//
//  SpotifyAppleScript.swift
//  MioIsland Music Plugin
//
//  AppleScript bridge for the Spotify desktop app. Spotify exposes a rich
//  scripting dictionary so we can pull title / artist / album / duration /
//  position and drive transport controls. Artwork URL is also scriptable
//  which makes this cheaper than any other source.
//
//  Threading: all scripts run on a background queue via runAppleScript.
//  NSAppleScript is NOT safe to share across threads; each call creates a
//  fresh instance. Duration from Spotify is in milliseconds (we divide by
//  1000 inside the script) and player position is in seconds.
//

import AppKit

struct AppleScriptTrackInfo {
    var title: String
    var artist: String
    var album: String
    var duration: TimeInterval
    var elapsedTime: TimeInterval
    var isPlaying: Bool
    var artworkURL: String?
    var source: String         // "Spotify" / "Apple Music"
    var bundleId: String
}

enum SpotifyAppleScript {
    static let bundleId = "com.spotify.client"
    private static let sourceName = "Spotify"

    /// Fast check: is Spotify actually running? When false, skip AppleScript
    /// entirely — the 2s `with timeout` would still trip but that's two
    /// wasted seconds per router pass for an app the user isn't using.
    static var isRunning: Bool {
        NSWorkspace.shared.runningApplications.contains {
            $0.bundleIdentifier == bundleId
        }
    }

    // MARK: - Fetch

    static func fetch() async -> AppleScriptTrackInfo? {
        // `with timeout of 2 seconds` bounds the tell block; if Spotify hangs,
        // AppleScript raises errAETimeout (-1712) and our Swift layer returns
        // nil so the source router can move on instead of the serial queue
        // stalling for the default 120-second AppleEvent timeout.
        let script = """
        tell application "System Events"
            if not (exists process "Spotify") then return "NOT_RUNNING"
        end tell
        with timeout of 2 seconds
            tell application "Spotify"
                if player state is playing or player state is paused then
                    set trackName to name of current track
                    set trackArtist to artist of current track
                    set trackAlbum to album of current track
                    set trackDuration to duration of current track
                    set trackPosition to player position
                    set stateString to "PAUSED"
                    if player state is playing then set stateString to "PLAYING"
                    set artURL to ""
                    try
                        set artURL to artwork url of current track
                    end try
                    return stateString & "||" & trackName & "||" & trackArtist & "||" & trackAlbum & "||" & (trackDuration / 1000) & "||" & trackPosition & "||" & artURL
                else
                    return "NOT_PLAYING"
                end if
            end tell
        end timeout
        """

        guard let raw = await runAppleScript(script, tag: "spotify") else { return nil }
        if raw == "NOT_RUNNING" || raw == "NOT_PLAYING" { return nil }

        let parts = raw.components(separatedBy: "||")
        guard parts.count >= 6 else { return nil }

        let isPlaying = parts[0] == "PLAYING"
        let artURL = parts.count >= 7 ? parts[6] : ""

        return AppleScriptTrackInfo(
            title: parts[1],
            artist: parts[2],
            album: parts[3],
            duration: TimeInterval(parts[4]) ?? 0,
            elapsedTime: TimeInterval(parts[5]) ?? 0,
            isPlaying: isPlaying,
            artworkURL: artURL.isEmpty ? nil : artURL,
            source: sourceName,
            bundleId: bundleId
        )
    }

    // MARK: - Artwork

    static func fetchArtwork() async -> NSImage? {
        let script = """
        tell application "System Events"
            if not (exists process "Spotify") then return ""
        end tell
        with timeout of 2 seconds
            tell application "Spotify"
                try
                    return artwork url of current track
                on error
                    return ""
                end try
            end tell
        end timeout
        """
        guard let urlString = await runAppleScript(script, tag: "spotify-art"),
              !urlString.isEmpty,
              let url = URL(string: urlString) else {
            return nil
        }
        return await downloadImage(from: url)
    }

    // MARK: - Controls

    static func togglePlay() {
        runAppleScriptFireAndForget(
            "tell application \"Spotify\" to playpause",
            tag: "spotify-toggle"
        )
    }

    static func next() {
        runAppleScriptFireAndForget(
            "tell application \"Spotify\" to next track",
            tag: "spotify-next"
        )
    }

    static func previous() {
        runAppleScriptFireAndForget(
            "tell application \"Spotify\" to previous track",
            tag: "spotify-prev"
        )
    }

    static func seek(to time: TimeInterval) {
        let clamped = max(0, time)
        runAppleScriptFireAndForget(
            "tell application \"Spotify\" to set player position to \(clamped)",
            tag: "spotify-seek"
        )
    }
}