package sfx

import (
	"fmt"
	"math/rand"
	"sort"
)

// Preset returns ready-made parameters for classic game sounds.
// seed 0 gives the canonical version; other seeds vary it slightly so
// agents can generate alternatives ("give me three coin variants").
func Preset(name string, seed int64) (*Params, error) {
	p := Defaults()
	p.Name = name
	switch name {
	case "jump":
		p.Wave = "square"
		p.Duty = 0.5
		p.Freq = 330
		p.FreqSlide = 900
		p.Attack = 0.01
		p.Sustain = 0.08
		p.Decay = 0.18
	case "coin":
		p.Wave = "square"
		p.Duty = 0.5
		p.Freq = 988
		p.ArpFactor = 1.335 // up a fourth: B5 -> E6
		p.ArpTime = 0.06
		p.Attack = 0.005
		p.Sustain = 0.08
		p.Decay = 0.25
	case "laser":
		p.Wave = "saw"
		p.Freq = 1400
		p.FreqSlide = -6000
		p.Attack = 0.005
		p.Sustain = 0.05
		p.Decay = 0.12
		p.HighPass = 300
	case "explosion":
		p.Wave = "noise"
		p.Freq = 900
		p.FreqSlide = -600
		p.Attack = 0.01
		p.Sustain = 0.15
		p.Decay = 0.55
		p.LowPass = 2200
	case "hurt":
		p.Wave = "saw"
		p.Freq = 300
		p.FreqSlide = -700
		p.Attack = 0.005
		p.Sustain = 0.04
		p.Decay = 0.14
	case "powerup":
		p.Wave = "square"
		p.Duty = 0.4
		p.Freq = 220
		p.FreqSlide = 700
		p.VibratoDepth = 25
		p.VibratoRate = 9
		p.Attack = 0.01
		p.Sustain = 0.25
		p.Decay = 0.25
	case "blip":
		p.Wave = "square"
		p.Duty = 0.4
		p.Freq = 660
		p.Attack = 0.002
		p.Sustain = 0.03
		p.Decay = 0.05
	default:
		return nil, fmt.Errorf("unknown preset %q (available: %s)", name, PresetNames())
	}
	if seed != 0 {
		vary(&p, seed)
	}
	if err := p.Validate(); err != nil {
		return nil, fmt.Errorf("preset %s (seed %d): %w", name, seed, err)
	}
	return &p, nil
}

// vary nudges the tonal parameters deterministically from the seed.
func vary(p *Params, seed int64) {
	rng := rand.New(rand.NewSource(seed))
	jitter := func(v, amount float64) float64 {
		return v * (1 + amount*(rng.Float64()*2-1))
	}
	p.Freq = jitter(p.Freq, 0.15)
	p.FreqSlide = jitter(p.FreqSlide, 0.25)
	p.Sustain = jitter(p.Sustain, 0.2)
	p.Decay = jitter(p.Decay, 0.2)
	if p.ArpFactor != 0 {
		p.ArpFactor = jitter(p.ArpFactor, 0.05)
	}
	p.Seed = seed // noise variation too
}

var presetNames = []string{"blip", "coin", "explosion", "hurt", "jump", "laser", "powerup"}

// PresetNames lists the available presets, sorted.
func PresetNames() string {
	sort.Strings(presetNames)
	out := ""
	for i, n := range presetNames {
		if i > 0 {
			out += ", "
		}
		out += n
	}
	return out
}