use crate::*;

/// Configuration: mode, view, and bind definitions.
///
/// ```
/// let config = tek::Config::default();
/// ```
///
/// ```
/// // Some dizzle.
/// // What indentation to use here lol?
/// let source = stringify!((mode :menu (name Menu)
///   (info Mode selector.) (keys :axis/y :confirm)
///   (view (bg (g 0) (bsp/s :ports/out
///     (bsp/n :ports/in
///       (bg (g 30) (bsp/s (fixed/y 7 :logo)
///         (fill :dialog/menu)))))))));
/// // Add this definition to the config and try to load it.
/// // A "mode" is basically a state machine
/// // with associated input and output definitions.
/// tek::Config::default().add(&source).unwrap().get_mode(":menu").unwrap();
/// ```
#[derive(Default, Debug)] pub struct Config {
    /// XDG base directories of running user.
    pub dirs:  BaseDirectories,
    /// Active collection of interaction modes.
    pub modes: Modes,
    /// Active collection of event bindings.
    pub binds: Binds,
    /// Active collection of view definitions.
    pub views: Views,
}

impl Config {
    const CONFIG_DIR: &'static str = "tek";
    const CONFIG_SUB: &'static str = "v0";
    const CONFIG:     &'static str = "tek.edn";
    const DEFAULTS:   &'static str = include_str!("../tek.edn");

    pub fn watch <T> (callback: impl FnOnce(Self)->T) -> Usually<T> {
        let config = Self::init_new(None)?;
        let result = callback(config);
        Ok(result)
    }

    pub fn init_new (dirs: Option<BaseDirectories>) -> Usually<Self> {
        let mut config = Self::new(None);
        config.init()?;
        Ok(config)
    }

    /// Create a new app configuration from a set of XDG base directories,
    pub fn new (dirs: Option<BaseDirectories>) -> Self {
        let default = ||BaseDirectories::with_profile(Self::CONFIG_DIR, Self::CONFIG_SUB);
        let dirs = dirs.unwrap_or_else(default);
        Self { dirs, ..Default::default() }
    }

    /// Write initial contents of configuration.
    pub fn init (&mut self) -> Usually<()> {
        self.init_one(Self::CONFIG, Self::DEFAULTS, |cfgs, dsl|{
            cfgs.add(&dsl)?;
            Ok(())
        })?;
        Ok(())
    }

    /// Write initial contents of a configuration file.
    pub fn init_one (
        &mut self, path: &str, defaults: &str, mut each: impl FnMut(&mut Self, &str)->Usually<()>
    ) -> Usually<()> {
        if self.dirs.find_config_file(path).is_none() {
            //println!("Creating {path:?}");
            std::fs::write(self.dirs.place_config_file(path)?, defaults)?;
        }
        Ok(if let Some(path) = self.dirs.find_config_file(path) {
            //println!("Loading {path:?}");
            let src = std::fs::read_to_string(&path)?;
            src.as_str().each(move|item|each(self, item))?;
        } else {
            return Err(format!("{path}: not found").into())
        })
    }

    /// Add statements to configuration from [Dsl] source.
    pub fn add (&mut self, dsl: impl Language) -> Usually<&mut Self> {
        dsl.each(|item|self.add_one(item))?;
        Ok(self)
    }

    fn add_one (&self, item: impl Language) -> Usually<()> {
        if let Some(expr) = item.expr()? {
            let head = expr.head()?;
            let tail = expr.tail()?;
            let name = tail.head()?;
            let body = tail.tail()?;
            //println!("Config::load: {} {} {}", head.unwrap_or_default(), name.unwrap_or_default(), body.unwrap_or_default());
            match head {
                Some("mode") if let Some(name) = name => self.modes.add(&name, &body)?,
                Some("keys") if let Some(name) = name => load_bind(&self.binds, &name, &body)?,
                Some("view") if let Some(name) = name => load_view(&self.views, &name, &body)?,
                _ => return Err(format!("Config::load: expected view/keys/mode, got: {item:?}").into())
            }
            Ok(())
        } else {
            return Err(format!("Config::load: expected expr, got: {item:?}").into())
        }
    }

    pub fn get_mode (&self, mode: impl AsRef<str>) -> Option<Arc<Mode<Arc<str>>>> {
        self.modes.get(mode)
    }
}

mod views; pub use self::views::*;
mod modes; pub use self::modes::*;
mod mode;  pub use self::mode::*;