/* github.com/strickyak/morse-code-coherent-cw

Input words as os.Args.
Output CCW morse code (dit=100ms, 800Hz)
with 8000 one-byte samples/second for /dev/audio.

  $ go run morse.go  vvv vvv cq cq de kph > /dev/audio

  $ go run morse.go  vvv vvv cq cq de kph | gst-launch-0.10 -v -m filesrc location=/dev/stdin ! audio/x-raw-int, endianness=4321, channels=1, rate=8000, width=8, depth=8, signed=true ! audioconvert ! audioresample ! alsasink

References:
http://www.sigidwiki.com/wiki/Coherent_CW
http://www.nu-ware.com/NuCode%20Help/index.html?morse_code_structure_and_timing_.htm

Hint to get your Linux /dev/audio back:
  modprobe snd_pcm_oss
  modprobe snd_seq_oss
  modprobe snd_mixer_oss
Thank You, Kilian Foth:
http://unix.stackexchange.com/questions/120701/what-is-the-modern-equivalent-of-reading-dev-audio

*/
package main

import (
	"os"
	"strings"
)

const speed = 1.0 // Use 1.0 for normal 12wpm CCW.

var Code = map[rune]string{
	'a':  ".-",
	'b':  "-...",
	'c':  "-.-.",
	'd':  "-..",
	'e':  ".",
	'f':  "..-.",
	'g':  "--.",
	'h':  "....",
	'i':  "..",
	'j':  ".---",
	'k':  "-.-",
	'l':  ".-..",
	'm':  "--",
	'n':  "-.",
	'o':  "---",
	'p':  ".--.",
	'q':  "--.-",
	'r':  ".-.",
	's':  "...",
	't':  "-",
	'u':  "..-",
	'v':  "...-",
	'w':  ".--",
	'x':  "-..-",
	'y':  "-.--",
	'z':  "--..",
	'1':  ".----",
	'2':  "..---",
	'3':  "...--",
	'4':  "....-",
	'5':  ".....",
	'6':  "-....",
	'7':  "--...",
	'8':  "---..",
	'9':  "----.",
	'0':  "-----",
	'/':  "-..-.",
	'.':  ".-.-.-",
	',':  "--..--",
	'?':  "..--..",
	'=':  "-...-",
	'-':  "-....-",
	'(':  "-.--.-",
	')':  "-.--.-",
	':':  "---...",
	'"':  ".-..-.",
	'\'': ".----.",
}

const Len800Hz = 8000 / 800

var Wave800Hz = [Len800Hz]byte{
	0xFF, 0x8F, 0x80, 0x80, 0x8F, 0xFF, 0x0F, 0x00, 0x00, 0x0F,
}

func Millis(tone bool, ms int) {
	numSamples := int(float64(ms*8) / speed)
	buf := make([]byte, numSamples)
	if tone {
		for i := 0; i < numSamples; i++ {
			buf[i] = Wave800Hz[i%Len800Hz]
		}
	}
	os.Stdout.Write(buf)
}

func Dit() {
	Millis(true, 100)
	Millis(false, 100)
}
func Dah() {
	Millis(true, 300)
	Millis(false, 100)
}

func Vocalize(s string) {
	for _, r := range strings.ToLower(s) {
		x, ok := Code[r]
		if !ok {
			x = Code['/'] // Use '/' for unknown chars.
		}
		for _, c := range x {
			switch c {
			case '.':
				Dit()
			case '-':
				Dah()
			default:
				panic(x)
			}
		}
		Millis(false, 200)
	}
	Millis(false, 400)
}

func main() {
	for _, w := range os.Args[1:] {
		Vocalize(w)
	}
}