volli-core 0.1.11

use eyre::{Report, eyre};
use once_cell::sync::Lazy;
use std::cell::RefCell;
use std::{path::Path, sync::RwLock, time::Duration};
thread_local! {
    static TLS_CONFIG_DIR: RefCell<Option<String>> = const { RefCell::new(None) };
}

#[derive(Debug, Clone, Default)]
pub struct EnvironmentConfig {
    pub quic_idle_ms: Option<u64>,
    pub backoff_ms: Option<u64>,
    pub interval_ms: Option<u64>,
    pub connect_timeout_ms: Option<u64>,
    pub auth_timeout_secs: Option<u64>,
    pub heartbeat_secs: Option<u64>,
    pub join_timeout_secs: Option<u64>,
    pub peer_cleanup_secs: Option<u64>,
    pub peer_check_secs: Option<u64>,
    /// Fractional improvement required to consider immediate rebalance (e.g. 0.05 = 5%)
    pub rebalance_improvement: Option<f64>,
    /// Multiplier for worker idle timeout (applied to heartbeat_secs)
    pub worker_idle_multiplier: Option<u64>,
    /// Worker-side rebalance: startup grace before considering rebalancing (secs)
    pub rebalance_startup_grace_secs: Option<u64>,
    /// Worker-side rebalance: interval between should_rebalance checks (secs)
    pub rebalance_check_interval_secs: Option<u64>,
    /// Worker-side rebalance controller: minimum interval between rebalances (secs)
    pub rebalance_min_interval_secs: Option<u64>,
    /// Worker-side migration: periodic check interval (secs)
    pub migration_check_interval_secs: Option<u64>,
    /// Worker-side migration: connection timeout (secs)
    pub migration_connection_timeout_secs: Option<u64>,
    /// Worker-side migration: handoff timeout (secs)
    pub migration_handoff_timeout_secs: Option<u64>,
    /// Rebalance: consider current connection "good" above this score; skip periodic rebalance
    pub rebalance_good_score_cutoff: Option<f64>,
    /// Rebalance (periodic): required fractional improvement over current (e.g. 0.30)
    pub rebalance_periodic_improvement: Option<f64>,
    /// Rebalance controller: required consecutive signals count (e.g. 3)
    pub rebalance_consecutive_signals: Option<u32>,
    /// Rebalance controller: max rebalances per hour
    pub rebalance_max_per_hour: Option<u32>,
    /// Rebalance scoring weights (health/history/breaker)
    pub rebalance_weight_health: Option<f64>,
    pub rebalance_weight_history: Option<f64>,
    pub rebalance_weight_breaker: Option<f64>,
    /// Empty-manager bonus: min delta between emptiest and next emptiest fullness
    pub rebalance_empty_delta_threshold: Option<f64>,
    /// Empty-manager bonus: scale factor for bonus
    pub rebalance_empty_bonus_weight: Option<f64>,
    /// Empty-manager bonus: minimum health score to qualify
    pub rebalance_empty_health_cutoff: Option<f64>,
    /// Rebalance: age threshold in seconds before health is considered stale
    pub rebalance_health_stale_secs: Option<u64>,
    /// Rebalance: factor applied to health score when stale (0.0-1.0)
    pub rebalance_health_stale_factor: Option<f64>,
}

impl EnvironmentConfig {
    pub const DEFAULT_HEARTBEAT_SECS: u64 = 2;
    pub const DEFAULT_AUTH_TIMEOUT_SECS: u64 = 5;
    pub const DEFAULT_JOIN_TIMEOUT_SECS: u64 = 30;
    pub const DEFAULT_CONNECT_TIMEOUT_MS: u64 = 10_000;

    fn from_env() -> Self {
        let mut cfg = Self {
            quic_idle_ms: std::env::var("VOLLI_TEST_QUIC_IDLE_MS")
                .ok()
                .and_then(|v| v.parse().ok()),
            backoff_ms: std::env::var("VOLLI_TEST_BACKOFF_MS")
                .ok()
                .and_then(|v| v.parse().ok()),
            interval_ms: std::env::var("VOLLI_TEST_INTERVAL_MS")
                .ok()
                .and_then(|v| v.parse().ok()),
            connect_timeout_ms: std::env::var("VOLLI_CONNECT_TIMEOUT_MS")
                .ok()
                .and_then(|v| v.parse().ok()),
            auth_timeout_secs: std::env::var("VOLLI_TEST_AUTH_TIMEOUT_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            heartbeat_secs: std::env::var("VOLLI_TEST_HEARTBEAT_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            join_timeout_secs: std::env::var("VOLLI_JOIN_TIMEOUT_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            peer_cleanup_secs: std::env::var("VOLLI_PEER_CLEANUP_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            peer_check_secs: std::env::var("VOLLI_PEER_CHECK_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_improvement: std::env::var("VOLLI_REBALANCE_IMPROVEMENT")
                .ok()
                .and_then(|v| v.parse().ok()),
            worker_idle_multiplier: std::env::var("VOLLI_WORKER_IDLE_MULTIPLIER")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_startup_grace_secs: std::env::var("VOLLI_REBALANCE_STARTUP_GRACE_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_check_interval_secs: std::env::var("VOLLI_REBALANCE_CHECK_INTERVAL_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_min_interval_secs: std::env::var("VOLLI_REBALANCE_MIN_INTERVAL_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            migration_check_interval_secs: std::env::var("VOLLI_MIGRATION_CHECK_INTERVAL_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            migration_connection_timeout_secs: std::env::var(
                "VOLLI_MIGRATION_CONNECTION_TIMEOUT_SECS",
            )
            .ok()
            .and_then(|v| v.parse().ok()),
            migration_handoff_timeout_secs: std::env::var("VOLLI_MIGRATION_HANDOFF_TIMEOUT_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_good_score_cutoff: std::env::var("VOLLI_REBALANCE_GOOD_SCORE_CUTOFF")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_periodic_improvement: std::env::var("VOLLI_REBALANCE_PERIODIC_IMPROVEMENT")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_consecutive_signals: std::env::var("VOLLI_REBALANCE_CONSECUTIVE_SIGNALS")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_max_per_hour: std::env::var("VOLLI_REBALANCE_MAX_PER_HOUR")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_weight_health: std::env::var("VOLLI_REBALANCE_WEIGHT_HEALTH")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_weight_history: std::env::var("VOLLI_REBALANCE_WEIGHT_HISTORY")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_weight_breaker: std::env::var("VOLLI_REBALANCE_WEIGHT_BREAKER")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_empty_delta_threshold: std::env::var("VOLLI_REBALANCE_EMPTY_DELTA")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_empty_bonus_weight: std::env::var("VOLLI_REBALANCE_EMPTY_BONUS_WEIGHT")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_empty_health_cutoff: std::env::var("VOLLI_REBALANCE_EMPTY_HEALTH_CUTOFF")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_health_stale_secs: std::env::var("VOLLI_REBALANCE_HEALTH_STALE_SECS")
                .ok()
                .and_then(|v| v.parse().ok()),
            rebalance_health_stale_factor: std::env::var("VOLLI_REBALANCE_HEALTH_STALE_FACTOR")
                .ok()
                .and_then(|v| v.parse().ok()),
        };
        // In test runners (nextest) or when VOLLI_FAST_TESTS is set (not "0"),
        // default to fast, deterministic timings unless explicitly overridden.
        let fast = std::env::var("VOLLI_FAST_TESTS")
            .map(|v| v != "0")
            .unwrap_or_else(|_| std::env::var("NEXTEST").is_ok());
        if fast {
            if cfg.connect_timeout_ms.is_none() {
                cfg.connect_timeout_ms = Some(50);
            }
            if cfg.backoff_ms.is_none() {
                cfg.backoff_ms = Some(0);
            }
            if cfg.interval_ms.is_none() {
                cfg.interval_ms = Some(1);
            }
            if cfg.auth_timeout_secs.is_none() {
                cfg.auth_timeout_secs = Some(1);
            }
            if cfg.heartbeat_secs.is_none() {
                cfg.heartbeat_secs = Some(1);
            }
        }
        cfg
    }

    pub fn heartbeat_secs(&self) -> u64 {
        self.heartbeat_secs.unwrap_or(Self::DEFAULT_HEARTBEAT_SECS)
    }

    pub fn auth_timeout_secs(&self) -> u64 {
        self.auth_timeout_secs
            .unwrap_or(Self::DEFAULT_AUTH_TIMEOUT_SECS)
    }

    pub fn join_timeout_secs(&self) -> u64 {
        self.join_timeout_secs
            .unwrap_or(Self::DEFAULT_JOIN_TIMEOUT_SECS)
    }

    pub fn connect_timeout_ms(&self) -> u64 {
        self.connect_timeout_ms
            .unwrap_or(Self::DEFAULT_CONNECT_TIMEOUT_MS)
    }

    pub fn quic_idle_duration(&self) -> Result<Duration, Report> {
        let hb = self.heartbeat_secs();
        let ms = self.quic_idle_ms.unwrap_or(hb * 3 * 1000);
        if ms <= hb * 1000 {
            return Err(eyre!(
                "quic idle timeout {ms}ms must exceed heartbeat interval {hb}s"
            ));
        }
        Ok(Duration::from_millis(ms))
    }

    /// Idle multiplier for worker connections (default 5 × heartbeat)
    pub fn worker_idle_multiplier(&self) -> u64 {
        self.worker_idle_multiplier.unwrap_or(5)
    }

    /// Worker-side rebalance: startup grace before considering rebalancing (default 300s)
    pub fn rebalance_startup_grace_secs(&self) -> u64 {
        self.rebalance_startup_grace_secs.unwrap_or(300)
    }

    /// Worker-side rebalance: interval between should_rebalance checks (default 600s)
    pub fn rebalance_check_interval_secs(&self) -> u64 {
        self.rebalance_check_interval_secs.unwrap_or(300)
    }

    /// Worker-side rebalance controller: minimum interval between rebalances (default 300s)
    pub fn rebalance_min_interval_secs(&self) -> u64 {
        self.rebalance_min_interval_secs.unwrap_or(300)
    }

    /// Worker-side migration: periodic check interval (default 180s)
    pub fn migration_check_interval_secs(&self) -> u64 {
        self.migration_check_interval_secs.unwrap_or(180)
    }

    /// Worker-side migration: connection timeout (default 15s)
    pub fn migration_connection_timeout_secs(&self) -> u64 {
        self.migration_connection_timeout_secs.unwrap_or(15)
    }

    /// Worker-side migration: handoff timeout (default 30s)
    pub fn migration_handoff_timeout_secs(&self) -> u64 {
        self.migration_handoff_timeout_secs.unwrap_or(30)
    }

    /// Periodic rebalance: consider current score "good" above this value
    pub fn rebalance_good_score_cutoff(&self) -> f64 {
        self.rebalance_good_score_cutoff.unwrap_or(0.6)
    }

    /// Periodic rebalance: required fractional improvement over current
    pub fn rebalance_periodic_improvement(&self) -> f64 {
        self.rebalance_periodic_improvement.unwrap_or(0.30)
    }

    /// Controller: required consecutive improvement signals
    pub fn rebalance_consecutive_signals(&self) -> u32 {
        self.rebalance_consecutive_signals.unwrap_or(1)
    }

    /// Controller: max rebalances per hour
    pub fn rebalance_max_per_hour(&self) -> u32 {
        self.rebalance_max_per_hour.unwrap_or(3)
    }

    /// Rebalance scoring weights; defaults to 0.6/0.2/0.2
    pub fn rebalance_weight_health(&self) -> f64 {
        self.rebalance_weight_health.unwrap_or(0.6)
    }
    pub fn rebalance_weight_history(&self) -> f64 {
        self.rebalance_weight_history.unwrap_or(0.2)
    }
    pub fn rebalance_weight_breaker(&self) -> f64 {
        self.rebalance_weight_breaker.unwrap_or(0.2)
    }

    /// Empty-manager bonus: required fullness delta between emptiest and next emptiest
    pub fn rebalance_empty_delta_threshold(&self) -> f64 {
        self.rebalance_empty_delta_threshold.unwrap_or(0.20)
    }

    /// Empty-manager bonus: bonus weight applied to emptiest manager score
    pub fn rebalance_empty_bonus_weight(&self) -> f64 {
        self.rebalance_empty_bonus_weight.unwrap_or(0.5)
    }

    /// Empty-manager bonus: minimum health score to qualify
    pub fn rebalance_empty_health_cutoff(&self) -> f64 {
        self.rebalance_empty_health_cutoff.unwrap_or(0.6)
    }

    pub fn rebalance_health_stale_secs(&self) -> u64 {
        self.rebalance_health_stale_secs.unwrap_or(60)
    }

    pub fn rebalance_health_stale_factor(&self) -> f64 {
        self.rebalance_health_stale_factor.unwrap_or(0.75)
    }
}

static CONFIG: Lazy<RwLock<EnvironmentConfig>> =
    Lazy::new(|| RwLock::new(EnvironmentConfig::from_env()));

static CONFIG_DIR: Lazy<RwLock<Option<String>>> =
    Lazy::new(|| RwLock::new(std::env::var("VOLLI_CONFIG_DIR").ok()));

pub fn env_config() -> EnvironmentConfig {
    CONFIG.read().unwrap().clone()
}

pub fn config_dir_env() -> Option<String> {
    // Prefer thread-local overrides to allow tests and scoped operations to run concurrently.
    if let Some(dir) = TLS_CONFIG_DIR.with(|c| c.borrow().clone()) {
        return Some(dir);
    }
    CONFIG_DIR.read().unwrap().clone()
}

pub fn profile_env() -> Option<String> {
    std::env::var("VOLLI_PROFILE").ok()
}

pub fn tcp_port_env() -> Option<u16> {
    std::env::var("VOLLI_TCP_PORT")
        .ok()
        .and_then(|v| v.parse().ok())
}

pub fn quic_port_env() -> Option<u16> {
    std::env::var("VOLLI_QUIC_PORT")
        .ok()
        .and_then(|v| v.parse().ok())
}

pub fn editor_env() -> Option<String> {
    std::env::var("EDITOR").ok()
}

pub struct ConfigDirGuard {
    prev_thread: Option<String>,
    prev_global: Option<String>,
}

pub fn override_config_dir<P: AsRef<Path>>(dir: Option<P>) -> ConfigDirGuard {
    let new = dir.map(|p| p.as_ref().to_string_lossy().to_string());
    let prev_thread = TLS_CONFIG_DIR.with(|c| {
        let mut b = c.borrow_mut();
        std::mem::replace(&mut *b, new.clone())
    });
    let prev_global = {
        let mut lock = CONFIG_DIR.write().unwrap();
        std::mem::replace(&mut *lock, new)
    };
    ConfigDirGuard {
        prev_thread,
        prev_global,
    }
}

pub struct ConfigGuard(Option<EnvironmentConfig>);

pub fn override_env_config(cfg: EnvironmentConfig) -> ConfigGuard {
    let prev = {
        let mut lock = CONFIG.write().unwrap();
        std::mem::replace(&mut *lock, cfg)
    };
    ConfigGuard(Some(prev))
}

/// Partially override the current environment config, preserving existing values
/// for fields not specified in the provided `patch`.
///
/// This is useful in tests that want to tweak a couple of timings (e.g.,
/// `interval_ms`, `backoff_ms`) while keeping the fast defaults established by
/// the test runner (Nextest) or a previous override.
pub fn override_env_config_patch(patch: EnvironmentConfig) -> ConfigGuard {
    let prev = CONFIG.read().unwrap().clone();
    // Merge: for each Option field, prefer `patch` if Some(..), otherwise keep `prev`.
    let merged = EnvironmentConfig {
        quic_idle_ms: patch.quic_idle_ms.or(prev.quic_idle_ms),
        backoff_ms: patch.backoff_ms.or(prev.backoff_ms),
        interval_ms: patch.interval_ms.or(prev.interval_ms),
        connect_timeout_ms: patch.connect_timeout_ms.or(prev.connect_timeout_ms),
        auth_timeout_secs: patch.auth_timeout_secs.or(prev.auth_timeout_secs),
        heartbeat_secs: patch.heartbeat_secs.or(prev.heartbeat_secs),
        join_timeout_secs: patch.join_timeout_secs.or(prev.join_timeout_secs),
        peer_cleanup_secs: patch.peer_cleanup_secs.or(prev.peer_cleanup_secs),
        peer_check_secs: patch.peer_check_secs.or(prev.peer_check_secs),
        rebalance_improvement: patch.rebalance_improvement.or(prev.rebalance_improvement),
        worker_idle_multiplier: patch.worker_idle_multiplier.or(prev.worker_idle_multiplier),
        rebalance_startup_grace_secs: patch
            .rebalance_startup_grace_secs
            .or(prev.rebalance_startup_grace_secs),
        rebalance_check_interval_secs: patch
            .rebalance_check_interval_secs
            .or(prev.rebalance_check_interval_secs),
        rebalance_min_interval_secs: patch
            .rebalance_min_interval_secs
            .or(prev.rebalance_min_interval_secs),
        migration_check_interval_secs: patch
            .migration_check_interval_secs
            .or(prev.migration_check_interval_secs),
        migration_connection_timeout_secs: patch
            .migration_connection_timeout_secs
            .or(prev.migration_connection_timeout_secs),
        migration_handoff_timeout_secs: patch
            .migration_handoff_timeout_secs
            .or(prev.migration_handoff_timeout_secs),
        rebalance_good_score_cutoff: patch
            .rebalance_good_score_cutoff
            .or(prev.rebalance_good_score_cutoff),
        rebalance_periodic_improvement: patch
            .rebalance_periodic_improvement
            .or(prev.rebalance_periodic_improvement),
        rebalance_consecutive_signals: patch
            .rebalance_consecutive_signals
            .or(prev.rebalance_consecutive_signals),
        rebalance_max_per_hour: patch.rebalance_max_per_hour.or(prev.rebalance_max_per_hour),
        rebalance_weight_health: patch
            .rebalance_weight_health
            .or(prev.rebalance_weight_health),
        rebalance_weight_history: patch
            .rebalance_weight_history
            .or(prev.rebalance_weight_history),
        rebalance_weight_breaker: patch
            .rebalance_weight_breaker
            .or(prev.rebalance_weight_breaker),
        rebalance_empty_delta_threshold: patch
            .rebalance_empty_delta_threshold
            .or(prev.rebalance_empty_delta_threshold),
        rebalance_empty_bonus_weight: patch
            .rebalance_empty_bonus_weight
            .or(prev.rebalance_empty_bonus_weight),
        rebalance_empty_health_cutoff: patch
            .rebalance_empty_health_cutoff
            .or(prev.rebalance_empty_health_cutoff),
        rebalance_health_stale_secs: patch
            .rebalance_health_stale_secs
            .or(prev.rebalance_health_stale_secs),
        rebalance_health_stale_factor: patch
            .rebalance_health_stale_factor
            .or(prev.rebalance_health_stale_factor),
    };
    let old = {
        let mut lock = CONFIG.write().unwrap();
        std::mem::replace(&mut *lock, merged)
    };
    ConfigGuard(Some(old))
}

impl Drop for ConfigGuard {
    fn drop(&mut self) {
        if let Some(prev) = self.0.take() {
            let mut lock = CONFIG.write().unwrap();
            *lock = prev;
        }
    }
}

impl Drop for ConfigDirGuard {
    fn drop(&mut self) {
        TLS_CONFIG_DIR.with(|c| {
            *c.borrow_mut() = self.prev_thread.take();
        });
        let mut lock = CONFIG_DIR.write().unwrap();
        *lock = self.prev_global.take();
    }
}

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

    #[test]
    fn quic_idle_default() {
        let cfg = EnvironmentConfig {
            heartbeat_secs: Some(2),
            ..Default::default()
        };
        assert_eq!(cfg.quic_idle_duration().unwrap(), Duration::from_secs(6));
    }

    #[test]
    fn quic_idle_invalid() {
        let cfg = EnvironmentConfig {
            heartbeat_secs: Some(5),
            quic_idle_ms: Some(4000),
            ..Default::default()
        };
        assert!(cfg.quic_idle_duration().is_err());
    }

    #[test]
    fn quic_idle_valid() {
        let cfg = EnvironmentConfig {
            heartbeat_secs: Some(5),
            quic_idle_ms: Some(11000),
            ..Default::default()
        };
        assert_eq!(
            cfg.quic_idle_duration().unwrap(),
            Duration::from_millis(11000)
        );
    }
}