//! Colours from the web themes (same palettes as the web UI, 24-bit).

use ratatui::style::Color;
use serde_json::Value;
use std::sync::OnceLock;

const PALETTES: &str = include_str!("palettes.json");

#[derive(Debug, Clone, Copy)]
#[allow(dead_code)]
pub struct Theme {
    pub bg0: Color,
    pub bg1: Color,
    pub bg2: Color,
    pub bg3: Color,
    pub fg0: Color,
    pub fg1: Color,
    pub fg2: Color,
    pub fg3: Color,
    pub muted: Color,
    pub accent: Color,
    pub accent2: Color,
    pub on_accent: Color,
    pub red: Color,
    pub green: Color,
    pub blue: Color,
    pub aqua: Color,
    pub purple: Color,
    pub keyword: Color,
    pub string: Color,
    pub comment: Color,
}

fn hex(v: &Value, key: &str, fallback: Color) -> Color {
    v[key]
        .as_str()
        .and_then(|s| {
            let s = s.trim_start_matches('#');
            Some(Color::Rgb(u8::from_str_radix(s.get(0..2)?, 16).ok()?, u8::from_str_radix(s.get(2..4)?, 16).ok()?, u8::from_str_radix(s.get(4..6)?, 16).ok()?))
        })
        .unwrap_or(fallback)
}

pub fn names() -> Vec<String> {
    let all: Value = serde_json::from_str(PALETTES).unwrap_or(Value::Null);
    let mut out: Vec<String> = all.as_object().map(|o| o.keys().filter_map(|k| k.rsplit_once('-').map(|(b, _)| b.to_string())).collect()).unwrap_or_default();
    out.dedup();
    out
}

/// Is the terminal background dark? (COLORFGBG, else assume dark)
fn terminal_dark() -> bool {
    std::env::var("COLORFGBG").ok().and_then(|v| v.rsplit(';').next().and_then(|b| b.parse::<u8>().ok())).map(|bg| bg < 7 || bg == 8).unwrap_or(true)
}

impl Theme {
    /// `base` e.g. "gruvbox", `mode` "light" | "dark" | "auto".
    pub fn load(base: &str, mode: &str) -> Self {
        let dark = match mode {
            "light" => false,
            "dark" => true,
            _ => terminal_dark(),
        };
        let all: Value = serde_json::from_str(PALETTES).unwrap_or(Value::Null);
        let key = format!("{base}-{}", if dark { "dark" } else { "light" });
        let p = all.get(&key).or_else(|| all.get(if dark { "gruvbox-dark" } else { "gruvbox-light" })).cloned().unwrap_or(Value::Null);
        let d = |k: &str, f: Color| hex(&p, k, f);
        Self {
            bg0: d("bg0", Color::Reset),
            bg1: d("bg1", Color::Reset),
            bg2: d("bg2", Color::DarkGray),
            bg3: d("bg3", Color::DarkGray),
            fg0: d("fg0", Color::White),
            fg1: d("fg1", Color::Reset),
            fg2: d("fg2", Color::Gray),
            fg3: d("fg3", Color::Gray),
            muted: d("muted", Color::DarkGray),
            accent: d("accent", Color::Yellow),
            accent2: d("accent2", Color::LightYellow),
            on_accent: d("on-accent", Color::Black),
            red: d("red", Color::Red),
            green: d("green", Color::Green),
            blue: d("blue", Color::Blue),
            aqua: d("aqua", Color::Cyan),
            purple: d("purple", Color::Magenta),
            keyword: d("syntax-keyword", Color::Red),
            string: d("syntax-string", Color::Green),
            comment: d("syntax-comment", Color::DarkGray),
        }
    }
}

static CURRENT: OnceLock<std::sync::RwLock<Theme>> = OnceLock::new();

pub fn set(t: Theme) {
    let lock = CURRENT.get_or_init(|| std::sync::RwLock::new(t));
    *lock.write().unwrap() = t;
}

pub fn get() -> Theme {
    *CURRENT.get_or_init(|| std::sync::RwLock::new(Theme::load("gruvbox", "auto"))).read().unwrap()
}