// ─────────────────────────────────────────────────────────────
// File Upload Component — Google Drive Backend
// ─────────────────────────────────────────────────────────────
//
// SETUP:
// 1. Replace PASTE_YOUR_FOLDER_URL_HERE with your Google Drive folder URL
//    Example: https://drive.google.com/drive/folders/1aBcDeFgHiJk
// 2. Save the project (Ctrl+S)
// 3. Deploy as Web App:
//    - Execute as: Me
//    - Who has access: Anyone
// 4. Copy the Web App URL and paste it into Framer
// ─────────────────────────────────────────────────────────────

const FOLDER_URL = "PASTE_YOUR_FOLDER_URL_HERE"

// ─────────────────────────────────────────────────────────────

function doPost(e) {
  try {

    // 1. Validate required parameters
    if (!e.parameter.filename) {
      return jsonError("Missing parameter: filename", 400)
    }
    if (!e.parameter.mimeType) {
      return jsonError("Missing parameter: mimeType", 400)
    }
    if (!e.postData || !e.postData.contents) {
      return jsonError("Missing file data in request body.", 400)
    }

    // 2. Sanitize filename
    const filename = sanitizeFilename(e.parameter.filename)
    if (!filename) {
      return jsonError("Invalid or empty filename.", 400)
    }
    const mimeType = e.parameter.mimeType

    // 3. Parse body — the component sends JSON.stringify([...new Int8Array(arrayBuffer)])
    let fileData
    try {
      fileData = JSON.parse(e.postData.contents)
    } catch (parseErr) {
      Logger.log("JSON parse error: " + parseErr.toString())
      return jsonError("Invalid file data format.", 400)
    }

    if (!Array.isArray(fileData) || fileData.length === 0) {
      return jsonError("File data is empty or not an array.", 400)
    }

    // 4. Get Drive folder (ID is extracted from FOLDER_URL automatically)
    const folderId = extractFolderId(FOLDER_URL)
    if (!folderId) {
      return jsonError("Invalid FOLDER_URL — could not extract folder ID.", 500)
    }

    let folder
    try {
      folder = DriveApp.getFolderById(folderId)
      folder.getName() // triggers error if folder is inaccessible
    } catch (folderErr) {
      Logger.log("Folder error: " + folderErr.toString())
      return jsonError("Cannot access Drive folder. Check FOLDER_URL and permissions.", 500)
    }

    // 5. Build Blob from byte array (proven working method)
    let blob
    try {
      const bytes = Utilities.newBlob(fileData).getBytes()
      blob = Utilities.newBlob(bytes, mimeType, filename)
    } catch (blobErr) {
      Logger.log("Blob error: " + blobErr.toString())
      return jsonError("Failed to process file data.", 400)
    }

    // 6. Save file to Drive
    let file
    try {
      file = folder.createFile(blob)
    } catch (createErr) {
      Logger.log("Create file error: " + createErr.toString())
      return jsonError("Failed to save file to Google Drive.", 500)
    }

    // 7. Make file publicly accessible via link
    try {
      file.setSharing(DriveApp.Access.ANYONE_WITH_LINK, DriveApp.Permission.VIEW)
    } catch (shareErr) {
      Logger.log("Share error (non-fatal): " + shareErr.toString())
    }

    // 8. Return success with file ID
    Logger.log("Upload success | ID: " + file.getId() + " | Name: " + filename)

    return ContentService
      .createTextOutput(JSON.stringify({
        success: true,
        fileId: file.getId(),
        fileName: file.getName(),
        mimeType: file.getMimeType()
      }))
      .setMimeType(ContentService.MimeType.JSON)

  } catch (err) {
    Logger.log("Unhandled error: " + err.toString())
    return jsonError("Internal server error: " + err.message, 500)
  }
}

// Health check — open the Web App URL in your browser to verify it's working
function doGet() {
  const folderId = extractFolderId(FOLDER_URL)
  return ContentService
    .createTextOutput(JSON.stringify({
      status: "File Upload Script is running ✓",
      folderConfigured: !!folderId,
      folderId: folderId || "NOT FOUND — check FOLDER_URL"
    }))
    .setMimeType(ContentService.MimeType.JSON)
}

// Extracts Folder ID from various Google Drive URL formats:
// - https://drive.google.com/drive/folders/FOLDER_ID
// - https://drive.google.com/drive/folders/FOLDER_ID?hl=id
// - Also accepts a raw folder ID string directly
function extractFolderId(url) {
  if (!url || typeof url !== "string") return null
  const match = url.match(/\/folders\/([a-zA-Z0-9_-]+)/)
  if (match && match[1]) return match[1]
  const matchQs = url.match(/[?&]id=([a-zA-Z0-9_-]+)/)
  if (matchQs && matchQs[1]) return matchQs[1]
  if (url.length >= 20 && url.length <= 60 && /^[a-zA-Z0-9_-]+$/.test(url)) return url
  return null
}

// Sanitizes filename to prevent path traversal and special character issues
function sanitizeFilename(filename) {
  if (!filename || typeof filename !== "string") return null
  let s = filename
    .replace(/\.\./g, "")
    .replace(/[\/\]/g, "")
    .replace(/[<>:"|?*]/g, "_")
    .replace(/[-]/g, "")
    .trim()
  if (s.length === 0) return null
  if (s.length > 255) {
    const ext = s.lastIndexOf(".") > -1 ? s.substring(s.lastIndexOf(".")) : ""
    s = s.substring(0, 255 - ext.length) + ext
  }
  return s
}

// Returns a structured JSON error response
function jsonError(message, statusCode) {
  Logger.log("ERROR " + statusCode + ": " + message)
  return ContentService
    .createTextOutput(JSON.stringify({
      success: false,
      error: message,
      statusCode: statusCode
    }))
    .setMimeType(ContentService.MimeType.JSON)
}