"""Module with helpers for serving static files."""

import os
import platform
import re
import stat
import mimetypes
import urllib.parse
import unicodedata

from email.generator import _make_boundary as make_boundary
from io import UnsupportedOperation

import cherrypy
from cherrypy._cpcompat import ntob
from cherrypy.lib import cptools, httputil, file_generator_limited


def _setup_mimetypes():
    """Pre-initialize global mimetype map."""
    if not mimetypes.inited:
        mimetypes.init()
    mimetypes.types_map['.dwg'] = 'image/x-dwg'
    mimetypes.types_map['.ico'] = 'image/x-icon'
    mimetypes.types_map['.bz2'] = 'application/x-bzip2'
    mimetypes.types_map['.gz'] = 'application/x-gzip'


_setup_mimetypes()


def _make_content_disposition(disposition, file_name):
    """Create HTTP header for downloading a file with a UTF-8 filename.

    This function implements the recommendations of :rfc:`6266#appendix-D`.
    See this and related answers: https://stackoverflow.com/a/8996249/2173868.
    """
    # As normalization algorithm for `unicodedata` is used composed form (NFC
    # and NFKC) with compatibility equivalence criteria (NFK), so "NFKC" is the
    # one. It first applies the compatibility decomposition, followed by the
    # canonical composition. Should be displayed in the same manner, should be
    # treated in the same way by applications such as alphabetizing names or
    # searching, and may be substituted for each other.
    # See: https://en.wikipedia.org/wiki/Unicode_equivalence.
    ascii_name = (
        unicodedata.normalize('NFKC', file_name).
        encode('ascii', errors='ignore').decode()
    )
    header = '{}; filename="{}"'.format(disposition, ascii_name)
    if ascii_name != file_name:
        quoted_name = urllib.parse.quote(file_name)
        header += '; filename*=UTF-8\'\'{}'.format(quoted_name)
    return header


def serve_file(path, content_type=None, disposition=None, name=None,
               debug=False):
    """Set status, headers, and body in order to serve the given path.

    The Content-Type header will be set to the content_type arg, if provided.
    If not provided, the Content-Type will be guessed by the file extension
    of the 'path' argument.

    If disposition is not None, the Content-Disposition header will be set
    to "<disposition>; filename=<name>; filename*=utf-8''<name>"
    as described in :rfc:`6266#appendix-D`.
    If name is None, it will be set to the basename of path.
    If disposition is None, no Content-Disposition header will be written.
    """
    response = cherrypy.serving.response

    # If path is relative, users should fix it by making path absolute.
    # That is, CherryPy should not guess where the application root is.
    # It certainly should *not* use cwd (since CP may be invoked from a
    # variety of paths). If using tools.staticdir, you can make your relative
    # paths become absolute by supplying a value for "tools.staticdir.root".
    if not os.path.isabs(path):
        msg = "'%s' is not an absolute path." % path
        if debug:
            cherrypy.log(msg, 'TOOLS.STATICFILE')
        raise ValueError(msg)

    try:
        st = os.stat(path)
    except (OSError, TypeError, ValueError):
        # OSError when file fails to stat
        # TypeError on Python 2 when there's a null byte
        # ValueError on Python 3 when there's a null byte
        if debug:
            cherrypy.log('os.stat(%r) failed' % path, 'TOOLS.STATIC')
        raise cherrypy.NotFound()

    # Check if path is a directory.
    if stat.S_ISDIR(st.st_mode):
        # Let the caller deal with it as they like.
        if debug:
            cherrypy.log('%r is a directory' % path, 'TOOLS.STATIC')
        raise cherrypy.NotFound()

    # Set the Last-Modified response header, so that
    # modified-since validation code can work.
    response.headers['Last-Modified'] = httputil.HTTPDate(st.st_mtime)
    cptools.validate_since()

    if content_type is None:
        # Set content-type based on filename extension
        ext = ''
        i = path.rfind('.')
        if i != -1:
            ext = path[i:].lower()
        content_type = mimetypes.types_map.get(ext, None)
    if content_type is not None:
        response.headers['Content-Type'] = content_type
    if debug:
        cherrypy.log('Content-Type: %r' % content_type, 'TOOLS.STATIC')

    cd = None
    if disposition is not None:
        if name is None:
            name = os.path.basename(path)
        cd = _make_content_disposition(disposition, name)
        response.headers['Content-Disposition'] = cd
    if debug:
        cherrypy.log('Content-Disposition: %r' % cd, 'TOOLS.STATIC')

    # Set Content-Length and use an iterable (file object)
    #   this way CP won't load the whole file in memory
    content_length = st.st_size
    fileobj = open(path, 'rb')
    return _serve_fileobj(fileobj, content_type, content_length, debug=debug)


def serve_fileobj(fileobj, content_type=None, disposition=None, name=None,
                  debug=False):
    """Set status, headers, and body in order to serve the given file object.

    The Content-Type header will be set to the content_type arg, if provided.

    If disposition is not None, the Content-Disposition header will be set
    to "<disposition>; filename=<name>; filename*=utf-8''<name>"
    as described in :rfc:`6266#appendix-D`.
    If name is None, 'filename' will not be set.
    If disposition is None, no Content-Disposition header will be written.

    CAUTION: If the request contains a 'Range' header, one or more seek()s will
    be performed on the file object.  This may cause undesired behavior if
    the file object is not seekable.  It could also produce undesired results
    if the caller set the read position of the file object prior to calling
    serve_fileobj(), expecting that the data would be served starting from that
    position.
    """
    response = cherrypy.serving.response

    try:
        st = os.fstat(fileobj.fileno())
    except AttributeError:
        if debug:
            cherrypy.log('os has no fstat attribute', 'TOOLS.STATIC')
        content_length = None
    except UnsupportedOperation:
        content_length = None
    else:
        # Set the Last-Modified response header, so that
        # modified-since validation code can work.
        response.headers['Last-Modified'] = httputil.HTTPDate(st.st_mtime)
        cptools.validate_since()
        content_length = st.st_size

    if content_type is not None:
        response.headers['Content-Type'] = content_type
    if debug:
        cherrypy.log('Content-Type: %r' % content_type, 'TOOLS.STATIC')

    cd = None
    if disposition is not None:
        if name is None:
            cd = disposition
        else:
            cd = _make_content_disposition(disposition, name)
        response.headers['Content-Disposition'] = cd
    if debug:
        cherrypy.log('Content-Disposition: %r' % cd, 'TOOLS.STATIC')

    return _serve_fileobj(fileobj, content_type, content_length, debug=debug)


def _serve_fileobj(fileobj, content_type, content_length, debug=False):
    """Internal. Set response.body to the given file object, perhaps ranged."""
    response = cherrypy.serving.response

    # HTTP/1.0 didn't have Range/Accept-Ranges headers, or the 206 code
    request = cherrypy.serving.request
    if request.protocol >= (1, 1):
        response.headers['Accept-Ranges'] = 'bytes'
        r = httputil.get_ranges(request.headers.get('Range'), content_length)
        if r == []:
            response.headers['Content-Range'] = 'bytes */%s' % content_length
            message = ('Invalid Range (first-byte-pos greater than '
                       'Content-Length)')
            if debug:
                cherrypy.log(message, 'TOOLS.STATIC')
            raise cherrypy.HTTPError(416, message)

        if r:
            if len(r) == 1:
                # Return a single-part response.
                start, stop = r[0]
                if stop > content_length:
                    stop = content_length
                r_len = stop - start
                if debug:
                    cherrypy.log(
                        'Single part; start: %r, stop: %r' % (start, stop),
                        'TOOLS.STATIC')
                response.status = '206 Partial Content'
                response.headers['Content-Range'] = (
                    'bytes %s-%s/%s' % (start, stop - 1, content_length))
                response.headers['Content-Length'] = r_len
                fileobj.seek(start)
                response.body = file_generator_limited(fileobj, r_len)
            else:
                # Return a multipart/byteranges response.
                response.status = '206 Partial Content'
                boundary = make_boundary()
                ct = 'multipart/byteranges; boundary=%s' % boundary
                response.headers['Content-Type'] = ct
                if 'Content-Length' in response.headers:
                    # Delete Content-Length header so finalize() recalcs it.
                    del response.headers['Content-Length']

                def file_ranges():
                    # Apache compatibility:
                    yield b'\r\n'

                    for start, stop in r:
                        if debug:
                            cherrypy.log(
                                'Multipart; start: %r, stop: %r' % (
                                    start, stop),
                                'TOOLS.STATIC')
                        yield ntob('--' + boundary, 'ascii')
                        yield ntob('\r\nContent-type: %s' % content_type,
                                   'ascii')
                        yield ntob(
                            '\r\nContent-range: bytes %s-%s/%s\r\n\r\n' % (
                                start, stop - 1, content_length),
                            'ascii')
                        fileobj.seek(start)
                        gen = file_generator_limited(fileobj, stop - start)
                        for chunk in gen:
                            yield chunk
                        yield b'\r\n'
                    # Final boundary
                    yield ntob('--' + boundary + '--', 'ascii')

                    # Apache compatibility:
                    yield b'\r\n'
                response.body = file_ranges()
            return response.body
        else:
            if debug:
                cherrypy.log('No byteranges requested', 'TOOLS.STATIC')

    # Set Content-Length and use an iterable (file object)
    #   this way CP won't load the whole file in memory
    response.headers['Content-Length'] = content_length
    response.body = fileobj
    return response.body


def serve_download(path, name=None):
    """Serve 'path' as an application/x-download attachment."""
    # This is such a common idiom I felt it deserved its own wrapper.
    return serve_file(path, 'application/x-download', 'attachment', name)


def _attempt(filename, content_types, debug=False):
    if debug:
        cherrypy.log('Attempting %r (content_types %r)' %
                     (filename, content_types), 'TOOLS.STATICDIR')
    try:
        # you can set the content types for a
        # complete directory per extension
        content_type = None
        if content_types:
            r, ext = os.path.splitext(filename)
            content_type = content_types.get(ext[1:], None)
        serve_file(filename, content_type=content_type, debug=debug)
        return True
    except cherrypy.NotFound:
        # If we didn't find the static file, continue handling the
        # request. We might find a dynamic handler instead.
        if debug:
            cherrypy.log('NotFound', 'TOOLS.STATICFILE')
        return False


def staticdir(section, dir, root='', match='', content_types=None, index='',
              debug=False):
    """Serve a static resource from the given (root +) dir.

    match
        If given, request.path_info will be searched for the given
        regular expression before attempting to serve static content.

    content_types
        If given, it should be a Python dictionary of
        {file-extension: content-type} pairs, where 'file-extension' is
        a string (e.g. "gif") and 'content-type' is the value to write
        out in the Content-Type response header (e.g. "image/gif").

    index
        If provided, it should be the (relative) name of a file to
        serve for directory requests. For example, if the dir argument is
        '/home/me', the Request-URI is 'myapp', and the index arg is
        'index.html', the file '/home/me/myapp/index.html' will be sought.
    """
    request = cherrypy.serving.request
    if request.method not in ('GET', 'HEAD'):
        if debug:
            cherrypy.log('request.method not GET or HEAD', 'TOOLS.STATICDIR')
        return False

    if match and not re.search(match, request.path_info):
        if debug:
            cherrypy.log('request.path_info %r does not match pattern %r' %
                         (request.path_info, match), 'TOOLS.STATICDIR')
        return False

    # Allow the use of '~' to refer to a user's home directory.
    dir = os.path.expanduser(dir)

    # If dir is relative, make absolute using "root".
    if not os.path.isabs(dir):
        if not root:
            msg = 'Static dir requires an absolute dir (or root).'
            if debug:
                cherrypy.log(msg, 'TOOLS.STATICDIR')
            raise ValueError(msg)
        dir = os.path.join(root, dir)

    # Determine where we are in the object tree relative to 'section'
    # (where the static tool was defined).
    if section == 'global':
        section = '/'
    section = section.rstrip(r'\/')
    branch = request.path_info[len(section) + 1:]
    branch = urllib.parse.unquote(branch.lstrip(r'\/'))

    # Requesting a file in sub-dir of the staticdir results
    # in mixing of delimiter styles, e.g. C:\static\js/script.js.
    # Windows accepts this form except not when the path is
    # supplied in extended-path notation, e.g. \\?\C:\static\js/script.js.
    # http://bit.ly/1vdioCX
    if platform.system() == 'Windows':
        branch = branch.replace('/', '\\')

    # If branch is "", filename will end in a slash
    filename = os.path.join(dir, branch)
    if debug:
        cherrypy.log('Checking file %r to fulfill %r' %
                     (filename, request.path_info), 'TOOLS.STATICDIR')

    # There's a chance that the branch pulled from the URL might
    # have ".." or similar uplevel attacks in it. Check that the final
    # filename is a child of dir.
    if not os.path.normpath(filename).startswith(os.path.normpath(dir)):
        raise cherrypy.HTTPError(403)  # Forbidden

    handled = _attempt(filename, content_types)
    if not handled:
        # Check for an index file if a folder was requested.
        if index:
            handled = _attempt(os.path.join(filename, index), content_types)
            if handled:
                request.is_index = filename[-1] in (r'\/')
    return handled


def staticfile(filename, root=None, match='', content_types=None, debug=False):
    """Serve a static resource from the given (root +) filename.

    match
        If given, request.path_info will be searched for the given
        regular expression before attempting to serve static content.

    content_types
        If given, it should be a Python dictionary of
        {file-extension: content-type} pairs, where 'file-extension' is
        a string (e.g. "gif") and 'content-type' is the value to write
        out in the Content-Type response header (e.g. "image/gif").

    """
    request = cherrypy.serving.request
    if request.method not in ('GET', 'HEAD'):
        if debug:
            cherrypy.log('request.method not GET or HEAD', 'TOOLS.STATICFILE')
        return False

    if match and not re.search(match, request.path_info):
        if debug:
            cherrypy.log('request.path_info %r does not match pattern %r' %
                         (request.path_info, match), 'TOOLS.STATICFILE')
        return False

    # If filename is relative, make absolute using "root".
    if not os.path.isabs(filename):
        if not root:
            msg = "Static tool requires an absolute filename (got '%s')." % (
                filename,)
            if debug:
                cherrypy.log(msg, 'TOOLS.STATICFILE')
            raise ValueError(msg)
        filename = os.path.join(root, filename)

    return _attempt(filename, content_types, debug=debug)
