package cwdecode

import (
	"math"
	"strings"
	"testing"
)

// reverse Morse map for the synthesizer.
func charToMorse() map[byte]string {
	m := map[byte]string{}
	for code, ch := range morse {
		m[ch] = code
	}
	return m
}

// keyMessage synthesizes a clean keyed tone for msg at the given WPM/pitch.
func keyMessage(msg string, fs, wpm int, pitch float64) []int16 {
	dot := fs * 1200 / (wpm * 1000) // samples per dot
	c2m := charToMorse()
	var out []int16
	phase := 0.0
	dphi := 2 * math.Pi * pitch / float64(fs)

	tone := func(n int) {
		for i := 0; i < n; i++ {
			out = append(out, int16(9000*math.Sin(phase)))
			phase += dphi
		}
	}
	silence := func(n int) {
		for i := 0; i < n; i++ {
			out = append(out, 0)
		}
	}

	silence(fs / 4) // 250 ms lead-in for AGC warmup
	for i := 0; i < len(msg); i++ {
		ch := msg[i]
		if ch == ' ' {
			silence(7 * dot)
			continue
		}
		code := c2m[ch]
		for j := 0; j < len(code); j++ {
			if code[j] == '.' {
				tone(dot)
			} else {
				tone(3 * dot)
			}
			silence(dot) // inter-element gap
		}
		silence(3 * dot) // inter-character gap (on top of the trailing element gap)
	}
	silence(fs / 4)
	return out
}

func TestDecodeCleanSignal(t *testing.T) {
	const fs = 16000
	var sb strings.Builder
	d := New(fs, func(s string) { sb.WriteString(s) }, nil)

	// Repeat so AGC warm-up only costs the first word.
	samples := keyMessage("PARIS PARIS PARIS", fs, 22, 700)
	// Feed in small chunks like the live capture would.
	for i := 0; i < len(samples); i += 256 {
		end := i + 256
		if end > len(samples) {
			end = len(samples)
		}
		d.Process(samples[i:end])
	}

	got := strings.ToUpper(sb.String())
	if !strings.Contains(got, "PARIS") {
		t.Fatalf("decoded %q, want it to contain PARIS", got)
	}
}

func TestDecodeNumbersAndProsign(t *testing.T) {
	const fs = 16000
	var sb strings.Builder
	d := New(fs, func(s string) { sb.WriteString(s) }, nil)
	samples := keyMessage("TEST 599 TEST", fs, 18, 650)
	for i := 0; i < len(samples); i += 200 {
		end := i + 200
		if end > len(samples) {
			end = len(samples)
		}
		d.Process(samples[i:end])
	}
	got := strings.ToUpper(sb.String())
	if !strings.Contains(got, "599") {
		t.Fatalf("decoded %q, want it to contain 599", got)
	}
}