mixboard/Sources/Export/AuditionExporter.swift

import Foundation

/// Exports a playlist as an Adobe Audition multitrack session (.sesx) file.
/// Based on the real Audition .sesx XML schema (version 1.9).
/// Each original track becomes a separate clip on the timeline, referencing
/// the original audio files by absolute path.
struct AuditionExporter: DAWExporter {
    static let formatID = "audition"
    static let formatName = "Adobe Audition Session"
    static let fileExtension = "sesx"

    static func export(playlist: Playlist, to url: URL, options: ExportOptions) throws {
        let entries = playlist.sortedEntries
        let sampleRate = options.targetSampleRate ?? 44100
        let totalSamples = timeToSamples(playlist.totalDuration, sampleRate: sampleRate)
        let sessionDir = url.deletingLastPathComponent().path

        // Collect unique file references
        var fileRefs: [(id: Int, absolutePath: String, relativePath: String, mediaHandler: String)] = []
        var fileIDMap = [String: Int]()

        for entry in entries {
            guard let track = entry.track else { continue }
            let path = track.filePath
            if fileIDMap[path] == nil {
                let fid = fileRefs.count
                fileIDMap[path] = fid
                let rel = makeRelativePath(from: sessionDir, to: path)
                let handler = mediaHandler(for: track.fileFormat)
                fileRefs.append((id: fid, absolutePath: path, relativePath: rel, mediaHandler: handler))
            }
        }

        // --- Build XML matching real Audition format ---

        var xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?>\n"
        xml += "<!DOCTYPE sesx>\n"
        xml += "<sesx version=\"1.9\">\n\n"

        // Session
        xml += "  <session appBuild=\"MixBoard\" appVersion=\"1.0\" "
        xml += "audioChannelType=\"stereo\" bitDepth=\"32\" "
        xml += "duration=\"\(totalSamples)\" sampleRate=\"\(Int(sampleRate))\">\n"

        // Tracks
        xml += "    <tracks>\n"

        // Audio track
        xml += "      <audioTrack automationLaneOpenState=\"false\" id=\"10001\" index=\"1\" select=\"false\" visible=\"true\">\n"
        xml += "        <trackParameters trackHeight=\"140\" trackHue=\"160\" trackMinimized=\"false\">\n"
        xml += "          <name>Mix</name>\n"
        xml += "        </trackParameters>\n"
        xml += "        <trackAudioParameters audioChannelType=\"stereo\" automationMode=\"1\" "
        xml += "monitoring=\"false\" recordArmed=\"false\" solo=\"false\" soloSafe=\"false\">\n"
        xml += "          <trackOutput outputID=\"10000\" type=\"trackID\"/>\n"
        xml += "          <component componentID=\"Audition.Fader\" id=\"trackFader\" name=\"volume\" powered=\"true\">\n"
        xml += "            <parameter index=\"0\" name=\"volume\" parameterValue=\"1\"/>\n"
        xml += "            <parameter index=\"1\" name=\"static gain\" parameterValue=\"1\"/>\n"
        xml += "          </component>\n"
        xml += "          <component componentID=\"Audition.Mute\" id=\"trackMute\" name=\"Mute\" powered=\"true\">\n"
        xml += "            <parameter index=\"0\" parameterValue=\"0\"/>\n"
        xml += "            <parameter index=\"1\" name=\"mute\" parameterValue=\"0\"/>\n"
        xml += "          </component>\n"
        xml += "          <component componentID=\"Audition.StereoPanner\" id=\"trackPan\" name=\"StereoPanner\" powered=\"true\">\n"
        xml += "            <parameter index=\"0\" name=\"Pan\" parameterValue=\"0\"/>\n"
        xml += "          </component>\n"
        xml += "        </trackAudioParameters>\n"

        // Audio clips on timeline
        var timelinePos: TimeInterval = 0

        for (index, entry) in entries.enumerated() {
            guard let track = entry.track else { continue }
            guard let fid = fileIDMap[track.filePath] else { continue }

            // Apply crossfade overlap
            if index > 0 && entry.crossfadeDuration > 0 {
                timelinePos -= entry.crossfadeDuration
            }

            let clipStart = timelinePos
            let startOffset = entry.startOffset
            let effectiveDuration = entry.effectiveDuration

            let startSample = timeToSamples(clipStart, sampleRate: sampleRate)
            let endSample = timeToSamples(clipStart + effectiveDuration, sampleRate: sampleRate)
            let sourceIn = timeToSamples(startOffset, sampleRate: sampleRate)
            let sourceOut = timeToSamples(startOffset + effectiveDuration, sampleRate: sampleRate)

            xml += "        <audioClip clipAutoCrossfade=\"true\" "
            xml += "crossFadeHeadClipID=\"-1\" crossFadeTailClipID=\"-1\" "
            xml += "endPoint=\"\(endSample)\" fileID=\"\(fid)\" hue=\"-1\" "
            xml += "id=\"\(index)\" lockedInTime=\"false\" looped=\"false\" "
            xml += "name=\"\(esc(track.title))\" offline=\"false\" select=\"false\" "
            xml += "sourceInPoint=\"\(sourceIn)\" sourceOutPoint=\"\(sourceOut)\" "
            xml += "startPoint=\"\(startSample)\" zOrder=\"\(127 + index)\">\n"
            xml += "        </audioClip>\n"

            timelinePos = clipStart + effectiveDuration
        }

        xml += "      </audioTrack>\n"

        // Master track
        xml += "      <masterTrack automationLaneOpenState=\"false\" id=\"10000\" index=\"0\" select=\"false\" visible=\"true\">\n"
        xml += "        <trackParameters trackHeight=\"70\" trackHue=\"-1\" trackMinimized=\"true\">\n"
        xml += "          <name>Master</name>\n"
        xml += "        </trackParameters>\n"
        xml += "        <trackAudioParameters audioChannelType=\"stereo\" automationMode=\"1\" "
        xml += "monitoring=\"false\" recordArmed=\"false\" solo=\"false\" soloSafe=\"false\">\n"
        xml += "          <component componentID=\"Audition.Fader\" id=\"trackFader\" name=\"volume\" powered=\"true\">\n"
        xml += "            <parameter index=\"0\" name=\"volume\" parameterValue=\"1\"/>\n"
        xml += "            <parameter index=\"1\" name=\"static gain\" parameterValue=\"1\"/>\n"
        xml += "          </component>\n"
        xml += "          <component componentID=\"Audition.Mute\" id=\"trackMute\" name=\"Mute\" powered=\"true\">\n"
        xml += "            <parameter index=\"0\" parameterValue=\"0\"/>\n"
        xml += "            <parameter index=\"1\" name=\"mute\" parameterValue=\"0\"/>\n"
        xml += "          </component>\n"
        xml += "        </trackAudioParameters>\n"
        xml += "      </masterTrack>\n"

        xml += "    </tracks>\n"
        xml += "  </session>\n\n"

        // Files section — AFTER </session>, before </sesx>
        xml += "  <files>\n"
        for ref in fileRefs {
            let uuid = UUID().uuidString.lowercased()
            xml += "    <file absolutePath=\"\(esc(ref.absolutePath))\" "
            xml += "id=\"\(ref.id)\" "
            xml += "mediaHandler=\"\(ref.mediaHandler)\" "
            xml += "recoveryID=\"\(uuid)\" "
            xml += "relativePath=\"\(esc(ref.relativePath))\"/>\n"
        }
        xml += "  </files>\n\n"

        xml += "</sesx>\n"

        try xml.write(to: url, atomically: true, encoding: .utf8)
    }

    // MARK: - Helpers

    private static func timeToSamples(_ time: TimeInterval, sampleRate: Double) -> Int64 {
        Int64(time * sampleRate)
    }

    private static func esc(_ string: String) -> String {
        string
            .replacingOccurrences(of: "&", with: "&amp;")
            .replacingOccurrences(of: "<", with: "&lt;")
            .replacingOccurrences(of: ">", with: "&gt;")
            .replacingOccurrences(of: "\"", with: "&quot;")
            .replacingOccurrences(of: "'", with: "&apos;")
    }

    private static func makeRelativePath(from sessionDir: String, to filePath: String) -> String {
        if filePath.hasPrefix(sessionDir) {
            let relative = String(filePath.dropFirst(sessionDir.count))
            return relative.hasPrefix("/") ? String(relative.dropFirst()) : relative
        }
        return filePath
    }

    /// Map file extension to Audition media handler identifier.
    private static func mediaHandler(for format: String) -> String {
        switch format.lowercased() {
        case "mp3":                     return "AmioMP3"
        case "wav":                     return "AmioWav"
        case "flac":                    return "AmioLSF"
        case "aif", "aiff":            return "AmioAIFF"
        case "m4a", "aac", "alac":     return "AmioQuickTime"
        case "ogg":                     return "AmioOGG"
        default:                        return "AmioGeneric"
        }
    }
}