zshrs 0.9.2

//! zshrs configuration file — `~/.config/zshrs/config.toml`
//!
//! Runtime settings that don't belong in .zshrc (shell script).
//! These control the Rust engine, not the shell language.
//!
//! Example config:
//! ```toml
//! [worker_pool]
//! size = 8            # number of worker threads (default: num_cpus, clamped [2, 18])
//!
//! [completion]
//! max_matches = 1000  # max completion results to display
//! fts_enabled = true  # use SQLite FTS5 for completion search
//! ast_cache = true    # pre-parse autoload functions to AST blobs
//!
//! [history]
//! async_writes = true # write history on worker pool (don't block prompt)
//! max_entries = 100000
//!
//! [glob]
//! parallel_threshold = 32  # min files before parallel metadata prefetch
//! recursive_parallel = true  # fan out **/ across worker pool
//!
//! [log]
//! level = "info"      # trace, debug, info, warn, error
//! ```

use serde::Deserialize;
use std::path::{Path, PathBuf};

/// Top-level config
#[derive(Debug, Clone, Deserialize)]
#[serde(default)]
pub struct ZshrsConfig {
    pub worker_pool: WorkerPoolConfig,
    pub completion: CompletionConfig,
    pub history: HistoryConfig,
    pub glob: GlobConfig,
    pub log: LogConfig,
}

#[derive(Debug, Clone, Deserialize)]
#[serde(default)]
pub struct WorkerPoolConfig {
    /// Number of worker threads. 0 = auto (num_cpus clamped [2, 18]).
    pub size: usize,
}

#[derive(Debug, Clone, Deserialize)]
#[serde(default)]
pub struct CompletionConfig {
    pub max_matches: usize,
    pub fts_enabled: bool,
    pub ast_cache: bool,
}

#[derive(Debug, Clone, Deserialize)]
#[serde(default)]
pub struct HistoryConfig {
    pub async_writes: bool,
    pub max_entries: usize,
}

#[derive(Debug, Clone, Deserialize)]
#[serde(default)]
pub struct GlobConfig {
    /// Minimum file count before parallel metadata prefetch kicks in.
    pub parallel_threshold: usize,
    /// Fan out **/ recursive globs across worker pool.
    pub recursive_parallel: bool,
}

#[derive(Debug, Clone, Deserialize)]
#[serde(default)]
pub struct LogConfig {
    pub level: String,
}

// ── Defaults ──

impl Default for ZshrsConfig {
    fn default() -> Self {
        Self {
            worker_pool: WorkerPoolConfig::default(),
            completion: CompletionConfig::default(),
            history: HistoryConfig::default(),
            glob: GlobConfig::default(),
            log: LogConfig::default(),
        }
    }
}

impl Default for WorkerPoolConfig {
    fn default() -> Self {
        Self { size: 0 } // 0 = auto
    }
}

impl Default for CompletionConfig {
    fn default() -> Self {
        Self {
            max_matches: 1000,
            fts_enabled: true,
            ast_cache: true,
        }
    }
}

impl Default for HistoryConfig {
    fn default() -> Self {
        Self {
            async_writes: true,
            max_entries: 100_000,
        }
    }
}

impl Default for GlobConfig {
    fn default() -> Self {
        Self {
            parallel_threshold: 32,
            recursive_parallel: true,
        }
    }
}

impl Default for LogConfig {
    fn default() -> Self {
        Self {
            level: "info".to_string(),
        }
    }
}

// ── Loading ──

/// Config file path: `~/.config/zshrs/config.toml`
pub fn config_path() -> PathBuf {
    dirs::config_dir()
        .unwrap_or_else(|| PathBuf::from("/tmp"))
        .join("zshrs")
        .join("config.toml")
}

/// Load config from disk. Returns defaults if file doesn't exist or is invalid.
pub fn load() -> ZshrsConfig {
    load_from(&config_path())
}

/// Load config from a specific path.
pub fn load_from(path: &Path) -> ZshrsConfig {
    match std::fs::read_to_string(path) {
        Ok(content) => match toml::from_str(&content) {
            Ok(config) => {
                tracing::info!(path = %path.display(), "config loaded");
                config
            }
            Err(e) => {
                tracing::warn!(
                    path = %path.display(),
                    error = %e,
                    "config parse error, using defaults"
                );
                ZshrsConfig::default()
            }
        },
        Err(_) => {
            // No config file — use defaults silently
            ZshrsConfig::default()
        }
    }
}

/// Resolve worker pool size from config.
/// 0 = auto = available_parallelism clamped [2, 18].
pub fn resolve_pool_size(config: &WorkerPoolConfig) -> usize {
    if config.size > 0 {
        config.size.clamp(1, 64)
    } else {
        std::thread::available_parallelism()
            .map(|n| n.get())
            .unwrap_or(4)
            .clamp(2, 18)
    }
}

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

    #[test]
    fn test_default_config() {
        let config = ZshrsConfig::default();
        assert_eq!(config.worker_pool.size, 0);
        assert_eq!(config.completion.max_matches, 1000);
        assert!(config.completion.fts_enabled);
        assert!(config.completion.ast_cache);
        assert!(config.history.async_writes);
        assert!(config.glob.recursive_parallel);
        assert_eq!(config.glob.parallel_threshold, 32);
    }

    #[test]
    fn test_parse_toml() {
        let toml = r#"
[worker_pool]
size = 4

[completion]
max_matches = 500
ast_cache = false

[glob]
parallel_threshold = 64
"#;
        let config: ZshrsConfig = toml::from_str(toml).unwrap();
        assert_eq!(config.worker_pool.size, 4);
        assert_eq!(config.completion.max_matches, 500);
        assert!(!config.completion.ast_cache);
        assert_eq!(config.glob.parallel_threshold, 64);
        // Unset fields use defaults
        assert!(config.history.async_writes);
        assert!(config.glob.recursive_parallel);
    }

    #[test]
    fn test_resolve_pool_size() {
        let auto = WorkerPoolConfig { size: 0 };
        let resolved = resolve_pool_size(&auto);
        assert!(resolved >= 2 && resolved <= 18);

        let explicit = WorkerPoolConfig { size: 4 };
        assert_eq!(resolve_pool_size(&explicit), 4);

        let clamped = WorkerPoolConfig { size: 999 };
        assert_eq!(resolve_pool_size(&clamped), 64);
    }

    #[test]
    fn test_missing_file_returns_defaults() {
        let config = load_from(Path::new("/nonexistent/config.toml"));
        assert_eq!(config.worker_pool.size, 0);
    }
}