package main

import (
	"fmt"
	"os"
	"strconv"
	"strings"
)

const (
	Increasing = 1
	Decreasing = -1
)

func absInt(x int) int {
	return absDiffInt(x, 0)
}

func absDiffInt(x, y int) int {
	if x < y {
		return y - x
	}
	return x - y
}

func checkDirection(x int) int {
	switch {
	case x < 0:
		return Increasing
	case x > 0:
		return Decreasing
	default:
		return 0
	}
}

func checklevel(report []int) bool {
	dir := checkDirection(report[0] - report[1])
	for i := 0; i < len(report)-1; i++ {
		zero := report[i]
		one := report[i+1]
		diff := zero - one
		if newDir := checkDirection(diff); newDir != dir {
			return false
		}
		absDiff := absInt(diff)
		if absDiff < 1 || absDiff > 3 {
			return false
		}
	}
	return true
}

func main() {

	lines, err := parse()
	if err != nil {
		fmt.Println("Error:", err)
	}

	var safes = 0

	for _, line := range lines {
		fmt.Println(line)
		numbers := strings.Fields(line)
		report := make([]int, len(numbers))
		for i, num := range numbers {
			x, err := strconv.Atoi(num)
			if err != nil {
				panic(err)
			}
			report[i] = x
		}
		if checklevel(report) {
			safes++
		}

	}

	fmt.Println(safes)

}

func parse() ([]string, error) {
	if len(os.Args) < 2 {
		return nil, fmt.Errorf("no file provided")
	}
	filePath := os.Args[1]
	data, err := os.ReadFile(filePath)
	if err != nil {
		return nil, fmt.Errorf("error opening file: %v", err)
	}
	chunks := strings.Split(string(data), "\n")
	var nonEmpthyChunks = []string{}

	for _, chunk := range chunks {
		if chunk != "" {
			nonEmpthyChunks = append(nonEmpthyChunks, chunk)
		}
	}
	return nonEmpthyChunks, nil
}