import mimetypes
import os

from webob import exc
from webob.dec import wsgify
from webob.response import Response

__all__ = ["FileApp", "DirectoryApp"]

mimetypes._winreg = None  # do not load mimetypes from windows registry
mimetypes.add_type(
    "text/javascript", ".js"
)  # stdlib default is application/x-javascript
mimetypes.add_type("image/x-icon", ".ico")  # not among defaults

BLOCK_SIZE = 1 << 16


class FileApp:
    """An application that will send the file at the given filename.

    Adds a mime type based on `mimetypes.guess_type()`.
    """

    def __init__(self, filename, **kw):
        self.filename = filename
        content_type, content_encoding = mimetypes.guess_type(filename)
        kw.setdefault("content_type", content_type)
        kw.setdefault("content_encoding", content_encoding)
        kw.setdefault("accept_ranges", "bytes")
        self.kw = kw
        # Used for testing purpose
        self._open = open

    @wsgify
    def __call__(self, req):
        if req.method not in ("GET", "HEAD"):
            return exc.HTTPMethodNotAllowed("You cannot %s a file" % req.method)
        try:
            stat = os.stat(self.filename)
        except OSError as e:
            msg = f"Can't open {self.filename!r}: {e}"
            return exc.HTTPNotFound(comment=msg)

        try:
            file = self._open(self.filename, "rb")
        except OSError as e:
            msg = "You are not permitted to view this file (%s)" % e
            return exc.HTTPForbidden(msg)

        if "wsgi.file_wrapper" in req.environ:
            app_iter = req.environ["wsgi.file_wrapper"](file, BLOCK_SIZE)
        else:
            app_iter = FileIter(file)

        return Response(
            app_iter=app_iter,
            content_length=stat.st_size,
            last_modified=stat.st_mtime,
            # @@ etag
            **self.kw,
        ).conditional_response_app


class FileIter:
    def __init__(self, file):
        self.file = file

    def app_iter_range(self, seek=None, limit=None, block_size=None):
        """Iter over the content of the file.

        You can set the `seek` parameter to read the file starting from a
        specific position.

        You can set the `limit` parameter to read the file up to specific
        position.

        Finally, you can change the number of bytes read at once by setting the
        `block_size` parameter.
        """

        if block_size is None:
            block_size = BLOCK_SIZE

        if seek:
            self.file.seek(seek)
            if limit is not None:
                limit -= seek
        try:
            while True:
                data = self.file.read(
                    min(block_size, limit) if limit is not None else block_size
                )
                if not data:
                    return
                yield data
                if limit is not None:
                    limit -= len(data)
                    if limit <= 0:
                        return
        finally:
            self.file.close()

    __iter__ = app_iter_range


class DirectoryApp:
    """An application that serves up the files in a given directory.

    This will serve index files (by default ``index.html``), or set
    ``index_page=None`` to disable this.  If you set
    ``hide_index_with_redirect=True`` (it defaults to False) then
    requests to, e.g., ``/index.html`` will be redirected to ``/``.

    To customize `FileApp` instances creation (which is what actually
    serves the responses), override the `make_fileapp` method.
    """

    def __init__(
        self, path, index_page="index.html", hide_index_with_redirect=False, **kw
    ):
        self.path = os.path.abspath(path)
        if not self.path.endswith(os.path.sep):
            self.path += os.path.sep
        if not os.path.isdir(self.path):
            raise OSError("Path does not exist or is not directory: %r" % self.path)
        self.index_page = index_page
        self.hide_index_with_redirect = hide_index_with_redirect
        self.fileapp_kw = kw

    def make_fileapp(self, path):
        return FileApp(path, **self.fileapp_kw)

    @wsgify
    def __call__(self, req):
        path = os.path.abspath(os.path.join(self.path, req.path_info.lstrip("/")))
        if os.path.isdir(path) and self.index_page:
            return self.index(req, path)
        if (
            self.index_page
            and self.hide_index_with_redirect
            and path.endswith(os.path.sep + self.index_page)
        ):
            new_url = req.path_url.rsplit("/", 1)[0]
            new_url += "/"
            if req.query_string:
                new_url += "?" + req.query_string
            return Response(status=301, location=new_url)
        if not path.startswith(self.path):
            return exc.HTTPForbidden()
        elif not os.path.isfile(path):
            return exc.HTTPNotFound(comment=path)
        else:
            return self.make_fileapp(path)

    def index(self, req, path):
        index_path = os.path.join(path, self.index_page)
        if not os.path.isfile(index_path):
            return exc.HTTPNotFound(comment=index_path)
        if not req.path_info.endswith("/"):
            url = req.path_url + "/"
            if req.query_string:
                url += "?" + req.query_string
            return Response(status=301, location=url)
        return self.make_fileapp(index_path)