Mini Shell

# -*- coding: utf-8 -*-
"""
    flask.debughelpers
    ~~~~~~~~~~~~~~~~~~

    Various helpers to make the development experience better.

    :copyright: 2010 Pallets
    :license: BSD-3-Clause
"""
import os
from warnings import warn

from ._compat import implements_to_string
from ._compat import text_type
from .app import Flask
from .blueprints import Blueprint
from .globals import _request_ctx_stack


class UnexpectedUnicodeError(AssertionError, UnicodeError):
    """Raised in places where we want some better error reporting for
    unexpected unicode or binary data.
    """


@implements_to_string
class DebugFilesKeyError(KeyError, AssertionError):
    """Raised from request.files during debugging.  The idea is that it can
    provide a better error message than just a generic KeyError/BadRequest.
    """

    def __init__(self, request, key):
        form_matches = request.form.getlist(key)
        buf = [
            'You tried to access the file "%s" in the request.files '
            "dictionary but it does not exist.  The mimetype for the request "
            'is "%s" instead of "multipart/form-data" which means that no '
            "file contents were transmitted.  To fix this error you should "
            'provide enctype="multipart/form-data" in your form.'
            % (key, request.mimetype)
        ]
        if form_matches:
            buf.append(
                "\n\nThe browser instead transmitted some file names. "
                "This was submitted: %s" % ", ".join('"%s"' % x for x in form_matches)
            )
        self.msg = "".join(buf)

    def __str__(self):
        return self.msg


class FormDataRoutingRedirect(AssertionError):
    """This exception is raised by Flask in debug mode if it detects a
    redirect caused by the routing system when the request method is not
    GET, HEAD or OPTIONS.  Reasoning: form data will be dropped.
    """

    def __init__(self, request):
        exc = request.routing_exception
        buf = [
            "A request was sent to this URL (%s) but a redirect was "
            'issued automatically by the routing system to "%s".'
            % (request.url, exc.new_url)
        ]

        # In case just a slash was appended we can be extra helpful
        if request.base_url + "/" == exc.new_url.split("?")[0]:
            buf.append(
                "  The URL was defined with a trailing slash so "
                "Flask will automatically redirect to the URL "
                "with the trailing slash if it was accessed "
                "without one."
            )

        buf.append(
            "  Make sure to directly send your %s-request to this URL "
            "since we can't make browsers or HTTP clients redirect "
            "with form data reliably or without user interaction." % request.method
        )
        buf.append("\n\nNote: this exception is only raised in debug mode")
        AssertionError.__init__(self, "".join(buf).encode("utf-8"))


def attach_enctype_error_multidict(request):
    """Since Flask 0.8 we're monkeypatching the files object in case a
    request is detected that does not use multipart form data but the files
    object is accessed.
    """
    oldcls = request.files.__class__

    class newcls(oldcls):
        def __getitem__(self, key):
            try:
                return oldcls.__getitem__(self, key)
            except KeyError:
                if key not in request.form:
                    raise
                raise DebugFilesKeyError(request, key)

    newcls.__name__ = oldcls.__name__
    newcls.__module__ = oldcls.__module__
    request.files.__class__ = newcls


def _dump_loader_info(loader):
    yield "class: %s.%s" % (type(loader).__module__, type(loader).__name__)
    for key, value in sorted(loader.__dict__.items()):
        if key.startswith("_"):
            continue
        if isinstance(value, (tuple, list)):
            if not all(isinstance(x, (str, text_type)) for x in value):
                continue
            yield "%s:" % key
            for item in value:
                yield "  - %s" % item
            continue
        elif not isinstance(value, (str, text_type, int, float, bool)):
            continue
        yield "%s: %r" % (key, value)


def explain_template_loading_attempts(app, template, attempts):
    """This should help developers understand what failed"""
    info = ['Locating template "%s":' % template]
    total_found = 0
    blueprint = None
    reqctx = _request_ctx_stack.top
    if reqctx is not None and reqctx.request.blueprint is not None:
        blueprint = reqctx.request.blueprint

    for idx, (loader, srcobj, triple) in enumerate(attempts):
        if isinstance(srcobj, Flask):
            src_info = 'application "%s"' % srcobj.import_name
        elif isinstance(srcobj, Blueprint):
            src_info = 'blueprint "%s" (%s)' % (srcobj.name, srcobj.import_name)
        else:
            src_info = repr(srcobj)

        info.append("% 5d: trying loader of %s" % (idx + 1, src_info))

        for line in _dump_loader_info(loader):
            info.append("       %s" % line)

        if triple is None:
            detail = "no match"
        else:
            detail = "found (%r)" % (triple[1] or "<string>")
            total_found += 1
        info.append("       -> %s" % detail)

    seems_fishy = False
    if total_found == 0:
        info.append("Error: the template could not be found.")
        seems_fishy = True
    elif total_found > 1:
        info.append("Warning: multiple loaders returned a match for the template.")
        seems_fishy = True

    if blueprint is not None and seems_fishy:
        info.append(
            "  The template was looked up from an endpoint that "
            'belongs to the blueprint "%s".' % blueprint
        )
        info.append("  Maybe you did not place a template in the right folder?")
        info.append("  See http://flask.pocoo.org/docs/blueprints/#templates")

    app.logger.info("\n".join(info))


def explain_ignored_app_run():
    if os.environ.get("WERKZEUG_RUN_MAIN") != "true":
        warn(
            Warning(
                "Silently ignoring app.run() because the "
                "application is run from the flask command line "
                "executable.  Consider putting app.run() behind an "
                'if __name__ == "__main__" guard to silence this '
                "warning."
            ),
            stacklevel=3,
        )