terminals-core 0.1.0

//! SubstrateEngine — Monomorphized API for WASM consumption.
//!
//! This module pins all generic substrate operations to concrete types
//! so the wasm-bindgen boundary only sees f32/u32/String. The engine
//! owns its atom buffer and exposes a tick-witness-extract loop:
//!
//!   JS: create → set embeddings → tick(audio) → read witness → extract sematon
//!
//! No wasm-bindgen dependency here — that lives in terminals-wasm.

use super::atom::ComputeAtom;
use super::coupling::{coupled_step, AudioMetrics};
use super::expert::ExpertProjection;
use super::fold::fold_to_json;
use super::graph::{GraphProjection, PadicAddr};
use super::kuramoto::KuramotoProjection;
use super::layout::ProjectionLayout;
use super::sematon::Sematon;
use super::splat::SplatProjection;
use super::witness::{compute_witness, ConvergenceWitness};
use crate::primitives::vector;

/// The substrate engine: N atoms, a layout, and physics parameters.
/// Single-owner — WASM is single-threaded so this is safe as a JS-side object.
pub struct SubstrateEngine {
    atoms: Vec<ComputeAtom>,
    layout: ProjectionLayout,
    step: u32,
    witness: ConvergenceWitness,
    k_base: f32,
    gravity_scale: f32,
}

impl SubstrateEngine {
    /// Create a new substrate with `n` atoms.
    /// `full_layout`: true = all 4 projections (1592 bytes/atom),
    ///                false = minimal Splat+Kuramoto (1548 bytes/atom).
    pub fn new(n: usize, full_layout: bool, k_base: f32, gravity_scale: f32) -> Self {
        let layout = if full_layout {
            ProjectionLayout::full()
        } else {
            ProjectionLayout::minimal()
        };
        let atoms = ComputeAtom::create_n(&layout, n);
        Self {
            atoms,
            layout,
            step: 0,
            witness: ConvergenceWitness::default(),
            k_base,
            gravity_scale,
        }
    }

    /// Run one physics step. Returns [R, entropy, converged (0.0/1.0), step].
    pub fn tick(&mut self, bass: f32, mid: f32, high: f32, entropy: f32, dt: f32) -> [f32; 4] {
        let audio = AudioMetrics {
            bass,
            mid,
            high,
            entropy,
        };

        coupled_step(
            &mut self.atoms,
            &audio,
            self.k_base,
            self.gravity_scale,
            dt,
        );

        self.step += 1;
        self.witness = compute_witness(&self.atoms, self.step);

        [
            self.witness.r,
            self.witness.entropy,
            if self.witness.converged { 1.0 } else { 0.0 },
            self.step as f32,
        ]
    }

    /// Read all Kuramoto phases as a flat f32 array.
    pub fn phases(&self) -> Vec<f32> {
        self.atoms
            .iter()
            .map(|a| {
                a.read_projection::<KuramotoProjection>()
                    .map(|k| k.theta)
                    .unwrap_or(0.0)
            })
            .collect()
    }

    /// Current witness as [R, entropy, converged, step].
    pub fn witness_array(&self) -> [f32; 4] {
        [
            self.witness.r,
            self.witness.entropy,
            if self.witness.converged { 1.0 } else { 0.0 },
            self.step as f32,
        ]
    }

    /// Set the 384-dim embedding for atom at `index`.
    /// Returns false if index out of bounds or embedding wrong length.
    pub fn set_embedding(&mut self, index: usize, embedding: &[f32]) -> bool {
        if index >= self.atoms.len() || embedding.len() != 384 {
            return false;
        }
        let mut splat = self.atoms[index]
            .read_projection::<SplatProjection>()
            .unwrap_or_default();
        splat.embedding.copy_from_slice(embedding);
        self.atoms[index].write_projection(&splat)
    }

    /// Set Kuramoto phase and natural frequency for atom at `index`.
    pub fn set_phase(&mut self, index: usize, theta: f32, omega: f32) -> bool {
        if index >= self.atoms.len() {
            return false;
        }
        let mut kp = self.atoms[index]
            .read_projection::<KuramotoProjection>()
            .unwrap_or_default();
        kp.theta = theta;
        kp.omega = omega;
        self.atoms[index].write_projection(&kp)
    }

    /// Set expert projection (intent routing) for atom at `index`.
    pub fn set_expert(&mut self, index: usize, intent: f32, activation: f32, gate: f32) -> bool {
        if index >= self.atoms.len() {
            return false;
        }
        if !self.layout.has(super::projection::ProjectionId::Expert) {
            return false;
        }
        let ep = ExpertProjection {
            intent,
            activation,
            gate,
        };
        self.atoms[index].write_projection(&ep)
    }

    /// Set graph neighbor at a slot for atom at `index`.
    pub fn set_neighbor(&mut self, index: usize, slot: usize, neighbor_index: u16) -> bool {
        if index >= self.atoms.len() || slot >= super::graph::MAX_NEIGHBORS {
            return false;
        }
        if !self.layout.has(super::projection::ProjectionId::Graph) {
            return false;
        }
        let mut gp = self.atoms[index]
            .read_projection::<GraphProjection>()
            .unwrap_or_default();
        gp.neighbors[slot] = neighbor_index;
        self.atoms[index].write_projection(&gp)
    }

    /// Number of atoms.
    pub fn atom_count(&self) -> usize {
        self.atoms.len()
    }

    /// Current step number.
    pub fn step_count(&self) -> u32 {
        self.step
    }

    /// Stride in bytes per atom.
    pub fn stride(&self) -> usize {
        self.layout.stride
    }

    /// Whether the substrate has converged (R >= 0.9).
    pub fn converged(&self) -> bool {
        self.witness.converged
    }

    /// Current order parameter R.
    pub fn order_parameter(&self) -> f32 {
        self.witness.r
    }

    /// All embeddings as a flat f32 array (n * 384 elements).
    pub fn embeddings_flat(&self) -> Vec<f32> {
        let mut out = Vec::with_capacity(self.atoms.len() * 384);
        for atom in &self.atoms {
            if let Some(splat) = atom.read_projection::<SplatProjection>() {
                out.extend_from_slice(&splat.embedding);
            } else {
                out.extend(std::iter::repeat(0.0f32).take(384));
            }
        }
        out
    }

    /// Compute the centroid embedding across all atoms.
    fn centroid_embedding(&self) -> Vec<f32> {
        let mut centroid = vec![0.0f32; 384];
        let mut count = 0usize;

        for atom in &self.atoms {
            if let Some(splat) = atom.read_projection::<SplatProjection>() {
                for (i, &v) in splat.embedding.iter().enumerate() {
                    centroid[i] += v;
                }
                count += 1;
            }
        }

        if count == 0 {
            return centroid;
        }

        let n = count as f32;
        for v in &mut centroid {
            *v /= n;
        }

        vector::normalize(&mut centroid);
        centroid
    }

    /// Extract a sematon from the current substrate state.
    /// Payload = centroid embedding. Returns JSON string of FoldedSematon.
    pub fn extract_sematon(&self, source: &str) -> String {
        let centroid = self.centroid_embedding();
        let address = PadicAddr {
            base: self.step,
            coeff0: self.atoms.len() as u16,
            coeff1: 0,
        };
        let sematon = Sematon::new(centroid, self.witness, address, source);
        fold_to_json(&sematon)
    }

    /// Read the shape hash for atom at `index`.
    pub fn atom_shape_hash(&self, index: usize) -> Option<u32> {
        self.atoms.get(index).map(|a| a.shape_hash)
    }

    /// Update coupling parameters (k_base, gravity_scale).
    pub fn set_coupling_params(&mut self, k_base: f32, gravity_scale: f32) {
        self.k_base = k_base;
        self.gravity_scale = gravity_scale;
    }
}

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

    #[test]
    fn test_engine_create_full() {
        let engine = SubstrateEngine::new(10, true, 1.0, 1.0);
        assert_eq!(engine.atom_count(), 10);
        assert_eq!(engine.stride(), 1612);
        assert_eq!(engine.step_count(), 0);
        assert!(!engine.converged());
    }

    #[test]
    fn test_engine_create_minimal() {
        let engine = SubstrateEngine::new(5, false, 1.0, 1.0);
        assert_eq!(engine.atom_count(), 5);
        assert_eq!(engine.stride(), 1548);
    }

    #[test]
    fn test_engine_set_and_read_embedding() {
        let mut engine = SubstrateEngine::new(3, true, 1.0, 1.0);
        let mut emb = vec![0.0f32; 384];
        emb[0] = 1.0;

        assert!(engine.set_embedding(0, &emb));
        assert!(engine.set_embedding(1, &emb));
        assert!(!engine.set_embedding(10, &emb)); // out of bounds
        assert!(!engine.set_embedding(0, &[1.0; 10])); // wrong length

        let flat = engine.embeddings_flat();
        assert_eq!(flat.len(), 3 * 384);
        assert!((flat[0] - 1.0).abs() < 1e-6);
    }

    #[test]
    fn test_engine_set_phase() {
        let mut engine = SubstrateEngine::new(3, false, 1.0, 1.0);
        assert!(engine.set_phase(0, 1.5, 0.1));
        assert!(engine.set_phase(2, 3.0, 0.2));
        assert!(!engine.set_phase(5, 0.0, 0.0)); // out of bounds

        let phases = engine.phases();
        assert_eq!(phases.len(), 3);
        assert!((phases[0] - 1.5).abs() < 1e-6);
        assert!((phases[2] - 3.0).abs() < 1e-6);
    }

    #[test]
    fn test_engine_set_expert() {
        let mut engine = SubstrateEngine::new(2, true, 1.0, 1.0);
        assert!(engine.set_expert(0, 0.5, 0.8, 1.0));

        // Minimal layout doesn't have Expert
        let mut engine_min = SubstrateEngine::new(2, false, 1.0, 1.0);
        assert!(!engine_min.set_expert(0, 0.5, 0.8, 1.0));
    }

    #[test]
    fn test_engine_tick_returns_witness() {
        let mut engine = SubstrateEngine::new(6, false, 5.0, 1.0);

        // Set same embedding direction for all atoms (high coupling)
        let mut emb = vec![0.0f32; 384];
        emb[0] = 1.0;
        for i in 0..6 {
            engine.set_embedding(i, &emb);
            engine.set_phase(i, i as f32, 0.0);
        }

        // Tick once
        let w = engine.tick(0.5, 0.3, 0.2, 0.5, 0.01);
        assert_eq!(w.len(), 4);
        assert!(w[0] >= 0.0 && w[0] <= 1.0); // R in [0,1]
        assert_eq!(w[3], 1.0); // step = 1
        assert_eq!(engine.step_count(), 1);
    }

    #[test]
    fn test_engine_convergence_after_many_ticks() {
        let mut engine = SubstrateEngine::new(6, false, 5.0, 1.0);

        // Same embedding (high gravity coupling)
        let mut emb = vec![0.0f32; 384];
        emb[0] = 1.0;
        for i in 0..6 {
            engine.set_embedding(i, &emb);
            engine.set_phase(i, i as f32, 0.0);
        }

        // Run many ticks
        for _ in 0..1000 {
            engine.tick(0.5, 0.3, 0.2, 0.5, 0.01);
        }

        assert!(
            engine.order_parameter() > 0.9,
            "R = {} (expected > 0.9)",
            engine.order_parameter()
        );
        assert!(engine.converged());
    }

    #[test]
    fn test_engine_extract_sematon() {
        let mut engine = SubstrateEngine::new(4, false, 5.0, 1.0);

        let mut emb = vec![0.0f32; 384];
        emb[0] = 1.0;
        for i in 0..4 {
            engine.set_embedding(i, &emb);
        }

        // Tick to get a witness
        engine.tick(0.5, 0.3, 0.2, 0.5, 0.01);

        let json = engine.extract_sematon("test-surface");
        assert!(!json.is_empty());
        assert!(json.contains("test-surface"));
        assert!(json.contains("witness_r"));
    }

    #[test]
    fn test_engine_witness_array_matches_tick() {
        let mut engine = SubstrateEngine::new(3, false, 1.0, 1.0);
        let tick_w = engine.tick(0.0, 0.0, 0.0, 0.0, 0.01);
        let read_w = engine.witness_array();

        assert_eq!(tick_w[0], read_w[0]); // R
        assert_eq!(tick_w[1], read_w[1]); // entropy
        assert_eq!(tick_w[2], read_w[2]); // converged
        assert_eq!(tick_w[3], read_w[3]); // step
    }

    #[test]
    fn test_engine_set_coupling_params() {
        let mut engine = SubstrateEngine::new(2, false, 1.0, 1.0);
        engine.set_coupling_params(10.0, 2.0);
        // Just verify no panic — the effect shows in tick behavior
        engine.tick(0.5, 0.0, 0.0, 0.0, 0.01);
    }

    #[test]
    fn test_engine_empty() {
        let mut engine = SubstrateEngine::new(0, true, 1.0, 1.0);
        assert_eq!(engine.atom_count(), 0);
        let w = engine.tick(0.0, 0.0, 0.0, 0.0, 0.01);
        assert_eq!(w[0], 0.0); // R = 0 for empty
        assert!(engine.phases().is_empty());
    }

    #[test]
    fn test_engine_atom_shape_hash() {
        let mut engine = SubstrateEngine::new(2, false, 1.0, 1.0);
        let h1 = engine.atom_shape_hash(0).unwrap();

        engine.set_phase(0, 3.14, 1.0);
        let h2 = engine.atom_shape_hash(0).unwrap();

        assert_ne!(h1, h2); // Hash changed after write
        assert!(engine.atom_shape_hash(99).is_none()); // Out of bounds
    }
}