package main

import (
	"fmt"
	"math/rand"
	"os"

	tea "github.com/charmbracelet/bubbletea"
)

// Create simple constants
const (
	ROW = 35
	COL = 70
)

// Just need a grid and buffer
type gol struct {
	grid   [ROW][COL]int
	buffer [ROW][COL]int
}

// Create array that holds field's to check for neighbours
var CHECK_ARRAY = [8][2]int{{-1, -1}, {-1, 0}, {-1, +1}, {0, -1}, {0, +1}, {+1, -1}, {+1, 0}, {+1, +1}}

// Initialize empty game of life
func initGol() gol {
	start := [ROW][COL]int{}
	// Intentionally skipping field around the array making it empty
	for i := 1; i < ROW-1; i++ {
		for j := 1; j < COL-1; j++ {
			if rand.Intn(2) == 1 {
				start[i][j] = 1
			} else {
				start[i][j] = 0
			}
		}
	}
	return gol{
		grid:   start,
		buffer: start,
	}
}

// Simple init
func (g gol) Init() tea.Cmd {
	return nil
}

// Check neighbours
func (g gol) countNeighbours(x int, y int) int {
	n := 0
	for i := 0; i < 8; i++ {
		if g.grid[x+CHECK_ARRAY[i][0]][y+CHECK_ARRAY[i][1]] == 1 {
			n += 1
		}
	}
	return n
}

// Life logic
func (g gol) Life() tea.Model {
	for i := 1; i < ROW-1; i++ {
		for j := 1; j < COL-1; j++ {
			n := g.countNeighbours(i, j)
			if g.grid[i][j] == 1 {
				if n < 2 || n > 3 {
					g.buffer[i][j] = 0
				}
			} else {
				if n == 3 {
					g.buffer[i][j] = 1
				}
			}
		}
	}
	g.grid = g.buffer
	return g
}

// Simple update
func (g gol) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	// Just quit when using ctrl+c or q
	case tea.KeyMsg:
		switch msg.String() {
		case "ctrl+c", "q":
			return g, tea.Quit
		case " ":
			g.Life()
			return g, nil
		}
	}
	return g, nil
}

// Let's draw this all simply
func (g gol) View() string {
	var s string
	// Making sure to not draw the empty field around the array
	for i := 1; i < ROW-1; i++ {
		for j := 1; j < COL-1; j++ {
			if g.grid[i][j] == 1 {
				s += "*"
			} else {
				s += " "
			}
		}
		s += "\n"
	}
	return s
}

func main() {
	p := tea.NewProgram(initGol())
	if _, err := p.Run(); err != nil {
		fmt.Printf("Oh no, an error: %v", err)
		os.Exit(1)
	}
}