//! How nodes and lines are drawn: borders, line kinds, arrowheads, colors.
//!
//! Each field of [`NodeLook`] and [`LineLook`] is an override, and `None`
//! means "whatever the theme says". The theme works a look out in layers: its
//! default, then a style set by one of the node's tags, then a named style,
//! then these fields. Each layer only states what it changes.
//!
//! The plain enums here derive serde, so document files can name them
//! directly (`border: Dashed`).

use serde::{Deserialize, Serialize};

use super::text::{ColorName, StyleName};

/// The border around a node's box.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum Border {
    Rounded,
    Square,
    Double,
    Thick,
    Dashed,
    /// No border: just the text.
    Hidden,
}

/// What a line looks like along its length.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum Stroke {
    Solid,
    Dashed,
    Dotted,
    Thick,
    Double,
}

/// Which ends of a line have an arrowhead. The end is where a cross-link
/// points to; for a branch it's the child.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum Arrows {
    Off,
    End,
    Start,
    Both,
}

/// The color of a line.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum LineColor {
    /// A color from the theme's palette.
    Named(ColorName),
    /// The color of the node the line comes from: a branch takes its
    /// parent's (so a node's color flows down the lines to its children,
    /// mind-map style), a cross-link its start's.
    FollowNode,
}

/// How a node is drawn, on top of what the theme says.
#[derive(Debug, Clone, Default, PartialEq, Eq, Hash)]
pub struct NodeLook {
    pub color: Option<ColorName>,
    pub border: Option<Border>,
    /// A named style from the theme, which can set the color and border.
    pub style: Option<StyleName>,
}

impl NodeLook {
    /// True when nothing is overridden: the node looks the way the theme says.
    pub fn is_default(&self) -> bool {
        *self == NodeLook::default()
    }
}

/// How a line is drawn (a branch or a cross-link), on top of what the theme
/// says.
#[derive(Debug, Clone, Default, PartialEq, Eq, Hash)]
pub struct LineLook {
    pub arrows: Option<Arrows>,
    pub line: Option<Stroke>,
    pub color: Option<LineColor>,
    /// A named style from the theme, which can set all of the above.
    pub style: Option<StyleName>,
}

impl LineLook {
    /// True when nothing is overridden: the line looks the way the theme says.
    pub fn is_default(&self) -> bool {
        *self == LineLook::default()
    }
}