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package main

import (
	"database/sql"
	"flag"
	"fmt"
	"os"
	"os/exec"

	_ "modernc.org/sqlite"
)

var file = flag.String("f", "cards", "cards file")

var seg = []int{}

func build(a *sql.Rows, l int, r int, n int) {
	if l == r {
		a.Scan(&seg[n])
		return
	}
	m := (l + r) >> 1
	build(a, l, m, n<<1)
	build(a, m+1, r, n<<1|1)
	seg[n] = seg[n<<1] + seg[n<<1|1]
}

func update(x int, v int, l int, r int, n int) {
	if l == r {
		seg[n] += v
		return
	}
	m := (l + r) >> 1
	if x <= m {
		update(x, v, l, m, n<<1)
	} else {
		update(x, v, m+1, r, n<<1|1)
	}
	seg[n] = seg[n<<1] + seg[n<<1|1]
}

func query(v int, l int, r int, n int) (int, int) {
	if l == r {
		return seg[n], n
	}
	m := (l + r) >> 1
	if seg[n<<1] < v {
		return query(v, l, m, n<<1)
	} else {
		return query(v-seg[n<<1], m+1, r, n<<1|1)
	}
}

func main() {
	flag.Parse()

	db, err := sql.Open("sqlite", *file)
	if err != nil {
		panic(err)
	}

	// Get number of cards
	var N int
	_ = db.QueryRow("SELECT COUNT(*) FROM cards").Scan(&N)
	seg = make([]int, 4*N)

	// Build segment tree
	rows, err := db.Query("SELECT * FROM cards")
	if err != nil {
		panic(err)
	}
	build(rows, 0, N-1, 1)

	// https://stackoverflow.com/questions/14094190/function-similar-to-getchar
	// disable input buffering
	exec.Command("stty", "-F", "/dev/tty", "cbreak", "min", "1").Run()
	// do not display entered characters on the screen
	exec.Command("stty", "-F", "/dev/tty", "-echo").Run()
	// restore the echoing state when exiting
	defer exec.Command("stty", "-F", "/dev/tty", "echo").Run()

	for {
		fmt.Println("hello world")

		var b []byte = make([]byte, 1)
		os.Stdin.Read(b)
		if b[0] == byte('y') {

		} else if b[0] == byte('n') {

		} else {

		}
	}
}