const IDManager = @import("id_manager.zig").IDManager;
const Entity = @import("entity.zig").Entity;

const std = @import("std");
const mem = std.mem;
const testing = std.testing;
const Allocator = mem.Allocator;

pub const EntityManager = struct {
    const Self = @This();

    allocator: *Allocator,
    idManager: IDManager,
    ids: std.AutoHashMap(usize, bool),

    pub fn init(allocator: *Allocator) Self {
        return Self {
            .allocator = allocator,
            .idManager = IDManager.init(allocator),
            .ids = std.AutoHashMap(usize, bool).init(allocator)
        };
    }

    pub fn deinit(self: *Self) void {
        self.idManager.deinit();
        self.ids.deinit();
    }

    pub fn create(self: *Self) !Entity {
        const id = self.idManager.next();
        var entity = Entity { .ID = id };
        self.ids.put(id, true) catch |err| return err;
        return entity;
    }

    pub fn exists(self: Self, entityID: usize) bool {
        return self.ids.contains(entityID);
    }
};

test "create" {
    var entity_manager = EntityManager.init(std.testing.allocator);
    defer entity_manager.deinit();

    var entity = try entity_manager.create();

    testing.expect(entity.ID == 0);
}

test "exists" {
    var entity_manager = EntityManager.init(std.testing.allocator);
    defer entity_manager.deinit();

    var entity = try entity_manager.create();

    testing.expect(entity_manager.exists(0));
}