/*
 * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
 * Copyright (c) 2019-2023, Shannon Booth <shannon@serenityos.org>
 * Copyright (c) 2024, Lucas Chollet <lucas.chollet@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Assertions.h>
#include <AK/ByteString.h>
#include <AK/Optional.h>
#include <AK/StringConversions.h>
#include <AK/Utf16String.h>
#include <AK/Utf16View.h>
#include <AK/Vector.h>
#include <LibGfx/Color.h>
#include <LibGfx/ColorConversion.h>
#include <LibIPC/Decoder.h>
#include <LibIPC/Encoder.h>
#include <ctype.h>

namespace Gfx {

namespace {

char nth_digit(u32 value, u8 digit)
{
    // This helper is used to format integers.
    // nth_digit(745, 1) -> '5'
    // nth_digit(745, 2) -> '4'
    // nth_digit(745, 3) -> '7'

    VERIFY(value < 1000);
    VERIFY(digit <= 3);
    VERIFY(digit > 0);

    while (digit > 1) {
        value /= 10;
        digit--;
    }

    return '0' + value % 10;
}

Array<char, 4> format_to_8bit_compatible(u8 value)
{
    // This function formats to the shortest string that roundtrips at 8 bits.
    // As an example:
    //      127 / 255 = 0.498 ± 0.001
    //      128 / 255 = 0.502 ± 0.001
    // But round(.5 * 255) == 128, so this function returns (note that it's only the fractional part):
    //      127 -> "498"
    //      128 -> "5"

    u32 const three_digits = (value * 1000u + 127) / 255;
    u32 const rounded_to_two_digits = (three_digits + 5) / 10 * 10;

    if ((rounded_to_two_digits * 255 / 100 + 5) / 10 != value)
        return { nth_digit(three_digits, 3), nth_digit(three_digits, 2), nth_digit(three_digits, 1), '\0' };

    u32 const rounded_to_one_digit = (three_digits + 50) / 100 * 100;
    if ((rounded_to_one_digit * 255 / 100 + 5) / 10 != value)
        return { nth_digit(rounded_to_two_digits, 3), nth_digit(rounded_to_two_digits, 2), '\0', '\0' };

    return { nth_digit(rounded_to_one_digit, 3), '\0', '\0', '\0' };
}

}

// https://www.w3.org/TR/css-color-4/#serializing-sRGB-values
void Color::serialize_a_srgb_value(StringBuilder& builder) const
{
    // The serialized form is derived from the computed value and thus, uses either the rgb() or rgba() form
    // (depending on whether the alpha is exactly 1, or not), with lowercase letters for the function name.
    // NOTE: Since we use Gfx::Color, having an "alpha of 1" means its value is 255.
    if (alpha() == 0)
        builder.appendff("rgba({}, {}, {}, 0)", red(), green(), blue());
    else if (alpha() == 255)
        builder.appendff("rgb({}, {}, {})", red(), green(), blue());
    else
        builder.appendff("rgba({}, {}, {}, 0.{})", red(), green(), blue(), format_to_8bit_compatible(alpha()).data());
}

String Color::serialize_a_srgb_value() const
{
    StringBuilder builder;
    serialize_a_srgb_value(builder);
    return builder.to_string_without_validation();
}

String Color::to_string(HTMLCompatibleSerialization html_compatible_serialization) const
{
    // If the following conditions are all true:

    // 1. The color space is sRGB
    // NOTE: This is currently always true for Gfx::Color.

    // 2. The alpha is 1
    // NOTE: An alpha value of 1 will be stored as 255 currently.

    // 3. The RGB component values are internally represented as integers between 0 and 255 inclusive (i.e. 8-bit unsigned integer)
    // NOTE: This is currently always true for Gfx::Color.

    // 4. HTML-compatible serialization is requested
    if (alpha() == 255
        && html_compatible_serialization == HTMLCompatibleSerialization::Yes) {
        return MUST(String::formatted("#{:02x}{:02x}{:02x}", red(), green(), blue()));
    }

    // Otherwise, for sRGB the CSS serialization of sRGB values is used and for other color spaces, the relevant serialization of the <color> value.
    return serialize_a_srgb_value();
}

String Color::to_string_without_alpha() const
{
    return MUST(String::formatted("#{:02x}{:02x}{:02x}", red(), green(), blue()));
}

Utf16String Color::to_utf16_string_without_alpha() const
{
    return Utf16String::formatted("#{:02x}{:02x}{:02x}", red(), green(), blue());
}

ByteString Color::to_byte_string() const
{
    return to_string().to_byte_string();
}

ByteString Color::to_byte_string_without_alpha() const
{
    return to_string_without_alpha().to_byte_string();
}

static Optional<Color> parse_rgb_color(StringView string)
{
    VERIFY(string.starts_with("rgb("sv, CaseSensitivity::CaseInsensitive));
    VERIFY(string.ends_with(')'));

    auto substring = string.substring_view(4, string.length() - 5);
    auto parts = substring.split_view(',');

    if (parts.size() != 3)
        return {};

    auto r = parts[0].to_number<double>().map(AK::clamp_to<u8, double>);
    auto g = parts[1].to_number<double>().map(AK::clamp_to<u8, double>);
    auto b = parts[2].to_number<double>().map(AK::clamp_to<u8, double>);

    if (!r.has_value() || !g.has_value() || !b.has_value())
        return {};

    return Color(*r, *g, *b);
}

static Optional<Color> parse_rgba_color(StringView string)
{
    VERIFY(string.starts_with("rgba("sv, CaseSensitivity::CaseInsensitive));
    VERIFY(string.ends_with(')'));

    auto substring = string.substring_view(5, string.length() - 6);
    auto parts = substring.split_view(',');

    if (parts.size() != 4)
        return {};

    auto r = parts[0].to_number<double>().map(AK::clamp_to<u8, double>);
    auto g = parts[1].to_number<double>().map(AK::clamp_to<u8, double>);
    auto b = parts[2].to_number<double>().map(AK::clamp_to<u8, double>);

    auto parse_result = AK::parse_first_number<double>(parts[3]);
    auto alpha = parse_result.has_value() ? parse_result->value : 0.0;

    unsigned a = alpha * 255;

    if (!r.has_value() || !g.has_value() || !b.has_value() || a > 255)
        return {};

    return Color(*r, *g, *b, a);
}

Optional<Color> Color::from_named_css_color_string(StringView string)
{
    if (string.is_empty())
        return {};

    struct WebColor {
        BGRA8888 color;
        StringView name;
    };

    constexpr Array web_colors {
        // CSS Level 1
        WebColor { 0x000000, "black"sv },
        WebColor { 0xc0c0c0, "silver"sv },
        WebColor { 0x808080, "gray"sv },
        WebColor { 0xffffff, "white"sv },
        WebColor { 0x800000, "maroon"sv },
        WebColor { 0xff0000, "red"sv },
        WebColor { 0x800080, "purple"sv },
        WebColor { 0xff00ff, "fuchsia"sv },
        WebColor { 0x008000, "green"sv },
        WebColor { 0x00ff00, "lime"sv },
        WebColor { 0x808000, "olive"sv },
        WebColor { 0xffff00, "yellow"sv },
        WebColor { 0x000080, "navy"sv },
        WebColor { 0x0000ff, "blue"sv },
        WebColor { 0x008080, "teal"sv },
        WebColor { 0x00ffff, "aqua"sv },
        // CSS Level 2 (Revision 1)
        WebColor { 0xffa500, "orange"sv },
        // CSS Color Module Level 3
        WebColor { 0xf0f8ff, "aliceblue"sv },
        WebColor { 0xfaebd7, "antiquewhite"sv },
        WebColor { 0x7fffd4, "aquamarine"sv },
        WebColor { 0xf0ffff, "azure"sv },
        WebColor { 0xf5f5dc, "beige"sv },
        WebColor { 0xffe4c4, "bisque"sv },
        WebColor { 0xffebcd, "blanchedalmond"sv },
        WebColor { 0x8a2be2, "blueviolet"sv },
        WebColor { 0xa52a2a, "brown"sv },
        WebColor { 0xdeb887, "burlywood"sv },
        WebColor { 0x5f9ea0, "cadetblue"sv },
        WebColor { 0x7fff00, "chartreuse"sv },
        WebColor { 0xd2691e, "chocolate"sv },
        WebColor { 0xff7f50, "coral"sv },
        WebColor { 0x6495ed, "cornflowerblue"sv },
        WebColor { 0xfff8dc, "cornsilk"sv },
        WebColor { 0xdc143c, "crimson"sv },
        WebColor { 0x00ffff, "cyan"sv },
        WebColor { 0x00008b, "darkblue"sv },
        WebColor { 0x008b8b, "darkcyan"sv },
        WebColor { 0xb8860b, "darkgoldenrod"sv },
        WebColor { 0xa9a9a9, "darkgray"sv },
        WebColor { 0x006400, "darkgreen"sv },
        WebColor { 0xa9a9a9, "darkgrey"sv },
        WebColor { 0xbdb76b, "darkkhaki"sv },
        WebColor { 0x8b008b, "darkmagenta"sv },
        WebColor { 0x556b2f, "darkolivegreen"sv },
        WebColor { 0xff8c00, "darkorange"sv },
        WebColor { 0x9932cc, "darkorchid"sv },
        WebColor { 0x8b0000, "darkred"sv },
        WebColor { 0xe9967a, "darksalmon"sv },
        WebColor { 0x8fbc8f, "darkseagreen"sv },
        WebColor { 0x483d8b, "darkslateblue"sv },
        WebColor { 0x2f4f4f, "darkslategray"sv },
        WebColor { 0x2f4f4f, "darkslategrey"sv },
        WebColor { 0x00ced1, "darkturquoise"sv },
        WebColor { 0x9400d3, "darkviolet"sv },
        WebColor { 0xff1493, "deeppink"sv },
        WebColor { 0x00bfff, "deepskyblue"sv },
        WebColor { 0x696969, "dimgray"sv },
        WebColor { 0x696969, "dimgrey"sv },
        WebColor { 0x1e90ff, "dodgerblue"sv },
        WebColor { 0xb22222, "firebrick"sv },
        WebColor { 0xfffaf0, "floralwhite"sv },
        WebColor { 0x228b22, "forestgreen"sv },
        WebColor { 0xdcdcdc, "gainsboro"sv },
        WebColor { 0xf8f8ff, "ghostwhite"sv },
        WebColor { 0xffd700, "gold"sv },
        WebColor { 0xdaa520, "goldenrod"sv },
        WebColor { 0xadff2f, "greenyellow"sv },
        WebColor { 0x808080, "grey"sv },
        WebColor { 0xf0fff0, "honeydew"sv },
        WebColor { 0xff69b4, "hotpink"sv },
        WebColor { 0xcd5c5c, "indianred"sv },
        WebColor { 0x4b0082, "indigo"sv },
        WebColor { 0xfffff0, "ivory"sv },
        WebColor { 0xf0e68c, "khaki"sv },
        WebColor { 0xe6e6fa, "lavender"sv },
        WebColor { 0xfff0f5, "lavenderblush"sv },
        WebColor { 0x7cfc00, "lawngreen"sv },
        WebColor { 0xfffacd, "lemonchiffon"sv },
        WebColor { 0xadd8e6, "lightblue"sv },
        WebColor { 0xf08080, "lightcoral"sv },
        WebColor { 0xe0ffff, "lightcyan"sv },
        WebColor { 0xfafad2, "lightgoldenrodyellow"sv },
        WebColor { 0xd3d3d3, "lightgray"sv },
        WebColor { 0x90ee90, "lightgreen"sv },
        WebColor { 0xd3d3d3, "lightgrey"sv },
        WebColor { 0xffb6c1, "lightpink"sv },
        WebColor { 0xffa07a, "lightsalmon"sv },
        WebColor { 0x20b2aa, "lightseagreen"sv },
        WebColor { 0x87cefa, "lightskyblue"sv },
        WebColor { 0x778899, "lightslategray"sv },
        WebColor { 0x778899, "lightslategrey"sv },
        WebColor { 0xb0c4de, "lightsteelblue"sv },
        WebColor { 0xffffe0, "lightyellow"sv },
        WebColor { 0x32cd32, "limegreen"sv },
        WebColor { 0xfaf0e6, "linen"sv },
        WebColor { 0xff00ff, "magenta"sv },
        WebColor { 0x66cdaa, "mediumaquamarine"sv },
        WebColor { 0x0000cd, "mediumblue"sv },
        WebColor { 0xba55d3, "mediumorchid"sv },
        WebColor { 0x9370db, "mediumpurple"sv },
        WebColor { 0x3cb371, "mediumseagreen"sv },
        WebColor { 0x7b68ee, "mediumslateblue"sv },
        WebColor { 0x00fa9a, "mediumspringgreen"sv },
        WebColor { 0x48d1cc, "mediumturquoise"sv },
        WebColor { 0xc71585, "mediumvioletred"sv },
        WebColor { 0x191970, "midnightblue"sv },
        WebColor { 0xf5fffa, "mintcream"sv },
        WebColor { 0xffe4e1, "mistyrose"sv },
        WebColor { 0xffe4b5, "moccasin"sv },
        WebColor { 0xffdead, "navajowhite"sv },
        WebColor { 0xfdf5e6, "oldlace"sv },
        WebColor { 0x6b8e23, "olivedrab"sv },
        WebColor { 0xff4500, "orangered"sv },
        WebColor { 0xda70d6, "orchid"sv },
        WebColor { 0xeee8aa, "palegoldenrod"sv },
        WebColor { 0x98fb98, "palegreen"sv },
        WebColor { 0xafeeee, "paleturquoise"sv },
        WebColor { 0xdb7093, "palevioletred"sv },
        WebColor { 0xffefd5, "papayawhip"sv },
        WebColor { 0xffdab9, "peachpuff"sv },
        WebColor { 0xcd853f, "peru"sv },
        WebColor { 0xffc0cb, "pink"sv },
        WebColor { 0xdda0dd, "plum"sv },
        WebColor { 0xb0e0e6, "powderblue"sv },
        WebColor { 0xbc8f8f, "rosybrown"sv },
        WebColor { 0x4169e1, "royalblue"sv },
        WebColor { 0x8b4513, "saddlebrown"sv },
        WebColor { 0xfa8072, "salmon"sv },
        WebColor { 0xf4a460, "sandybrown"sv },
        WebColor { 0x2e8b57, "seagreen"sv },
        WebColor { 0xfff5ee, "seashell"sv },
        WebColor { 0xa0522d, "sienna"sv },
        WebColor { 0x87ceeb, "skyblue"sv },
        WebColor { 0x6a5acd, "slateblue"sv },
        WebColor { 0x708090, "slategray"sv },
        WebColor { 0x708090, "slategrey"sv },
        WebColor { 0xfffafa, "snow"sv },
        WebColor { 0x00ff7f, "springgreen"sv },
        WebColor { 0x4682b4, "steelblue"sv },
        WebColor { 0xd2b48c, "tan"sv },
        WebColor { 0xd8bfd8, "thistle"sv },
        WebColor { 0xff6347, "tomato"sv },
        WebColor { 0x40e0d0, "turquoise"sv },
        WebColor { 0xee82ee, "violet"sv },
        WebColor { 0xf5deb3, "wheat"sv },
        WebColor { 0xf5f5f5, "whitesmoke"sv },
        WebColor { 0x9acd32, "yellowgreen"sv },
        // CSS Color Module Level 4
        WebColor { 0x663399, "rebeccapurple"sv },
    };

    for (auto const& web_color : web_colors) {
        if (string.equals_ignoring_ascii_case(web_color.name))
            return Color::from_bgrx(web_color.color);
    }

    return {};
}

static Optional<Color> hex_string_to_color(StringView string)
{
    auto hex_nibble_to_u8 = [](char nibble) -> Optional<u8> {
        if (!isxdigit(nibble))
            return {};
        if (nibble >= '0' && nibble <= '9')
            return nibble - '0';
        return 10 + (tolower(nibble) - 'a');
    };

    if (string.length() == 4) {
        Optional<u8> r = hex_nibble_to_u8(string[1]);
        Optional<u8> g = hex_nibble_to_u8(string[2]);
        Optional<u8> b = hex_nibble_to_u8(string[3]);
        if (!r.has_value() || !g.has_value() || !b.has_value())
            return {};
        return Color(r.value() * 17, g.value() * 17, b.value() * 17);
    }

    if (string.length() == 5) {
        Optional<u8> r = hex_nibble_to_u8(string[1]);
        Optional<u8> g = hex_nibble_to_u8(string[2]);
        Optional<u8> b = hex_nibble_to_u8(string[3]);
        Optional<u8> a = hex_nibble_to_u8(string[4]);
        if (!r.has_value() || !g.has_value() || !b.has_value() || !a.has_value())
            return {};
        return Color(r.value() * 17, g.value() * 17, b.value() * 17, a.value() * 17);
    }

    if (string.length() != 7 && string.length() != 9)
        return {};

    auto to_hex = [&](char c1, char c2) -> Optional<u8> {
        auto nib1 = hex_nibble_to_u8(c1);
        auto nib2 = hex_nibble_to_u8(c2);
        if (!nib1.has_value() || !nib2.has_value())
            return {};
        return nib1.value() << 4 | nib2.value();
    };

    Optional<u8> r = to_hex(string[1], string[2]);
    Optional<u8> g = to_hex(string[3], string[4]);
    Optional<u8> b = to_hex(string[5], string[6]);
    Optional<u8> a = string.length() == 9 ? to_hex(string[7], string[8]) : Optional<u8>(255);

    if (!r.has_value() || !g.has_value() || !b.has_value() || !a.has_value())
        return {};

    return Color(r.value(), g.value(), b.value(), a.value());
}

Optional<Color> Color::from_string(StringView string)
{
    if (string.is_empty())
        return {};

    if (string[0] == '#')
        return hex_string_to_color(string);

    if (string.starts_with("rgb("sv, CaseSensitivity::CaseInsensitive) && string.ends_with(')'))
        return parse_rgb_color(string);

    if (string.starts_with("rgba("sv, CaseSensitivity::CaseInsensitive) && string.ends_with(')'))
        return parse_rgba_color(string);

    if (string.equals_ignoring_ascii_case("transparent"sv))
        return Color::from_bgra(0x00000000);

    if (auto const color = from_named_css_color_string(string); color.has_value())
        return color;

    return {};
}

Optional<Color> Color::from_utf16_string(Utf16View const& string)
{
    return from_string(string.to_utf8_but_should_be_ported_to_utf16());
}

Vector<Color> Color::shades(u32 steps, float max) const
{
    float shade = 1.f;
    float step = max / steps;
    Vector<Color> shades;
    for (u32 i = 0; i < steps; i++) {
        shade -= step;
        shades.append(this->darkened(shade));
    }
    return shades;
}

Vector<Color> Color::tints(u32 steps, float max) const
{
    float shade = 1.f;
    float step = max / steps;
    Vector<Color> tints;
    for (u32 i = 0; i < steps; i++) {
        shade += step;
        tints.append(this->lightened(shade));
    }
    return tints;
}

static Color color_from_linear_srgb(ColorComponents const& linear)
{
    auto srgb = linear_srgb_to_srgb(linear);
    return Color(
        clamp(lroundf(srgb[0] * 255.0f), 0, 255),
        clamp(lroundf(srgb[1] * 255.0f), 0, 255),
        clamp(lroundf(srgb[2] * 255.0f), 0, 255),
        clamp(lroundf(srgb.alpha() * 255.0f), 0, 255));
}

Color Color::from_linear_srgb(float red, float green, float blue, float alpha)
{
    return color_from_linear_srgb({ red, green, blue, alpha });
}

Color Color::from_linear_display_p3(float r, float g, float b, float alpha)
{
    auto xyz = linear_display_p3_to_xyz65({ r, g, b, alpha });
    return from_xyz65(xyz[0], xyz[1], xyz[2], xyz.alpha());
}

// https://www.w3.org/TR/css-color-4/#predefined-a98-rgb
Color Color::from_a98rgb(float r, float g, float b, float alpha)
{
    auto xyz = a98rgb_to_xyz65({ r, g, b, alpha });
    return from_xyz65(xyz[0], xyz[1], xyz[2], xyz.alpha());
}

// https://www.w3.org/TR/css-color-4/#predefined-a98-rgb
Color Color::from_display_p3(float r, float g, float b, float alpha)
{
    auto linear = display_p3_to_linear_display_p3({ r, g, b, alpha });
    return from_linear_display_p3(linear[0], linear[1], linear[2], linear.alpha());
}

// https://www.w3.org/TR/css-color-4/#predefined-prophoto-rgb
Color Color::from_pro_photo_rgb(float r, float g, float b, float alpha)
{
    auto xyz = pro_photo_rgb_to_xyz50({ r, g, b, alpha });
    return from_xyz50(xyz[0], xyz[1], xyz[2], xyz.alpha());
}

// https://www.w3.org/TR/css-color-4/#predefined-rec2020
Color Color::from_rec2020(float r, float g, float b, float alpha)
{
    auto xyz = rec2020_to_xyz65({ r, g, b, alpha });
    return from_xyz65(xyz[0], xyz[1], xyz[2], xyz.alpha());
}

Color Color::from_xyz50(float x, float y, float z, float alpha)
{
    auto linear = xyz50_to_linear_srgb({ x, y, z, alpha });
    return color_from_linear_srgb(linear);
}

Color Color::from_xyz65(float x, float y, float z, float alpha)
{
    auto linear = xyz65_to_linear_srgb({ x, y, z, alpha });
    return color_from_linear_srgb(linear);
}

Color Color::from_lab(float L, float a, float b, float alpha)
{
    auto xyz = lab_to_xyz50({ L, a, b, alpha });
    return from_xyz50(xyz[0], xyz[1], xyz[2], xyz.alpha());
}

}

template<>
ErrorOr<void> IPC::encode(Encoder& encoder, Color const& color)
{
    return encoder.encode(color.value());
}

template<>
ErrorOr<Gfx::Color> IPC::decode(Decoder& decoder)
{
    auto rgba = TRY(decoder.decode<u32>());
    return Gfx::Color::from_bgra(rgba);
}

ErrorOr<void> AK::Formatter<Gfx::Color>::format(FormatBuilder& builder, Gfx::Color value)
{
    return Formatter<StringView>::format(builder, value.to_byte_string());
}

ErrorOr<void> AK::Formatter<Gfx::YUV>::format(FormatBuilder& builder, Gfx::YUV value)
{
    return Formatter<FormatString>::format(builder, "{} {} {}"sv, value.y, value.u, value.v);
}

ErrorOr<void> AK::Formatter<Gfx::HSV>::format(FormatBuilder& builder, Gfx::HSV value)
{
    return Formatter<FormatString>::format(builder, "{} {} {}"sv, value.hue, value.saturation, value.value);
}

ErrorOr<void> AK::Formatter<Gfx::Oklab>::format(FormatBuilder& builder, Gfx::Oklab value)
{
    return Formatter<FormatString>::format(builder, "{} {} {}"sv, value.L, value.a, value.b);
}