from state import State
FIELDWIDTH, FIELDCOUNT = 50, 16

def succ(st: State):
    successors = []

    if st.orientation == 'N':
        successors.append(State(st, 'LEFT', st.xpos, st.ypos, 'W'))
        successors.append(State(st, 'RIGHT', st.xpos, st.ypos, 'E'))
        if st.ypos > 0:
            successors.append(State(st, 'FORWARD', st.xpos, st.ypos - FIELDWIDTH , 'N'))
    
    if st.orientation == 'S':
        successors.append(State(st, 'LEFT', st.xpos, st.ypos, 'E'))
        successors.append(State(st,'RIGHT', st.xpos, st.ypos, 'W'))
        if st.ypos < FIELDWIDTH * (FIELDCOUNT  - 1):
            successors.append(State(st, 'FORWARD', st.xpos, st.ypos + FIELDWIDTH , 'S'))

    if st.orientation == 'W':
        successors.append(State(st, 'LEFT', st.xpos, st.ypos, 'S'))
        successors.append(State(st,'RIGHT', st.xpos, st.ypos, 'N'))
        if st.xpos > 0:
            successors.append(State(st, 'FORWARD', st.xpos - FIELDWIDTH , st.ypos, 'W'))

    if st.orientation == 'E':
        successors.append(State(st, 'LEFT', st.xpos, st.ypos, 'N'))
        successors.append(State(st, 'RIGHT', st.xpos, st.ypos, 'S'))
        if st.xpos < FIELDWIDTH * (FIELDCOUNT  - 1):
            successors.append(State(st, 'FORWARD', st.xpos + FIELDWIDTH , st.ypos, 'E'))
    return successors