module es {
    /**
     * 计算路径给定的IUnweightedGraph和开始/目标位置
     */
    export class BreadthFirstPathfinder {
        public static search<T>(graph: IUnweightedGraph<T>, start: T, goal: T): T[] {
            let foundPath = false;
            let frontier = [];
            frontier.unshift(start);

            let cameFrom = new Map<T, T>();
            cameFrom.set(start, start);

            while (frontier.length > 0) {
                let current = frontier.shift();
                if (JSON.stringify(current) == JSON.stringify(goal)) {
                    foundPath = true;
                    break;
                }

                graph.getNeighbors(current).forEach(next => {
                    if (!this.hasKey(cameFrom, next)) {
                        frontier.unshift(next);
                        cameFrom.set(next, current);
                    }
                });
            }

            return foundPath ? AStarPathfinder.recontructPath(cameFrom, start, goal) : null;
        }

        private static hasKey<T>(map: Map<T, T>, compareKey: T) {
            let iterator = map.keys();
            let r: IteratorResult<T>;
            while (r = iterator.next() , !r.done) {
                if (JSON.stringify(r.value) == JSON.stringify(compareKey))
                    return true;
            }

            return false;
        }
    }
}