//! ## Object Rhai API
//!
//! ### Getters
//!
//! - x, y -> Board location of object
//! - id -> The object's board-unique id
//! - name -> The object's name, or ()
//! - waiting -> bool for whether or not the front of this object's queue is a delay action
//! - queue -> the action queue for this object
//! - tags -> Array of tags for this object
//! - glyph -> The object's current glyph
//!
//! ### Functions
//!
//! - has_tag(tag) -> Whether the object has this tag
//! - delay(secs) -> Queue a delay action
//! - can_push(dir) -> Whether a push in this direction would succeed
//! - blocked(dir) -> Whether a solid neighbors me in this direction
//!
//! Note on blocking: can_push and blocked only take into account the contents of the board
//! at the start of the call; if another thing moves before your actions are flushed to the
//! gamestate, a move might still fail. This is a TODO.

use rhai::{Dynamic, Engine};
use crate::api::board::BoardRef;
use crate::api::queue::ObjQueue;
use crate::Direction;
use crate::action::BoardAction;
use crate::object_def::ObjectDef;
use crate::script::Registerable;
use crate::utils::{ErrorSink, ObjectId};

/// A snapshot of one board object, returned by `Board.tagged`, `Board.named`,
/// and `Board.get`. Passed by value — scripts read fields, not a live reference.
/// It also contains things like script_name used by ScriptHost, since we can't keep a live
/// borrow of the board while doing anything: we create one of these loose and then
/// it borrows the board only for the duration of what it needs.
#[derive(Clone)]
pub struct ObjectInfo {
    pub id: ObjectId,
    pub x: i64,
    pub y: i64,
    pub board: BoardRef,
    pub script_name: Option<String>,
    pub queue: ObjQueue
}

impl ObjectInfo {
    pub fn from_id(id: ObjectId, board: BoardRef) -> Option<ObjectInfo> {
        let b = board.borrow();
        let obj = b.objects.get(&id)?;
        Some(ObjectInfo {
            id,
            x: obj.x as i64,
            y: obj.y as i64,
            board: board.clone(),
            script_name: obj.script_name.clone(),
            queue: obj.queue.clone()
        })
    }

    pub fn from_def(obj: &ObjectDef, board: BoardRef) -> ObjectInfo {
        Self {
            id: obj.id,
            x: obj.x as i64,
            y: obj.y as i64,
            board: board.clone(),
            script_name: obj.script_name.clone(),
            queue: obj.queue.clone()
        }
    }

    pub fn drain(&mut self, target: &mut Vec<BoardAction>, dt: f64) {
        let mut b = self.board.borrow_mut();
        if let Some(def) = b.objects.get_mut(&self.id) {
            def.queue.drain(self.id, target, dt)
        }
    }
}

impl Registerable for ObjectInfo {
    fn register(engine: &mut Engine, _error_sink: ErrorSink) {
        engine.register_type_with_name::<ObjectInfo>("ObjectInfo")
            .register_get("x", |obj: &mut ObjectInfo| obj.x)
            .register_get("y", |obj: &mut ObjectInfo| obj.y)
            .register_get("id", |obj: &mut ObjectInfo| obj.id as i64)
            .register_get("waiting", |obj: &mut ObjectInfo| obj.queue.waiting())
            .register_get("queue", |obj: &mut ObjectInfo| obj.queue.clone());

        engine.register_get("name", |o: &mut ObjectInfo| {
            let board = o.board.borrow();
            let obj = board.objects.get(&o.id);
            if let Some(ObjectDef { name: Some(name), ..}) = obj {
                Dynamic::from(name.clone())
            } else {
                Dynamic::UNIT
            }
        });

        engine.register_get("tags", |o: &mut ObjectInfo| -> rhai::Array {
            let board = o.board.borrow();
            let obj = board.objects.get(&o.id);
            if let Some(ObjectDef { tags, .. }) = obj {
                tags.iter().map(|t| Dynamic::from(t.clone())).collect()
            } else {
                rhai::Array::new()
            }
        });

        engine.register_get("glyph", |o: &mut ObjectInfo| {
            let board = o.board.borrow();
            let obj = board.objects.get(&o.id).unwrap();
            obj.glyph
        });

        engine.register_fn("has_tag", |o: &mut ObjectInfo, t: String| {
            if let Some(ObjectDef { tags, .. }) = o.board.borrow().objects.get(&o.id) {
                tags.contains(&t)
            } else {
                false
            }
        });

        engine.register_fn("delay", |o: &mut ObjectInfo, dt: f64| o.queue.delay(dt));

        engine.register_fn("can_push", move |o: &mut ObjectInfo, dir: Direction| {
            let board = o.board.borrow();
            board.in_bounds((o.x, o.y)) && board.can_push(o.x as usize, o.y as usize, dir)
        });

        engine.register_fn("blocked", move |o: &mut ObjectInfo, dir: Direction| -> bool {
            let board = o.board.borrow();
            let tx = o.x + dir.dx();
            let ty = o.y + dir.dy();
            board.in_bounds((o.x, o.y)) && !board.is_passable(tx as usize, ty as usize)
        });
    }
}