package main

import (
    "fmt"
    "math"
)

type Point struct {
    X int
    Y int
}

func (p Point) String() string {
    return fmt.Sprintf("[%d,%d]", p.X, p.Y)
}

type Route struct {
    From Point
    To   Point
}

func (r Route) Diagonal() bool {
    return math.Abs(float64(r.From.X)-float64(r.To.X)) == math.Abs(float64(r.From.Y)-float64(r.To.Y))
}

func (r Route) Draw() []Point {
    f := func(i int, j int) (min int, max int) {
        if i > j {
            return j, i
        }
        return i, j
    }
    p := make([]Point, 0)
    // horizontal
    if r.From.Y == r.To.Y {
        min, max := f(r.From.X, r.To.X) //direction doesn't matter
        for i := min; i <= max; i++ {
            p = append(p, Point{i, r.From.Y})
        }
    }
    // vertical
    if r.From.X == r.To.X {
        min, max := f(r.From.Y, r.To.Y) //direction doesn't matter
        for i := min; i <= max; i++ {
            p = append(p, Point{r.From.X, i})
        }
    }
    // diagonal
    if r.Diagonal() {
        // there are 4 cases, 4 diagonal.
        // always start from the lower x, direction doesn't matter
        // and simplify the cases to 2
        if r.From.X > r.To.X {
            r.From, r.To = r.To, r.From
        }
        for i := 0; i <= r.To.X-r.From.X; i++ {
            if r.From.Y > r.To.Y {
                p = append(p, Point{r.From.X + i, r.From.Y - i})
            } else {
                p = append(p, Point{r.From.X + i, r.From.Y + i})
            }
        }
    }
    return p
}

func PartOne(values []Route) int {
    m := make(map[string]int)
    for _, v := range values {
        if v.Diagonal() {
            continue
        }
        points := v.Draw()
        for _, p := range points {
            if _, ok := m[p.String()]; ok {
                m[p.String()]++
                continue
            }
            m[p.String()] = 1
        }
    }
    for k, v := range m {
        if v == 1 {
            delete(m, k)
        }
    }
    return len(m)
}

func PartTwo(values []Route) int {
    m := make(map[string]int)
    for _, v := range values {
        points := v.Draw()
        for _, p := range points {
            if _, ok := m[p.String()]; ok {
                m[p.String()]++
                continue
            }
            m[p.String()] = 1
        }
    }
    for k, v := range m {
        if v == 1 {
            delete(m, k)
        }
    }
    return len(m)
}