rich/

style.rs

//! Text styles.
//!
//! Port of upstream `rich/style.py` (core attributes). A [`Style`] holds an
//! optional foreground/background [`Color`] plus a set of boolean attributes
//! (bold, italic, …). Each attribute is tri-state: `Some(true)` = on,
//! `Some(false)` = explicitly off, `None` = unset — this preserves upstream's
//! `_set_attributes`/`_attributes` bitmask semantics under [`Style::combine`].

use crate::color::{Color, ColorSystem};
use crate::errors::{Result, RichError};

/// The 13 boolean attributes, in the SGR order upstream emits them.
const ATTR_COUNT: usize = 13;

/// SGR codes per attribute index (`rich.style._STYLE_MAP`).
const ATTR_SGR: [&str; ATTR_COUNT] = [
    "1", "2", "3", "4", "5", "6", "7", "8", "9", "21", "51", "52", "53",
];

/// Canonical attribute names per index.
const ATTR_NAMES: [&str; ATTR_COUNT] = [
    "bold",
    "dim",
    "italic",
    "underline",
    "blink",
    "blink2",
    "reverse",
    "conceal",
    "strike",
    "underline2",
    "frame",
    "encircle",
    "overline",
];

/// Map a style word (including upstream's short aliases) to its attribute index.
fn attribute_index(word: &str) -> Option<usize> {
    let canonical = match word {
        "b" => "bold",
        "d" => "dim",
        "i" => "italic",
        "u" => "underline",
        "r" => "reverse",
        "c" => "conceal",
        "s" => "strike",
        "uu" => "underline2",
        "o" => "overline",
        other => other,
    };
    ATTR_NAMES.iter().position(|&n| n == canonical)
}

/// A style, or the *name* of one to be looked up later. Port of upstream's
/// `StyleType = Union[str, "Style"]` (`rich/style.py`).
///
/// A [`Span`](crate::text::Span) that holds a [`Name`](StyleType::Name) is
/// resolved when it is rendered, against the theme of the console doing the
/// rendering — so the same [`Text`](crate::text::Text) printed to two differently
/// themed consoles comes out in two different colours, as it does upstream.
/// Resolving eagerly instead would freeze the colours at construction time.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum StyleType {
    /// A theme key (`"repr.number"`) or a style definition (`"bold red"`),
    /// resolved by [`Theme::get_style`](crate::theme::Theme::get_style).
    Name(String),
    /// An already-resolved style.
    Style(Style),
}

impl Default for StyleType {
    fn default() -> Self {
        StyleType::Style(Style::new())
    }
}

impl StyleType {
    /// True when this is an already-resolved style that sets nothing. A
    /// [`Name`](StyleType::Name) is never null — it may resolve to anything.
    pub fn is_null_style(&self) -> bool {
        matches!(self, StyleType::Style(style) if style.is_null())
    }
}

impl From<Style> for StyleType {
    fn from(style: Style) -> Self {
        StyleType::Style(style)
    }
}

impl From<&Style> for StyleType {
    fn from(style: &Style) -> Self {
        StyleType::Style(style.clone())
    }
}

impl From<String> for StyleType {
    fn from(name: String) -> Self {
        StyleType::Name(name)
    }
}

impl From<&str> for StyleType {
    fn from(name: &str) -> Self {
        StyleType::Name(name.to_string())
    }
}

/// A terminal text style. Mirrors `rich.style.Style`.
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct Style {
    color: Option<Color>,
    bgcolor: Option<Color>,
    attrs: [Option<bool>; ATTR_COUNT],
    /// An OSC 8 hyperlink target, if any.
    link: Option<String>,
}

impl Style {
    /// The empty (null) style — sets nothing.
    pub fn new() -> Self {
        Style::default()
    }

    /// A style carrying only a foreground and/or background color.
    /// Port of `Style.from_color`.
    pub fn from_color(color: Option<Color>, bgcolor: Option<Color>) -> Self {
        Style {
            color,
            bgcolor,
            attrs: [None; ATTR_COUNT],
            link: None,
        }
    }

    pub fn with_color(mut self, color: Color) -> Self {
        self.color = Some(color);
        self
    }

    /// Attach an OSC 8 hyperlink target. Port of `Style(link=…)`.
    pub fn with_link(mut self, url: impl Into<String>) -> Self {
        self.link = Some(url.into());
        self
    }

    /// The hyperlink target, if set.
    pub fn link(&self) -> Option<&str> {
        self.link.as_deref()
    }

    /// Return a copy with the hyperlink target set (`Some`) or cleared (`None`),
    /// leaving every other attribute unchanged. Port of `Style.update_link`.
    pub fn update_link(&self, link: Option<String>) -> Style {
        let mut style = self.clone();
        style.link = link;
        style
    }

    pub fn with_bgcolor(mut self, color: Color) -> Self {
        self.bgcolor = Some(color);
        self
    }

    pub fn color(&self) -> Option<&Color> {
        self.color.as_ref()
    }

    pub fn bgcolor(&self) -> Option<&Color> {
        self.bgcolor.as_ref()
    }

    /// A copy with the foreground and background colours removed; attributes
    /// and link survive. Port of `Style.without_color`.
    pub fn without_color(&self) -> Style {
        Style {
            color: None,
            bgcolor: None,
            attrs: self.attrs,
            link: self.link.clone(),
        }
    }

    /// The tri-state value of attribute `index` (see the internal `attrs` order:
    /// 0=bold, 1=dim, 2=italic, 3=underline, 6=reverse, 8=strike, …).
    pub fn attr(&self, index: usize) -> Option<bool> {
        self.attrs.get(index).copied().flatten()
    }

    /// True when nothing at all is set (renders as a no-op).
    pub fn is_null(&self) -> bool {
        self.color.is_none()
            && self.bgcolor.is_none()
            && self.link.is_none()
            && self.attrs.iter().all(Option::is_none)
    }

    /// Regenerate the style definition string. Port of `Style.__str__`.
    ///
    /// Attributes come first in their canonical order, then the foreground
    /// colour, then `on <bgcolour>`, then `link <url>`. A style that sets nothing
    /// is `"none"` — never the empty string, which upstream reserves for "no
    /// style at all".
    pub fn definition(&self) -> String {
        let mut parts: Vec<String> = Vec::new();
        for (index, name) in ATTR_NAMES.iter().enumerate() {
            match self.attrs[index] {
                Some(true) => parts.push((*name).to_string()),
                Some(false) => parts.push(format!("not {name}")),
                None => {}
            }
        }
        if let Some(color) = &self.color {
            parts.push(color.name.clone());
        }
        if let Some(bgcolor) = &self.bgcolor {
            parts.push("on".to_string());
            parts.push(bgcolor.name.clone());
        }
        if let Some(link) = &self.link {
            parts.push("link".to_string());
            parts.push(link.clone());
        }
        if parts.is_empty() {
            "none".to_string()
        } else {
            parts.join(" ")
        }
    }

    /// Canonicalise a style definition so that definitions with the same effect
    /// have the same string. Port of `Style.normalize`.
    ///
    /// A definition that parses round-trips through [`definition`](Self::definition),
    /// so `"b"` and `"BOLD"` both become `"bold"`. One that does not parse is
    /// merely trimmed and lowercased — that is the path a *theme name* like
    /// `"repr.number"` takes, and it is why theme lookups are effectively
    /// case-insensitive on the markup side while [`Theme::get_style`] itself is
    /// case-sensitive.
    ///
    /// [`Theme::get_style`]: crate::theme::Theme::get_style
    pub fn normalize(definition: &str) -> String {
        match Style::parse(definition) {
            Ok(style) => style.definition(),
            Err(_) => definition.trim().to_lowercase(),
        }
    }

    /// Parse a style definition such as `"bold red on blue"`.
    ///
    /// Port of `Style.parse` covering attributes, `not <attr>`, `link <url>`, and
    /// `<color> on <color>`. (`meta` is deferred — see DIVERGENCES.)
    pub fn parse(definition: &str) -> Result<Self> {
        // Port of upstream's leading guard:
        //     if style_definition.strip() == "none" or not style_definition
        // `none` is only valid as the WHOLE definition — upstream raises on
        // `"bold none"`, because inside the word loop `none` is treated as a
        // colour name and fails to parse. Many `DEFAULT_STYLES` entries are
        // exactly `"none"`, so without this they would all be dropped.
        if definition.is_empty() || definition.trim() == "none" {
            return Ok(Style::new());
        }
        let mut style = Style::new();
        let mut words = definition.split_whitespace();
        while let Some(raw) = words.next() {
            let word = raw.to_ascii_lowercase();
            match word.as_str() {
                "on" => {
                    let color_word = words.next().ok_or_else(|| {
                        RichError::StyleSyntax("color expected after 'on'".to_string())
                    })?;
                    style.bgcolor = Some(Color::parse(color_word)?);
                }
                "not" => {
                    let attr_word = words.next().ok_or_else(|| {
                        RichError::StyleSyntax("attribute expected after 'not'".to_string())
                    })?;
                    // Deliberately NOT lowercased: upstream folds case only on
                    // the loop word, and looks the `not` operand up verbatim —
                    // so `"not BOLD"` is a syntax error there, and must be here.
                    let idx = attribute_index(attr_word).ok_or_else(|| {
                        RichError::StyleSyntax(format!(
                            "{attr_word:?} is not a recognized attribute"
                        ))
                    })?;
                    style.attrs[idx] = Some(false);
                }
                "link" => {
                    // A bare `link` is a syntax error upstream, not an empty
                    // link — accepting it would emit a hyperlink to nowhere.
                    let url = words.next().filter(|url| !url.is_empty()).ok_or_else(|| {
                        RichError::StyleSyntax("URL expected after 'link'".to_string())
                    })?;
                    style.link = Some(url.to_string());
                }
                _ => {
                    if let Some(idx) = attribute_index(&word) {
                        style.attrs[idx] = Some(true);
                    } else {
                        style.color = Some(Color::parse(&word)?);
                    }
                }
            }
        }
        Ok(style)
    }

    /// Combine two styles, `other` winning wherever it sets a value.
    ///
    /// Port of `Style.__add__`.
    pub fn combine(&self, other: &Style) -> Style {
        let mut attrs = self.attrs;
        for (slot, over) in attrs.iter_mut().zip(other.attrs.iter()) {
            if over.is_some() {
                *slot = *over;
            }
        }
        Style {
            color: other.color.clone().or_else(|| self.color.clone()),
            bgcolor: other.bgcolor.clone().or_else(|| self.bgcolor.clone()),
            attrs,
            link: other.link.clone().or_else(|| self.link.clone()),
        }
    }

    /// The SGR parameter list (e.g. `"1;31;44"`) for a given color system.
    ///
    /// Port of `Style._make_ansi_codes`.
    pub fn ansi_codes(&self, system: ColorSystem) -> String {
        let mut sgr: Vec<String> = Vec::new();
        for (idx, attr) in self.attrs.iter().enumerate() {
            if *attr == Some(true) {
                sgr.push(ATTR_SGR[idx].to_string());
            }
        }
        if let Some(color) = &self.color {
            sgr.extend(color.downgrade(system).ansi_codes(true));
        }
        if let Some(bgcolor) = &self.bgcolor {
            sgr.extend(bgcolor.downgrade(system).ansi_codes(false));
        }
        sgr.join(";")
    }

    /// The CSS declarations for this style under `theme` (for HTML export).
    /// Port of `Style.get_html_style`.
    pub fn get_html_style(&self, theme: &crate::terminal_theme::TerminalTheme) -> String {
        use crate::terminal_theme::blend_rgb;
        let mut css: Vec<String> = Vec::new();

        let mut color = self.color.clone();
        let mut bgcolor = self.bgcolor.clone();
        // reverse (attr index 6): swap fore/background.
        if self.attrs[6] == Some(true) {
            std::mem::swap(&mut color, &mut bgcolor);
        }
        // dim (attr index 1): blend the foreground halfway to the background.
        if self.attrs[1] == Some(true) {
            let fg = match &color {
                Some(c) => theme.resolve(c, true),
                None => theme.foreground,
            };
            let blended = blend_rgb(fg, theme.background, 0.5);
            color = Some(Color::from_rgb(blended.red, blended.green, blended.blue));
        }

        if let Some(c) = &color {
            let hex = theme.resolve(c, true).hex();
            css.push(format!("color: {hex}"));
            css.push(format!("text-decoration-color: {hex}"));
        }
        if let Some(c) = &bgcolor {
            let hex = theme.resolve(c, false).hex();
            css.push(format!("background-color: {hex}"));
        }
        if self.attrs[0] == Some(true) {
            css.push("font-weight: bold".to_string());
        }
        if self.attrs[2] == Some(true) {
            css.push("font-style: italic".to_string());
        }
        if self.attrs[3] == Some(true) {
            css.push("text-decoration: underline".to_string());
        }
        if self.attrs[8] == Some(true) {
            css.push("text-decoration: line-through".to_string());
        }
        if self.attrs[12] == Some(true) {
            css.push("text-decoration: overline".to_string());
        }
        css.join("; ")
    }

    /// The SVG `<text>` CSS declarations for this style under `theme`. Port of
    /// the `get_svg_style` closure in `Console.export_svg`. Unlike
    /// [`get_html_style`](Self::get_html_style), the colour is always resolved to
    /// a concrete triplet (the theme fore/background stands in for a missing or
    /// default colour), `dim` blends 40% toward the background (not 50%), and the
    /// rules are joined with a bare `;`.
    pub fn get_svg_style(&self, theme: &crate::terminal_theme::TerminalTheme) -> String {
        use crate::terminal_theme::blend_rgb;
        // Resolve fore/background to concrete triplets (theme defaults fill in for
        // a None/default colour, exactly as `theme.resolve` does for `Default`).
        let mut color = self
            .color
            .as_ref()
            .map_or(theme.foreground, |c| theme.resolve(c, true));
        let mut bgcolor = self
            .bgcolor
            .as_ref()
            .map_or(theme.background, |c| theme.resolve(c, false));
        if self.attrs[6] == Some(true) {
            std::mem::swap(&mut color, &mut bgcolor);
        }
        if self.attrs[1] == Some(true) {
            color = blend_rgb(color, bgcolor, 0.4);
        }
        let mut rules = vec![format!("fill: {}", color.hex())];
        if self.attrs[0] == Some(true) {
            rules.push("font-weight: bold".to_string());
        }
        if self.attrs[2] == Some(true) {
            rules.push("font-style: italic;".to_string());
        }
        if self.attrs[3] == Some(true) {
            rules.push("text-decoration: underline;".to_string());
        }
        if self.attrs[8] == Some(true) {
            rules.push("text-decoration: line-through;".to_string());
        }
        rules.join(";")
    }

    /// Wrap `text` in this style's escape sequence for `system`.
    ///
    /// With `system == None` (no color) or a null style, `text` is returned
    /// unchanged. A [`link`](Self::with_link) additionally wraps the result in an
    /// OSC 8 hyperlink. Port of `Style.render`.
    ///
    /// **Divergence:** upstream tags each hyperlink with a random `id=` field (to
    /// group multi-segment links for hover); we omit it so output is
    /// deterministic. See docs/DIVERGENCES.md.
    pub fn render(&self, text: &str, system: Option<ColorSystem>) -> String {
        let Some(system) = system else {
            return text.to_string();
        };
        if text.is_empty() {
            return text.to_string();
        }
        let codes = self.ansi_codes(system);
        let rendered = if codes.is_empty() {
            text.to_string()
        } else {
            format!("\x1b[{codes}m{text}\x1b[0m")
        };
        match &self.link {
            Some(url) => format!("\x1b]8;;{url}\x1b\\{rendered}\x1b]8;;\x1b\\"),
            None => rendered,
        }
    }
}

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

    /// `normalize` round-trips a parseable definition through `definition()` and
    /// merely trims+lowercases one that isn't. Every expectation here was taken
    /// from real rich 15.0.0's `Style.normalize`.
    #[test]
    fn normalize_matches_upstream() {
        for (input, expected) in [
            ("b", "bold"),
            ("bold", "bold"),
            ("BOLD", "bold"),
            ("  Bold  ", "bold"),
            ("dim i", "dim italic"),
            ("not bold", "not bold"),
            ("bold red", "bold red"),
            ("red on blue", "red on blue"),
            ("link https://x", "link https://x"),
            // Not a style definition, so it falls through to trim+lowercase —
            // this is the path every theme name takes.
            ("nope", "nope"),
            ("REPR.Number", "repr.number"),
            // `not` is case-sensitive upstream, so this fails to parse and takes
            // the fallback, which happens to produce the same string.
            ("not BOLD", "not bold"),
        ] {
            assert_eq!(Style::normalize(input), expected, "normalize({input:?})");
        }
    }

    /// A style that sets nothing renders as `"none"`, never as an empty string.
    #[test]
    fn definition_of_null_style_is_none() {
        assert_eq!(Style::new().definition(), "none");
        assert_eq!(Style::parse("none").unwrap().definition(), "none");
    }

    /// `not <attr>` is case-sensitive, matching upstream, which looks the operand
    /// up without folding and raises when it misses. Accepting `not BOLD` would
    /// silently *cancel* an enclosing bold instead of being ignored.
    #[test]
    fn not_operand_is_case_sensitive() {
        assert!(Style::parse("not bold").is_ok());
        assert!(Style::parse("not BOLD").is_err());
    }

    /// `link <url>` is a style keyword, not a colour name. Without it the whole
    /// definition failed to parse and the hyperlink was silently dropped.
    #[test]
    fn parse_understands_link() {
        let style = Style::parse("link https://example.com").expect("link parses");
        assert_eq!(style.link.as_deref(), Some("https://example.com"));
        assert_eq!(style.definition(), "link https://example.com");
        // A bare `link` is a syntax error, exactly as upstream — accepting it
        // would emit a hyperlink to nowhere.
        assert!(Style::parse("link").is_err());
    }

    #[test]
    fn parse_bold_red() {
        let style = Style::parse("bold red").unwrap();
        assert_eq!(style.ansi_codes(ColorSystem::Truecolor), "1;31");
        assert_eq!(
            style.render("hello", Some(ColorSystem::Truecolor)),
            "\x1b[1;31mhello\x1b[0m"
        );
    }

    #[test]
    fn svg_style_matches_upstream() {
        // Captured from real rich 15.0.0 `export_svg`'s `get_svg_style` under
        // `SVG_EXPORT_THEME`. Note: bgcolor is excluded from the fill style,
        // `reverse` swaps to the background, and dim blends 40% toward it.
        use crate::terminal_theme::SVG_EXPORT_THEME as theme;
        let svg = |spec: &str| Style::parse(spec).unwrap().get_svg_style(&theme);
        assert_eq!(Style::new().get_svg_style(&theme), "fill: #c5c8c6");
        assert_eq!(svg("bold red"), "fill: #cc555a;font-weight: bold");
        assert_eq!(svg("italic green"), "fill: #98a84b;font-style: italic;");
        assert_eq!(svg("dim"), "fill: #868887");
        assert_eq!(
            svg("underline blue on yellow"),
            "fill: #608ab1;text-decoration: underline;"
        );
        assert_eq!(svg("reverse"), "fill: #292929");
    }

    #[test]
    fn link_wraps_in_osc8() {
        let style = Style::parse("underline blue")
            .unwrap()
            .with_link("https://example.com");
        assert_eq!(
            style.render("click", Some(ColorSystem::Truecolor)),
            "\x1b]8;;https://example.com\x1b\\\x1b[4;34mclick\x1b[0m\x1b]8;;\x1b\\"
        );
        // A link-only style still wraps (no SGR inside).
        let bare = Style::new().with_link("https://x.com");
        assert_eq!(
            bare.render("y", Some(ColorSystem::Truecolor)),
            "\x1b]8;;https://x.com\x1b\\y\x1b]8;;\x1b\\"
        );
        assert!(!bare.is_null());
    }

    #[test]
    fn parse_fg_on_bg() {
        let style = Style::parse("white on blue").unwrap();
        assert_eq!(style.ansi_codes(ColorSystem::Truecolor), "37;44");
    }

    #[test]
    fn combine_overrides() {
        let base = Style::parse("bold red").unwrap();
        let over = Style::parse("blue").unwrap();
        let combined = base.combine(&over);
        // bold retained from base, color replaced by blue (34)
        assert_eq!(combined.ansi_codes(ColorSystem::Truecolor), "1;34");
    }

    #[test]
    fn no_color_system_is_plaintext() {
        let style = Style::parse("bold red").unwrap();
        assert_eq!(style.render("hello", None), "hello");
    }

    #[test]
    fn null_style_does_not_wrap() {
        let style = Style::new();
        assert_eq!(style.render("hello", Some(ColorSystem::Truecolor)), "hello");
    }
}