#!/usr/bin/env bash
set -euo pipefail

error() {
    printf "✗ %s\n" "$*" >&2
    exit 1
}

usage() {
    cat <<'EOF'
Usage:
  record-audio [options] [output-file]

Records system audio (default sink monitor) and microphone (default source) using ffmpeg (MP3).
Stops on Ctrl+C.

Options:
  --system-only        Record only system audio (what you hear)
  --mic-only           Record only microphone
  -o, --out FILE       Output file
  -h, --help           Show help

Default output:
  recording-YYYYmmdd-HHMMSS.mp3
EOF
}

require_cmd() {
    command -v "$1" >/dev/null 2>&1 || error "Missing dependency: $1"
}

timestamp() {
    date +%Y%m%d-%H%M%S
}

main() {
    local mode="mix"
    local out=""

    while [[ $# -gt 0 ]]; do
        case $1 in
            --system-only)
                mode="system"
                shift
                ;;
            --mic-only)
                mode="mic"
                shift
                ;;
            -o|--out)
                out="${2:-}"
                [[ -n $out ]] || error "--out requires a file path"
                shift 2
                ;;
            -h|--help)
                usage
                exit 0
                ;;
            *)
                if [[ -z $out ]]; then
                    out="$1"
                    shift
                else
                    error "Unknown argument: $1"
                fi
                ;;
        esac
    done

    require_cmd pactl
    require_cmd ffmpeg

    if [[ -z $out ]]; then
        out="recording-$(timestamp).mp3"
    fi

    if [[ -e $out ]]; then
        error "Refusing to overwrite existing file: $out"
    fi

    local sink
    local source
    sink="$(pactl get-default-sink)"
    source="$(pactl get-default-source)"

    [[ -n $sink ]] || error "No default sink found"
    [[ -n $source ]] || error "No default source found"

    local monitor="${sink}.monitor"

    printf "Recording mode: %s\n" "$mode"
    printf "Default sink: %s\n" "$sink"
    printf "Default source: %s\n" "$source"
    printf "Output: %s\n" "$out"
    printf "Stop: Ctrl+C\n"

    case $mode in
        system)
            exec ffmpeg -f pulse -i "$monitor" -c:a libmp3lame -q:a 4 "$out"
            ;;
        mic)
            exec ffmpeg -f pulse -i "$source" -c:a libmp3lame -q:a 4 "$out"
            ;;
        mix)
            exec ffmpeg \
                -f pulse -i "$monitor" \
                -f pulse -i "$source" \
                -filter_complex '[0:a]aformat=sample_rates=48000:channel_layouts=stereo[a0];[1:a]aformat=sample_rates=48000:channel_layouts=stereo[a1];[a0][a1]amix=inputs=2:duration=longest:dropout_transition=0' \
                -c:a libmp3lame -q:a 4 \
                "$out"
            ;;
        *)
            error "Unknown mode: $mode"
            ;;
    esac
}

main "$@"