# --- Day 5: Hydrothermal Venture ---

# You come across a field of hydrothermal vents on the ocean floor! These vents
# constantly produce large, opaque clouds, so it would be best to avoid them if
# possible.

# They tend to form in lines; the submarine helpfully produces a list of nearby
# lines of vents (your puzzle input) for you to review. For example:

# 0,9 -> 5,9
# 8,0 -> 0,8
# 9,4 -> 3,4
# 2,2 -> 2,1
# 7,0 -> 7,4
# 6,4 -> 2,0
# 0,9 -> 2,9
# 3,4 -> 1,4
# 0,0 -> 8,8
# 5,5 -> 8,2

# Each line of vents is given as a line segment in the format x1,y1 -> x2,y2
# where x1,y1 are the coordinates of one end the line segment and x2,y2 are the
# coordinates of the other end. These line segments include the points at both
# ends. In other words:

#     An entry like 1,1 -> 1,3 covers points 1,1, 1,2, and 1,3.
#     An entry like 9,7 -> 7,7 covers points 9,7, 8,7, and 7,7.

# For now, only consider horizontal and vertical lines: lines where either
# x1 = x2 or y1 = y2.

# So, the horizontal and vertical lines from the above list would produce the
# following diagram:

# .......1..
# ..1....1..
# ..1....1..
# .......1..
# .112111211
# ..........
# ..........
# ..........
# ..........
# 222111....

# In this diagram, the top left corner is 0,0 and the bottom right corner is
# 9,9. Each position is shown as the number of lines which cover that point or
# . if no line covers that point. The top-left pair of 1s, for example, comes
# from 2,2 -> 2,1; the very bottom row is formed by the overlapping lines 0,9
# -> 5,9 and 0,9 -> 2,9.

# To avoid the most dangerous areas, you need to determine the number of points
# where at least two lines overlap. In the above example, this is anywhere in
# the diagram with a 2 or larger - a total of 5 points.

# Consider only horizontal and vertical lines. At how many points do at least
# two lines overlap?

from collections import defaultdict
from typing import DefaultDict, Tuple

with open("files/P5.txt") as f:
    points = [
        points
        for line in f.read().strip().split("\n")
        for points in line.split(" -> ")
    ]


point_1 = points[::2]
x1y1 = [int(val) for p in point_1 for val in p.split(",")]
x_1 = x1y1[::2]
y_1 = x1y1[1::2]

point_2 = points[1::2]
x2y2 = [int(val) for p in point_2 for val in p.split(",")]
x_2 = x2y2[::2]
y_2 = x2y2[1::2]


def get_range(p1: int, p2: int) -> Tuple[int, int, int]:
    if p1 > p2:
        step = -1
        p2 -= 1
    else:
        step = 1
        p2 += 1
    return p1, p2, step


def part_1() -> None:
    grid: DefaultDict[Tuple[int, int], int] = defaultdict(int)
    for idx in range(len(points) // 2):
        if x_1[idx] == x_2[idx]:
            start, stop, step = get_range(y_1[idx], y_2[idx])
            for pos in range(start, stop, step):
                grid[x_1[idx], pos] += 1
        elif y_1[idx] == y_2[idx]:
            start, stop, step = get_range(x_1[idx], x_2[idx])
            for pos in range(start, stop, step):
                grid[pos, y_1[idx]] += 1

    print(sum(1 for key in grid.values() if key > 1))


# --- Part Two ---

# Unfortunately, considering only horizontal and vertical lines doesn't give
# you the full picture; you need to also consider diagonal lines.

# Because of the limits of the hydrothermal vent mapping system, the lines in
# your list will only ever be horizontal, vertical, or a diagonal line at
# exactly 45 degrees. In other words:

#     An entry like 1,1 -> 3,3 covers points 1,1, 2,2, and 3,3.
#     An entry like 9,7 -> 7,9 covers points 9,7, 8,8, and 7,9.

# Considering all lines from the above example would now produce the following
# diagram:

# 1.1....11.
# .111...2..
# ..2.1.111.
# ...1.2.2..
# .112313211
# ...1.2....
# ..1...1...
# .1.....1..
# 1.......1.
# 222111....

# You still need to determine the number of points where at least two lines
# overlap. In the above example, this is still anywhere in the diagram with a 2
# or larger - now a total of 12 points.

# Consider all of the lines. At how many points do at least two lines overlap?


def part_2() -> None:
    grid: DefaultDict[Tuple[int, int], int] = defaultdict(int)
    for idx in range(len(points) // 2):
        # print(idx)
        if x_1[idx] == x_2[idx]:
            start, stop, step = get_range(y_1[idx], y_2[idx])
            for pos in range(start, stop, step):
                grid[x_1[idx], pos] += 1
        elif y_1[idx] == y_2[idx]:
            start, stop, step = get_range(x_1[idx], x_2[idx])
            for pos in range(start, stop, step):
                grid[pos, y_1[idx]] += 1
        elif abs(x_1[idx] - x_2[idx]) == abs(y_1[idx] - y_2[idx]):
            start_x, stop_x, step_x = get_range(x_1[idx], x_2[idx])
            start_y, stop_y, step_y = get_range(y_1[idx], y_2[idx])
            pos_x = [pos_x for pos_x in range(start_x, stop_x, step_x)]
            pos_y = [pos_y for pos_y in range(start_y, stop_y, step_y)]
            for px, py in zip(pos_x, pos_y):
                grid[px, py] += 1

    print(sum(1 for key in grid.values() if key > 1))


if __name__ == "__main__":
    part_1()
    part_2()