStrategy,
      context: FileContext.execute_code,
      usage: isUpdate ? (claimed.usage ?? 0) + 1 : 1,
      createdAt: isUpdate ? claimed.createdAt : formattedDate,
      // Always set `text` explicitly (string or null) so that an update which
      // produces a binary or oversized artifact clears any previously cached
      // text — `createFile` uses findOneAndUpdate with $set semantics, which
      // would otherwise leave a stale value behind.
      text: text ?? null,
    };

    await createFile(file, true);
    return Object.assign(file, { messageId, toolCallId });
  } catch (error) {
    if (error?.message === 'Path traversal detected in filename') {
      logger.warn(
        `[processCodeOutput] Path traversal blocked for file "${name}" | conv=${conversationId}`,
      );
    }
    logAxiosError({
      message: 'Error downloading/processing code environment file',
      error,
    });

    // Fallback for download errors - return download URL so user can still manually download
    return createDownloadFallback({
      id,
      name,
      messageId,
      toolCallId,
      session_id,
      conversationId,
      expiresAt: currentDate.getTime() + 86400000,
    });
  }
};

function checkIfActive(dateString) {
  const givenDate = new Date(dateString);
  const currentDate = new Date();
  const timeDifference = currentDate - givenDate;
  const hoursPassed = timeDifference / (1000 * 60 * 60);
  return hoursPassed < 23;
}

/**
 * Retrieves the `lastModified` time string for a specified file from Code Execution Server.
 *
 * @param {string} fileIdentifier - The identifier for the file (e.g., "session_id/fileId").
 *
 * @returns {Promise<string|null>}
 *          A promise that resolves to the `lastModified` time string of the file if successful, or null if there is an
 *          error in initialization or fetching the info.
 */
async function getSessionInfo(fileIdentifier) {
  try {
    const baseURL = getCodeBaseURL();
    const [path, queryString] = fileIdentifier.split('?');
    const [session_id, fileId] = path.split('/');
    let queryParams = {};
    if (queryString) {
      queryParams = Object.fromEntries(new URLSearchParams(queryString).entries());
    }

    const response = await axios({
      method: 'get',
      url: `${baseURL}/sessions/${session_id}/objects/${fileId}`,
      params: queryParams,
      headers: {
        'User-Agent': 'LibreChat/1.0',
      },
      httpAgent: codeServerHttpAgent,
      httpsAgent: codeServerHttpsAgent,
      timeout: 5000,
    });

    return response.data?.lastModified;
  } catch (error) {
    logAxiosError({
      message: `Error fetching session info: ${error.message}`,
      error,
    });
    return null;
  }
}

/**
 *
 * @param {Object} options
 * @param {ServerRequest} options.req
 * @param {Agent['tool_resources']} options.tool_resources
 * @param {string} [options.agentId] - The agent ID for file access control
 * @returns {Promise<{
 * files: Array<{ id: string; session_id: string; name: string }>,
 * toolContext: string,
 * }>}
 */
const primeFiles = async (options) => {
  const { tool_resources, req, agentId } = options;
  const file_ids = tool_resources?.[EToolResources.execute_code]?.file_ids ?? [];
  const agentResourceIds = new Set(file_ids);
  const resourceFiles = tool_resources?.[EToolResources.execute_code]?.files ?? [];

  // Get all files first
  const allFiles = (await getFiles({ file_id: { $in: file_ids } }, null, { text: 0 })) ?? [];

  // Filter by access if user and agent are provided
  let dbFiles;
  if (req?.user?.id && agentId) {
    dbFiles = await filterFilesByAgentAccess({
      files: allFiles,
      userId: req.user.id,
      role: req.user.role,
      agentId,
    });
  } else {
    dbFiles = allFiles;
  }

  dbFiles = dbFiles.concat(resourceFiles);

  const files = [];
  const sessions = new Map();
  let toolContext = '';

  for (let i = 0; i < dbFiles.length; i++) {
    const file = dbFiles[i];
    if (!file) {
      continue;
    }

    if (file.metadata.fileIdentifier) {
      const [path, queryString] = file.metadata.fileIdentifier.split('?');
      const [session_id, id] = path.split('/');

      /**
       * `pushFile` accepts optional overrides so the reupload path can
       * push the FRESH `(session_id, id)` parsed off the new
       * `fileIdentifier`. Without these overrides, the closure would
       * capture the stale pre-reupload refs from the outer loop and
       * the in-memory `files` array (now consumed by
       * `buildInitialToolSessions` to seed `Graph.sessions`) would
       * point at a sandbox object that no longer exists. The DB record
       * gets the new identifier via `updateFile`, but the seed would
       * still inject the old one — bash_tool / read_file would 404
       * trying to mount the file until the next turn re-reads metadata.
       */
      const pushFile = (overrideSessionId, overrideId) => {
        if (!toolContext) {
          toolContext = `- Note: The following files are available in the "${Tools.execute_code}" tool environment:`;
        }

        let fileSuffix = '';
        if (!agentResourceIds.has(file.file_id)) {
          fileSuffix =
            file.context === FileContext.execute_code
              ? ' (from previous code execution)'
              : ' (attached by user)';
        }

        toolContext += `\n\t- /mnt/data/${file.filename}${fileSuffix}`;
        files.push({
          id: overrideId ?? id,
          session_id: overrideSessionId ?? session_id,
          name: file.filename,
        });
      };

      if (sessions.has(session_id)) {
        pushFile();
        continue;
      }

      let queryParams = {};
      if (queryString) {
        queryParams = Object.fromEntries(new URLSearchParams(queryString).entries());
      }

      const reuploadFile = async () => {
        try {
          const { getDownloadStream } = getStrategyFunctions(file.source);
          const { handleFileUpload: uploadCodeEnvFile } = getStrategyFunctions(
            FileSources.execute_code,
          );
          const stream = await getDownloadStream(options.req, file.filepath);
          const fileIdentifier = await uploadCodeEnvFile({
            req: options.req,
            stream,
            filename: file.filename,
            entity_id: queryParams.entity_id,
          });

          // Preserve existing metadata when adding fileIdentifier
          const updatedMetadata = {
            ...file.metadata, // Preserve existing metadata (like S3 storage info)
            fileIdentifier, // Add fileIdentifier
          };

          await updateFile({
            file_id: file.file_id,
            metadata: updatedMetadata,
          });
          /**
           * Parse the FRESH fileIdentifier returned by the reupload and
           * route it through both the dedupe Map and the in-memory
           * `files` list. The original `(session_id, id)` parsed at the
           * top of this iteration refer to the old, expired/missing
           * sandbox object — using them here would silently re-introduce
           * the bug `Graph.sessions` seeding is supposed to fix.
           */
          const [newPath] = fileIdentifier.split('?');
          const [newSessionId, newId] = newPath.split('/');
          sessions.set(newSessionId, true);
          pushFile(newSessionId, newId);
        } catch (error) {
          logger.error(
            `Error re-uploading file ${id} in session ${session_id}: ${error.message}`,
            error,
          );
        }
      };
      const uploadTime = await getSessionInfo(file.metadata.fileIdentifier);
      if (!uploadTime) {
        logger.warn(`Failed to get upload time for file ${id} in session ${session_id}`);
        await reuploadFile();
        continue;
      }
      if (!checkIfActive(uploadTime)) {
        await reuploadFile();
        continue;
      }
      sessions.set(session_id, true);
      pushFile();
    }
  }

  return { files, toolContext };
};

/**
 * Reads a single file from the code-execution sandbox by shelling `cat`
 * through the sandbox `/exec` endpoint. Used by the `read_file` host
 * handler when the requested path is a code-env path (`/mnt/data/...`)
 * or otherwise not resolvable as a skill file. Resolves to
 * `{ content }` from stdout on success, or `null` when the codeapi base
 * URL isn't configured / the read returns no content (caller turns that
 * into a model-visible error). Throws axios-style errors on transport
 * failure so the caller can surface a meaningful error message.
 *
 * `session_id` and `files` come from the seeded `tc.codeSessionContext`
 * (emitted by the agents-side `ToolNode` for `read_file` calls in
 * v3.1.72+) so the read lands in the same sandbox session that holds
 * the agent's prior-turn artifacts.
 *
 * @param {Object} params
 * @param {string} params.file_path - Absolute path inside the sandbox (e.g. `/mnt/data/foo.txt`).
 * @param {string} [params.session_id] - Sandbox session id from the seeded context.
 * @param {Array<{id: string, name: string, session_id?: string}>} [params.files] - File refs to mount.
 * @returns {Promise<{content: string} | null>}
 */
async function readSandboxFile({ file_path, session_id, files }) {
  const baseURL = getCodeBaseURL();
  if (!baseURL) {
    return null;
  }

  /** Single-quote `file_path` with embedded-quote escaping so a malicious
   *  filename can't break out of the `cat` command. The handler upstream
   *  has already established this is a code-env path the model
   *  legitimately asked to read; this just keeps the shell quoting safe. */
  const safePath = `'${file_path.replace(/'/g, `'\\''`)}'`;
  /** @type {Record<string, unknown>} */
  const postData = { lang: 'bash', code: `cat ${safePath}` };
  if (session_id) {
    postData.session_id = session_id;
  }
  if (files && files.length > 0) {
    postData.files = files;
  }

  try {
    const response = await axios({
      method: 'post',
      url: `${baseURL}/exec`,
      data: postData,
      headers: {
        'Content-Type': 'application/json',
        'User-Agent': 'LibreChat/1.0',
      },
      httpAgent: codeServerHttpAgent,
      httpsAgent: codeServerHttpsAgent,
      timeout: 15000,
    });
    const result = response?.data ?? {};
    if (result.stderr && (result.stdout == null || result.stdout === '')) {
      throw new Error(String(result.stderr).trim());
    }
    if (result.stdout == null) {
      return null;
    }
    return { content: String(result.stdout) };
  } catch (error) {
    logAxiosError({
      message: `Error reading sandbox file "${file_path}"`,
      error,
    });
    throw error;
  }
}

module.exports = {
  primeFiles,
  checkIfActive,
  getSessionInfo,
  processCodeOutput,
  readSandboxFile,
};