strop-editor 0.3.4

//! Configuration (0005-lite): real TOML from day one, embedded defaults,
//! never bricks (0005 §2). The full layering/hot-reload/settings-popup
//! arrives with 0005 proper; this is the editor-facing config object.
//!
//! `$XDG_CONFIG_HOME/strop/config.toml` (or ~/.config/strop/config.toml):
//! ```toml
//! tab_size = 4
//! ```
//!
//! LSP server config is a separate file with its own layering —
//! `languages.toml`, helix-shaped, owned by strop-lsp (0012): project
//! `.strop/languages.toml` > XDG > the embedded registry.

use serde::Deserialize;

#[derive(Debug, Clone, Deserialize)]
#[serde(default)]
pub struct Config {
    /// Indent unit in spaces (`>>`, auto-indent). Tabs land with 0005's
    /// full option set.
    pub tab_size: usize,
    /// Indent guides (dim │ per level) on/off.
    pub indent_guides: bool,
}

impl Default for Config {
    fn default() -> Self {
        Self {
            tab_size: 4,
            indent_guides: true,
        }
    }
}

/// Knob metadata (0005 §6): the settings popup renders from this table;
/// descriptions live here, never in popup code.
pub struct Knob {
    pub key: &'static str,
    pub kind: &'static str, // "bool" | "number"
    pub desc: &'static str,
}

pub const KNOBS: &[Knob] = &[
    Knob {
        key: "tab_size",
        kind: "number",
        desc: "indent width in spaces",
    },
    Knob {
        key: "indent_guides",
        kind: "bool",
        desc: "dim │ guide per indent level",
    },
];

impl Config {
    /// `strop config`: the knobs with live values (KNOBS is the data
    /// source; this is its first consumer — the settings popup is next).
    pub fn print_knobs(&self) {
        for k in KNOBS {
            let value = match k.key {
                "tab_size" => self.tab_size.to_string(),
                "indent_guides" => self.indent_guides.to_string(),
                _ => "?".into(),
            };
            println!("  {:<16} {:<7} {:<8} {}", k.key, k.kind, value, k.desc);
        }
    }

    /// Load the user config; errors are returned as a message for the
    /// statusline — the editor always starts with defaults (0005 §2).
    pub fn load() -> (Self, Option<String>) {
        let Some(path) = config_path() else {
            return (Self::default(), None);
        };
        let Ok(text) = std::fs::read_to_string(&path) else {
            return (Self::default(), None); // absent is fine
        };
        match toml::from_str::<Config>(&text) {
            Ok(c) => (c, None),
            Err(e) => (
                Self::default(),
                Some(format!("config {}: {e} — using defaults", path.display())),
            ),
        }
    }

    pub fn indent(&self) -> String {
        " ".repeat(self.tab_size)
    }
}

fn config_path() -> Option<std::path::PathBuf> {
    let base = std::env::var_os("XDG_CONFIG_HOME")
        .map(std::path::PathBuf::from)
        .or_else(|| {
            std::env::var_os("HOME").map(|h| std::path::PathBuf::from(h).join(".config"))
        })?;
    Some(base.join("strop").join("config.toml"))
}

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

    #[test]
    fn defaults_when_absent() {
        let (c, err) = Config::load();
        let _ = err; // present only when a malformed file exists
        assert!(c.tab_size >= 2);
    }

    #[test]
    fn parses_tab_size() {
        let c: Config = toml::from_str("tab_size = 2").unwrap();
        assert_eq!(c.tab_size, 2);
        assert_eq!(c.indent(), "  ");
    }

    #[test]
    fn parses_indent_guides() {
        let c: Config = toml::from_str("indent_guides = false").unwrap();
        assert!(!c.indent_guides);
        // absent → default on
        let c: Config = toml::from_str("").unwrap();
        assert!(c.indent_guides);
    }

    #[test]
    fn knobs_table_covers_every_field() {
        // the popup renders from KNOBS; a field without a knob is invisible
        // to users — keep the two in lockstep
        assert_eq!(KNOBS.len(), 2);
    }

    #[test]
    fn malformed_falls_back() {
        assert!(toml::from_str::<Config>("tab_size = \"oops\"").is_err());
    }
}