use crate::sys::agent::ReadData;
use common::{
    comp::{buff::BuffKind, Alignment, Pos},
    consts::GRAVITY,
    terrain::{Block, TerrainGrid},
    util::Dir,
    vol::ReadVol,
};
use specs::{
    saveload::{Marker, MarkerAllocator},
    Entity as EcsEntity,
};
use vek::*;

pub fn can_see_tgt(terrain: &TerrainGrid, pos: &Pos, tgt_pos: &Pos, dist_sqrd: f32) -> bool {
    terrain
        .ray(pos.0 + Vec3::unit_z(), tgt_pos.0 + Vec3::unit_z())
        .until(Block::is_opaque)
        .cast()
        .0
        .powi(2)
        >= dist_sqrd
}

pub fn is_dead_or_invulnerable(entity: EcsEntity, read_data: &ReadData) -> bool {
    is_dead(entity, read_data) || is_invulnerable(entity, read_data)
}

pub fn is_dead(entity: EcsEntity, read_data: &ReadData) -> bool {
    let health = read_data.healths.get(entity);
    health.map_or(false, |a| a.is_dead)
}

// FIXME: The logic that is used in this function and throughout the code
// shouldn't be used to mean that a character is in a safezone.
pub fn is_invulnerable(entity: EcsEntity, read_data: &ReadData) -> bool {
    let buffs = read_data.buffs.get(entity);

    buffs.map_or(false, |b| b.kinds.contains_key(&BuffKind::Invulnerability))
}

/// Attempts to get alignment of owner if entity has Owned alignment
pub fn try_owner_alignment<'a>(
    alignment: Option<&'a Alignment>,
    read_data: &'a ReadData,
) -> Option<&'a Alignment> {
    if let Some(Alignment::Owned(owner_uid)) = alignment {
        if let Some(owner) = get_entity_by_id(owner_uid.id(), read_data) {
            return read_data.alignments.get(owner);
        }
    }
    alignment
}

/// Projectile motion: Returns the direction to aim for the projectile to reach
/// target position. Does not take any forces but gravity into account.
pub fn aim_projectile(speed: f32, pos: Vec3<f32>, tgt: Vec3<f32>) -> Option<Dir> {
    let mut to_tgt = tgt - pos;
    let dist_sqrd = to_tgt.xy().magnitude_squared();
    let u_sqrd = speed.powi(2);
    to_tgt.z = (u_sqrd
        - (u_sqrd.powi(2) - GRAVITY * (GRAVITY * dist_sqrd + 2.0 * to_tgt.z * u_sqrd))
            .sqrt()
            .max(0.0))
        / GRAVITY;

    Dir::from_unnormalized(to_tgt)
}

pub fn get_entity_by_id(id: u64, read_data: &ReadData) -> Option<EcsEntity> {
    read_data.uid_allocator.retrieve_entity_internal(id)
}