
import json

from twisted.web import http, static
from twisted.internet import defer
from nevow import url, rend
from nevow.inevow import IRequest

from allmydata.interfaces import ExistingChildError
from allmydata.monitor import Monitor
from allmydata.immutable.upload import FileHandle
from allmydata.mutable.publish import MutableFileHandle
from allmydata.mutable.common import MODE_READ
from allmydata.util import log, base32
from allmydata.util.encodingutil import quote_output
from allmydata.blacklist import FileProhibited, ProhibitedNode

from allmydata.web.common import text_plain, WebError, RenderMixin, \
     boolean_of_arg, get_arg, should_create_intermediate_directories, \
     MyExceptionHandler, parse_replace_arg, parse_offset_arg, \
     get_format, get_mutable_type, get_filenode_metadata
from allmydata.web.check_results import CheckResultsRenderer, \
     CheckAndRepairResultsRenderer, LiteralCheckResultsRenderer
from allmydata.web.info import MoreInfo

class ReplaceMeMixin:
    def replace_me_with_a_child(self, req, client, replace):
        # a new file is being uploaded in our place.
        file_format = get_format(req, "CHK")
        mutable_type = get_mutable_type(file_format)
        if mutable_type is not None:
            data = MutableFileHandle(req.content)
            d = client.create_mutable_file(data, version=mutable_type)
            def _uploaded(newnode):
                d2 = self.parentnode.set_node(self.name, newnode,
                                              overwrite=replace)
                d2.addCallback(lambda res: newnode)
                return d2
            d.addCallback(_uploaded)
        else:
            assert file_format == "CHK"
            uploadable = FileHandle(req.content, convergence=client.convergence)
            d = self.parentnode.add_file(self.name, uploadable,
                                         overwrite=replace)
        def _done(filenode):
            log.msg("webish upload complete",
                    facility="tahoe.webish", level=log.NOISY, umid="TCjBGQ")
            if self.node:
                # we've replaced an existing file (or modified a mutable
                # file), so the response code is 200
                req.setResponseCode(http.OK)
            else:
                # we've created a new file, so the code is 201
                req.setResponseCode(http.CREATED)
            return filenode.get_uri()
        d.addCallback(_done)
        return d

    def replace_me_with_a_childcap(self, req, client, replace):
        req.content.seek(0)
        childcap = req.content.read()
        childnode = client.create_node_from_uri(childcap, None, name=self.name)
        d = self.parentnode.set_node(self.name, childnode, overwrite=replace)
        d.addCallback(lambda res: childnode.get_uri())
        return d


    def replace_me_with_a_formpost(self, req, client, replace):
        # create a new file, maybe mutable, maybe immutable
        file_format = get_format(req, "CHK")
        contents = req.fields["file"]
        if file_format in ("SDMF", "MDMF"):
            mutable_type = get_mutable_type(file_format)
            uploadable = MutableFileHandle(contents.file)
            d = client.create_mutable_file(uploadable, version=mutable_type)
            def _uploaded(newnode):
                d2 = self.parentnode.set_node(self.name, newnode,
                                              overwrite=replace)
                d2.addCallback(lambda res: newnode.get_uri())
                return d2
            d.addCallback(_uploaded)
            return d

        uploadable = FileHandle(contents.file, convergence=client.convergence)
        d = self.parentnode.add_file(self.name, uploadable, overwrite=replace)
        d.addCallback(lambda newnode: newnode.get_uri())
        return d


class PlaceHolderNodeHandler(RenderMixin, rend.Page, ReplaceMeMixin):
    def __init__(self, client, parentnode, name):
        rend.Page.__init__(self)
        self.client = client
        assert parentnode
        self.parentnode = parentnode
        self.name = name
        self.node = None

    def render_PUT(self, ctx):
        req = IRequest(ctx)
        t = get_arg(req, "t", "").strip()
        replace = parse_replace_arg(get_arg(req, "replace", "true"))

        assert self.parentnode and self.name
        if req.getHeader("content-range"):
            raise WebError("Content-Range in PUT not yet supported",
                           http.NOT_IMPLEMENTED)
        if not t:
            return self.replace_me_with_a_child(req, self.client, replace)
        if t == "uri":
            return self.replace_me_with_a_childcap(req, self.client, replace)

        raise WebError("PUT to a file: bad t=%s" % t)

    def render_POST(self, ctx):
        req = IRequest(ctx)
        t = get_arg(req, "t", "").strip()
        replace = boolean_of_arg(get_arg(req, "replace", "true"))
        if t == "upload":
            # like PUT, but get the file data from an HTML form's input field.
            # We could get here from POST /uri/mutablefilecap?t=upload,
            # or POST /uri/path/file?t=upload, or
            # POST /uri/path/dir?t=upload&name=foo . All have the same
            # behavior, we just ignore any name= argument
            d = self.replace_me_with_a_formpost(req, self.client, replace)
        else:
            # t=mkdir is handled in DirectoryNodeHandler._POST_mkdir, so
            # there are no other t= values left to be handled by the
            # placeholder.
            raise WebError("POST to a file: bad t=%s" % t)

        when_done = get_arg(req, "when_done", None)
        if when_done:
            d.addCallback(lambda res: url.URL.fromString(when_done))
        return d


class FileNodeHandler(RenderMixin, rend.Page, ReplaceMeMixin):
    def __init__(self, client, node, parentnode=None, name=None):
        rend.Page.__init__(self)
        self.client = client
        assert node
        self.node = node
        self.parentnode = parentnode
        self.name = name

    def childFactory(self, ctx, name):
        req = IRequest(ctx)
        if isinstance(self.node, ProhibitedNode):
            raise FileProhibited(self.node.reason)
        if should_create_intermediate_directories(req):
            raise WebError("Cannot create directory %s, because its "
                           "parent is a file, not a directory" % quote_output(name, encoding='utf-8'))
        raise WebError("Files have no children, certainly not named %s"
                       % quote_output(name, encoding='utf-8'))

    def render_GET(self, ctx):
        req = IRequest(ctx)
        t = get_arg(req, "t", "").strip()

        # t=info contains variable ophandles, so is not allowed an ETag.
        FIXED_OUTPUT_TYPES = ["", "json", "uri", "readonly-uri"]
        if not self.node.is_mutable() and t in FIXED_OUTPUT_TYPES:
            # if the client already has the ETag then we can
            # short-circuit the whole process.
            si = self.node.get_storage_index()
            if si and req.setETag('%s-%s' % (base32.b2a(si), t or "")):
                return ""

        if not t:
            # just get the contents
            # the filename arrives as part of the URL or in a form input
            # element, and will be sent back in a Content-Disposition header.
            # Different browsers use various character sets for this name,
            # sometimes depending upon how language environment is
            # configured. Firefox sends the equivalent of
            # urllib.quote(name.encode("utf-8")), while IE7 sometimes does
            # latin-1. Browsers cannot agree on how to interpret the name
            # they see in the Content-Disposition header either, despite some
            # 11-year old standards (RFC2231) that explain how to do it
            # properly. So we assume that at least the browser will agree
            # with itself, and echo back the same bytes that we were given.
            filename = get_arg(req, "filename", self.name) or "unknown"
            d = self.node.get_best_readable_version()
            d.addCallback(lambda dn: FileDownloader(dn, filename))
            return d
        if t == "json":
            # We do this to make sure that fields like size and
            # mutable-type (which depend on the file on the grid and not
            # just on the cap) are filled in. The latter gets used in
            # tests, in particular.
            #
            # TODO: Make it so that the servermap knows how to update in
            # a mode specifically designed to fill in these fields, and
            # then update it in that mode.
            if self.node.is_mutable():
                d = self.node.get_servermap(MODE_READ)
            else:
                d = defer.succeed(None)
            if self.parentnode and self.name:
                d.addCallback(lambda ignored:
                    self.parentnode.get_metadata_for(self.name))
            else:
                d.addCallback(lambda ignored: None)
            d.addCallback(lambda md: FileJSONMetadata(ctx, self.node, md))
            return d
        if t == "info":
            return MoreInfo(self.node)
        if t == "uri":
            return FileURI(ctx, self.node)
        if t == "readonly-uri":
            return FileReadOnlyURI(ctx, self.node)
        raise WebError("GET file: bad t=%s" % t)

    def render_HEAD(self, ctx):
        req = IRequest(ctx)
        t = get_arg(req, "t", "").strip()
        if t:
            raise WebError("HEAD file: bad t=%s" % t)
        filename = get_arg(req, "filename", self.name) or "unknown"
        d = self.node.get_best_readable_version()
        d.addCallback(lambda dn: FileDownloader(dn, filename))
        return d

    def render_PUT(self, ctx):
        req = IRequest(ctx)
        t = get_arg(req, "t", "").strip()
        replace = parse_replace_arg(get_arg(req, "replace", "true"))
        offset = parse_offset_arg(get_arg(req, "offset", None))

        if not t:
            if not replace:
                # this is the early trap: if someone else modifies the
                # directory while we're uploading, the add_file(overwrite=)
                # call in replace_me_with_a_child will do the late trap.
                raise ExistingChildError()

            if self.node.is_mutable():
                # Are we a readonly filenode? We shouldn't allow callers
                # to try to replace us if we are.
                if self.node.is_readonly():
                    raise WebError("PUT to a mutable file: replace or update"
                                   " requested with read-only cap")
                if offset is None:
                    return self.replace_my_contents(req)

                if offset >= 0:
                    return self.update_my_contents(req, offset)

                raise WebError("PUT to a mutable file: Invalid offset")

            else:
                if offset is not None:
                    raise WebError("PUT to a file: append operation invoked "
                                   "on an immutable cap")

                assert self.parentnode and self.name
                return self.replace_me_with_a_child(req, self.client, replace)

        if t == "uri":
            if not replace:
                raise ExistingChildError()
            assert self.parentnode and self.name
            return self.replace_me_with_a_childcap(req, self.client, replace)

        raise WebError("PUT to a file: bad t=%s" % t)

    def render_POST(self, ctx):
        req = IRequest(ctx)
        t = get_arg(req, "t", "").strip()
        replace = boolean_of_arg(get_arg(req, "replace", "true"))
        if t == "check":
            d = self._POST_check(req)
        elif t == "upload":
            # like PUT, but get the file data from an HTML form's input field
            # We could get here from POST /uri/mutablefilecap?t=upload,
            # or POST /uri/path/file?t=upload, or
            # POST /uri/path/dir?t=upload&name=foo . All have the same
            # behavior, we just ignore any name= argument
            if self.node.is_mutable():
                d = self.replace_my_contents_with_a_formpost(req)
            else:
                if not replace:
                    raise ExistingChildError()
                assert self.parentnode and self.name
                d = self.replace_me_with_a_formpost(req, self.client, replace)
        else:
            raise WebError("POST to file: bad t=%s" % t)

        when_done = get_arg(req, "when_done", None)
        if when_done:
            d.addCallback(lambda res: url.URL.fromString(when_done))
        return d

    def _maybe_literal(self, res, Results_Class):
        if res:
            return Results_Class(self.client, res)
        return LiteralCheckResultsRenderer(self.client)

    def _POST_check(self, req):
        verify = boolean_of_arg(get_arg(req, "verify", "false"))
        repair = boolean_of_arg(get_arg(req, "repair", "false"))
        add_lease = boolean_of_arg(get_arg(req, "add-lease", "false"))
        if repair:
            d = self.node.check_and_repair(Monitor(), verify, add_lease)
            d.addCallback(self._maybe_literal, CheckAndRepairResultsRenderer)
        else:
            d = self.node.check(Monitor(), verify, add_lease)
            d.addCallback(self._maybe_literal, CheckResultsRenderer)
        return d

    def render_DELETE(self, ctx):
        assert self.parentnode and self.name
        d = self.parentnode.delete(self.name)
        d.addCallback(lambda res: self.node.get_uri())
        return d

    def replace_my_contents(self, req):
        req.content.seek(0)
        new_contents = MutableFileHandle(req.content)
        d = self.node.overwrite(new_contents)
        d.addCallback(lambda res: self.node.get_uri())
        return d


    def update_my_contents(self, req, offset):
        req.content.seek(0)
        added_contents = MutableFileHandle(req.content)

        d = self.node.get_best_mutable_version()
        d.addCallback(lambda mv:
            mv.update(added_contents, offset))
        d.addCallback(lambda ignored:
            self.node.get_uri())
        return d


    def replace_my_contents_with_a_formpost(self, req):
        # we have a mutable file. Get the data from the formpost, and replace
        # the mutable file's contents with it.
        new_contents = req.fields['file']
        new_contents = MutableFileHandle(new_contents.file)

        d = self.node.overwrite(new_contents)
        d.addCallback(lambda res: self.node.get_uri())
        return d


class FileDownloader(rend.Page):
    def __init__(self, filenode, filename):
        rend.Page.__init__(self)
        self.filenode = filenode
        self.filename = filename

    def parse_range_header(self, range):
        # Parse a byte ranges according to RFC 2616 "14.35.1 Byte
        # Ranges".  Returns None if the range doesn't make sense so it
        # can be ignored (per the spec).  When successful, returns a
        # list of (first,last) inclusive range tuples.

        filesize = self.filenode.get_size()
        assert isinstance(filesize, (int,long)), filesize

        try:
            # byte-ranges-specifier
            units, rangeset = range.split('=', 1)
            if units != 'bytes':
                return None     # nothing else supported

            def parse_range(r):
                first, last = r.split('-', 1)

                if first is '':
                    # suffix-byte-range-spec
                    first = filesize - long(last)
                    last = filesize - 1
                else:
                    # byte-range-spec

                    # first-byte-pos
                    first = long(first)

                    # last-byte-pos
                    if last is '':
                        last = filesize - 1
                    else:
                        last = long(last)

                if last < first:
                    raise ValueError

                return (first, last)

            # byte-range-set
            #
            # Note: the spec uses "1#" for the list of ranges, which
            # implicitly allows whitespace around the ',' separators,
            # so strip it.
            return [ parse_range(r.strip()) for r in rangeset.split(',') ]
        except ValueError:
            return None

    def renderHTTP(self, ctx):
        req = IRequest(ctx)
        gte = static.getTypeAndEncoding
        ctype, encoding = gte(self.filename,
                              static.File.contentTypes,
                              static.File.contentEncodings,
                              defaultType="text/plain")
        req.setHeader("content-type", ctype)
        if encoding:
            req.setHeader("content-encoding", encoding)

        if boolean_of_arg(get_arg(req, "save", "False")):
            # tell the browser to save the file rather display it we don't
            # try to encode the filename, instead we echo back the exact same
            # bytes we were given in the URL. See the comment in
            # FileNodeHandler.render_GET for the sad details.
            req.setHeader("content-disposition",
                          'attachment; filename="%s"' % self.filename)

        filesize = self.filenode.get_size()
        assert isinstance(filesize, (int,long)), filesize
        first, size = 0, None
        contentsize = filesize
        req.setHeader("accept-ranges", "bytes")

        # TODO: for mutable files, use the roothash. For LIT, hash the data.
        # or maybe just use the URI for CHK and LIT.
        rangeheader = req.getHeader('range')
        if rangeheader:
            ranges = self.parse_range_header(rangeheader)

            # ranges = None means the header didn't parse, so ignore
            # the header as if it didn't exist.  If is more than one
            # range, then just return the first for now, until we can
            # generate multipart/byteranges.
            if ranges is not None:
                first, last = ranges[0]

                if first >= filesize:
                    raise WebError('First beyond end of file',
                                   http.REQUESTED_RANGE_NOT_SATISFIABLE)
                else:
                    first = max(0, first)
                    last = min(filesize-1, last)

                    req.setResponseCode(http.PARTIAL_CONTENT)
                    req.setHeader('content-range',"bytes %s-%s/%s" %
                                  (str(first), str(last),
                                   str(filesize)))
                    contentsize = last - first + 1
                    size = contentsize

        req.setHeader("content-length", b"%d" % contentsize)
        if req.method == "HEAD":
            return ""

        finished = []
        def _request_finished(ign):
            finished.append(True)
        req.notifyFinish().addBoth(_request_finished)

        d = self.filenode.read(req, first, size)

        def _finished(ign):
            if not finished:
                req.finish()
        def _error(f):
            lp = log.msg("error during GET", facility="tahoe.webish", failure=f,
                         level=log.UNUSUAL, umid="xSiF3w")
            if finished:
                log.msg("but it's too late to tell them", parent=lp,
                        level=log.UNUSUAL, umid="j1xIbw")
                return
            req._tahoe_request_had_error = f # for HTTP-style logging
            if req.startedWriting:
                # The content-type is already set, and the response code has
                # already been sent, so we can't provide a clean error
                # indication. We can emit text (which a browser might
                # interpret as something else), and if we sent a Size header,
                # they might notice that we've truncated the data. Keep the
                # error message small to improve the chances of having our
                # error response be shorter than the intended results.
                #
                # We don't have a lot of options, unfortunately.
                req.write("problem during download\n")
                req.finish()
            else:
                # We haven't written anything yet, so we can provide a
                # sensible error message.
                eh = MyExceptionHandler()
                eh.renderHTTP_exception(ctx, f)
        d.addCallbacks(_finished, _error)
        return req.deferred


def FileJSONMetadata(ctx, filenode, edge_metadata):
    rw_uri = filenode.get_write_uri()
    ro_uri = filenode.get_readonly_uri()
    data = ("filenode", get_filenode_metadata(filenode))
    if ro_uri:
        data[1]['ro_uri'] = ro_uri
    if rw_uri:
        data[1]['rw_uri'] = rw_uri
    verifycap = filenode.get_verify_cap()
    if verifycap:
        data[1]['verify_uri'] = verifycap.to_string()
    if edge_metadata is not None:
        data[1]['metadata'] = edge_metadata

    return text_plain(json.dumps(data, indent=1) + "\n", ctx)

def FileURI(ctx, filenode):
    return text_plain(filenode.get_uri(), ctx)

def FileReadOnlyURI(ctx, filenode):
    if filenode.is_readonly():
        return text_plain(filenode.get_uri(), ctx)
    return text_plain(filenode.get_readonly_uri(), ctx)

class FileNodeDownloadHandler(FileNodeHandler):
    def childFactory(self, ctx, name):
        return FileNodeDownloadHandler(self.client, self.node, name=name)
