from pprint import pprint as pp
import shared
import matrix

MATRIX_SIZE = 500
#MATRIX_SIZE = 40 # sample
HALF = MATRIX_SIZE // 2

H = [HALF,HALF]
T = [HALF,HALF]


# returns (x,y) - so remember to take dx,dy lower
DIRS = {
    'U': matrix.M_U, # (0, -1)
    'D': matrix.M_D,
    'L': matrix.M_L,
    'R': matrix.M_R,

    'UR': matrix.M_UR, # (+1, -1)
    'DR': matrix.M_DR,
    'UL': matrix.M_UL,
    'DL': matrix.M_DL,
}

def part1(steps):
    field = matrix.matrix_of_size(MATRIX_SIZE,MATRIX_SIZE)

    for direction, amount in steps:
        # move HEAD
        amount = int(amount)
        for x in range(amount):

            dx,dy = DIRS[direction]
            H[0] += dy 
            H[1] += dx
            HY,bX = H
            # head is in new position
            kY,kX = T
            field[kY][kX] = 1 # 'T'

            # Check if same
            if kY == HY and kX == bX:
                continue
            touching = False
            for _, d in DIRS.items():
                dx,dy = d
                t_y, t_x = H[0]+dy, H[1]+dx
                if kY == t_y and kX == t_x:
                    touching = True
                    break
            if touching:
                continue

            # assume the same row/column, no movement needed
            tY = 0
            tX = 0
    
            # if Head X is less than Tail X, move Tail X 1 left
            if bX < kX:
                tX = -1
            # if Head X is greater than Tail X, move Tail X 1 left
            elif bX > kX:
                tX = 1
    
    
            # if Head Y is less than Tail Y, move Tail Y 1 up
            if HY < kY:
                tY = -1
            # if Head Y is greater than Tail Y, move Tail Y 1 down
            elif HY > kY:
                tY = 1
    
            T[0] += tY
            T[1] += tX

        field[T[0]][T[1]] = 1 # mark visited tails
    print(matrix.sum_matrix(field))

        
def part2(steps):
    field = matrix.matrix_of_size(MATRIX_SIZE,MATRIX_SIZE)
    S = [[HALF,HALF],] # HEAD ONLY
    for x in range(9):
        S.append([HALF,HALF])

    for direction, amount in steps:
        # move HEAD
        amount = int(amount)
        for x in range(amount):
            HEAD_dx,HEAD_dy = DIRS[direction]
            S[0][0] += HEAD_dy 
            S[0][1] += HEAD_dx
            #print(HEAD_dy,HEAD_dx, S)
            # HEAD MOVED one step
            
            for knot_idx, _  in enumerate(S):
                if knot_idx == 0:
                    # Skip Head
                    continue
                knot = S[knot_idx]
                kY,kX = knot

                bY,bX = S[knot_idx-1]

                # Check if same 
                if kY == bY and kX == bX:
                    continue

                touching = False
                for _, d in DIRS.items():
                    dx,dy = d
                    t_y, t_x = S[knot_idx-1][0]+dy, S[knot_idx-1][1]+dx
                    if kY == t_y and kX == t_x:
                        touching = True
                        break
                if touching:
                    continue

                # assume the same row/column, no movement needed
                tY, tX = 0,0
    
                # if Head X is less than Tail X, move Tail X 1 left
                if bX < kX:
                    tX = -1
                # if Head X is greater than Tail X, move Tail X 1 left
                elif bX > kX:
                    tX = 1
    
                # if Head Y is less than Tail Y, move Tail Y 1 up
                if bY < kY:
                    tY = -1
                # if Head Y is greater than Tail Y, move Tail Y 1 down
                elif bY > kY:
                    tY = 1
    
                S[knot_idx][0] += tY
                S[knot_idx][1] += tX

            field[S[-1][0]][S[-1][1]] = 1 # mark visited tails
    print(matrix.sum_matrix(field))



def main():
    rows = [x.split(" ") for x in shared.load_rows(9)]
    part1(rows)
    part2(rows)


if __name__ == "__main__":
    main()