johnameyer / repost-bot

A bot that can scan a groupme chat for reposts. It first hashes all the images, and then upon receiving a new image, it either checks with a human or calls it out.

Files:

• build_kd.sh
  • Responsible for building the kdtree executable
• callback.php
  • Entry point for callbacks from the GroupMe API for the main group
• composer.*
  • Handles dependencies for php
• groupme.php
  • Basic utility functions for cURLing the GroupMe API
• human.php
  • Entry point for callbacks from the GroupMe API for the repost checking group
• init.php
  • Handles initialization for a new GroupMe
• kd_tree.sh
  • Handles interactions with the kdtree executable including startup and timeout
• kd_tree_setup.sh
  • Setups the tmp/ input, output, and store files and starts the kdtree program
• kd_tree_sleep.sh
  • Cleans up the environment at the end of the timeout by killing kdtree and removing files
• main.cpp
  • kdtree main execution code, compiled with the kdtree library

Expected Execution Flow:

• callback.php

  • First, a post comes in from the groupme to the ./callback.php endpoint. This request also comes with a json payload of the message.
  • The php file then checks if there is an image attached and if so, execution continues by hashing the image.
  • kd_tree.sh
    • Once hashed, the id and the hash are passed to the ./kd_tree.sh script, which notes that there is no kdtree executable currently running.
    • kd_tree_setup.sh
      • As such, it hands off the current file configuration to the setup script, which setups the pipe and starts the executable with the created files and returns.
    • Once it has done this, it writes out a csv row of id,hash to the input pipe
    • This input is picked up by the kdtree executable, which then writes out the id,similar_id row to the output
    • The kd_tree.sh script waits for the id it was passed to appear in the ouput and then cuts to get the similar id, which is then echo-returned
    • Before exiting, the timeout script (./kd_tree_sleep.sh) is placed into the background
  • Once the most-similar-id is returned, the php file continues by grabbing the message and then hashes that image as well.
  • The distance between the two hashes is then compared, and if entirely similar a message is sent to the groupme.
  • If the distance is not zero, but is less than some predefined threshold, a message is then sent to an admin chat that asks for user input in discerning the two images while also saving the two images' post json.

• human.php

  • Once a user in the admin chat responds, another payload is sent to this endpoint.
  • Upon receiving, the chat does a check to see if it is a bot and then if the message was an affirmativve.
  • If affirmative, the chat then calls out the user in the chat before deleting the images' post json.

• kdtree

  • The executable first loads all the hashes from the hash store csv.
  • Upon receiving an id,hash tuple from the pipe, the program first seaches the constructed kdtree for the nearest hash.
  • Upon finding the closest, it then does a linear search over the mid-execution hashes (as the kdtree does not allow for additions after the tree is constructed.
  • After finishing the search, it appends the id,similar-id tuple to the output file

Todos

- message templates
- add support for tesseract ocr comparison
- check text similarity if image similar enough
- migrate from current kd tree setup
	- use different Points supporting bitwise nature of data
	- use self balancing kd tree http://jcgt.org/published/0004/01/03/paper.pdf
- be able to write this tree state out to a file for easy start/stop operations
- make some messages nicer
- figure out thresholds - possibly a dynamic process?