param(
    [string]$DataJson = "vocab_audio_output\vocab_days.json",
    [string]$OutDir = "vocab_audio_output\audio",
    [string]$Voice = "Microsoft Zira Desktop",
    [int]$Rate = -2,
    [int]$Volume = 100
)

$ErrorActionPreference = "Stop"

Add-Type -AssemblyName System.Speech

$data = Get-Content -LiteralPath $DataJson -Encoding UTF8 -Raw | ConvertFrom-Json
New-Item -ItemType Directory -Force -Path $OutDir | Out-Null

$synth = New-Object System.Speech.Synthesis.SpeechSynthesizer
$synth.SelectVoice($Voice)
$synth.Rate = $Rate
$synth.Volume = $Volume

$format = New-Object System.Speech.AudioFormat.SpeechAudioFormatInfo(
    16000,
    [System.Speech.AudioFormat.AudioBitsPerSample]::Sixteen,
    [System.Speech.AudioFormat.AudioChannel]::Mono
)
$breakShort = [TimeSpan]::FromMilliseconds(320)
$breakLong = [TimeSpan]::FromMilliseconds(640)

foreach ($day in $data.days) {
    $dayNumber = [int]$day.day
    $path = Join-Path $OutDir ("Day{0:D2}.wav" -f $dayNumber)
    $builder = New-Object System.Speech.Synthesis.PromptBuilder(
        [System.Globalization.CultureInfo]::GetCultureInfo("en-US")
    )

    foreach ($entry in $day.entries) {
        $term = ([string]$entry.spoken).Trim()
        if ([string]::IsNullOrWhiteSpace($term)) {
            continue
        }
        $builder.AppendText($term)
        $builder.AppendBreak($breakShort)
        $builder.AppendText($term)
        $builder.AppendBreak($breakLong)
    }

    $synth.SetOutputToWaveFile($path, $format)
    $synth.Speak($builder)
    $synth.SetOutputToNull()
    Write-Host ("Day {0:D2}: wrote {1}" -f $dayNumber, $path)
}

$synth.Dispose()