import collections
import logging
import time

from mopidy import exceptions
from mopidy.audio import tags as tags_lib
from mopidy.audio import utils
from mopidy.internal import log
from mopidy.internal.gi import Gst, GstPbutils

# GST_ELEMENT_FACTORY_LIST:
_DECODER = 1 << 0
_AUDIO = 1 << 50
_DEMUXER = 1 << 5
_DEPAYLOADER = 1 << 8
_PARSER = 1 << 6

# GST_TYPE_AUTOPLUG_SELECT_RESULT:
_SELECT_TRY = 0
_SELECT_EXPOSE = 1

_Result = collections.namedtuple(
    "_Result", ("uri", "tags", "duration", "seekable", "mime", "playable")
)

logger = logging.getLogger(__name__)


def _trace(*args, **kwargs):
    logger.log(log.TRACE_LOG_LEVEL, *args, **kwargs)


# TODO: replace with a scan(uri, timeout=1000, proxy_config=None)?
class Scanner:

    """
    Helper to get tags and other relevant info from URIs.

    :param timeout: timeout for scanning a URI in ms
    :param proxy_config: dictionary containing proxy config strings.
    :type event: int
    """

    def __init__(self, timeout=1000, proxy_config=None):
        self._timeout_ms = int(timeout)
        self._proxy_config = proxy_config or {}

    def scan(self, uri, timeout=None):
        """
        Scan the given uri collecting relevant metadata.

        :param uri: URI of the resource to scan.
        :type uri: string
        :param timeout: timeout for scanning a URI in ms. Defaults to the
            ``timeout`` value used when creating the scanner.
        :type timeout: int
        :return: A named tuple containing
            ``(uri, tags, duration, seekable, mime)``.
            ``tags`` is a dictionary of lists for all the tags we found.
            ``duration`` is the length of the URI in milliseconds, or
            :class:`None` if the URI has no duration. ``seekable`` is boolean.
            indicating if a seek would succeed.
        """
        timeout = int(timeout or self._timeout_ms)
        tags, duration, seekable, mime = None, None, None, None
        pipeline, signals = _setup_pipeline(uri, self._proxy_config)

        try:
            _start_pipeline(pipeline)
            tags, mime, have_audio, duration = _process(pipeline, timeout)
            seekable = _query_seekable(pipeline)
        finally:
            signals.clear()
            pipeline.set_state(Gst.State.NULL)
            del pipeline

        return _Result(uri, tags, duration, seekable, mime, have_audio)


# Turns out it's _much_ faster to just create a new pipeline for every as
# decodebins and other elements don't seem to take well to being reused.
def _setup_pipeline(uri, proxy_config=None):
    src = Gst.Element.make_from_uri(Gst.URIType.SRC, uri)
    if not src:
        raise exceptions.ScannerError(f"GStreamer can not open: {uri}")

    if proxy_config:
        utils.setup_proxy(src, proxy_config)

    signals = utils.Signals()
    pipeline = Gst.ElementFactory.make("pipeline")
    pipeline.add(src)

    if _has_src_pads(src):
        _setup_decodebin(src, src.get_static_pad("src"), pipeline, signals)
    elif _has_dynamic_src_pad(src):
        signals.connect(src, "pad-added", _setup_decodebin, pipeline, signals)
    else:
        raise exceptions.ScannerError("No pads found in source element.")

    return pipeline, signals


def _has_src_pads(element):
    pads = []
    element.iterate_src_pads().foreach(pads.append)
    return bool(pads)


def _has_dynamic_src_pad(element):
    for template in element.get_pad_template_list():
        if template.direction == Gst.PadDirection.SRC:
            if template.presence == Gst.PadPresence.SOMETIMES:
                return True
    return False


def _setup_decodebin(element, pad, pipeline, signals):
    typefind = Gst.ElementFactory.make("typefind")
    decodebin = Gst.ElementFactory.make("decodebin")

    for element in (typefind, decodebin):
        pipeline.add(element)
        element.sync_state_with_parent()

    pad.link(typefind.get_static_pad("sink"))
    typefind.link(decodebin)

    signals.connect(typefind, "have-type", _have_type, decodebin)
    signals.connect(decodebin, "pad-added", _pad_added, pipeline)
    signals.connect(decodebin, "autoplug-select", _autoplug_select)


def _have_type(element, probability, caps, decodebin):
    decodebin.set_property("sink-caps", caps)
    struct = Gst.Structure.new_empty("have-type")
    struct.set_value("caps", caps.get_structure(0))
    element.get_bus().post(Gst.Message.new_application(element, struct))


def _pad_added(element, pad, pipeline):
    sink = Gst.ElementFactory.make("fakesink")
    sink.set_property("sync", False)

    pipeline.add(sink)
    sink.sync_state_with_parent()
    pad.link(sink.get_static_pad("sink"))

    if pad.query_caps().is_subset(Gst.Caps.from_string("audio/x-raw")):
        # Probably won't happen due to autoplug-select fix, but lets play it
        # safe until we've tested more.
        struct = Gst.Structure.new_empty("have-audio")
        element.get_bus().post(Gst.Message.new_application(element, struct))


def _autoplug_select(element, pad, caps, factory):
    if factory.list_is_type(_DECODER | _AUDIO):
        struct = Gst.Structure.new_empty("have-audio")
        element.get_bus().post(Gst.Message.new_application(element, struct))
    if not factory.list_is_type(_DEMUXER | _DEPAYLOADER | _PARSER):
        return _SELECT_EXPOSE
    return _SELECT_TRY


def _start_pipeline(pipeline):
    result = pipeline.set_state(Gst.State.PAUSED)
    if result == Gst.StateChangeReturn.NO_PREROLL:
        pipeline.set_state(Gst.State.PLAYING)


def _query_duration(pipeline):
    success, duration = pipeline.query_duration(Gst.Format.TIME)
    if not success:
        duration = None  # Make sure error case preserves None.
    elif duration < 0:
        duration = None  # Stream without duration.
    else:
        duration = int(duration // Gst.MSECOND)
    return success, duration


def _query_seekable(pipeline):
    query = Gst.Query.new_seeking(Gst.Format.TIME)
    pipeline.query(query)
    return query.parse_seeking()[1]


def _process(pipeline, timeout_ms):
    bus = pipeline.get_bus()
    tags = {}
    mime = None
    have_audio = False
    missing_message = None
    duration = None

    types = (
        Gst.MessageType.ELEMENT
        | Gst.MessageType.APPLICATION
        | Gst.MessageType.ERROR
        | Gst.MessageType.EOS
        | Gst.MessageType.ASYNC_DONE
        | Gst.MessageType.DURATION_CHANGED
        | Gst.MessageType.TAG
    )

    timeout = timeout_ms
    start = int(time.time() * 1000)
    while timeout > 0:
        msg = bus.timed_pop_filtered(timeout * Gst.MSECOND, types)
        if msg is None:
            break

        if logger.isEnabledFor(log.TRACE_LOG_LEVEL) and msg.get_structure():
            debug_text = msg.get_structure().to_string()
            if len(debug_text) > 77:
                debug_text = debug_text[:77] + "..."
            _trace("element %s: %s", msg.src.get_name(), debug_text)

        if msg.type == Gst.MessageType.ELEMENT:
            if GstPbutils.is_missing_plugin_message(msg):
                missing_message = msg
        elif msg.type == Gst.MessageType.APPLICATION:
            if msg.get_structure().get_name() == "have-type":
                mime = msg.get_structure().get_value("caps").get_name()
                if mime and (
                    mime.startswith("text/") or mime == "application/xml"
                ):
                    return tags, mime, have_audio, duration
            elif msg.get_structure().get_name() == "have-audio":
                have_audio = True
        elif msg.type == Gst.MessageType.ERROR:
            error, _debug = msg.parse_error()
            if missing_message and not mime:
                caps = missing_message.get_structure().get_value("detail")
                mime = caps.get_structure(0).get_name()
                return tags, mime, have_audio, duration
            raise exceptions.ScannerError(str(error))
        elif msg.type == Gst.MessageType.EOS:
            return tags, mime, have_audio, duration
        elif msg.type == Gst.MessageType.ASYNC_DONE:
            success, duration = _query_duration(pipeline)
            if tags and success:
                return tags, mime, have_audio, duration

            # Don't try workaround for non-seekable sources such as mmssrc:
            if not _query_seekable(pipeline):
                return tags, mime, have_audio, duration

            # Workaround for upstream bug which causes tags/duration to arrive
            # after pre-roll. We get around this by starting to play the track
            # and then waiting for a duration change.
            # https://bugzilla.gnome.org/show_bug.cgi?id=763553
            logger.debug("Using workaround for duration missing before play.")
            result = pipeline.set_state(Gst.State.PLAYING)
            if result == Gst.StateChangeReturn.FAILURE:
                return tags, mime, have_audio, duration

        elif msg.type == Gst.MessageType.DURATION_CHANGED and tags:
            # VBR formats sometimes seem to not have a duration by the time we
            # go back to paused. So just try to get it right away.
            success, duration = _query_duration(pipeline)
            pipeline.set_state(Gst.State.PAUSED)
            if success:
                return tags, mime, have_audio, duration
        elif msg.type == Gst.MessageType.TAG:
            taglist = msg.parse_tag()
            # Note that this will only keep the last tag.
            tags.update(tags_lib.convert_taglist(taglist))

        timeout = timeout_ms - (int(time.time() * 1000) - start)

    raise exceptions.ScannerError(f"Timeout after {timeout_ms:d}ms")


if __name__ == "__main__":
    import os
    import sys

    from mopidy.internal import path

    logging.basicConfig(
        format="%(asctime)-15s %(levelname)s %(message)s",
        level=log.TRACE_LOG_LEVEL,
    )

    scanner = Scanner(5000)
    for uri in sys.argv[1:]:
        if not Gst.uri_is_valid(uri):
            uri = path.path_to_uri(os.path.abspath(uri))
        try:
            result = scanner.scan(uri)
            for key in ("uri", "mime", "duration", "playable", "seekable"):
                value = getattr(result, key)
                print(f"{key:<20}   {value}")
            print("tags")
            for tag, value in result.tags.items():
                line = f"{tag:<20}   {value}"
                if len(line) > 77:
                    line = line[:77] + "..."
                print(line)
        except exceptions.ScannerError as error:
            print(f"{uri}: {error}")
