u_nesting_d3/

ga_packing.rs

//! Genetic Algorithm based 3D bin packing optimization.
//!
//! This module provides GA-based optimization for 3D bin packing problems,
//! using permutation + orientation chromosome representation and layer-based decoding.

use crate::boundary::Boundary3D;
use crate::geometry::Geometry3D;
use rand::prelude::*;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use u_nesting_core::ga::{GaConfig, GaProblem, GaRunner, Individual};
use u_nesting_core::geometry::{Boundary, Geometry};
use u_nesting_core::solver::Config;
use u_nesting_core::{Placement, SolveResult};

/// Packing chromosome representing placement order and orientations.
#[derive(Debug, Clone)]
pub struct PackingChromosome {
    /// Permutation of instance indices (placement order).
    pub order: Vec<usize>,
    /// Orientation index for each instance (0-5 for boxes with Any constraint).
    pub orientations: Vec<usize>,
    /// Cached fitness value.
    fitness: f64,
    /// Number of placed pieces.
    placed_count: usize,
    /// Total instances count.
    total_count: usize,
}

impl PackingChromosome {
    /// Creates a new chromosome for the given number of instances.
    pub fn new(num_instances: usize) -> Self {
        Self {
            order: (0..num_instances).collect(),
            orientations: vec![0; num_instances],
            fitness: f64::NEG_INFINITY,
            placed_count: 0,
            total_count: num_instances,
        }
    }

    /// Creates a random chromosome with given orientation options per instance.
    pub fn random_with_options<R: Rng>(
        num_instances: usize,
        orientation_counts: &[usize],
        rng: &mut R,
    ) -> Self {
        let mut order: Vec<usize> = (0..num_instances).collect();
        order.shuffle(rng);

        let orientations: Vec<usize> = orientation_counts
            .iter()
            .map(|&count| rng.gen_range(0..count.max(1)))
            .collect();

        Self {
            order,
            orientations,
            fitness: f64::NEG_INFINITY,
            placed_count: 0,
            total_count: num_instances,
        }
    }

    /// Sets the fitness value.
    pub fn set_fitness(&mut self, fitness: f64, placed_count: usize) {
        self.fitness = fitness;
        self.placed_count = placed_count;
    }

    /// Order crossover (OX1) for permutation genes.
    pub fn order_crossover<R: Rng>(
        &self,
        other: &Self,
        orientation_counts: &[usize],
        rng: &mut R,
    ) -> Self {
        let n = self.order.len();
        if n < 2 {
            return self.clone();
        }

        // Select two crossover points
        let (mut p1, mut p2) = (rng.gen_range(0..n), rng.gen_range(0..n));
        if p1 > p2 {
            std::mem::swap(&mut p1, &mut p2);
        }

        // Copy segment from parent1
        let mut child_order = vec![usize::MAX; n];
        let mut used = vec![false; n];

        for i in p1..=p2 {
            child_order[i] = self.order[i];
            used[self.order[i]] = true;
        }

        // Fill remaining from parent2
        let mut j = (p2 + 1) % n;
        for i in 0..n {
            let idx = (p2 + 1 + i) % n;
            if child_order[idx] == usize::MAX {
                while used[other.order[j]] {
                    j = (j + 1) % n;
                }
                child_order[idx] = other.order[j];
                used[other.order[j]] = true;
                j = (j + 1) % n;
            }
        }

        // Crossover orientations (uniform with bounds checking)
        let orientations: Vec<usize> = self
            .orientations
            .iter()
            .zip(&other.orientations)
            .enumerate()
            .map(|(i, (a, b))| {
                let max_orient = orientation_counts.get(i).copied().unwrap_or(1);
                let chosen = if rng.gen() { *a } else { *b };
                chosen % max_orient.max(1)
            })
            .collect();

        Self {
            order: child_order,
            orientations,
            fitness: f64::NEG_INFINITY,
            placed_count: 0,
            total_count: self.total_count,
        }
    }

    /// Swap mutation for order genes.
    pub fn swap_mutate<R: Rng>(&mut self, rng: &mut R) {
        if self.order.len() < 2 {
            return;
        }

        let i = rng.gen_range(0..self.order.len());
        let j = rng.gen_range(0..self.order.len());
        self.order.swap(i, j);
        self.fitness = f64::NEG_INFINITY;
    }

    /// Orientation mutation.
    pub fn orientation_mutate<R: Rng>(&mut self, orientation_counts: &[usize], rng: &mut R) {
        if self.orientations.is_empty() {
            return;
        }

        let idx = rng.gen_range(0..self.orientations.len());
        let max_orient = orientation_counts.get(idx).copied().unwrap_or(1);
        if max_orient > 1 {
            self.orientations[idx] = rng.gen_range(0..max_orient);
            self.fitness = f64::NEG_INFINITY;
        }
    }

    /// Inversion mutation (reverses a segment of the order).
    pub fn inversion_mutate<R: Rng>(&mut self, rng: &mut R) {
        let n = self.order.len();
        if n < 2 {
            return;
        }

        let (mut p1, mut p2) = (rng.gen_range(0..n), rng.gen_range(0..n));
        if p1 > p2 {
            std::mem::swap(&mut p1, &mut p2);
        }

        self.order[p1..=p2].reverse();
        self.fitness = f64::NEG_INFINITY;
    }
}

impl Individual for PackingChromosome {
    type Fitness = f64;

    fn fitness(&self) -> f64 {
        self.fitness
    }

    fn random<R: Rng>(_rng: &mut R) -> Self {
        // Default: empty, will be overridden by problem's initialize_population
        Self::new(0)
    }

    fn crossover<R: Rng>(&self, other: &Self, rng: &mut R) -> Self {
        // Default crossover without orientation bounds - should use problem's crossover
        let fake_counts = vec![6; self.orientations.len()];
        self.order_crossover(other, &fake_counts, rng)
    }

    fn mutate<R: Rng>(&mut self, rng: &mut R) {
        // 50% swap, 30% inversion, 20% orientation
        let r: f64 = rng.gen();
        if r < 0.5 {
            self.swap_mutate(rng);
        } else if r < 0.8 {
            self.inversion_mutate(rng);
        } else {
            // Orientation mutation with max 6 options
            let fake_counts = vec![6; self.orientations.len()];
            self.orientation_mutate(&fake_counts, rng);
        }
    }
}

/// Instance information for decoding.
#[derive(Debug, Clone)]
struct InstanceInfo {
    /// Index into the geometries array.
    geometry_idx: usize,
    /// Instance number within this geometry's quantity.
    instance_num: usize,
    /// Number of allowed orientations.
    orientation_count: usize,
}

/// Problem definition for GA-based 3D bin packing.
pub struct PackingProblem {
    /// Input geometries.
    geometries: Vec<Geometry3D>,
    /// Boundary container.
    boundary: Boundary3D,
    /// Solver configuration.
    config: Config,
    /// Instance mapping.
    instances: Vec<InstanceInfo>,
    /// Orientation counts per instance.
    orientation_counts: Vec<usize>,
    /// Cancellation flag.
    cancelled: Arc<AtomicBool>,
}

impl PackingProblem {
    /// Creates a new packing problem.
    pub fn new(
        geometries: Vec<Geometry3D>,
        boundary: Boundary3D,
        config: Config,
        cancelled: Arc<AtomicBool>,
    ) -> Self {
        // Build instance mapping
        let mut instances = Vec::new();
        let mut orientation_counts = Vec::new();

        for (geom_idx, geom) in geometries.iter().enumerate() {
            let orient_count = geom.allowed_orientations().len();

            for instance_num in 0..geom.quantity() {
                instances.push(InstanceInfo {
                    geometry_idx: geom_idx,
                    instance_num,
                    orientation_count: orient_count,
                });
                orientation_counts.push(orient_count);
            }
        }

        Self {
            geometries,
            boundary,
            config,
            instances,
            orientation_counts,
            cancelled,
        }
    }

    /// Returns the total number of instances.
    pub fn num_instances(&self) -> usize {
        self.instances.len()
    }

    /// Returns orientation counts per instance.
    pub fn orientation_counts(&self) -> &[usize] {
        &self.orientation_counts
    }

    /// Decodes a chromosome into placements using layer-based packing.
    pub fn decode(&self, chromosome: &PackingChromosome) -> (Vec<Placement<f64>>, f64, usize) {
        let mut placements = Vec::new();

        let margin = self.config.margin;
        let spacing = self.config.spacing;

        let bound_max_x = self.boundary.width() - margin;
        let bound_max_y = self.boundary.depth() - margin;
        let bound_max_z = self.boundary.height() - margin;

        // Track current position in layer-based packing
        let mut current_x = margin;
        let mut current_y = margin;
        let mut current_z = margin;
        let mut row_depth = 0.0_f64;
        let mut layer_height = 0.0_f64;

        let mut total_placed_volume = 0.0;
        let mut total_placed_mass = 0.0;
        let mut placed_count = 0;

        // Place items in the order specified by chromosome
        for &instance_idx in &chromosome.order {
            if self.cancelled.load(Ordering::Relaxed) {
                break;
            }

            if instance_idx >= self.instances.len() {
                continue;
            }

            let info = &self.instances[instance_idx];
            let geom = &self.geometries[info.geometry_idx];

            // Get orientation from chromosome
            let orientation_idx = chromosome
                .orientations
                .get(instance_idx)
                .copied()
                .unwrap_or(0);
            let orientation_idx = orientation_idx % info.orientation_count.max(1);

            // Get dimensions for this orientation
            let dims = geom.dimensions_for_orientation(orientation_idx);
            let g_width = dims.x;
            let g_depth = dims.y;
            let g_height = dims.z;

            // Check mass constraint
            if let (Some(max_mass), Some(item_mass)) = (self.boundary.max_mass(), geom.mass()) {
                if total_placed_mass + item_mass > max_mass {
                    continue;
                }
            }

            // Try to fit in current row
            if current_x + g_width > bound_max_x {
                // Move to next row
                current_x = margin;
                current_y += row_depth + spacing;
                row_depth = 0.0;
            }

            // Check if fits in current layer (y direction)
            if current_y + g_depth > bound_max_y {
                // Move to next layer
                current_x = margin;
                current_y = margin;
                current_z += layer_height + spacing;
                row_depth = 0.0;
                layer_height = 0.0;
            }

            // Check if fits in container height
            if current_z + g_height > bound_max_z {
                continue;
            }

            // Place the item
            let placement = Placement::new_3d(
                geom.id().clone(),
                info.instance_num,
                current_x,
                current_y,
                current_z,
                0.0,
                0.0,
                0.0, // Orientation is encoded in orientation_idx, not Euler angles
            );

            placements.push(placement);
            total_placed_volume += geom.measure();
            if let Some(mass) = geom.mass() {
                total_placed_mass += mass;
            }
            placed_count += 1;

            // Update position for next item
            current_x += g_width + spacing;
            row_depth = row_depth.max(g_depth);
            layer_height = layer_height.max(g_height);
        }

        let utilization = total_placed_volume / self.boundary.measure();
        (placements, utilization, placed_count)
    }
}

impl GaProblem for PackingProblem {
    type Individual = PackingChromosome;

    fn evaluate(&self, individual: &mut Self::Individual) {
        let (_, utilization, placed_count) = self.decode(individual);

        // Fitness = placement ratio * 100 + utilization * 10
        let placement_ratio = placed_count as f64 / individual.total_count.max(1) as f64;
        let fitness = placement_ratio * 100.0 + utilization * 10.0;

        individual.set_fitness(fitness, placed_count);
    }

    fn initialize_population<R: Rng>(&self, size: usize, rng: &mut R) -> Vec<Self::Individual> {
        (0..size)
            .map(|_| {
                PackingChromosome::random_with_options(
                    self.num_instances(),
                    &self.orientation_counts,
                    rng,
                )
            })
            .collect()
    }

    fn on_generation(
        &self,
        generation: u32,
        best: &Self::Individual,
        _population: &[Self::Individual],
    ) {
        log::debug!(
            "GA 3D Packing Gen {}: fitness={:.4}, placed={}/{}",
            generation,
            best.fitness(),
            best.placed_count,
            best.total_count
        );
    }
}

/// Runs GA-based 3D bin packing optimization.
pub fn run_ga_packing(
    geometries: &[Geometry3D],
    boundary: &Boundary3D,
    config: &Config,
    ga_config: GaConfig,
    cancelled: Arc<AtomicBool>,
) -> SolveResult<f64> {
    let problem = PackingProblem::new(
        geometries.to_vec(),
        boundary.clone(),
        config.clone(),
        cancelled.clone(),
    );

    let runner = GaRunner::new(ga_config, problem);

    // Connect cancellation
    let cancel_handle = runner.cancel_handle();
    let cancelled_clone = cancelled.clone();
    std::thread::spawn(move || {
        while !cancelled_clone.load(Ordering::Relaxed) {
            std::thread::sleep(std::time::Duration::from_millis(100));
        }
        cancel_handle.store(true, Ordering::Relaxed);
    });

    let ga_result = runner.run();

    // Decode the best chromosome
    let problem = PackingProblem::new(
        geometries.to_vec(),
        boundary.clone(),
        config.clone(),
        Arc::new(AtomicBool::new(false)),
    );

    let (placements, utilization, _placed_count) = problem.decode(&ga_result.best);

    // Build unplaced list
    let mut unplaced = Vec::new();
    let mut placed_ids: std::collections::HashSet<String> = std::collections::HashSet::new();
    for p in &placements {
        placed_ids.insert(p.geometry_id.clone());
    }
    for geom in geometries {
        if !placed_ids.contains(geom.id()) {
            unplaced.push(geom.id().clone());
        }
    }

    let mut result = SolveResult::new();
    result.placements = placements;
    result.unplaced = unplaced;
    result.boundaries_used = 1;
    result.utilization = utilization;
    result.computation_time_ms = ga_result.elapsed.as_millis() as u64;
    result.generations = Some(ga_result.generations);
    result.best_fitness = Some(ga_result.best.fitness());
    result.fitness_history = Some(ga_result.history);
    result.strategy = Some("GeneticAlgorithm".to_string());
    result.cancelled = cancelled.load(Ordering::Relaxed);
    result.target_reached = ga_result.target_reached;

    result
}

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

    #[test]
    fn test_packing_chromosome_crossover() {
        let mut rng = thread_rng();
        let orientation_counts = vec![6, 6, 6, 6, 6];
        let parent1 = PackingChromosome::random_with_options(5, &orientation_counts, &mut rng);
        let parent2 = PackingChromosome::random_with_options(5, &orientation_counts, &mut rng);

        let child = parent1.order_crossover(&parent2, &orientation_counts, &mut rng);

        // Child should be a valid permutation
        assert_eq!(child.order.len(), 5);
        let mut sorted = child.order.clone();
        sorted.sort();
        assert_eq!(sorted, (0..5).collect::<Vec<_>>());

        // Orientations should be within bounds
        for (i, &orient) in child.orientations.iter().enumerate() {
            assert!(orient < orientation_counts[i]);
        }
    }

    #[test]
    fn test_packing_chromosome_mutation() {
        let mut rng = thread_rng();
        let orientation_counts = vec![6, 6, 6, 6, 6];
        let mut chromosome =
            PackingChromosome::random_with_options(5, &orientation_counts, &mut rng);

        chromosome.swap_mutate(&mut rng);

        // Should still be a valid permutation
        let mut sorted = chromosome.order.clone();
        sorted.sort();
        assert_eq!(sorted, (0..5).collect::<Vec<_>>());
    }

    #[test]
    fn test_ga_packing_basic() {
        let geometries = vec![
            Geometry3D::new("B1", 20.0, 20.0, 20.0).with_quantity(2),
            Geometry3D::new("B2", 15.0, 15.0, 15.0).with_quantity(2),
        ];

        let boundary = Boundary3D::new(100.0, 80.0, 50.0);
        let config = Config::default();
        let ga_config = GaConfig::default()
            .with_population_size(20)
            .with_max_generations(10);

        let result = run_ga_packing(
            &geometries,
            &boundary,
            &config,
            ga_config,
            Arc::new(AtomicBool::new(false)),
        );

        assert!(result.utilization > 0.0);
        assert!(!result.placements.is_empty());
    }

    #[test]
    fn test_ga_packing_all_placed() {
        let geometries = vec![Geometry3D::new("B1", 20.0, 20.0, 20.0).with_quantity(4)];

        let boundary = Boundary3D::new(100.0, 100.0, 100.0);
        let config = Config::default();
        let ga_config = GaConfig::default()
            .with_population_size(30)
            .with_max_generations(20);

        let result = run_ga_packing(
            &geometries,
            &boundary,
            &config,
            ga_config,
            Arc::new(AtomicBool::new(false)),
        );

        // All 4 boxes should fit easily
        assert_eq!(result.placements.len(), 4);
        assert!(result.unplaced.is_empty());
    }

    #[test]
    fn test_ga_packing_with_orientations() {
        use crate::geometry::OrientationConstraint;
        // Long boxes that benefit from rotation
        let geometries = vec![Geometry3D::new("B1", 50.0, 10.0, 10.0)
            .with_quantity(3)
            .with_orientation(OrientationConstraint::Any)];

        let boundary = Boundary3D::new(60.0, 60.0, 60.0);
        let config = Config::default();
        let ga_config = GaConfig::default()
            .with_population_size(30)
            .with_max_generations(20);

        let result = run_ga_packing(
            &geometries,
            &boundary,
            &config,
            ga_config,
            Arc::new(AtomicBool::new(false)),
        );

        assert!(result.utilization > 0.0);
        assert!(!result.placements.is_empty());
    }

    #[test]
    fn test_packing_problem_decode() {
        let geometries = vec![Geometry3D::new("B1", 20.0, 20.0, 20.0).with_quantity(2)];

        let boundary = Boundary3D::new(100.0, 100.0, 100.0);
        let config = Config::default();
        let cancelled = Arc::new(AtomicBool::new(false));

        let problem = PackingProblem::new(geometries, boundary, config, cancelled);

        assert_eq!(problem.num_instances(), 2);

        // Create a chromosome and decode
        let chromosome = PackingChromosome::new(2);
        let (placements, utilization, placed_count) = problem.decode(&chromosome);

        assert_eq!(placed_count, 2);
        assert_eq!(placements.len(), 2);
        assert!(utilization > 0.0);
    }

    #[test]
    fn test_ga_packing_mass_constraint() {
        let geometries = vec![Geometry3D::new("B1", 20.0, 20.0, 20.0)
            .with_quantity(10)
            .with_mass(100.0)];

        let boundary = Boundary3D::new(100.0, 100.0, 100.0).with_max_mass(350.0);
        let config = Config::default();
        let ga_config = GaConfig::default()
            .with_population_size(20)
            .with_max_generations(10);

        let result = run_ga_packing(
            &geometries,
            &boundary,
            &config,
            ga_config,
            Arc::new(AtomicBool::new(false)),
        );

        // Should only place 3 boxes due to 350 mass limit
        assert!(result.placements.len() <= 3);
    }
}