"""More comprehensive traceback formatting for Python scripts.
To enable this module, do:
    import tracebackplus; tracebackplus.enable()
at the top of your script.  The optional arguments to enable() are:
    logdir      - if set, tracebacks are written to files in this directory
    context     - number of lines of source code to show for each stack frame
By default, tracebacks are displayed but not saved and the context is 5 lines.
Alternatively, if you have caught an exception and want tracebackplus to display it
for you, call tracebackplus.handler().  The optional argument to handler() is a
3-item tuple (etype, evalue, etb) just like the value of sys.exc_info().
"""

'''
tracebackplus was derived from the cgitb standard library module. As cgitb is being
deprecated, this simplified version of cgitb was created.

https://github.com/python/cpython/blob/3.8/Lib/cgitb.py

"Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Python Software Foundation;
All Rights Reserved"

PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
--------------------------------------------

1. This LICENSE AGREEMENT is between the Python Software Foundation
("PSF"), and the Individual or Organization ("Licensee") accessing and
otherwise using this software ("Python") in source or binary form and
its associated documentation.

2. Subject to the terms and conditions of this License Agreement, PSF hereby
grants Licensee a nonexclusive, royalty-free, world-wide license to reproduce,
analyze, test, perform and/or display publicly, prepare derivative works,
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All Rights Reserved" are retained in Python alone or in any derivative version
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or incorporates Python or any part thereof, and wants to make
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Licensee hereby agrees to include in any such work a brief summary of
the changes made to Python.

4. PSF is making Python available to Licensee on an "AS IS"
basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
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DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
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5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.

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7. Nothing in this License Agreement shall be deemed to create any
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products or services of Licensee, or any third party.

8. By copying, installing or otherwise using Python, Licensee
agrees to be bound by the terms and conditions of this License
Agreement.
'''

import inspect
import keyword
import linecache
import os
import pydoc
import sys
import tempfile
import time
import tokenize
import traceback


__UNDEF__ = []                          # a special sentinel object


def lookup(name, frame, locals):
    """Find the value for a given name in the given environment."""
    if name in locals:
        return 'local', locals[name]
    if name in frame.f_globals:
        return 'global', frame.f_globals[name]
    if '__builtins__' in frame.f_globals:
        builtins = frame.f_globals['__builtins__']
        if isinstance(builtins, dict):
            if name in builtins:
                return 'builtin', builtins[name]
        else:
            if hasattr(builtins, name):
                return 'builtin', getattr(builtins, name)
    return None, __UNDEF__


def scanvars(reader, frame, locals):
    """Scan one logical line of Python and look up values of variables used."""
    vars, lasttoken, parent, prefix, value = [], None, None, '', __UNDEF__
    for ttype, token, start, end, line in tokenize.generate_tokens(reader):
        if ttype == tokenize.NEWLINE:
            break
        if ttype == tokenize.NAME and token not in keyword.kwlist:
            if lasttoken == '.':
                if parent is not __UNDEF__:
                    value = getattr(parent, token, __UNDEF__)
                    vars.append((prefix + token, prefix, value))
            else:
                where, value = lookup(token, frame, locals)
                vars.append((token, where, value))
        elif token == '.':
            prefix += lasttoken + '.'
            parent = value
        else:
            parent, prefix = None, ''
        lasttoken = token
    return vars


def text(einfo, context=5):
    """Return a plain text document describing a given traceback."""
    etype, evalue, etb = einfo
    if isinstance(etype, type):
        etype = etype.__name__
    pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable
    date = time.ctime(time.time())
    head = '%s\n%s\n%s\n' % (str(etype), pyver, date) + '''
A problem occurred in a Python script.  Here is the sequence of
function calls leading up to the error, in the order they occurred.
'''

    frames = []
    records = inspect.getinnerframes(etb, context)
    for frame, file, lnum, func, lines, index in records:
        file = file and os.path.abspath(file) or '?'
        args, varargs, varkw, locals = inspect.getargvalues(frame)
        call = ''
        if func != '?':
            call = 'in ' + func + \
                inspect.formatargvalues(args, varargs, varkw, locals,
                                        formatvalue=lambda value: '=' + pydoc.text.repr(value))

        highlight = {}

        def reader(lnum=[lnum]):
            highlight[lnum[0]] = 1
            try:
                return linecache.getline(file, lnum[0])
            finally:
                lnum[0] += 1
        vars = scanvars(reader, frame, locals)

        rows = [' %s %s' % (file, call)]
        if index is not None:
            i = lnum - index
            for line in lines:
                num = '%5d ' % i
                rows.append(num + line.rstrip())
                i += 1

        done, dump = {}, []
        for name, where, value in vars:
            if name in done:
                continue
            done[name] = 1
            if value is not __UNDEF__:
                if where == 'global':
                    name = 'global ' + name
                elif where != 'local':
                    name = where + name.split('.')[-1]
                dump.append('%s = %s' % (name, pydoc.text.repr(value)))
            else:
                dump.append(name + ' undefined')

        rows.append('\n'.join(dump))
        frames.append('\n%s\n' % '\n'.join(rows))

    exception = ['%s: %s' % (str(etype), str(evalue))]
    for name in dir(evalue):
        value = pydoc.text.repr(getattr(evalue, name))
        exception.append('\n%s%s = %s' % (' ' * 4, name, value))

    return head + ''.join(frames) + ''.join(exception) + '''

The above is a description of an error in a Python program.  Here is
the original traceback:

%s
''' % ''.join(traceback.format_exception(etype, evalue, etb))


class Hook:
    """A hook to replace sys.excepthook"""

    def __init__(self, logdir=None, context=5, file=None):
        self.logdir = logdir            # log tracebacks to files if not None
        self.context = context          # number of source code lines per frame
        self.file = file or sys.stdout  # place to send the output

    def __call__(self, etype, evalue, etb):
        self.handle((etype, evalue, etb))

    def handle(self, info=None):
        info = info or sys.exc_info()

        formatter = text

        try:
            doc = formatter(info, self.context)
        except:                         # just in case something goes wrong
            doc = ''.join(traceback.format_exception(*info))

        self.file.write(doc + '\n')

        if self.logdir is not None:
            suffix = '.txt'
            (fd, path) = tempfile.mkstemp(suffix=suffix, dir=self.logdir)

            try:
                with os.fdopen(fd, 'w') as file:
                    file.write(doc)
                msg = '%s contains the description of this error.' % path
            except:
                msg = 'Tried to save traceback to %s, but failed.' % path

            self.file.write(msg + '\n')

        try:
            self.file.flush()
        except:
            pass


handler = Hook().handle


def enable(logdir=None, context=5):
    """Install an exception handler that sends verbose tracebacks to STDOUT."""
    sys.excepthook = Hook(logdir=logdir, context=context)