package coffee.liz.rookery.audio

import kotlin.math.PI
import kotlin.math.exp
import kotlin.math.pow
import kotlin.math.sin

/**
 * A tiny 8-bit synth: pulse and triangle voices with a plucky envelope, rendered to 16-bit mono PCM.
 * Generated in code so there's no audio asset to ship or license.
 */
object Chime {
    const val SAMPLE_RATE = 44_100

    enum class Voice { PULSE25, PULSE50, TRIANGLE }

    /** A note: MIDI pitch (null = rest), start and length in sixteenth notes. */
    data class Note(val midi: Int?, val start: Int, val len: Int, val voice: Voice = Voice.PULSE25, val vol: Double = 0.5)

    /** The single-PB jingle: a rising arpeggio and a sparkly resolution. */
    val PB = listOf(
        Note(72, 0, 1), Note(76, 1, 1), Note(79, 2, 1), Note(84, 3, 3, Voice.PULSE50),
        Note(83, 6, 1), Note(84, 7, 4, Voice.PULSE50),
        Note(48, 0, 3, Voice.TRIANGLE, 0.6), Note(55, 3, 3, Voice.TRIANGLE, 0.6), Note(60, 6, 5, Voice.TRIANGLE, 0.6),
        Note(91, 8, 1, Voice.PULSE25, 0.25), Note(96, 9, 2, Voice.PULSE25, 0.2),
    )

    /** Longer fanfare for average PBs. */
    val AVERAGE_PB = listOf(
        Note(67, 0, 1), Note(72, 1, 1), Note(76, 2, 1), Note(79, 3, 2),
        Note(76, 5, 1), Note(79, 6, 4, Voice.PULSE50),
        Note(77, 10, 1), Note(81, 11, 1), Note(84, 12, 1), Note(89, 13, 5, Voice.PULSE50),
        Note(43, 0, 5, Voice.TRIANGLE, 0.6), Note(48, 5, 5, Voice.TRIANGLE, 0.6), Note(53, 10, 3, Voice.TRIANGLE, 0.6), Note(48, 13, 5, Voice.TRIANGLE, 0.6),
        Note(96, 14, 1, Voice.PULSE25, 0.2), Note(100, 15, 1, Voice.PULSE25, 0.2), Note(103, 16, 2, Voice.PULSE25, 0.2),
    )

    /** Inspection calls: one pip at eight seconds, two at twelve. */
    val EIGHT = listOf(Note(81, 0, 1, Voice.PULSE50, 0.3))
    val TWELVE = listOf(Note(81, 0, 1, Voice.PULSE50, 0.3), Note(81, 2, 1, Voice.PULSE50, 0.3))

    /** Short descending blip for a DNF. */
    val DNF = listOf(Note(64, 0, 1, Voice.PULSE50, 0.35), Note(57, 1, 2, Voice.PULSE50, 0.35))

    fun render(notes: List<Note>, bpm: Int = 150, volume: Double = 0.35): ShortArray {
        val sixteenth = SAMPLE_RATE * 60.0 / bpm / 4
        val total = ((notes.maxOf { it.start + it.len } + 2) * sixteenth).toInt()
        val mix = DoubleArray(total)
        for (note in notes) {
            val midi = note.midi ?: continue
            val freq = 440.0 * 2.0.pow((midi - 69) / 12.0)
            val start = (note.start * sixteenth).toInt()
            val len = (note.len * sixteenth).toInt()
            val release = (0.04 * SAMPLE_RATE).toInt()
            for (i in 0 until len + release) {
                val idx = start + i
                if (idx >= total) break
                val phase = (i * freq / SAMPLE_RATE) % 1.0
                val wave = when (note.voice) {
                    Voice.PULSE25 -> if (phase < 0.25) 1.0 else -1.0
                    Voice.PULSE50 -> if (phase < 0.5) 1.0 else -1.0
                    Voice.TRIANGLE -> 4 * kotlin.math.abs(phase - 0.5) - 1
                }
                val attack = minOf(1.0, i / (0.004 * SAMPLE_RATE))
                val decay = exp(-i / (len * 0.9 + 1))
                val tail = if (i < len) 1.0 else 1.0 - (i - len).toDouble() / release
                // a dash of vibrato on long notes, NES-style
                val vib = if (i > SAMPLE_RATE / 10) 1 + 0.003 * sin(2 * PI * 6 * i / SAMPLE_RATE) else 1.0
                mix[idx] += wave * vib * note.vol * attack * (0.35 + 0.65 * decay) * tail
            }
        }
        return ShortArray(total) { i -> (mix[i] * volume * Short.MAX_VALUE).coerceIn(-32767.0, 32767.0).toInt().toShort() }
    }
}