From c3975b22aee3218725612b2cc617a56d8af170ca Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B8ren=20Rasmussen?= <sr@jondahl.net>
Date: Mon, 14 Dec 2020 15:26:16 +0100
Subject: [PATCH] Day 12, part 2

---
 2020/12/main.py | 137 ++++++++++++++++++++++++++++++++++++------------
 1 file changed, 104 insertions(+), 33 deletions(-)

diff --git a/2020/12/main.py b/2020/12/main.py
index be9e67c..f3ed867 100644
--- a/2020/12/main.py
+++ b/2020/12/main.py
@@ -1,8 +1,19 @@
-class Ferry:
+import math
+
+class Waypoint:
 	def __init__(self):
 		self.heading = 90  # east
 		self.pos_north = 0
 		self.pos_east = 0
+		self.commands = {
+			"N": self.move_north,
+			"S": self.move_south,
+			"E": self.move_east,
+			"W": self.move_west,
+			"L": self.rotate_left,
+			"R": self.rotate_right,
+			"F": self.move_forward,
+		}
 
 	def load(self, filename):
 		with open(filename, "r", encoding="utf-8") as f:
@@ -10,50 +21,110 @@ class Ferry:
 				data = line.rstrip()
 				self.process(data)
 
-	def rotate(self, degrees):
+	def move_north(self, value):
+		self.pos_north += value
+
+	def move_south(self, value):
+		self.pos_north -= value
+
+	def move_east(self, value):
+		self.pos_east += value
+
+	def move_west(self, value):
+		self.pos_east -= value
+
+	def rotate_left(self, degrees):
+		self.heading -= degrees
+		self.__fix_heading()
+
+	def rotate_right(self, degrees):
 		self.heading += degrees
+		self.__fix_heading()
+
+	def move_forward(self, value):
+		if self.heading == 0:
+			self.pos_north += value
+		elif self.heading == 90:
+			self.pos_east += value
+		elif self.heading == 180:
+			self.pos_north -= value
+		elif self.heading == 270:
+			self.pos_east -= value
+		else:
+			raise Exception(self.heading)
+
+	def __fix_heading(self):
 		while self.heading < 0:
 			self.heading += 360
 		while self.heading >= 360:
 			self.heading -= 360
 
 	def process(self, input):
-		command = input[:1]
+		cchar = input[:1]
 		value = int(input[1:])
-
-		if command == "N":
-			self.pos_north += value
-		elif command == "S":
-			self.pos_north -= value
-		elif command == "E":
-			self.pos_east += value
-		elif command == "W":
-			self.pos_east -= value
-		elif command == "L":
-			self.rotate(-value)
-		elif command == "R":
-			self.rotate(value)
-		elif command == "F":
-			if self.heading == 0:
-				self.pos_north += value
-			elif self.heading == 90:
-				self.pos_east += value
-			elif self.heading == 180:
-				self.pos_north -= value
-			elif self.heading == 270:
-				self.pos_east -= value
-			else:
-				raise Exception(self.heading)
-		else:
-			raise Exception(command)
-
-		print(input, self.pos_east, self.pos_north)
+		command = self.commands[cchar]
+		command(value)
 
 	def get_md(self):
 		return abs(self.pos_east) + abs(self.pos_north)
 
+
+class Ship:
+	def __init__(self):
+		self.waypoint = Waypoint()
+		self.pos_north = 0
+		self.pos_east = 0
+		self.commands = {
+			"F": self.move_forward,
+			"L": self.rotate_left,
+			"R": self.rotate_right,
+		}
+
+	def load(self, filename):
+		with open(filename, "r", encoding="utf-8") as f:
+			for line in f:
+				data = line.rstrip()
+				self.process(data)
+
+	def process(self, input):
+		cchar = input[:1]
+		value = int(input[1:])
+		if cchar in self.commands:
+			command = self.commands[cchar]
+			command(value)
+		else:
+			self.waypoint.process(input)
+
+	def move_forward(self, value):
+		self.pos_north += self.waypoint.pos_north * value
+		self.pos_east += self.waypoint.pos_east * value
+
+	def rotate_right(self, degrees):
+		self.rotate_left(-degrees)
+
+	def rotate_left(self, degrees):
+		radians = degrees / 180 * math.pi
+		c = math.cos(radians)
+		s = math.sin(radians)
+		e = c * self.waypoint.pos_east - s * self.waypoint.pos_north
+		n = s * self.waypoint.pos_east + c * self.waypoint.pos_north
+		self.waypoint.pos_east = round(e)
+		self.waypoint.pos_north = round(n)
+
+	def get_md(self):
+		return abs(self.pos_east) + abs(self.pos_north)
+
+
+
 if __name__ == "__main__":
-	f = Ferry()
+	f = Waypoint()
 	f.load("data.txt")
 	md = f.get_md()
-	print(f"Manhattan distance is {md}")
+	print(f"1: Manhattan distance is {md}")
+
+	f = Ship()
+	f.waypoint.pos_east = 10
+	f.waypoint.pos_north = 1
+	f.load("data.txt")
+	md = f.get_md()
+	print(f"2: Manhattan distance is {md}")