// loop.el — Six-tier runtime heartbeat for the Neuron daemon.
//
// Implements the self-pacing cognitive loop described in the architecture
// doc. The loop runs in its own OS thread (spawned via `spawn_thread`)
// and communicates with the rest of the daemon through global shared
// state (`state_get` / `state_set`).
//
// The six tiers:
//   resting   — 30 min     (low signal, diffuse)
//   watching  — 10 min     (ambient monitoring)
//   working   — 15 sec     (background task in progress)
//   active    —  500 ms    (conversation in progress)
//   critical  —   10 ms    (bell fired)
//   realtime  — busy loop  (physical actuator pinned)
//
// Tier transition rules:
//   1. Bell is sacred — escalates to Critical immediately, never dropped.
//   2. Escalation is immediate — loop re-enters without finishing sleep.
//   3. Step-down is earned — 4 consecutive idle ticks before stepping down.
//   4. Floor is configurable — never drops below `loop_min_tier`.
//
// State keys this file reads / writes:
//   loop_tier, loop_min_tier, loop_ticks, loop_bell_fires,
//   loop_tier_changes, loop_idle_ticks, loop_signal, loop_override_tier
//
// Cognitive substrate:
//   loop manages WHEN to tick; agent.el manages WHAT to do on each tick.
//   loop_do_tick() calls agent_tick() after confirming neuronrs is live.

import "agent.el"
import "plugins/host.el"

// ── Tier constants and ordering ───────────────────────────────────────────────

fn loop_tier_rank(tier: String) -> Int {
    if str_eq(tier, "resting")  { return 0 }
    if str_eq(tier, "watching") { return 1 }
    if str_eq(tier, "working")  { return 2 }
    if str_eq(tier, "active")   { return 3 }
    if str_eq(tier, "critical") { return 4 }
    if str_eq(tier, "realtime") { return 5 }
    return 1
}

fn loop_tier_from_rank(rank: Int) -> String {
    if rank <= 0 { return "resting" }
    if rank == 1 { return "watching" }
    if rank == 2 { return "working" }
    if rank == 3 { return "active" }
    if rank == 4 { return "critical" }
    return "realtime"
}

// Sleep interval in milliseconds for each tier.
// Returns 0 for realtime (busy loop, no sleep at all).
fn loop_tier_interval(tier: String) -> Int {
    if str_eq(tier, "resting")  { return 1800000 }
    if str_eq(tier, "watching") { return 600000 }
    if str_eq(tier, "working")  { return 15000 }
    if str_eq(tier, "active")   { return 500 }
    if str_eq(tier, "critical") { return 10 }
    if str_eq(tier, "realtime") { return 0 }
    return 600000
}

// ── Signal handling ───────────────────────────────────────────────────────────

// Apply a signal to the current tier and return the new tier.
//
// Bell is special: it always escalates to at least Critical, regardless
// of `min_tier`. Other escalations clamp to max(needed, min_tier) so a
// configured floor cannot trap us above an explicit step-down.
fn loop_apply_signal(current: String, signal: String, min_tier: String) -> String {
    let cur_rank: Int = loop_tier_rank(current)
    let min_rank: Int = loop_tier_rank(min_tier)

    // Bell — sacred. Always go to at least Critical.
    if str_eq(signal, "bell") {
        let crit_rank: Int = 4
        if cur_rank >= crit_rank {
            return current
        }
        return "critical"
    }

    // Realtime escalation pins us at the top.
    if str_eq(signal, "realtime") {
        return "realtime"
    }

    // Release-realtime drops us back to Critical.
    if str_eq(signal, "release-realtime") {
        if str_eq(current, "realtime") {
            return "critical"
        }
        return current
    }

    // Active escalates to at least Active.
    if str_eq(signal, "active") {
        let need: Int = 3
        if cur_rank >= need {
            return current
        }
        return "active"
    }

    // Task escalates to at least Working.
    if str_eq(signal, "task") {
        let need: Int = 2
        if cur_rank >= need {
            return current
        }
        return "working"
    }

    // Sleep is an explicit step-down request — drop one tier
    // (respecting the floor).
    if str_eq(signal, "sleep") {
        return loop_step_down(current, min_tier)
    }

    // Idle / drain just contribute to the idle counter; the tier
    // itself does not change here.
    return current
}

// Step down one tier, but never below the configured min_tier.
fn loop_step_down(current: String, min_tier: String) -> String {
    let cur_rank: Int = loop_tier_rank(current)
    let min_rank: Int = loop_tier_rank(min_tier)
    if cur_rank <= min_rank {
        return min_tier
    }
    let new_rank: Int = cur_rank - 1
    if new_rank < min_rank {
        return min_tier
    }
    return loop_tier_from_rank(new_rank)
}

// ── Bell-aware sleep ──────────────────────────────────────────────────────────

// Tail-recursive sleep that wakes early if a bell signal arrives.
// Sleeps in 100ms chunks, peeking at `loop_signal` between each chunk.
fn loop_sleep_chunked(remaining_ms: Int) -> Void {
    if remaining_ms <= 0 {
        // done
    } else {
        let pending: String = state_get("loop_signal")
        if str_eq(pending, "bell") {
            // Bell detected mid-sleep — return immediately so the
            // outer loop can re-enter and escalate.
        } else {
            let chunk: Int = if remaining_ms < 100 { remaining_ms } else { 100 }
            sleep_ms(chunk)
            loop_sleep_chunked(remaining_ms - chunk)
        }
    }
}

// Public sleep entry point. realtime (interval == 0) is a no-op.
fn loop_sleep(remaining_ms: Int) -> Void {
    if remaining_ms > 0 {
        loop_sleep_chunked(remaining_ms)
    }
}

// ── Tick ──────────────────────────────────────────────────────────────────────

// Perform one cognitive tick.
//
// First pings neuronrs /health to confirm the substrate is live.
// If live, delegates to agent_tick() — the cognitive work is in agent.el.
// loop manages WHEN; agent manages WHAT.
//
// Side effect: writes "1" or "0" to `loop_last_tick_idle` so the
// caller can see whether the tick was idle (no live counterpart).
fn loop_do_tick(tier: String) -> Void {
    let url: String = "http://localhost:7770/health"
    let resp: String = http_get(url)
    let live: Bool = str_contains(resp, "ok")
    if live {
        state_set("loop_last_tick_idle", "0")
        // Delegate to the agent cognitive substrate.
        agent_tick({})
    } else {
        state_set("loop_last_tick_idle", "1")
    }
    // Drain the plugin event bus on every tick, regardless of substrate liveness.
    // Plugins interact through events only — host_tick routes events to all
    // plugins that subscribed to them. No hooks, no direct callbacks.
    host_tick({})
    println("[loop] tick tier=" + tier + " live=" + bool_to_str(live))
}

// ── Counters ──────────────────────────────────────────────────────────────────

fn loop_incr_state_int(key: String) -> Void {
    let raw: String = state_get(key)
    let n: Int = if str_eq(raw, "") { 0 } else { str_to_int(raw) }
    state_set(key, int_to_str(n + 1))
}

fn loop_set_int(key: String, value: Int) -> Void {
    state_set(key, int_to_str(value))
}

// ── Core loop ─────────────────────────────────────────────────────────────────

// One iteration of the heartbeat. Tail-recursive: each tick re-enters
// itself with the (possibly updated) tier and idle counter.
fn loop_run(tier: String, idle_count: Int) -> Void {
    // 1. Read floor and pending signals.
    let min_tier: String = state_get("loop_min_tier")
    let floor: String = if str_eq(min_tier, "") { "resting" } else { min_tier }

    let pending: String = state_get("loop_signal")
    let override_tier: String = state_get("loop_override_tier")

    // 2. Apply override (explicit set tier — wins over signal).
    let after_override: String = if str_eq(override_tier, "") {
        tier
    } else {
        override_tier
    }
    if !str_eq(override_tier, "") {
        state_set("loop_override_tier", "")
        loop_incr_state_int("loop_tier_changes")
    }

    // 3. Apply signal.
    let after_signal: String = if str_eq(pending, "") {
        after_override
    } else {
        loop_apply_signal(after_override, pending, floor)
    }
    let signal_changed: Bool = !str_eq(pending, "")
    if signal_changed {
        state_set("loop_signal", "")
        if str_eq(pending, "bell") {
            loop_incr_state_int("loop_bell_fires")
        }
        if !str_eq(after_signal, after_override) {
            loop_incr_state_int("loop_tier_changes")
        }
    }

    // 4. Persist current tier.
    state_set("loop_tier", after_signal)

    // 5. Sleep for this tier's interval (bell-aware, chunked).
    let interval_ms: Int = loop_tier_interval(after_signal)
    loop_sleep(interval_ms)

    // 6. If a bell arrived during sleep, re-enter immediately without
    //    ticking — the next iteration will re-read the signal and
    //    escalate.
    let after_sleep_signal: String = state_get("loop_signal")
    if str_eq(after_sleep_signal, "bell") {
        loop_run(after_signal, idle_count)
    } else {
        // 7. Run the cognitive tick.
        loop_do_tick(after_signal)
        loop_incr_state_int("loop_ticks")

        // 8. Update idle counter and step down if earned.
        let last_idle: String = state_get("loop_last_tick_idle")
        let was_idle: Bool = str_eq(last_idle, "1")

        let new_idle_count: Int = if was_idle { idle_count + 1 } else { 0 }

        // Idle / drain signals also push the counter forward, but
        // `loop_apply_signal` does not change the tier for them.
        let idle_signal: Bool = str_eq(pending, "idle") || str_eq(pending, "drain")
        let bumped_idle_count: Int = if idle_signal {
            new_idle_count + 1
        } else {
            new_idle_count
        }

        // Realtime is pinned — only `release-realtime` can lower it.
        let pinned: Bool = str_eq(after_signal, "realtime")

        if !pinned && bumped_idle_count >= 4 {
            let stepped: String = loop_step_down(after_signal, floor)
            if !str_eq(stepped, after_signal) {
                loop_incr_state_int("loop_tier_changes")
            }
            loop_set_int("loop_idle_ticks", 0)
            loop_run(stepped, 0)
        } else {
            loop_set_int("loop_idle_ticks", bumped_idle_count)
            loop_run(after_signal, bumped_idle_count)
        }
    }
}

// Entry point — called by `spawn_thread("loop_main")`.
fn loop_main() -> Void {
    let start_tier: String = state_get("loop_tier")
    let initial: String = if str_eq(start_tier, "") { "watching" } else { start_tier }
    println("[loop] starting at tier=" + initial)
    loop_run(initial, 0)
}

// ── Status JSON ───────────────────────────────────────────────────────────────

fn loop_status_field(key: String, default: String) -> String {
    let v: String = state_get(key)
    if str_eq(v, "") { return default }
    return v
}

fn loop_status_json() -> String {
    let tier: String = loop_status_field("loop_tier", "watching")
    let min_tier: String = loop_status_field("loop_min_tier", "resting")
    let ticks: String = loop_status_field("loop_ticks", "0")
    let bell_fires: String = loop_status_field("loop_bell_fires", "0")
    let tier_changes: String = loop_status_field("loop_tier_changes", "0")
    let idle_ticks: String = loop_status_field("loop_idle_ticks", "0")
    let signal: String = loop_status_field("loop_signal", "")

    let parts: String = "{\"current_tier\":\"" + tier + "\""
    let p2: String = parts + ",\"min_tier\":\"" + min_tier + "\""
    let p3: String = p2 + ",\"ticks\":" + ticks
    let p4: String = p3 + ",\"bell_fires\":" + bell_fires
    let p5: String = p4 + ",\"tier_changes\":" + tier_changes
    let p6: String = p5 + ",\"idle_ticks\":" + idle_ticks
    let p7: String = p6 + ",\"pending_signal\":\"" + signal + "\"}"
    return p7
}