use glam::{IVec2, Vec2};
use rapier2d::dynamics::RigidBodyBuilder;

use crate::{
    content::{materials::MaterialId, vfx::VfxMaterialId},
    input::Input,
    sim::{
        cell::Cell,
        entity::{EntityBehaviour, EntityCells, EntityDef, EntityUpdateCtx},
        lib::force::apply_bullet,
        sim_manager::SimCtx,
    },
    vfx::VfxLine,
};

struct BulletEmitterEntityBehaviour {
    shot_timer: f32,
    life: f32,
    target: Option<Vec2>,
}

impl EntityBehaviour for BulletEmitterEntityBehaviour {
    fn update(&mut self, update_ctx: &mut EntityUpdateCtx, ctx: &mut SimCtx, delta_time: f32) {
        if self.target.is_none() && ctx.input_manager.pressed(Input::Action4) {
            self.target = Some(ctx.input_manager.world_mouse_pos);
        }

        if let Some(target) = self.target {
            let pos = update_ctx.entity_data.transform(ctx).unwrap().0;
            let dir = (target - pos).normalize();
            let from = pos + (dir * 4.0);

            self.shot_timer -= delta_time;
            if self.shot_timer <= 0.0 {
                apply_bullet(ctx, from, target, 70);
                // 0.1 seconds to travel 200 cells
                let lifetime = (target - from).length() / 1000.0;
                ctx.vfx_writer.write_vfx_line(VfxLine::new(
                    from,
                    target,
                    1.3,
                    VfxMaterialId::Tracer,
                    lifetime,
                ));
                self.shot_timer = 0.2;
            }

            self.life -= delta_time;
            if self.life <= 0.0 {
                update_ctx.deferred_destroy(update_ctx.entity_data.id);
            }
        }
    }
}

pub fn entity_bullet_emitter_def(position: Vec2, life: f32) -> EntityDef {
    let w = 6;
    let h = 3;
    let mut raw_cells = vec![Cell::void(); (w * h) as usize];

    for x in 0..w {
        for y in 0..h {
            let cell_idx = x + y * w;
            raw_cells[cell_idx as usize] = Cell::from_material(MaterialId::Steel);
            raw_cells[cell_idx as usize].set_entity_integrated(true);
        }
    }

    let entity_cells = EntityCells {
        cells: raw_cells,
        size: IVec2::new(w, h),
    };

    let rb = RigidBodyBuilder::dynamic()
        .translation(position)
        .gravity_scale(0.0)
        .build();

    EntityDef::from_cells_and_rb(
        entity_cells,
        rb,
        Some(Box::new(BulletEmitterEntityBehaviour {
            shot_timer: 0.0,
            life,
            target: None,
        })),
    )
}