Rewrote a lot, added a lot

calc.py

@@ -1,28 +1,90 @@
 from helpers import *
 import threading
+import time
 
-calc_users = open_json_file("calc", [])
+calc_users        = open_json_file("calc", [])
+math_operators    = ["+", "-", "*", "/", "%", ">", "<", "^", "&", "|"]
+allowed_strings   = ["0b", "0x", "(", ")", "hex(", "bin(", "abs(", "int(", "min(", "max(", "round(", "float("]
 calc_perm = "utils.calc"
+calc_perm_power = "utils.calc.power"
 
-def calculate(text):
-    pass
+def calc(sender, text):
+    """
+    extracts a mathematical expression from `text`
+    returns (expression, result) or None
+    """
+    expression = ""
+    should_calc = False
+    i = 0
+    while True:
+        if i >= len(text):
+            break
+        char = text[i]
+        if i < len(text) - 5 and str(char + text[i+1] + text[i+2] + text[i+3] + text[i+4] + text[i+5]) in allowed_strings:
+            expression += char
+            expression += text[i + 1]
+            expression += text[i + 2]
+            expression += text[i + 3]
+            expression += text[i + 4]
+            expression += text[i + 5]
+            i += 5
+            should_calc = True
+        elif i < len(text) - 3 and str(char + text[i+1] + text[i+2] + text[i+3]) in allowed_strings:
+            expression += char
+            expression += text[i + 1]
+            expression += text[i + 2]
+            expression += text[i + 3]
+            i += 3
+            should_calc = True
+        elif i < len(text) - 1 and str(char + text[i + 1]) in allowed_strings:
+            expression += char
+            expression += text[i + 1]
+            i += 1
+            should_calc = True
+        elif char.isdigit() or (expression and char == ".") or (should_calc and char == " ") or (should_calc and char == ","):
+            expression += char
+            should_calc = True
+        elif char in math_operators or char in ["(", ")"]:
+            # calculation must include at least 1 operator
+            should_calc = True
+            expression += char
+        elif should_calc and char.isalpha():
+            # don't include any more text in the calculation
+            break
+        i += 1
+    last_char = ' '
+    for char in expression:
+        if last_char == '*' and char == '*':
+            if sender.hasPermission(calc_perm_power):
+                break
+            else:
+                return None
+        last_char = char
+    if should_calc:
+        try:
+            result = str(eval(expression)) # pylint: disable = W0123
+        except: # pylint: disable = W0702
+            # we can run into all kinds of errors here
+            # most probably SyntaxError
+            return None
+        return (expression, result)
+    return None
 
-def calc(text, sender):
-    try:
-        result = calculate(text)
-        msg(sender, "&2=== Calc:&6 %s" % result)
-    except:
-        msg(sender, "&2=== Calc:&c Something went wrong while calculating - calulation aborted")
+def thread_calc(message, sender):
+    output = calc(sender, message)
+    if output and sender.isOnline():
+        msg(sender, "&2=== Calc: &e" + output[0] + " &2= &c" + output[1])
 
 @hook.event("player.AsyncPlayerChatEvent", "monitor")
 def on_calc_chat(event):
     sender = event.getPlayer()
     message = event.getMessage()
     if not event.isCancelled() and uid(sender) in calc_users and sender.hasPermission(calc_perm):
-        thread = threading.Thread(target=calc, args=(message, sender))
+        thread = threading.Thread(target=thread_calc, args=(message, sender))
         thread.daemon = True
         thread.start()
 
+
 @hook.command("calc", description="Toggles chat calculations")
 def on_calc_command(sender, command, label, args):
     plugin_header(sender, "Chat Calculator")