// =============================================================================
// Auth: Alex Celani
// File: boot.go
// Revn: 10-10-2023  1.0
// Func: Blink a light when the pi boots (or on login, but who cares)
//
// TODO: create
// =============================================================================
// CHANGE LOG
// -----------------------------------------------------------------------------
// 06-23-2022: init
// 10-10-2023: imported flag
//             added flag to define gpio pin at runtime
//
// =============================================================================

package main


import (
    "flag"      // IntVar, Parse
    "fmt"       // Println
    // rpio.Pin, Pin, Open, Close, Output, Toggle
    "github.com/stianeikeland/go-rpio"
    "os"        // Exit
    "time"      // Sleep, time.Second
)


/*
Toggles a LED on physical pin 19 (mcu pin 10)
Connect a LED with resistor from pin 19 to ground.
*/


var pin rpio.Pin    // global pin object
var num int         // flag variable, holds pin number


func main() {

    // map input flag to variable
    flag.IntVar( &num, "p", 10, "pin number" )
    flag.Parse()

    // create pin object at given pin number
    pin = rpio.Pin( num )
    // Open and map memory to access gpio, check for errors
    if err := rpio.Open(); err != nil {
        fmt.Println( "Fatal: pin open failed" )
        fmt.Println( "Error: ", err.Error() )
        os.Exit(1)
    }

    // Unmap gpio memory when done
    defer rpio.Close()

    // Set pin to output mode
    pin.Output()

    // Toggle pin 2 times
    for i := 0; i < 4; i++ {
        pin.Toggle()
        time.Sleep(time.Second / 10)
    }
}