use super::{Deserialize, Serialize};

/// Stable per-document object id. Never reused.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)]
#[serde(transparent)]
pub struct NodeId(pub u64);

impl std::fmt::Display for NodeId {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "#{}", self.0)
    }
}

/// Layer colours used for selection highlighting (index into [`LAYER_COLORS`]) or a custom RGB.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum LayerColor {
    Preset(u8),
    Custom([u8; 3]),
}

/// Layer highlight colours, assigned in sequence to new layers. First is Illustrator-like light blue.
pub const LAYER_COLORS: [(&str, [u8; 3]); 27] = [
    ("Light Blue", [0x4f, 0x80, 0xff]),
    ("Red", [0xff, 0x4f, 0x4f]),
    ("Green", [0x4f, 0xff, 0x4f]),
    ("Blue", [0x4f, 0x4f, 0xff]),
    ("Yellow", [0xff, 0xff, 0x4f]),
    ("Magenta", [0xff, 0x4f, 0xff]),
    ("Cyan", [0x4f, 0xff, 0xff]),
    ("Gray", [0x80, 0x80, 0x80]),
    ("Black", [0x00, 0x00, 0x00]),
    ("Orange", [0xff, 0x66, 0x00]),
    ("Dark Green", [0x00, 0x80, 0x00]),
    ("Teal", [0x00, 0x80, 0x80]),
    ("Tan", [0xcc, 0x99, 0x66]),
    ("Brown", [0x99, 0x33, 0x00]),
    ("Violet", [0x99, 0x33, 0xff]),
    ("Gold", [0xff, 0x99, 0x00]),
    ("Dark Blue", [0x00, 0x00, 0x80]),
    ("Pink", [0xff, 0x99, 0xcc]),
    ("Lavender", [0x99, 0x99, 0xff]),
    ("Brick Red", [0x99, 0x00, 0x00]),
    ("Olive Green", [0x66, 0x66, 0x00]),
    ("Peach", [0xff, 0x99, 0x99]),
    ("Burgundy", [0x99, 0x00, 0x33]),
    ("Grass Green", [0x99, 0xcc, 0x00]),
    ("Ochre", [0x99, 0x66, 0x00]),
    ("Purple", [0x66, 0x00, 0x99]),
    ("Light Gray", [0xbb, 0xbb, 0xbb]),
];

impl LayerColor {
    pub fn rgb(self) -> [u8; 3] {
        match self {
            LayerColor::Preset(i) => LAYER_COLORS[i as usize % LAYER_COLORS.len()].1,
            LayerColor::Custom(c) => c,
        }
    }

    /// The color as text: a preset's name from [`LAYER_COLORS`], else `#rrggbb` (lowercase).
    pub fn label_text(self) -> String {
        let preset = match self {
            LayerColor::Preset(i) => LAYER_COLORS.get(usize::from(i)),
            LayerColor::Custom(_) => None,
        };
        preset.map_or_else(
            || {
                let [r, g, b] = self.rgb();
                format!("#{r:02x}{g:02x}{b:02x}")
            },
            |(name, _)| (*name).to_string(),
        )
    }

    /// The color [`LayerColor::label_text`] names: a preset's name exactly as [`LAYER_COLORS`]
    /// spells it, or `#rrggbb` with six hex digits. None for anything else.
    pub fn from_label_text(s: &str) -> Option<Self> {
        if let Some(i) = LAYER_COLORS.iter().position(|(name, _)| *name == s) {
            return u8::try_from(i).ok().map(LayerColor::Preset);
        }
        let hex = s.strip_prefix('#').filter(|h| h.len() == 6 && h.bytes().all(|b| b.is_ascii_hexdigit()))?;
        let byte = |k: usize| u8::from_str_radix(&hex[k..k + 2], 16).ok();
        Some(LayerColor::Custom([byte(0)?, byte(2)?, byte(4)?]))
    }
}