use super::GlobalFunctionMap;

use num_traits::One;

use super::Builtin;
use crate::color::Color;
use crate::common::QuoteKind;
use crate::unit::Unit;
use crate::value::{Number, Value};

pub(crate) fn register(f: &mut GlobalFunctionMap) {
    f.insert(
        "hsl",
        Builtin::new(|mut args, scope, super_selector| {
            if args.is_empty() {
                return Err(("Missing argument $channels.", args.span()).into());
            }

            if args.len() == 1 {
                let mut channels = match arg!(args, scope, super_selector, 0, "channels") {
                    Value::List(v, ..) => v,
                    _ => return Err(("Missing argument $channels.", args.span()).into()),
                };

                if channels.len() > 3 {
                    return Err((
                        format!(
                            "Only 3 elements allowed, but {} were passed.",
                            channels.len()
                        ),
                        args.span(),
                    )
                        .into());
                }

                let lightness = match channels.pop() {
                    Some(Value::Dimension(n, _)) => n / Number::from(100),
                    Some(v) => {
                        return Err((
                            format!(
                                "$lightness: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                    None => return Err(("Missing element $lightness.", args.span()).into()),
                };

                let saturation = match channels.pop() {
                    Some(Value::Dimension(n, _)) => n / Number::from(100),
                    Some(v) => {
                        return Err((
                            format!(
                                "$saturation: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                    None => return Err(("Missing element $saturation.", args.span()).into()),
                };

                let hue = match channels.pop() {
                    Some(Value::Dimension(n, _)) => n,
                    Some(v) => {
                        return Err((
                            format!("$hue: {} is not a number.", v.to_css_string(args.span())?),
                            args.span(),
                        )
                            .into())
                    }
                    None => return Err(("Missing element $hue.", args.span()).into()),
                };

                Ok(Value::Color(Box::new(Color::from_hsla(
                    hue,
                    saturation,
                    lightness,
                    Number::one(),
                ))))
            } else {
                let hue = match arg!(args, scope, super_selector, 0, "hue") {
                    Value::Dimension(n, _) => n,
                    v if v.is_special_function() => {
                        let saturation = arg!(args, scope, super_selector, 1, "saturation");
                        let lightness = arg!(args, scope, super_selector, 2, "lightness");
                        let mut string = format!(
                            "hsl({}, {}, {}",
                            v.to_css_string(args.span())?,
                            saturation.to_css_string(args.span())?,
                            lightness.to_css_string(args.span())?
                        );
                        if !args.is_empty() {
                            string.push_str(", ");
                            string.push_str(
                                &arg!(args, scope, super_selector, 3, "alpha")
                                    .to_css_string(args.span())?,
                            );
                        }
                        string.push(')');
                        return Ok(Value::Ident(string, QuoteKind::None));
                    }
                    v => {
                        return Err((
                            format!("$hue: {} is not a number.", v.to_css_string(args.span())?),
                            args.span(),
                        )
                            .into())
                    }
                };
                let saturation = match arg!(args, scope, super_selector, 1, "saturation") {
                    Value::Dimension(n, _) => n / Number::from(100),
                    v if v.is_special_function() => {
                        let lightness = arg!(args, scope, super_selector, 2, "lightness");
                        let mut string = format!(
                            "hsl({}, {}, {}",
                            hue,
                            v.to_css_string(args.span())?,
                            lightness.to_css_string(args.span())?
                        );
                        if !args.is_empty() {
                            string.push_str(", ");
                            string.push_str(
                                &arg!(args, scope, super_selector, 3, "alpha")
                                    .to_css_string(args.span())?,
                            );
                        }
                        string.push(')');
                        return Ok(Value::Ident(string, QuoteKind::None));
                    }
                    v => {
                        return Err((
                            format!(
                                "$saturation: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                };
                let lightness = match arg!(args, scope, super_selector, 2, "lightness") {
                    Value::Dimension(n, _) => n / Number::from(100),
                    v if v.is_special_function() => {
                        let mut string = format!(
                            "hsl({}, {}, {}",
                            hue,
                            saturation,
                            v.to_css_string(args.span())?
                        );
                        if !args.is_empty() {
                            string.push_str(", ");
                            string.push_str(
                                &arg!(args, scope, super_selector, 3, "alpha")
                                    .to_css_string(args.span())?,
                            );
                        }
                        string.push(')');
                        return Ok(Value::Ident(string, QuoteKind::None));
                    }
                    v => {
                        return Err((
                            format!(
                                "$lightness: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                };
                let alpha = match arg!(
                    args,
                    scope,
                    super_selector,
                    3,
                    "alpha" = Value::Dimension(Number::one(), Unit::None)
                ) {
                    Value::Dimension(n, Unit::None) => n,
                    Value::Dimension(n, Unit::Percent) => n / Number::from(100),
                    v @ Value::Dimension(..) => {
                        return Err((
                            format!(
                                "$alpha: Expected {} to have no units or \"%\".",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                    v if v.is_special_function() => {
                        return Ok(Value::Ident(
                            format!(
                                "hsl({}, {}, {}, {})",
                                hue,
                                saturation,
                                lightness,
                                v.to_css_string(args.span())?
                            ),
                            QuoteKind::None,
                        ));
                    }
                    v => {
                        return Err((
                            format!("$alpha: {} is not a number.", v.to_css_string(args.span())?),
                            args.span(),
                        )
                            .into())
                    }
                };
                Ok(Value::Color(Box::new(Color::from_hsla(
                    hue, saturation, lightness, alpha,
                ))))
            }
        }),
    );
    f.insert(
        "hsla",
        Builtin::new(|mut args, scope, super_selector| {
            if args.is_empty() {
                return Err(("Missing argument $channels.", args.span()).into());
            }

            if args.len() == 1 {
                let mut channels = match arg!(args, scope, super_selector, 0, "channels") {
                    Value::List(v, ..) => v,
                    _ => return Err(("Missing argument $channels.", args.span()).into()),
                };

                if channels.len() > 3 {
                    return Err((
                        format!(
                            "Only 3 elements allowed, but {} were passed.",
                            channels.len()
                        ),
                        args.span(),
                    )
                        .into());
                }

                let lightness = match channels.pop() {
                    Some(Value::Dimension(n, _)) => n / Number::from(100),
                    Some(v) => {
                        return Err((
                            format!(
                                "$lightness: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                    None => return Err(("Missing element $lightness.", args.span()).into()),
                };

                let saturation = match channels.pop() {
                    Some(Value::Dimension(n, _)) => n / Number::from(100),
                    Some(v) => {
                        return Err((
                            format!(
                                "$saturation: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                    None => return Err(("Missing element $saturation.", args.span()).into()),
                };

                let hue = match channels.pop() {
                    Some(Value::Dimension(n, _)) => n,
                    Some(v) => {
                        return Err((
                            format!("$hue: {} is not a number.", v.to_css_string(args.span())?),
                            args.span(),
                        )
                            .into())
                    }
                    None => return Err(("Missing element $hue.", args.span()).into()),
                };

                Ok(Value::Color(Box::new(Color::from_hsla(
                    hue,
                    saturation,
                    lightness,
                    Number::one(),
                ))))
            } else {
                let hue = match arg!(args, scope, super_selector, 0, "hue") {
                    Value::Dimension(n, _) => n,
                    v if v.is_special_function() => {
                        let saturation = arg!(args, scope, super_selector, 1, "saturation");
                        let lightness = arg!(args, scope, super_selector, 2, "lightness");
                        let mut string = format!(
                            "hsla({}, {}, {}",
                            v.to_css_string(args.span())?,
                            saturation.to_css_string(args.span())?,
                            lightness.to_css_string(args.span())?
                        );
                        if !args.is_empty() {
                            string.push_str(", ");
                            string.push_str(
                                &arg!(args, scope, super_selector, 3, "alpha")
                                    .to_css_string(args.span())?,
                            );
                        }
                        string.push(')');
                        return Ok(Value::Ident(string, QuoteKind::None));
                    }
                    v => {
                        return Err((
                            format!("$hue: {} is not a number.", v.to_css_string(args.span())?),
                            args.span(),
                        )
                            .into())
                    }
                };
                let saturation = match arg!(args, scope, super_selector, 1, "saturation") {
                    Value::Dimension(n, _) => n / Number::from(100),
                    v if v.is_special_function() => {
                        let lightness = arg!(args, scope, super_selector, 2, "lightness");
                        let mut string = format!(
                            "hsla({}, {}, {}",
                            hue,
                            v.to_css_string(args.span())?,
                            lightness.to_css_string(args.span())?
                        );
                        if !args.is_empty() {
                            string.push_str(", ");
                            string.push_str(
                                &arg!(args, scope, super_selector, 3, "alpha")
                                    .to_css_string(args.span())?,
                            );
                        }
                        string.push(')');
                        return Ok(Value::Ident(string, QuoteKind::None));
                    }
                    v => {
                        return Err((
                            format!(
                                "$saturation: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                };
                let lightness = match arg!(args, scope, super_selector, 2, "lightness") {
                    Value::Dimension(n, _) => n / Number::from(100),
                    v if v.is_special_function() => {
                        let mut string = format!(
                            "hsla({}, {}, {}",
                            hue,
                            saturation,
                            v.to_css_string(args.span())?
                        );
                        if !args.is_empty() {
                            string.push_str(", ");
                            string.push_str(
                                &arg!(args, scope, super_selector, 3, "alpha")
                                    .to_css_string(args.span())?,
                            );
                        }
                        string.push(')');
                        return Ok(Value::Ident(string, QuoteKind::None));
                    }
                    v => {
                        return Err((
                            format!(
                                "$lightness: {} is not a number.",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                };
                let alpha = match arg!(
                    args,
                    scope,
                    super_selector,
                    3,
                    "alpha" = Value::Dimension(Number::one(), Unit::None)
                ) {
                    Value::Dimension(n, Unit::None) => n,
                    Value::Dimension(n, Unit::Percent) => n / Number::from(100),
                    v @ Value::Dimension(..) => {
                        return Err((
                            format!(
                                "$alpha: Expected {} to have no units or \"%\".",
                                v.to_css_string(args.span())?
                            ),
                            args.span(),
                        )
                            .into())
                    }
                    v if v.is_special_function() => {
                        return Ok(Value::Ident(
                            format!(
                                "hsl({}, {}, {}, {})",
                                hue,
                                saturation,
                                lightness,
                                v.to_css_string(args.span())?
                            ),
                            QuoteKind::None,
                        ));
                    }
                    v => {
                        return Err((
                            format!("$alpha: {} is not a number.", v.to_css_string(args.span())?),
                            args.span(),
                        )
                            .into())
                    }
                };
                Ok(Value::Color(Box::new(Color::from_hsla(
                    hue, saturation, lightness, alpha,
                ))))
            }
        }),
    );
    f.insert(
        "hue",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(1)?;
            match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => Ok(Value::Dimension(c.hue(), Unit::Deg)),
                v => Err((
                    format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                    args.span(),
                )
                    .into()),
            }
        }),
    );
    f.insert(
        "saturation",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(1)?;
            match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => Ok(Value::Dimension(c.saturation(), Unit::Percent)),
                v => Err((
                    format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                    args.span(),
                )
                    .into()),
            }
        }),
    );
    f.insert(
        "lightness",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(1)?;
            match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => Ok(Value::Dimension(c.lightness(), Unit::Percent)),
                v => Err((
                    format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                    args.span(),
                )
                    .into()),
            }
        }),
    );
    f.insert(
        "adjust-hue",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(2)?;
            let color = match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => c,
                v => {
                    return Err((
                        format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                        args.span(),
                    )
                        .into())
                }
            };
            let degrees = match arg!(args, scope, super_selector, 1, "degrees") {
                Value::Dimension(n, _) => n,
                v => {
                    return Err((
                        format!(
                            "$degrees: {} is not a number.",
                            v.to_css_string(args.span())?
                        ),
                        args.span(),
                    )
                        .into())
                }
            };
            Ok(Value::Color(Box::new(color.adjust_hue(degrees))))
        }),
    );
    f.insert(
        "lighten",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(2)?;
            let color = match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => c,
                v => {
                    return Err((
                        format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                        args.span(),
                    )
                        .into())
                }
            };
            let amount = match arg!(args, scope, super_selector, 1, "amount") {
                Value::Dimension(n, u) => bound!(args, "amount", n, u, 0, 100) / Number::from(100),
                v => {
                    return Err((
                        format!(
                            "$amount: {} is not a number.",
                            v.to_css_string(args.span())?
                        ),
                        args.span(),
                    )
                        .into())
                }
            };
            Ok(Value::Color(Box::new(color.lighten(amount))))
        }),
    );
    f.insert(
        "darken",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(2)?;
            let color = match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => c,
                v => {
                    return Err((
                        format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                        args.span(),
                    )
                        .into())
                }
            };
            let amount = match arg!(args, scope, super_selector, 1, "amount") {
                Value::Dimension(n, u) => bound!(args, "amount", n, u, 0, 100) / Number::from(100),
                v => {
                    return Err((
                        format!(
                            "$amount: {} is not a number.",
                            v.to_css_string(args.span())?
                        ),
                        args.span(),
                    )
                        .into())
                }
            };
            Ok(Value::Color(Box::new(color.darken(amount))))
        }),
    );
    f.insert(
        "saturate",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(2)?;
            if args.len() == 1 {
                return Ok(Value::Ident(
                    format!(
                        "saturate({})",
                        arg!(args, scope, super_selector, 0, "amount")
                            .to_css_string(args.span())?
                    ),
                    QuoteKind::None,
                ));
            }

            let amount = match arg!(args, scope, super_selector, 1, "amount") {
                Value::Dimension(n, u) => bound!(args, "amount", n, u, 0, 100) / Number::from(100),
                v => {
                    return Err((
                        format!(
                            "$amount: {} is not a number.",
                            v.to_css_string(args.span())?
                        ),
                        args.span(),
                    )
                        .into())
                }
            };
            let color = match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => c,
                Value::Dimension(n, u) => {
                    return Ok(Value::Ident(
                        format!("saturate({}{})", n, u),
                        QuoteKind::None,
                    ))
                }
                v => {
                    return Err((
                        format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                        args.span(),
                    )
                        .into())
                }
            };
            Ok(Value::Color(Box::new(color.saturate(amount))))
        }),
    );
    f.insert(
        "desaturate",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(2)?;
            let color = match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => c,
                v => {
                    return Err((
                        format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                        args.span(),
                    )
                        .into())
                }
            };
            let amount = match arg!(args, scope, super_selector, 1, "amount") {
                Value::Dimension(n, u) => bound!(args, "amount", n, u, 0, 100) / Number::from(100),
                v => {
                    return Err((
                        format!(
                            "$amount: {} is not a number.",
                            v.to_css_string(args.span())?
                        ),
                        args.span(),
                    )
                        .into())
                }
            };
            Ok(Value::Color(Box::new(color.desaturate(amount))))
        }),
    );
    f.insert(
        "grayscale",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(1)?;
            let color = match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => c,
                Value::Dimension(n, u) => {
                    return Ok(Value::Ident(
                        format!("grayscale({}{})", n, u),
                        QuoteKind::None,
                    ))
                }
                v => {
                    return Err((
                        format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                        args.span(),
                    )
                        .into())
                }
            };
            Ok(Value::Color(Box::new(color.desaturate(Number::one()))))
        }),
    );
    f.insert(
        "complement",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(1)?;
            let color = match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => c,
                v => {
                    return Err((
                        format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                        args.span(),
                    )
                        .into())
                }
            };
            Ok(Value::Color(Box::new(color.complement())))
        }),
    );
    f.insert(
        "invert",
        Builtin::new(|mut args, scope, super_selector| {
            args.max_args(2)?;
            let weight = match arg!(
                args,
                scope,
                super_selector,
                1,
                "weight" = Value::Dimension(Number::from(100), Unit::Percent)
            ) {
                Value::Dimension(n, u) => bound!(args, "weight", n, u, 0, 100) / Number::from(100),
                v => {
                    return Err((
                        format!(
                            "$weight: {} is not a number.",
                            v.to_css_string(args.span())?
                        ),
                        args.span(),
                    )
                        .into())
                }
            };
            match arg!(args, scope, super_selector, 0, "color") {
                Value::Color(c) => Ok(Value::Color(Box::new(c.invert(weight)))),
                Value::Dimension(n, Unit::Percent) => {
                    Ok(Value::Ident(format!("invert({}%)", n), QuoteKind::None))
                }
                Value::Dimension(..) => Err((
                    "Only one argument may be passed to the plain-CSS invert() function.",
                    args.span(),
                )
                    .into()),
                v => Err((
                    format!("$color: {} is not a color.", v.to_css_string(args.span())?),
                    args.span(),
                )
                    .into()),
            }
        }),
    );
}