package main

import (
	"context"
	"database/sql"
	"fmt"
	"os"

	_ "github.com/lib/pq"
)

// User is a row from the `user` table.
type User struct {
	userid   int
	username string
}

/*
This is the PostgreSQL table.

lutz> select * from users limit 10;
+----------+-------------+--------------+-------------+-------------+-----------+-----------------------------+--------------+-----------------+
| userid   | username    | first_name   | last_name   | city        | state     | email                       | phone        | is_like_sport   |
|----------+-------------+--------------+-------------+-------------+-----------+-----------------------------+--------------+-----------------|
| 1        | cmelling0   | Caitrin      | Melling     | Cincinnati  | Ohio      | cmelling0@printfriendly.com | 513-466-6207 | True            |
| 2        | mbarkess1   | Margo        | Barkess     | Spring      | Texas     | mbarkess1@topsy.com         | 409-737-5285 | True            |
| 3        | ssquibb2    | Sybille      | Squibb      | Tampa       | Florida   | ssquibb2@berkeley.edu       | 813-195-3652 | False           |
| 4        | akirk3      | Atalanta     | Kirk        | Arlington   | Virginia  | akirk3@wikimedia.org        | 571-945-2093 | True            |
| 5        | kelcomb4    | Krishna      | Elcomb      | Saint Paul  | Minnesota | kelcomb4@example.com        | 952-557-6819 | True            |
| 6        | lcoldbathe5 | Laure        | Coldbathe   | Cheyenne    | Wyoming   | lcoldbathe5@icq.com         | 307-277-9971 | False           |
| 7        | ibutcher6   | Isa          | Butcher     | Punta Gorda | Florida   | ibutcher6@mozilla.org       | 941-900-2248 | False           |
| 8        | wdarnbrook7 | Whitman      | Darnbrook   | Miami       | Florida   | wdarnbrook7@csmonitor.com   | 305-204-6425 | True            |
| 9        | bcoraini8   | Brenda       | Coraini     | Phoenix     | Arizona   | bcoraini8@wordpress.com     | 602-642-5096 | True            |
| 10       | wplews9     | Ward         | Plews       | Nashville   | Tennessee | wplews9@cafepress.com       | 615-429-0570 | False           |
+----------+-------------+--------------+-------------+-------------+-----------+-----------------------------+--------------+-----------------+
*/

func main() {
	db, err := sql.Open("postgres", "host=localhost")
	if err != nil {
		fmt.Printf("failed to open database connection: %s\n", err)
		os.Exit(1)
	}
	defer db.Close()

	ctx := context.Background()
	rows, err := db.QueryContext(ctx, "select userid, username from users limit 10")
	if err != nil {
		fmt.Printf("failed to get rows: %s\n", err)
		os.Exit(1)
	}
	defer rows.Close()

	for rows.NextResultSet() {
		if rows.Next() {
			var user User
			if err := rows.Scan(&user.userid, &user.username); err != nil {
				fmt.Printf("failed to scan user: %s\n", err)
				continue
			}
			fmt.Printf("%q\n", user)
		}
	}

}