# This file is part of Xpra.
# Copyright (C) 2012-2024 Antoine Martin <antoine@xpra.org>
# Xpra is released under the terms of the GNU GPL v2, or, at your option, any
# later version. See the file COPYING for details.

import os
from typing import Any
from weakref import WeakSet
from dataclasses import dataclass, field, asdict
from collections.abc import Callable, Iterable, Sequence

from xpra.util.objects import typedict
from xpra.util.env import envint

# noinspection PyPep8


FAST_DECODE_MIN_SPEED: int = envint("XPRA_FAST_DECODE_MIN_SPEED", 70)


# note: this is just for defining the order of encodings,
# so we have both core encodings (rgb24/rgb32) and regular encodings (rgb) in here:
PREFERRED_ENCODING_ORDER: Sequence[str] = (
    "h264", "vp9", "vp8", "mpeg4",
    "mpeg4+mp4", "h264+mp4", "vp8+webm", "vp9+webm",
    "png", "png/P", "png/L", "webp", "avif",
    "rgb", "rgb24", "rgb32", "jpeg", "jpega",
    "h265", "av1",
    "scroll",
    "grayscale",
    "stream",
)

PSEUDO_LOSSLESS_ENCODINGS: Sequence[str] = ("rgb", "png", "png/P", "png/L", "webp", "avif", "jpeg", "jpega")

TRUE_LOSSLESS_ENCODINGS: Sequence[str] = ("rgb", "png", "png/P", "png/L", "webp", "avif")

PREFERRED_REFRESH_ENCODING_ORDER: Sequence[str] = (
    "webp", "avif", "png", "png/P", "png/L", "rgb", "rgb24", "rbg32", "jpeg", "jpega",
)
STREAM_ENCODINGS: Sequence[str] = (
    "h264", "vp9", "vp8", "mpeg4",
    "mpeg4+mp4", "h264+mp4", "vp8+webm", "vp9+webm",
    "h265", "av1",
)

# encoding order for edges (usually one pixel high or wide):
EDGE_ENCODING_ORDER: Sequence[str] = (
    "rgb24", "rgb32",
    "png", "webp",
    "png/P", "png/L", "rgb", "jpeg", "jpega",
)

HELP_ORDER: Sequence[str] = (
    "auto",
    "stream",
    "grayscale",
    "h264", "h265", "av1", "vp8", "vp9", "mpeg4",
    "png", "png/P", "png/L", "webp", "avif",
    "rgb", "jpeg", "jpega",
    "scroll",
)


# value: how much smaller the output is
LOSSY_PIXEL_FORMATS: dict[str, float | int] = {
    "NV12": 2,
    "YUV420P": 2,
    "YUV422P": 1.5,
}

CSC_ALIAS: dict[str, str] = {"NV12": "YUV420P"}


def get_plane_name(pixel_format: str = "YUV420P", index: int = 0) -> str:
    return {
        "NV12": ("Y", "UV"),
    }.get(pixel_format, list(pixel_format))[index]


PIXEL_SUBSAMPLING : dict[str, Sequence[tuple[int, int]]] = {
    # NV12 is actually subsampled horizontally too - just like YUV420P
    # (but combines U and V planes so the resulting rowstride for the UV plane is the same as the Y plane):
    "NV12"      : ((1, 1), (1, 2)),
    "YUV420P"   : ((1, 1), (2, 2), (2, 2)),
    "YUV422P"   : ((1, 1), (2, 1), (2, 1)),
    "YUV444P"   : ((1, 1), (1, 1), (1, 1)),
    "YUV400P"   : ((1, 1), ),
    "GBRP"      : ((1, 1), (1, 1), (1, 1)),
    "GBRP9LE"   : ((1, 1), (1, 1), (1, 1)),
    "GBRP10"    : ((1, 1), (1, 1), (1, 1)),
    "YUV444P10" : ((1, 1), (1, 1), (1, 1)),
    "YUV444P16" : ((1, 1), (1, 1), (1, 1)),
}


def get_subsampling_divs(pixel_format: str) -> Sequence[tuple[int, int]]:
    # Return size dividers for the given pixel format
    #  (Y_w, Y_h), (U_w, U_h), (V_w, V_h)
    if pixel_format not in PIXEL_SUBSAMPLING:
        raise ValueError(f"invalid pixel format: {pixel_format!r}")
    return PIXEL_SUBSAMPLING[pixel_format]


def preforder(encodings: Iterable[str]) -> Sequence[str]:
    encs: set[str] = set(encodings)
    return tuple(x for x in PREFERRED_ENCODING_ORDER if x in encs)


def get_profile(options: typedict, encoding: str = "h264", csc_mode: str = "YUV420P",
                default_profile: str = "constrained-baseline") -> str:
    for x in (
        options.strget(f"{encoding}.{csc_mode}.profile"),
        options.strget(f"{encoding}.profile"),
        os.environ.get(f"XPRA_{encoding.upper()}_{csc_mode}_PROFILE"),
        os.environ.get(f"XPRA_{encoding.upper()}_PROFILE"),
        default_profile,
    ):
        if x:
            return x
    return ""


def get_x264_quality(pct: int, profile: str = "") -> int:
    if pct >= 100 and profile == "high444":
        return 0
    return 50 - (min(100, max(0, pct)) * 49 // 100)


def get_x264_preset(speed: int = 50, fast_decode: bool = False) -> int:
    if fast_decode:
        speed = max(FAST_DECODE_MIN_SPEED, speed)
    if speed > 99:
        # only allow "ultrafast" if pct > 99
        return 0
    return 5 - max(0, min(4, speed // 20))


RGB_FORMATS: Sequence[str] = (
    "XRGB",
    "BGRX",
    "ARGB",
    "BGRA",
    "RGB",
    "BGR",
    "r210",
)


class TransientCodecException(Exception):
    pass


class CodecStateException(Exception):
    pass


@dataclass(kw_only=True)
class CodecSpec:

    codec_class     : Callable
    codec_type      : str
    quality         : int = 50
    speed           : int = 50
    size_efficiency : int = 50
    setup_cost      : int = 50
    cpu_cost        : int = 100
    gpu_cost        : int = 0
    min_w           : int = 1
    min_h           : int = 1
    max_w           : int = 4 * 1024
    max_h           : int = 4 * 1024
    can_scale       : bool = False
    score_boost     : int = 0
    width_mask      : int = 0xFFFF
    height_mask     : int = 0xFFFF
    max_instances   : int = 0
    skipped_fields : Sequence[str] = ("instances", "skipped_fields", )
    # not exported:
    instances       : WeakSet[Any] = field(default_factory=WeakSet)

    def make_instance(self) -> object:
        # pylint: disable=import-outside-toplevel
        # I can't imagine why someone would have more than this many
        # encoders or csc modules active at the same time!
        WARN_LIMIT = envint("XPRA_CODEC_INSTANCE_COUNT_WARN", 25)
        from xpra.log import Logger
        log = Logger("encoding")
        cur = self.get_instance_count()
        if 0 < self.max_instances < cur or cur >= WARN_LIMIT:
            instances = tuple(self.instances)
            log.warn(f"Warning: already {cur} active instances of {self.codec_class}:")
            try:
                import gc
                for i in instances:
                    refs = gc.get_referrers(i)
                    log.warn(f" referers({i})={refs}")
            except Exception:
                pass
        else:
            log("make_instance() %s - instance count=%s", self.codec_type, cur)
        v = self.codec_class()
        self.instances.add(v)
        return v

    def get_instance_count(self) -> int:
        return len(self.instances)

    def to_dict(self) -> dict[str, Any]:
        v = asdict(self)
        for k in self.skipped_fields:
            v.pop(k, None)
        return v

    def get_runtime_factor(self) -> float:
        # a cost multiplier that some encoder may want to override
        # 1.0 means no change:
        mi = self.max_instances
        ic = len(self.instances)
        if ic == 0 or mi == 0:
            return 1.0                      # no problem
        if ic >= mi:
            return 0                        # not possible
        if mi > 0 and ic > 0:
            # squared slope: 50% utilisation -> value=0.75
            return max(0.0, 1.0 - (1.0*ic/mi)**2)
        return 1.0


@dataclass(kw_only=True)
class VideoSpec(CodecSpec):

    encoding           : str = "invalid"
    input_colorspace   : str = "invalid"
    output_colorspaces : Sequence[str] = ()      # ie: ("YUV420P" : "YUV420P", ...)
    has_lossless_mode   : bool = False

    def __repr__(self):
        return f"{self.codec_type}({self.input_colorspace} to {self.encoding})"


@dataclass(kw_only=True)
class CSCSpec(CodecSpec):

    input_colorspace: str = "invalid"
    output_colorspace: str = "invalid"

    def __repr__(self):
        return f"{self.codec_type}({self.input_colorspace} to {self.output_colorspace})"


def main():
    # pylint: disable=import-outside-toplevel
    from xpra.platform import program_context
    with program_context("Codec-Constants", "Codec Constants Info"):
        import sys
        from xpra.log import Logger, consume_verbose_argv
        consume_verbose_argv(sys.argv, "encoding")
        log = Logger("encoding")
        log.info("LOSSY_PIXEL_FORMATS=%s", LOSSY_PIXEL_FORMATS)
        log.info("PIXEL_SUBSAMPLING=%s", PIXEL_SUBSAMPLING)
        log.info("RGB_FORMATS=%s", RGB_FORMATS)


if __name__ == "__main__":
    main()
