module TK.SpaceTac {
    // Target for a capability
    //  This could be a location in space, or a ship
    export class Target {
        // Coordinates of the target
        x: number
        y: number

        // If the target is a ship, this attribute will be set
        ship_id: RObjectId | null

        // Standard constructor
        constructor(x: number, y: number, ship: Ship | RObjectId | null = null) {
            this.x = x;
            this.y = y;
            this.ship_id = (ship === null) ? null : rid(ship);
        }

        jasmineToString() {
            if (this.ship_id) {
                return `(${this.x},${this.y}) ship_id=${this.ship_id}}`;
            } else {
                return `(${this.x},${this.y})`;
            }
        }

        // Constructor to target a single ship
        static newFromShip(ship: Ship): Target {
            return new Target(ship.arena_x, ship.arena_y, ship);
        }

        // Constructor to target a location in space
        static newFromLocation(x: number, y: number): Target {
            return new Target(x, y, null);
        }

        /**
         * Snap to battle grid
         */
        snap(grid: ArenaGrid): Target {
            let location = grid.snap(this);
            return new Target(location.x, location.y, this.ship_id);
        }

        // Get distance to another target
        getDistanceTo(other: { x: number, y: number }): number {
            var dx = other.x - this.x;
            var dy = other.y - this.y;
            return Math.sqrt(dx * dx + dy * dy);
        }

        // Get the normalized angle, in radians, to another target
        getAngleTo(other: { x: number, y: number }): number {
            var dx = other.x - this.x;
            var dy = other.y - this.y;
            return Math.atan2(dy, dx);
        }

        /**
         * Returns true if the target is a ship
         * 
         * If a ship or ship id is passed, also check that it is the targetted one
         */
        isShip(ship?: Ship | RObject): boolean {
            return this.ship_id !== null && (typeof ship == "undefined" || rid(ship) == this.ship_id);
        }

        /**
         * Get the targetted ship in a battle
         */
        getShip(battle: Battle): Ship | null {
            if (this.isShip()) {
                return battle.getShip(this.ship_id);
            } else {
                return null;
            }
        }
    }
}