"""
Color definitions are used as per the CSS3
[CSS Color Module Level 3](http://www.w3.org/TR/css3-color/#svg-color) specification.

A few colors have multiple names referring to the sames colors, eg. `grey` and `gray` or `aqua` and `cyan`.

In these cases the _last_ color when sorted alphabetically takes preferences,
eg. `Color((0, 255, 255)).as_named() == 'cyan'` because "cyan" comes after "aqua".
"""

from __future__ import annotations

import math
import re
from colorsys import hls_to_rgb, rgb_to_hls
from typing import Any, Callable, Literal, Tuple, Union, cast

from pydantic import GetJsonSchemaHandler
from pydantic._internal import _repr
from pydantic.json_schema import JsonSchemaValue
from pydantic_core import CoreSchema, PydanticCustomError, core_schema

ColorTuple = Union[Tuple[int, int, int], Tuple[int, int, int, float]]
ColorType = Union[ColorTuple, str, 'Color']
HslColorTuple = Union[Tuple[float, float, float], Tuple[float, float, float, float]]


class RGBA:
    """
    Internal use only as a representation of a color.
    """

    __slots__ = 'r', 'g', 'b', 'alpha', '_tuple'

    def __init__(self, r: float, g: float, b: float, alpha: float | None):
        self.r = r
        self.g = g
        self.b = b
        self.alpha = alpha

        self._tuple: tuple[float, float, float, float | None] = (r, g, b, alpha)

    def __getitem__(self, item: Any) -> Any:
        return self._tuple[item]


# these are not compiled here to avoid import slowdown, they'll be compiled the first time they're used, then cached
_r_255 = r'(\d{1,3}(?:\.\d+)?)'
_r_comma = r'\s*,\s*'
_r_alpha = r'(\d(?:\.\d+)?|\.\d+|\d{1,2}%)'
_r_h = r'(-?\d+(?:\.\d+)?|-?\.\d+)(deg|rad|turn)?'
_r_sl = r'(\d{1,3}(?:\.\d+)?)%'
r_hex_short = r'\s*(?:#|0x)?([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])?\s*'
r_hex_long = r'\s*(?:#|0x)?([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})?\s*'
# CSS3 RGB examples: rgb(0, 0, 0), rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 50%)
r_rgb = rf'\s*rgba?\(\s*{_r_255}{_r_comma}{_r_255}{_r_comma}{_r_255}(?:{_r_comma}{_r_alpha})?\s*\)\s*'
# CSS3 HSL examples: hsl(270, 60%, 50%), hsla(270, 60%, 50%, 0.5), hsla(270, 60%, 50%, 50%)
r_hsl = rf'\s*hsla?\(\s*{_r_h}{_r_comma}{_r_sl}{_r_comma}{_r_sl}(?:{_r_comma}{_r_alpha})?\s*\)\s*'
# CSS4 RGB examples: rgb(0 0 0), rgb(0 0 0 / 0.5), rgb(0 0 0 / 50%), rgba(0 0 0 / 50%)
r_rgb_v4_style = rf'\s*rgba?\(\s*{_r_255}\s+{_r_255}\s+{_r_255}(?:\s*/\s*{_r_alpha})?\s*\)\s*'
# CSS4 HSL examples: hsl(270 60% 50%), hsl(270 60% 50% / 0.5), hsl(270 60% 50% / 50%), hsla(270 60% 50% / 50%)
r_hsl_v4_style = rf'\s*hsla?\(\s*{_r_h}\s+{_r_sl}\s+{_r_sl}(?:\s*/\s*{_r_alpha})?\s*\)\s*'

# colors where the two hex characters are the same, if all colors match this the short version of hex colors can be used
repeat_colors = {int(c * 2, 16) for c in '0123456789abcdef'}
rads = 2 * math.pi


class Color(_repr.Representation):
    """
    Represents a color.
    """

    __slots__ = '_original', '_rgba'

    def __init__(self, value: ColorType) -> None:
        self._rgba: RGBA
        self._original: ColorType
        if isinstance(value, (tuple, list)):
            self._rgba = parse_tuple(value)
        elif isinstance(value, str):
            self._rgba = parse_str(value)
        elif isinstance(value, Color):
            self._rgba = value._rgba
            value = value._original
        else:
            raise PydanticCustomError(
                'color_error',
                'value is not a valid color: value must be a tuple, list or string',
            )

        # if we've got here value must be a valid color
        self._original = value

    @classmethod
    def __get_pydantic_json_schema__(
        cls, core_schema: core_schema.CoreSchema, handler: GetJsonSchemaHandler
    ) -> JsonSchemaValue:
        field_schema: dict[str, Any] = {}
        field_schema.update(type='string', format='color')
        return field_schema

    def original(self) -> ColorType:
        """
        Original value passed to `Color`.
        """
        return self._original

    def as_named(self, *, fallback: bool = False) -> str:
        """
        Returns the name of the color if it can be found in `COLORS_BY_VALUE` dictionary,
        otherwise returns the hexadecimal representation of the color or raises `ValueError`.

        Args:
            fallback: If True, falls back to returning the hexadecimal representation of
                the color instead of raising a ValueError when no named color is found.

        Returns:
            The name of the color, or the hexadecimal representation of the color.

        Raises:
            ValueError: When no named color is found and fallback is `False`.
        """
        if self._rgba.alpha is None:
            rgb = cast(Tuple[int, int, int], self.as_rgb_tuple())
            try:
                return COLORS_BY_VALUE[rgb]
            except KeyError as e:
                if fallback:
                    return self.as_hex()
                else:
                    raise ValueError('no named color found, use fallback=True, as_hex() or as_rgb()') from e
        else:
            return self.as_hex()

    def as_hex(self, format: Literal['short', 'long'] = 'short') -> str:
        """Returns the hexadecimal representation of the color.

        Hex string representing the color can be 3, 4, 6, or 8 characters depending on whether the string
        a "short" representation of the color is possible and whether there's an alpha channel.

        Returns:
            The hexadecimal representation of the color.
        """
        values = [float_to_255(c) for c in self._rgba[:3]]
        if self._rgba.alpha is not None:
            values.append(float_to_255(self._rgba.alpha))

        as_hex = ''.join(f'{v:02x}' for v in values)
        if format == 'short' and all(c in repeat_colors for c in values):
            as_hex = ''.join(as_hex[c] for c in range(0, len(as_hex), 2))
        return '#' + as_hex

    def as_rgb(self) -> str:
        """
        Color as an `rgb(<r>, <g>, <b>)` or `rgba(<r>, <g>, <b>, <a>)` string.
        """
        if self._rgba.alpha is None:
            return f'rgb({float_to_255(self._rgba.r)}, {float_to_255(self._rgba.g)}, {float_to_255(self._rgba.b)})'
        else:
            return (
                f'rgba({float_to_255(self._rgba.r)}, {float_to_255(self._rgba.g)}, {float_to_255(self._rgba.b)}, '
                f'{round(self._alpha_float(), 2)})'
            )

    def as_rgb_tuple(self, *, alpha: bool | None = None) -> ColorTuple:
        """
        Returns the color as an RGB or RGBA tuple.

        Args:
            alpha: Whether to include the alpha channel. There are three options for this input:

                - `None` (default): Include alpha only if it's set. (e.g. not `None`)
                - `True`: Always include alpha.
                - `False`: Always omit alpha.

        Returns:
            A tuple that contains the values of the red, green, and blue channels in the range 0 to 255.
                If alpha is included, it is in the range 0 to 1.
        """
        r, g, b = (float_to_255(c) for c in self._rgba[:3])
        if alpha is None:
            if self._rgba.alpha is None:
                return r, g, b
            else:
                return r, g, b, self._alpha_float()
        elif alpha:
            return r, g, b, self._alpha_float()
        else:
            # alpha is False
            return r, g, b

    def as_hsl(self) -> str:
        """
        Color as an `hsl(<h>, <s>, <l>)` or `hsl(<h>, <s>, <l>, <a>)` string.
        """
        if self._rgba.alpha is None:
            h, s, li = self.as_hsl_tuple(alpha=False)  # type: ignore
            return f'hsl({h * 360:0.0f}, {s:0.0%}, {li:0.0%})'
        else:
            h, s, li, a = self.as_hsl_tuple(alpha=True)  # type: ignore
            return f'hsl({h * 360:0.0f}, {s:0.0%}, {li:0.0%}, {round(a, 2)})'

    def as_hsl_tuple(self, *, alpha: bool | None = None) -> HslColorTuple:
        """
        Returns the color as an HSL or HSLA tuple.

        Args:
            alpha: Whether to include the alpha channel.

                - `None` (default): Include the alpha channel only if it's set (e.g. not `None`).
                - `True`: Always include alpha.
                - `False`: Always omit alpha.

        Returns:
            The color as a tuple of hue, saturation, lightness, and alpha (if included).
                All elements are in the range 0 to 1.

        Note:
            This is HSL as used in HTML and most other places, not HLS as used in Python's `colorsys`.
        """
        h, l, s = rgb_to_hls(self._rgba.r, self._rgba.g, self._rgba.b)
        if alpha is None:
            if self._rgba.alpha is None:
                return h, s, l
            else:
                return h, s, l, self._alpha_float()
        if alpha:
            return h, s, l, self._alpha_float()
        else:
            # alpha is False
            return h, s, l

    def _alpha_float(self) -> float:
        return 1 if self._rgba.alpha is None else self._rgba.alpha

    @classmethod
    def __get_pydantic_core_schema__(
        cls, source: type[Any], handler: Callable[[Any], CoreSchema]
    ) -> core_schema.CoreSchema:
        return core_schema.with_info_plain_validator_function(
            cls._validate, serialization=core_schema.to_string_ser_schema()
        )

    @classmethod
    def _validate(cls, __input_value: Any, _: Any) -> Color:
        return cls(__input_value)

    def __str__(self) -> str:
        return self.as_named(fallback=True)

    def __repr_args__(self) -> _repr.ReprArgs:
        return [(None, self.as_named(fallback=True))] + [('rgb', self.as_rgb_tuple())]

    def __eq__(self, other: Any) -> bool:
        return isinstance(other, Color) and self.as_rgb_tuple() == other.as_rgb_tuple()

    def __hash__(self) -> int:
        return hash(self.as_rgb_tuple())


def parse_tuple(value: tuple[Any, ...]) -> RGBA:
    """Parse a tuple or list to get RGBA values.

    Args:
        value: A tuple or list.

    Returns:
        An `RGBA` tuple parsed from the input tuple.

    Raises:
        PydanticCustomError: If tuple is not valid.
    """
    if len(value) == 3:
        r, g, b = (parse_color_value(v) for v in value)
        return RGBA(r, g, b, None)
    elif len(value) == 4:
        r, g, b = (parse_color_value(v) for v in value[:3])
        return RGBA(r, g, b, parse_float_alpha(value[3]))
    else:
        raise PydanticCustomError('color_error', 'value is not a valid color: tuples must have length 3 or 4')


def parse_str(value: str) -> RGBA:
    """
    Parse a string representing a color to an RGBA tuple.

    Possible formats for the input string include:

    * named color, see `COLORS_BY_NAME`
    * hex short eg. `<prefix>fff` (prefix can be `#`, `0x` or nothing)
    * hex long eg. `<prefix>ffffff` (prefix can be `#`, `0x` or nothing)
    * `rgb(<r>, <g>, <b>)`
    * `rgba(<r>, <g>, <b>, <a>)`
    * `transparent`

    Args:
        value: A string representing a color.

    Returns:
        An `RGBA` tuple parsed from the input string.

    Raises:
        ValueError: If the input string cannot be parsed to an RGBA tuple.
    """
    value_lower = value.lower()
    try:
        r, g, b = COLORS_BY_NAME[value_lower]
    except KeyError:
        pass
    else:
        return ints_to_rgba(r, g, b, None)

    m = re.fullmatch(r_hex_short, value_lower)
    if m:
        *rgb, a = m.groups()
        r, g, b = (int(v * 2, 16) for v in rgb)
        if a:
            alpha: float | None = int(a * 2, 16) / 255
        else:
            alpha = None
        return ints_to_rgba(r, g, b, alpha)

    m = re.fullmatch(r_hex_long, value_lower)
    if m:
        *rgb, a = m.groups()
        r, g, b = (int(v, 16) for v in rgb)
        if a:
            alpha = int(a, 16) / 255
        else:
            alpha = None
        return ints_to_rgba(r, g, b, alpha)

    m = re.fullmatch(r_rgb, value_lower) or re.fullmatch(r_rgb_v4_style, value_lower)
    if m:
        return ints_to_rgba(*m.groups())  # type: ignore

    m = re.fullmatch(r_hsl, value_lower) or re.fullmatch(r_hsl_v4_style, value_lower)
    if m:
        return parse_hsl(*m.groups())  # type: ignore

    if value_lower == 'transparent':
        return RGBA(0, 0, 0, 0)

    raise PydanticCustomError(
        'color_error',
        'value is not a valid color: string not recognised as a valid color',
    )


def ints_to_rgba(
    r: int | str,
    g: int | str,
    b: int | str,
    alpha: float | None = None,
) -> RGBA:
    """
    Converts integer or string values for RGB color and an optional alpha value to an `RGBA` object.

    Args:
        r: An integer or string representing the red color value.
        g: An integer or string representing the green color value.
        b: An integer or string representing the blue color value.
        alpha: A float representing the alpha value. Defaults to None.

    Returns:
        An instance of the `RGBA` class with the corresponding color and alpha values.
    """
    return RGBA(
        parse_color_value(r),
        parse_color_value(g),
        parse_color_value(b),
        parse_float_alpha(alpha),
    )


def parse_color_value(value: int | str, max_val: int = 255) -> float:
    """
    Parse the color value provided and return a number between 0 and 1.

    Args:
        value: An integer or string color value.
        max_val: Maximum range value. Defaults to 255.

    Raises:
        PydanticCustomError: If the value is not a valid color.

    Returns:
        A number between 0 and 1.
    """
    try:
        color = float(value)
    except ValueError:
        raise PydanticCustomError(
            'color_error',
            'value is not a valid color: color values must be a valid number',
        )
    if 0 <= color <= max_val:
        return color / max_val
    else:
        raise PydanticCustomError(
            'color_error',
            'value is not a valid color: color values must be in the range 0 to {max_val}',
            {'max_val': max_val},
        )


def parse_float_alpha(value: None | str | float | int) -> float | None:
    """
    Parse an alpha value checking it's a valid float in the range 0 to 1.

    Args:
        value: The input value to parse.

    Returns:
        The parsed value as a float, or `None` if the value was None or equal 1.

    Raises:
        PydanticCustomError: If the input value cannot be successfully parsed as a float in the expected range.
    """
    if value is None:
        return None
    try:
        if isinstance(value, str) and value.endswith('%'):
            alpha = float(value[:-1]) / 100
        else:
            alpha = float(value)
    except ValueError:
        raise PydanticCustomError(
            'color_error',
            'value is not a valid color: alpha values must be a valid float',
        )

    if math.isclose(alpha, 1):
        return None
    elif 0 <= alpha <= 1:
        return alpha
    else:
        raise PydanticCustomError(
            'color_error',
            'value is not a valid color: alpha values must be in the range 0 to 1',
        )


def parse_hsl(h: str, h_units: str, sat: str, light: str, alpha: float | None = None) -> RGBA:
    """
    Parse raw hue, saturation, lightness, and alpha values and convert to RGBA.

    Args:
        h: The hue value.
        h_units: The unit for hue value.
        sat: The saturation value.
        light: The lightness value.
        alpha: Alpha value.

    Returns:
        An instance of `RGBA`.
    """
    s_value, l_value = parse_color_value(sat, 100), parse_color_value(light, 100)

    h_value = float(h)
    if h_units in {None, 'deg'}:
        h_value = h_value % 360 / 360
    elif h_units == 'rad':
        h_value = h_value % rads / rads
    else:
        # turns
        h_value = h_value % 1

    r, g, b = hls_to_rgb(h_value, l_value, s_value)
    return RGBA(r, g, b, parse_float_alpha(alpha))


def float_to_255(c: float) -> int:
    """
    Converts a float value between 0 and 1 (inclusive) to an integer between 0 and 255 (inclusive).

    Args:
        c: The float value to be converted. Must be between 0 and 1 (inclusive).

    Returns:
        The integer equivalent of the given float value rounded to the nearest whole number.
    """
    return round(c * 255)


COLORS_BY_NAME = {
    'aliceblue': (240, 248, 255),
    'antiquewhite': (250, 235, 215),
    'aqua': (0, 255, 255),
    'aquamarine': (127, 255, 212),
    'azure': (240, 255, 255),
    'beige': (245, 245, 220),
    'bisque': (255, 228, 196),
    'black': (0, 0, 0),
    'blanchedalmond': (255, 235, 205),
    'blue': (0, 0, 255),
    'blueviolet': (138, 43, 226),
    'brown': (165, 42, 42),
    'burlywood': (222, 184, 135),
    'cadetblue': (95, 158, 160),
    'chartreuse': (127, 255, 0),
    'chocolate': (210, 105, 30),
    'coral': (255, 127, 80),
    'cornflowerblue': (100, 149, 237),
    'cornsilk': (255, 248, 220),
    'crimson': (220, 20, 60),
    'cyan': (0, 255, 255),
    'darkblue': (0, 0, 139),
    'darkcyan': (0, 139, 139),
    'darkgoldenrod': (184, 134, 11),
    'darkgray': (169, 169, 169),
    'darkgreen': (0, 100, 0),
    'darkgrey': (169, 169, 169),
    'darkkhaki': (189, 183, 107),
    'darkmagenta': (139, 0, 139),
    'darkolivegreen': (85, 107, 47),
    'darkorange': (255, 140, 0),
    'darkorchid': (153, 50, 204),
    'darkred': (139, 0, 0),
    'darksalmon': (233, 150, 122),
    'darkseagreen': (143, 188, 143),
    'darkslateblue': (72, 61, 139),
    'darkslategray': (47, 79, 79),
    'darkslategrey': (47, 79, 79),
    'darkturquoise': (0, 206, 209),
    'darkviolet': (148, 0, 211),
    'deeppink': (255, 20, 147),
    'deepskyblue': (0, 191, 255),
    'dimgray': (105, 105, 105),
    'dimgrey': (105, 105, 105),
    'dodgerblue': (30, 144, 255),
    'firebrick': (178, 34, 34),
    'floralwhite': (255, 250, 240),
    'forestgreen': (34, 139, 34),
    'fuchsia': (255, 0, 255),
    'gainsboro': (220, 220, 220),
    'ghostwhite': (248, 248, 255),
    'gold': (255, 215, 0),
    'goldenrod': (218, 165, 32),
    'gray': (128, 128, 128),
    'green': (0, 128, 0),
    'greenyellow': (173, 255, 47),
    'grey': (128, 128, 128),
    'honeydew': (240, 255, 240),
    'hotpink': (255, 105, 180),
    'indianred': (205, 92, 92),
    'indigo': (75, 0, 130),
    'ivory': (255, 255, 240),
    'khaki': (240, 230, 140),
    'lavender': (230, 230, 250),
    'lavenderblush': (255, 240, 245),
    'lawngreen': (124, 252, 0),
    'lemonchiffon': (255, 250, 205),
    'lightblue': (173, 216, 230),
    'lightcoral': (240, 128, 128),
    'lightcyan': (224, 255, 255),
    'lightgoldenrodyellow': (250, 250, 210),
    'lightgray': (211, 211, 211),
    'lightgreen': (144, 238, 144),
    'lightgrey': (211, 211, 211),
    'lightpink': (255, 182, 193),
    'lightsalmon': (255, 160, 122),
    'lightseagreen': (32, 178, 170),
    'lightskyblue': (135, 206, 250),
    'lightslategray': (119, 136, 153),
    'lightslategrey': (119, 136, 153),
    'lightsteelblue': (176, 196, 222),
    'lightyellow': (255, 255, 224),
    'lime': (0, 255, 0),
    'limegreen': (50, 205, 50),
    'linen': (250, 240, 230),
    'magenta': (255, 0, 255),
    'maroon': (128, 0, 0),
    'mediumaquamarine': (102, 205, 170),
    'mediumblue': (0, 0, 205),
    'mediumorchid': (186, 85, 211),
    'mediumpurple': (147, 112, 219),
    'mediumseagreen': (60, 179, 113),
    'mediumslateblue': (123, 104, 238),
    'mediumspringgreen': (0, 250, 154),
    'mediumturquoise': (72, 209, 204),
    'mediumvioletred': (199, 21, 133),
    'midnightblue': (25, 25, 112),
    'mintcream': (245, 255, 250),
    'mistyrose': (255, 228, 225),
    'moccasin': (255, 228, 181),
    'navajowhite': (255, 222, 173),
    'navy': (0, 0, 128),
    'oldlace': (253, 245, 230),
    'olive': (128, 128, 0),
    'olivedrab': (107, 142, 35),
    'orange': (255, 165, 0),
    'orangered': (255, 69, 0),
    'orchid': (218, 112, 214),
    'palegoldenrod': (238, 232, 170),
    'palegreen': (152, 251, 152),
    'paleturquoise': (175, 238, 238),
    'palevioletred': (219, 112, 147),
    'papayawhip': (255, 239, 213),
    'peachpuff': (255, 218, 185),
    'peru': (205, 133, 63),
    'pink': (255, 192, 203),
    'plum': (221, 160, 221),
    'powderblue': (176, 224, 230),
    'purple': (128, 0, 128),
    'red': (255, 0, 0),
    'rosybrown': (188, 143, 143),
    'royalblue': (65, 105, 225),
    'saddlebrown': (139, 69, 19),
    'salmon': (250, 128, 114),
    'sandybrown': (244, 164, 96),
    'seagreen': (46, 139, 87),
    'seashell': (255, 245, 238),
    'sienna': (160, 82, 45),
    'silver': (192, 192, 192),
    'skyblue': (135, 206, 235),
    'slateblue': (106, 90, 205),
    'slategray': (112, 128, 144),
    'slategrey': (112, 128, 144),
    'snow': (255, 250, 250),
    'springgreen': (0, 255, 127),
    'steelblue': (70, 130, 180),
    'tan': (210, 180, 140),
    'teal': (0, 128, 128),
    'thistle': (216, 191, 216),
    'tomato': (255, 99, 71),
    'turquoise': (64, 224, 208),
    'violet': (238, 130, 238),
    'wheat': (245, 222, 179),
    'white': (255, 255, 255),
    'whitesmoke': (245, 245, 245),
    'yellow': (255, 255, 0),
    'yellowgreen': (154, 205, 50),
}

COLORS_BY_VALUE = {v: k for k, v in COLORS_BY_NAME.items()}