commit 0578d398e624c69ba1f562d748be2e202f323e2f
Author: hex <hex@punk.lgbt>
Date:   Thu Jul 10 19:42:22 2025 +0000

    Yoinked from my Confluence proof-of-concept page.

diff --git a/engine.py b/engine.py
new file mode 100644
index 0000000..9ed0b6d
--- /dev/null
+++ b/engine.py
@@ -0,0 +1,163 @@
+# Config Generator
+# Written by Hex Ripley
+import re
+import ipaddress
+ 
+#### Regex Templates ####
+ 
+# Valid IP/CIDR notation pattern
+ip_cidr_pattern = re.compile(r'^(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}|\[?[a-fA-F0-9:\.]+\]?)\/(\d{1,2})$') # Regex identifies valid ip/cidr input
+# use with ValueError | if ip_cidr_pattern.match(ip_cidr):
+# when building       |     ...
+# interpreters and    | else:
+# evaluators          |    raise ValueError("Invalid IP/CIDR notation")
+ 
+# Valid JUNOS interface pattern E.G. ae0 or xe-0/1/2
+interface_pattern = re.compile(r'^(ae[0-9]{1,2}|[gx]e-[0-9]\/[0-9]\/[0-9])$')
+ 
+#### Input interpreters ####
+ 
+def get_cidr(ip_cidr): # Grab the CIDR notation off a user's input
+    if ip_cidr_pattern.match(ip_cidr):
+        network = ipaddress.ip_network(ip_cidr, strict=False)
+        prefix_length = network.prefixlen
+        return prefix_length
+    else:
+        raise ValueError("Invalid ip/cidr notation on get_cidr call")
+ 
+def get_network_block(ip_cidr): # If the user gives an address that is not the network address, find the network address.
+    if ip_cidr_pattern.match(ip_cidr):
+        network = ipaddress.ip_network(ip_cidr, strict=False)
+        network_address = network.network_address
+        prefix_length = network.prefixlen
+        network_block = f"{network_address}/{prefix_length}"
+        return network_block
+    else:
+        raise ValueError("Invalid ip/cidr notation on get_network_block call")
+ 
+def get_next_ip_in_subnet(ip_cidr): # Return the next IP within the subnet
+    if ip_cidr_pattern.match(ip_cidr):
+        network = ipaddress.ip_network(ip_cidr, strict=False)
+        ip = ipaddress.ip_address(ip_cidr.split('/')[0])
+        if ip == network.broadcast_address:
+            raise ValueError("IP address is the broadcast address; no next IP in the subnet.")
+        next_ip = ip + 1
+        if next_ip in network: # Make sure next IP is within subnet
+            return f"{next_ip}/{network.prefixlen}"
+        else:
+            raise ValueError("Next IP address is outside the subnet.")
+ 
+#### Evaluator Engine ####
+ 
+def template_engine(config_data_template): # Does the work!
+    data_strings = {}
+    template_strings = config_data_template["template_output"]
+    evaluation_functions = config_data_template["evaluation_functions"]
+    interpreter_functions = config_data_template["interpreter_functions"]
+     
+    for evaluator in evaluation_functions.items():
+        template_string = evaluator[0]
+        prompt_and_evaluator = evaluator[1]
+        evaluated_input = get_valid_input(prompt_and_evaluator[0],prompt_and_evaluator[1])
+        data_strings[template_string] = evaluated_input
+     
+    for interpreter in interpreter_functions.items():
+        template_string = interpreter[0]
+        interpreter_and_key = interpreter[1]
+        interpreted_value = interpreter_and_key[0](data_strings[interpreter_and_key[1]])
+        data_strings[template_string] = interpreted_value
+     
+    adjusted_strings = replace_target_words(template_strings,data_strings)
+    print("\n ---- \n")
+    for string in adjusted_strings:
+        print(string)
+    print("\n")
+ 
+def replace_target_words(strings, replacements): # Function to replace words in a string
+    def replace_in_string(s):
+        # Find all target words in braces (e.g., {word})
+        return re.sub(r'\{([a-zA-Z0-9_]+)\}', lambda match: replacements.get(match.group(1), match.group(1)), s)
+ 
+    # Apply replacement to all strings
+    return [replace_in_string(s) for s in strings]
+ 
+def get_valid_input(prompt, eval_func): # Input validater, does not proceed until validation function is satisfied.
+    while True:
+        user_input = input(prompt+" > ")
+        try:
+            # Attempt to evaluate the input using the provided function
+            result = eval_func(user_input)
+            return result
+        except Exception as e:
+            # Print error message and prompt again
+            print(f"Invalid input: {e}. Please try again.")
+ 
+#### Evaluator Functions ####
+ 
+def eval_interface(interface): # Check if interface is valid.
+    if interface_pattern.match(interface):
+        return interface
+    else:
+        raise ValueError("Invalid Interface: Correct examples ae0, ge-1/2/4")
+     
+def eval_unit_number(unit_number): # Check if unit number is valid for what we expect to be configured.
+    try:
+        if unit_number is not None and 0 < int(unit_number) < 30000:
+            return unit_number
+        else:
+            return ValueError()
+    except:
+        raise ValueError("Invalid Unit Number: Enter a unit greater than 0 and less than 30,000")
+     
+def eval_access_block(access_block):
+    if ip_cidr_pattern.match(access_block):
+        return access_block
+    else:
+        raise ValueError("Invalid ip/cidr notation")
+ 
+def eval_transport_block(transport_block):
+    if ip_cidr_pattern.match(transport_block):
+        if get_cidr(transport_block) == 64:
+            return transport_block
+        else:
+            raise ValueError("Transport Block CIDR must be 64")
+    else:
+        raise ValueError("Invalid ip/cidr notation")
+ 
+#### Data Template ####
+ 
+#### Data Templates are a dict with three keys:
+ 
+## template_output ##
+ 
+#template_output is a list of lines of strings containing lines of config with desired variables in braces.
+ 
+## evaluation_functions ##
+ 
+#evaluation_functions is a dict with the keys being the target variable and the values being a list containing the input for the get_valid_input function, which takes the first value as a prompt to show to the user and the second value as an evaluator function to run on the user's input.
+ 
+## interpreter_functions ##
+ 
+#interpreter_functions is a dict with keys being the target variable and the values being a list containing the desired interpreter function and the target value for the interpreter function. The target value for the interpreter function can be the key of a previous evaluation function or previous interpreter_function.
+ 
+config_ipv6_junos = {
+"template_output" : [
+  "set interfaces {interface} unit {unit_number} family inet6 address {access_first}",
+  "set routing-options rib inet6.0 static route {transport_block} next-hop {access_second}",
+  "set routing-options rib inet6.0 static route {transport_block} tag 101",
+  "set policy-options prefix-list bgp-advertise-v6 {access_block}"
+] ,
+"evaluation_functions" : {
+  "interface" : ["What is the user's interface?",eval_interface],
+  "unit_number" : ["What is the user's unit number?",eval_unit_number],
+  "access_block" : ["What is the IPv6 Access Block?",eval_access_block],
+  "transport_block" : ["What is the IPv6 Transport Block?",eval_transport_block]
+} ,
+"interpreter_functions" : {
+  "access_first" : [get_next_ip_in_subnet,"access_block"],
+  "access_second" : [get_next_ip_in_subnet,"access_first"]
+} }
+ 
+### Run this example
+ 
+template_engine(config_ipv6_junos)
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