/// Manage conversion of a user provided string
/// defining foreground and background colors into
/// a string with TTY colors

use {
    crate::errors::InvalidSkinError,
    crossterm::style::{
        Attribute::{self, *},
        Attributes,
        Color::{self, *},
    },
    std::result::Result,
    super::*,
    termimad::CompoundStyle,
};

/// parsed content of a [skin] line of the conf.toml file
pub struct SkinEntry {
    focused: CompoundStyle,
    unfocused: Option<CompoundStyle>,
}

impl SkinEntry {
    pub fn new(focused: CompoundStyle, unfocused: Option<CompoundStyle>) -> Self {
        Self { focused, unfocused }
    }
    pub fn get_focused(&self) -> &CompoundStyle {
        &self.focused
    }
    pub fn get_unfocused(&self) -> &CompoundStyle {
        self.unfocused.as_ref().unwrap_or(&self.focused)
    }
    /// parse a string representation of a skin entry.
    ///
    /// The general form is either "<focused>" or "<focused> / <unfocused>":
    /// It may be just the focused compound_style, or both
    /// the focused and the unfocused ones, in which case there's
    /// a '/' as separator.
    ///
    /// Each part is "<foreground color> <background color> <attributes>"
    /// where the attributes list may be empty.
    pub fn parse(s: &str) -> Result<Self, InvalidSkinError> {
        let mut parts = s.split('/');
        let focused = parse_compound_style(parts.next().unwrap())?;
        let unfocused = parts.next()
            .map(|p| parse_compound_style(p))
            .transpose()?;
        Ok(Self { focused, unfocused })
    }
}


/// read a color from a string.
/// It may be either
/// - "none"
/// - one of the few known color name. Example: "darkred"
/// - grayscale with level in [0,24[. Example: "grey(5)"
/// - an Ansi code. Example "ansi(106)"
/// - RGB. Example: "rgb(25, 100, 0)"
/// This function needs a lowercase string (assuming lowercasing
/// has be done before, to ensure case-insensitive parsing)
fn parse_color(s: &str) -> Result<Option<Color>, InvalidSkinError> {
    if let Some(c) = regex!(r"^ansi\((?P<value>\d+)\)$").captures(&s) {
        let value: &str = c.name("value").unwrap().as_str();
        let value = value.parse();
        if let Ok(value) = value {
            return Ok(ansi(value)); // all ANSI values are ok
        } else {
            return Err(InvalidSkinError::InvalidColor { raw: s.to_owned() });
        }
    }

    if let Some(c) = regex!(r"^gr[ae]y(?:scale)?\((?P<level>\d+)\)$").captures(&s) {
        let level: &str = c.name("level").unwrap().as_str();
        let level = level.parse();
        if let Ok(level) = level {
            if level > 23 {
                return Err(InvalidSkinError::InvalidGreyLevel { level });
            }
            return Ok(gray(level));
        } else {
            return Err(InvalidSkinError::InvalidColor { raw: s.to_owned() });
        }
    }

    if let Some(c) = regex!(r"^rgb\((?P<r>\d+),\s*(?P<g>\d+),\s*(?P<b>\d+)\)$").captures(&s) {
        let r = c.name("r").unwrap().as_str().parse();
        let g = c.name("g").unwrap().as_str().parse();
        let b = c.name("b").unwrap().as_str().parse();
        if let (Ok(r), Ok(g), Ok(b)) = (r, g, b) {
            return Ok(rgb(r, g, b));
        } else {
            return Err(InvalidSkinError::InvalidColor { raw: s.to_owned() });
        }
    }

    match s {
        "black" => Ok(rgb(0, 0, 0)), // crossterm black isn't black
        "blue" => Ok(Some(Blue)),
        "cyan" => Ok(Some(Cyan)),
        "darkblue" => Ok(Some(DarkBlue)),
        "darkcyan" => Ok(Some(DarkCyan)),
        "darkgreen" => Ok(Some(DarkGreen)),
        "darkmagenta" => Ok(Some(DarkMagenta)),
        "darkred" => Ok(Some(DarkRed)),
        "green" => Ok(Some(Green)),
        "grey" => Ok(Some(Grey)),
        "magenta" => Ok(Some(Magenta)),
        "red" => Ok(Some(Red)),
        "yellow" => Ok(Some(Yellow)),
        "darkyellow" => Ok(Some(DarkYellow)),
        "white" => Ok(Some(White)),
        "none" => Ok(None),
        _ => Err(InvalidSkinError::InvalidColor { raw: s.to_owned() }),
    }
}

fn parse_attribute(s: &str) -> Result<Attribute, InvalidSkinError> {
    match s {
        "bold" => Ok(Bold),
        "crossedout" => Ok(CrossedOut),
        "dim" => Ok(Dim), // does it do anything ?
        "italic" => Ok(Italic),
        "reverse" => Ok(Reverse),
        "underlined" => Ok(Underlined),
        "overlined" => Ok(OverLined),
        // following ones aren't supported by crossterm yet
        // "defaultforegroundcolor" => Ok(DefaultForegroundColor),
        // "defaultbackgroundcolor" => Ok(DefaultBackgroundColor),
        "slowblink" => Ok(SlowBlink),
        "rapidblink" => Ok(RapidBlink),
        _ => Err(InvalidSkinError::InvalidAttribute { raw: s.to_owned() }),
    }
}

/// parse a sequence of space separated style attributes
fn parse_attributes(s: &str) -> Result<Vec<Attribute>, InvalidSkinError> {
    s.split_whitespace().map(|t| parse_attribute(t)).collect()
}

fn parse_compound_style(s: &str) -> Result<CompoundStyle, InvalidSkinError> {
    let s = s.to_ascii_lowercase();
    let parts_rex = regex!(
        r"(?x)
        ^
        \s*
        (?P<fg>\w+(\([\d,\s]+\))?)
        \s+
        (?P<bg>\w+(\([\d,\s]+\))?)
        (?P<attributes>.*)
        \s*
        $
        "
    );
    if let Some(c) = parts_rex.captures(&s) {
        let fg_color = parse_color(c.name("fg").unwrap().as_str())?;
        let bg_color = parse_color(c.name("bg").unwrap().as_str())?;
        let attrs = parse_attributes(c.name("attributes").unwrap().as_str())?;
        Ok(CompoundStyle::new(
            fg_color,
            bg_color,
            Attributes::from(attrs.as_slice()),
        ))
    } else {
        Err(InvalidSkinError::InvalidStyle {
            style: s.to_owned(),
        })
    }
}