import os
from IPython.display import Markdown as md

report = False

def consent():
    """
    Ask for consent the first time, and remember this by storing a dot file
    """

    fname = os.path.expanduser("~/.phys105_report")
    
    if os.path.isfile(fname):
        with open(".report", "r") as f:
            report = bool(int(f.read().strip("\n")))
        return report

    text = "Do you agree to consent? "
    
    pos = ["y", "yes"]
    neg = ["n", "no"]
    
    answer = input(text).lower()
    while answer not in pos + neg:
        answer = input("Please input Yes (Y) or No (N) ").lower()
        
    with open(fname, "w") as f:
        if answer in pos:
            f.write("1")
            return True
        else:
            f.write("0")            
            return False
            
    return
    

def custom_exc(shell, etype, evalue, tb, tb_offset=None):

    final = """

If you are still unsure, please ask one of the demonstrators"""
    
    shell.showtraceback((etype, evalue, tb), tb_offset=tb_offset)

    if etype == ModuleNotFoundError:
        display(md(
"""
## ModuleNotFoundError
Python is telling you it cannot find the module you tried to import.
What to do: take a look at the line number indicated by the error message, near where the ^ points
and  
* Check that the you spelt the module name correctly
* If so, check that the package is installed on your system. 
""" + final))

    elif etype == SyntaxError:
        display(md(
"""
## SyntaxError
Python is telling you that what you have written is not valid python code.  


What to do: take a look at the line number indicated by the error message, near where the ^ points 
(or the end of the pervious line if it points to the start of a line) and check 
* If you are missing an opening or closing bracket/brace
* If you have too many openning or closing brackets/braces
* if you are missing a comma or have one in an unexpected place

""" + final))

    elif etype == IndentationError:
        display(md(
"""
## IndentationError

Python is telling you that it has found an inconsistent level of indentation.
This could be e.g. in a function defintion, loop or conditional statement.

What to do: take a look at the line number indicated by the error message, near where the ^ points
and check * That the Identation is all of the same amount (i.e. same number of spaces or tabs) 
""" + final))

    elif etype == TabError:
        display(md(
"""
## TabError

Python is telling you that it has found a mix of spaces and tabs used to denote indentation.
This could be e.g. in a function defintion, loop or conditional statement.

What to do: take a look at the line number indicated by the error message, near where the ^ points and
*  Try deleting the indentation and replacing it with either spaces or tabs in each case, not a mix.
""" + final))

    elif etype == NameError:
        display(md(
"""
## NameError

Python is telling you that the variable, function or module you are trying to use cannot be found.

What to do: take a look at the line number indicated by the error message, near where the ^ points 
(or the end of the pervious line if it points to the start of a line) and check
* You have spelt the name of the variable/function correctly
* You have imported the necessary module
* That you have run the cell that has the defintion or import 
""" + final))

    elif etype == TypeError:
        display(md(
"""
## TypeError

Python is telling you that you are trying to do something with the wrong type of variable or
combine/compare variables that are of incompatible type

What to do: take a look at the line number indicated by the error message, near where the ^ points 
* Make sure you have convereted a number from a string to an int/float if you are trying to do
mathematical calculations
* Print the type() of the variable and check it is what you expect

""" + final))

    elif etype == ValueError:
        display(md(
"""
## ValueError

Python is telling you that the variable you are using has the correct type but that the value is not
acceptable.

What to do: take a look at the line number indicated by the error message, near where the ^ points
and check:
* If you are using a negative value where a positive one is requiered (e.g. in sqrt)

""" + final))

    elif etype == AttributeError:
        display(md(
""" 
## AttributeError

Python is telling you that you are asking an object or module for a variable or function it doesn't provide 

What to do: take a look at the line number indicated by the error message, near where the ^ points
and:
* Check that the variable or function is spelt correctly
* Print the type() of the variable and check it is what you expect 

""" + final))


    elif etype == KeyError:
        display(md(
"""
## KeyError

Python is telling you that you are trying to access an element of a dictionary using a key that
doesn't exist

What to do: take a look at the line number indicated by the error message, near where the ^ points
and:

* Check if the key is spelt correctly
* Print out the dict to see what it contains


""" + final))


    elif etype == IndexError:
        display(md(
"""
## IndexError

Python is telling you that you are trying to access an element of a data structure
(e.g. list/tuple/string/array etc) that is bigger than the size of the structure

What to do: take a look at the line number indicated by the error message, near where the ^ points
and:

* If you are using a variable as the index, print it out and make sure the value is what you expect
* Print out the len() of the data structure
* Make sure that you are remember that indices in python start from 0 and go to size - 1


""" + final))

    elif etype == ZeroDivisionError:
        display(md(
"""
## ZeroDivisionError:

Python is telling you that you are trying to divide a number by zero.

What to do: take a look at the line number indicated by the error message, near where the ^ points
and:

* Check if the denominator is unexpectedley zero
* Use a conditional statement to check the denominator is not zero before performing the division 


""" + final))

    else:
        display(md(
"""
We have not implemented an explanation for this error.   Try

* Looking at the python error documentation: https://docs.python.org/3/library/exceptions.html
* Try googling the error

""" + final))

        
    return 

report = consent()
del consent


# this registers a custom exception handler for the whole current notebook
get_ipython().set_custom_exc((Exception,), custom_exc)
del custom_exc