use gpui::{
    AnyElement, App, Div, ElementId, FontWeight, Hsla, ImageSource, IntoElement, ObjectFit,
    ParentElement, RenderOnce, SharedString, Styled, Window, div, prelude::*,
};

use crate::{
    primitives::{Icon, IconName, Image},
    theme::{ActiveTheme, AvatarSize, IconSize, Palette, Radius, TextSize},
};

/// Whether someone is around.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Presence {
    Online,
    Away,
    Busy,
    Offline,
}

impl Presence {
    pub fn color(self, colors: &Palette) -> Hsla {
        match self {
            Self::Online => colors.success,
            Self::Away => colors.warning,
            Self::Busy => colors.danger,
            Self::Offline => colors.fg_subtle,
        }
    }

    pub fn label(self) -> &'static str {
        match self {
            Self::Online => "Online",
            Self::Away => "Away",
            Self::Busy => "Busy",
            Self::Offline => "Offline",
        }
    }
}

/// Up to two capitals from a name's first and last words.
pub(crate) fn initials(name: &str) -> String {
    let words: Vec<&str> = name.split_whitespace().collect();
    let first = |word: &str| word.chars().next().into_iter().flat_map(char::to_uppercase);
    match words.as_slice() {
        [] => String::new(),
        [only] => first(only).collect(),
        [head, .., tail] => first(head).chain(first(tail)).collect(),
    }
}

/// The chart color a name keeps, so the same person reads the same way everywhere.
fn tint(name: &str, colors: &Palette) -> Hsla {
    let hash = name.bytes().fold(0u32, |hash, byte| {
        hash.wrapping_mul(31).wrapping_add(u32::from(byte))
    });
    colors.chart[hash as usize % colors.chart.len()]
}

/// A person or a team at a glance: their picture, or their initials on a tone kept by the name, or an icon. A presence dot can sit on the corner; squares suit teams.
#[derive(IntoElement)]
pub struct Avatar {
    id: ElementId,
    name: SharedString,
    image: Option<ImageSource>,
    icon: Option<IconName>,
    size: AvatarSize,
    square: bool,
    ring: bool,
    ring_color: Option<Hsla>,
    presence: Option<Presence>,
}

impl Avatar {
    /// The name gives the initials and the tone when there is no picture.
    pub fn new(id: impl Into<ElementId>, name: impl Into<SharedString>) -> Self {
        Self {
            id: id.into(),
            name: name.into(),
            image: None,
            icon: None,
            size: AvatarSize::default(),
            square: false,
            ring: false,
            ring_color: None,
            presence: None,
        }
    }

    /// A picture, cropped to fill the avatar.
    pub fn image(mut self, source: impl Into<ImageSource>) -> Self {
        self.image = Some(source.into());
        self
    }

    /// Shown instead of initials, for a bot or a place.
    pub fn icon(mut self, icon: IconName) -> Self {
        self.icon = Some(icon);
        self
    }

    pub fn size(mut self, size: AvatarSize) -> Self {
        self.size = size;
        self
    }

    /// Whether it is a rounded square rather than a circle.
    pub(crate) fn is_square(&self) -> bool {
        self.square
    }

    /// A rounded square, as teams and apps take.
    pub fn square(mut self) -> Self {
        self.square = true;
        self
    }

    /// A ring in the page color, so avatars that overlap stay apart.
    pub fn ring(mut self) -> Self {
        self.ring = true;
        self
    }

    /// A ring in `color`, as someone's own color marks them.
    pub fn ring_color(mut self, color: Hsla) -> Self {
        self.ring = true;
        self.ring_color = Some(color);
        self
    }

    pub fn presence(mut self, presence: Presence) -> Self {
        self.presence = Some(presence);
        self
    }
}

impl RenderOnce for Avatar {
    fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
        let theme = cx.theme();
        let colors = &theme.colors;
        let side = theme.avatar_size(self.size);
        let rounded = |element: gpui::Div| {
            if self.square {
                element.rounded(theme.radius(Radius::Md))
            } else {
                element.rounded_full()
            }
        };
        let tone = tint(&self.name, colors);
        let text = match self.size {
            AvatarSize::Xs | AvatarSize::Sm => TextSize::Xs,
            AvatarSize::Md => TextSize::Sm,
            AvatarSize::Lg => TextSize::Md,
            AvatarSize::Xl => TextSize::Lg,
        };
        let face: AnyElement = match (self.image, self.icon) {
            (Some(source), _) => {
                let mut picture = Image::new((self.id.clone(), "picture"), source)
                    .fit(ObjectFit::Cover)
                    .size_full();
                picture = if self.square {
                    picture.rounded(theme.radius(Radius::Md))
                } else {
                    picture.rounded_full()
                };
                picture.into_any_element()
            }
            (None, Some(icon)) => Icon::new(icon)
                .size(IconSize::Md)
                .color(colors.fg_muted)
                .into_any_element(),
            (None, None) => initials(&self.name).into_any_element(),
        };
        let dot = self.presence.map(|presence| {
            div()
                .absolute()
                .right_0()
                .bottom_0()
                .size(side * 0.28)
                .rounded_full()
                .border_2()
                .border_color(colors.bg)
                .bg(presence.color(colors))
        });
        div()
            .relative()
            .flex_none()
            .size(side)
            .child(
                rounded(div())
                    .size_full()
                    .flex()
                    .items_center()
                    .justify_center()
                    .bg(tone.opacity(0.16))
                    .text_color(tone)
                    .text_size(theme.text_size(text))
                    .font_weight(FontWeight::SEMIBOLD)
                    .when(self.ring, |face| {
                        face.border_2()
                            .border_color(self.ring_color.unwrap_or(colors.bg))
                    })
                    .child(face),
            )
            .children(dot)
    }
}

/// An avatar's slot in a row, tucked under the one before unless `first`.
pub(crate) fn tucked(first: bool, size: AvatarSize) -> Div {
    match (first, size) {
        (true, _) => div(),
        (false, AvatarSize::Xs | AvatarSize::Sm) => div().ml_neg_1(),
        (false, AvatarSize::Md) => div().ml_neg_2(),
        (false, AvatarSize::Lg | AvatarSize::Xl) => div().ml_neg_3(),
    }
}

/// The count that stands for `rest` people past the ones shown.
pub(crate) fn more(rest: usize, size: AvatarSize, cx: &App) -> Div {
    let theme = cx.theme();
    div()
        .flex()
        .items_center()
        .justify_center()
        .size(theme.avatar_size(size))
        .rounded_full()
        .border_2()
        .border_color(theme.colors.bg)
        .bg(theme.colors.hover)
        .text_size(theme.text_size(TextSize::Xs))
        .font_weight(FontWeight::MEDIUM)
        .text_color(theme.colors.fg_muted)
        .child(format!("+{rest}"))
}

/// People side by side, each tucked under the next, and a count of the rest.
#[derive(IntoElement)]
pub struct AvatarGroup {
    people: Vec<Avatar>,
    max: usize,
    size: AvatarSize,
}

impl AvatarGroup {
    pub fn new(people: impl IntoIterator<Item = Avatar>) -> Self {
        Self {
            people: people.into_iter().collect(),
            max: 4,
            size: AvatarSize::default(),
        }
    }

    /// How many show before the rest become +N.
    pub fn max(mut self, max: usize) -> Self {
        assert!(max > 0, "a group shows at least one avatar");
        self.max = max;
        self
    }

    pub fn size(mut self, size: AvatarSize) -> Self {
        self.size = size;
        self
    }
}

impl RenderOnce for AvatarGroup {
    fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
        let rest = self.people.len().saturating_sub(self.max);
        let size = self.size;
        let shown = self
            .people
            .into_iter()
            .take(self.max)
            .enumerate()
            .map(|(ix, person)| tucked(ix == 0, size).child(person.size(size).ring()));
        let extra = (rest > 0).then(|| tucked(false, size).child(more(rest, size, cx)));
        div().flex().items_center().children(shown).children(extra)
    }
}

/// Someone named in a line or a field: a small avatar and the name, in a pill.
#[derive(IntoElement)]
pub struct UserChip {
    avatar: Avatar,
    name: SharedString,
}

impl UserChip {
    pub fn new(id: impl Into<ElementId>, name: impl Into<SharedString>) -> Self {
        let name = name.into();
        Self {
            avatar: Avatar::new(id, name.clone()).size(AvatarSize::Xs),
            name,
        }
    }

    pub fn image(mut self, source: impl Into<ImageSource>) -> Self {
        self.avatar = self.avatar.image(source);
        self
    }
}

impl RenderOnce for UserChip {
    fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
        let theme = cx.theme();
        div()
            .flex()
            .flex_none()
            .items_center()
            .gap_1p5()
            .pl_0p5()
            .pr_2()
            .py_0p5()
            .rounded_full()
            .bg(theme.colors.hover)
            .text_size(theme.text_size(TextSize::Sm))
            .text_color(theme.colors.fg)
            .child(self.avatar)
            .child(self.name)
    }
}

#[cfg(test)]
mod tests {
    use super::initials;

    #[test]
    fn initials_take_the_first_and_last_words() {
        assert_eq!(initials("Ada Lovelace"), "AL");
        assert_eq!(initials("Grace Brewster Murray Hopper"), "GH");
        assert_eq!(initials("mia"), "M");
        assert_eq!(initials("  "), "");
        assert_eq!(initials("élodie durand"), "ÉD");
    }
}