Sync all skills and memories 2026-04-14 07:27

skills/creative/excalidraw/scripts/upload.py

@@ -0,0 +1,133 @@
+#!/usr/bin/env python3
+"""
+Upload an .excalidraw file to excalidraw.com and print a shareable URL.
+
+No account required. The diagram is encrypted client-side (AES-GCM) before
+upload -- the encryption key is embedded in the URL fragment, so the server
+never sees plaintext.
+
+Requirements:
+    pip install cryptography
+
+Usage:
+    python upload.py <path-to-file.excalidraw>
+
+Example:
+    python upload.py ~/diagrams/architecture.excalidraw
+    # prints: https://excalidraw.com/#json=abc123,encryptionKeyHere
+"""
+
+import json
+import os
+import struct
+import sys
+import zlib
+import base64
+import urllib.request
+
+try:
+    from cryptography.hazmat.primitives.ciphers.aead import AESGCM
+except ImportError:
+    print("Error: 'cryptography' package is required for upload.")
+    print("Install it with: pip install cryptography")
+    sys.exit(1)
+
+# Excalidraw public upload endpoint (no auth needed)
+UPLOAD_URL = "https://json.excalidraw.com/api/v2/post/"
+
+
+def concat_buffers(*buffers: bytes) -> bytes:
+    """
+    Build the Excalidraw v2 concat-buffers binary format.
+
+    Layout: [version=1 (4B big-endian)] then for each buffer:
+            [length (4B big-endian)] [data bytes]
+    """
+    parts = [struct.pack(">I", 1)]  # version = 1
+    for buf in buffers:
+        parts.append(struct.pack(">I", len(buf)))
+        parts.append(buf)
+    return b"".join(parts)
+
+
+def upload(excalidraw_json: str) -> str:
+    """
+    Encrypt and upload Excalidraw JSON to excalidraw.com.
+
+    Args:
+        excalidraw_json: The full .excalidraw file content as a string.
+
+    Returns:
+        Shareable URL string.
+    """
+    # 1. Inner payload: concat_buffers(file_metadata, data)
+    file_metadata = json.dumps({}).encode("utf-8")
+    data_bytes = excalidraw_json.encode("utf-8")
+    inner_payload = concat_buffers(file_metadata, data_bytes)
+
+    # 2. Compress with zlib
+    compressed = zlib.compress(inner_payload)
+
+    # 3. AES-GCM 128-bit encrypt
+    raw_key = os.urandom(16)   # 128-bit key
+    iv = os.urandom(12)        # 12-byte nonce
+    aesgcm = AESGCM(raw_key)
+    encrypted = aesgcm.encrypt(iv, compressed, None)
+
+    # 4. Encoding metadata
+    encoding_meta = json.dumps({
+        "version": 2,
+        "compression": "pako@1",
+        "encryption": "AES-GCM",
+    }).encode("utf-8")
+
+    # 5. Outer payload: concat_buffers(encoding_meta, iv, encrypted)
+    payload = concat_buffers(encoding_meta, iv, encrypted)
+
+    # 6. Upload
+    req = urllib.request.Request(UPLOAD_URL, data=payload, method="POST")
+    with urllib.request.urlopen(req, timeout=30) as resp:
+        if resp.status != 200:
+            raise RuntimeError(f"Upload failed with HTTP {resp.status}")
+        result = json.loads(resp.read().decode("utf-8"))
+
+    file_id = result.get("id")
+    if not file_id:
+        raise RuntimeError(f"Upload returned no file ID. Response: {result}")
+
+    # 7. Key as base64url (JWK 'k' format, no padding)
+    key_b64 = base64.urlsafe_b64encode(raw_key).rstrip(b"=").decode("ascii")
+
+    return f"https://excalidraw.com/#json={file_id},{key_b64}"
+
+
+def main():
+    if len(sys.argv) < 2:
+        print("Usage: python upload.py <path-to-file.excalidraw>")
+        sys.exit(1)
+
+    file_path = sys.argv[1]
+
+    if not os.path.isfile(file_path):
+        print(f"Error: File not found: {file_path}")
+        sys.exit(1)
+
+    with open(file_path, "r", encoding="utf-8") as f:
+        content = f.read()
+
+    # Basic validation: should be valid JSON with an "elements" key
+    try:
+        doc = json.loads(content)
+    except json.JSONDecodeError as e:
+        print(f"Error: File is not valid JSON: {e}")
+        sys.exit(1)
+
+    if "elements" not in doc:
+        print("Warning: File does not contain an 'elements' key. Uploading anyway.")
+
+    url = upload(content)
+    print(url)
+
+
+if __name__ == "__main__":
+    main()