gizmo-ai 0.1.7

use gizmo_math::Vec3;
use std::cmp::Ordering;
use std::collections::{BinaryHeap, HashMap, HashSet};

#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
pub struct GridPos {
    pub x: i32,
    pub y: i32,
    pub z: i32, // Katman veya yükseklik
}

impl GridPos {
    pub fn new(x: i32, y: i32, z: i32) -> Self {
        Self { x, y, z }
    }
}

pub struct NavGrid {
    pub cell_size: f32,
    pub width: i32,
    pub height: i32,
    pub obstacles: HashSet<GridPos>,
    pub needs_rebuild: bool,
}

impl NavGrid {
    pub fn new(cell_size: f32, width: i32, height: i32) -> Self {
        Self {
            cell_size,
            width,
            height,
            obstacles: HashSet::new(),
            needs_rebuild: true,
        }
    }

    pub fn add_obstacle_world(&mut self, world_pos: Vec3) {
        let gp = self.world_to_grid(world_pos);
        self.obstacles.insert(gp);
    }

    pub fn remove_obstacle_world(&mut self, world_pos: Vec3) {
        let gp = self.world_to_grid(world_pos);
        self.obstacles.remove(&gp);
    }

    pub fn world_to_grid(&self, pos: Vec3) -> GridPos {
        GridPos {
            x: (pos.x / self.cell_size).floor() as i32,
            y: (pos.y / self.cell_size).floor() as i32,
            z: (pos.z / self.cell_size).floor() as i32, // Genelde yer zemindir ama 3D de olabilir
        }
    }

    pub fn grid_to_world(&self, gp: GridPos) -> Vec3 {
        Vec3::new(
            (gp.x as f32 + 0.5) * self.cell_size,
            (gp.y as f32 + 0.5) * self.cell_size, // eğer y = Z ekseni yukarıysa buna göre güncelleyebiliriz
            (gp.z as f32 + 0.5) * self.cell_size,
        )
    }

    pub fn is_walkable(&self, pos: GridPos) -> bool {
        if pos.x < 0 || pos.x >= self.width || pos.z < 0 || pos.z >= self.height {
            return false;
        }
        !self.obstacles.contains(&pos) // Engel yoksa yürünebilir
    }

    // Yalnızca X,Z düzleminde Dört yön hareket algılayan komşuluk.
    pub fn get_neighbors(&self, pos: GridPos) -> Vec<GridPos> {
        let mut neighbors = Vec::with_capacity(8);
        let dirs = [(1, 0), (-1, 0), (0, 1), (0, -1)];
        let diagonals = [(1, 1), (-1, -1), (-1, 1), (1, -1)];

        // 1. Düz yönler
        for (dx, dz) in dirs.iter() {
            let n = GridPos::new(pos.x + dx, pos.y, pos.z + dz);
            if self.is_walkable(n) {
                neighbors.push(n);
            }
        }

        // 2. Çapraz yönler (Köşeden geçerken her iki kenarın da açık olması şart! Yoksa çarpar)
        for (dx, dz) in diagonals.iter() {
            let n = GridPos::new(pos.x + dx, pos.y, pos.z + dz);
            let side1 = GridPos::new(pos.x + dx, pos.y, pos.z);
            let side2 = GridPos::new(pos.x, pos.y, pos.z + dz);

            if self.is_walkable(n) && self.is_walkable(side1) && self.is_walkable(side2) {
                neighbors.push(n);
            }
        }
        neighbors
    }

    /// Fizik dünyasındaki statik nesneleri tarayıp navigasyon engel ızgarasını (NavMesh) günceller
    pub fn update_from_physics_world(&mut self, physics: &gizmo_physics_rigid::world::PhysicsWorld) {
        let cell_size = self.cell_size;

        let world_to_grid_fn = |pos: Vec3| -> GridPos {
            GridPos {
                x: (pos.x / cell_size).floor() as i32,
                y: (pos.y / cell_size).floor() as i32,
                z: (pos.z / cell_size).floor() as i32,
            }
        };

        let chunk_size = (physics.entities.len() / 8).max(1);

        self.obstacles = std::thread::scope(|s| {
            let mut handles = Vec::new();

            let mut start = 0;
            while start < physics.entities.len() {
                let end = (start + chunk_size).min(physics.entities.len());
                handles.push(s.spawn(move || {
                    let mut local_obs = HashSet::new();
                    for i in start..end {
                        let rb = &physics.rigid_bodies[i];
                        if rb.body_type == gizmo_physics_rigid::components::BodyType::Dynamic {
                            continue;
                        }
                        let transform = &physics.transforms[i];
                        let collider = &physics.colliders[i];

                        let aabb = collider.compute_aabb(transform.position, transform.rotation);
                        let min_grid = world_to_grid_fn(aabb.min.into());
                        let max_grid = world_to_grid_fn(aabb.max.into());

                        for x in min_grid.x..=max_grid.x {
                            for y in min_grid.y..=max_grid.y {
                                for z in min_grid.z..=max_grid.z {
                                    local_obs.insert(GridPos::new(x, y, z));
                                }
                            }
                        }
                    }
                    local_obs
                }));
                start = end;
            }

            let mut combined = HashSet::new();
            for handle in handles {
                combined.extend(handle.join().unwrap());
            }
            combined
        });

        self.needs_rebuild = false;
    }
}

#[derive(Copy, Clone, PartialEq)]
struct AStarNode {
    pos: GridPos,
    cost: u32, // f_cost
}

impl Eq for AStarNode {}

// BinaryHeap büyükten küçüğe sıralar, küçük cost için tersine çalışması lazım.
impl Ord for AStarNode {
    fn cmp(&self, other: &Self) -> Ordering {
        other
            .cost
            .cmp(&self.cost) // Ters çevirildi
            .then_with(|| self.pos.x.cmp(&other.pos.x))
            .then_with(|| self.pos.y.cmp(&other.pos.y))
            .then_with(|| self.pos.z.cmp(&other.pos.z))
    }
}

impl PartialOrd for AStarNode {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

/// Octile mesafe tahmini (Çapraz harekete uygun)
fn heuristic(a: GridPos, b: GridPos) -> u32 {
    let dx = (a.x - b.x).unsigned_abs();
    let dz = (a.z - b.z).unsigned_abs();
    let (mn, mx) = if dx < dz { (dx, dz) } else { (dz, dx) };
    14 * mn + 10 * (mx - mn)
}

impl NavGrid {
    /// A* Pathfinding Fonksiyonu
    pub fn find_path(&self, start_world: Vec3, end_world: Vec3) -> Option<Vec<Vec3>> {
        let start = self.world_to_grid(start_world);
        let end = self.world_to_grid(end_world);

        if !self.is_walkable(end) || !self.is_walkable(start) {
            return None; // Hedef duvar içinde
        }

        let mut open_set = BinaryHeap::new();
        let mut came_from: HashMap<GridPos, GridPos> = HashMap::new();
        let mut g_score: HashMap<GridPos, u32> = HashMap::new();
        let mut closed_set: HashSet<GridPos> = HashSet::new();

        open_set.push(AStarNode {
            pos: start,
            cost: 0,
        });
        g_score.insert(start, 0);

        let max_iterations = 25_000usize;

        let mut iterations = 0usize;
        while let Some(current_node) = open_set.pop() {
            iterations += 1;
            if iterations > max_iterations {
                tracing::error!(
                    "[AI] Pathfinding limit aşıldı ({}/{}). Ulaşılamaz rota?",
                    iterations, max_iterations
                );
                break;
            }

            let current = current_node.pos;

            if closed_set.contains(&current) {
                continue;
            }
            closed_set.insert(current);

            if current == end {
                // Yolu Geri İzle
                let mut path = Vec::new();
                let mut curr = end;
                while curr != start {
                    path.push(self.grid_to_world(curr));
                    curr = match came_from.get(&curr) {
                        Some(p) => *p,
                        None => break,
                    };
                }
                path.reverse();
                return Some(path);
            }

            let curr_g = *g_score.get(&current).unwrap_or(&u32::MAX);

            for neighbor in self.get_neighbors(current) {
                // Çaprazlar 14, düzler 10 birim maliyet.
                let move_cost = if neighbor.x != current.x && neighbor.z != current.z {
                    14
                } else {
                    10
                };
                let tentative_g = curr_g + move_cost;

                if tentative_g < *g_score.get(&neighbor).unwrap_or(&u32::MAX) {
                    came_from.insert(neighbor, current);
                    g_score.insert(neighbor, tentative_g);

                    let f_score = tentative_g + heuristic(neighbor, end);
                    open_set.push(AStarNode {
                        pos: neighbor,
                        cost: f_score,
                    });
                }
            }
        }

        None // Yol bulunamadı
    }
}