pragma Singleton

import QtQuick
import Quickshell.Services.Mpris

QtObject {
    id: root

    readonly property var players: (Mpris.players.values ?? []).filter(p => p.trackTitle || p.playbackState === MprisPlaybackState.Playing || p.playbackState === MprisPlaybackState.Paused)
    property int playerIdx: 0
    readonly property MprisPlayer player: players[playerIdx] ?? players[0] ?? null
    readonly property bool playing: player?.playbackState === MprisPlaybackState.Playing

    // Track the identity of the selected player so we can find it after list changes
    property string _selectedIdentity: ""

    // Track which player played most recently (by identity)
    property var _lastPlayedTime: ({})

    // Track previous playing state per player to detect transitions
    property var _wasPlaying: ({})

    onPlayerChanged: {
        if (player)
            _selectedIdentity = player.identity ?? "";
    }

    onPlayersChanged: {
        // Try to find the previously selected player by identity
        if (_selectedIdentity) {
            const idx = players.findIndex(p => (p.identity ?? "") === _selectedIdentity);
            if (idx >= 0) {
                playerIdx = idx;
            } else {
                // Selected player disappeared - switch to best alternative
                _switchToBest();
            }
        } else if (playerIdx >= players.length) {
            playerIdx = 0;
        }
    }

    // Poll playback states to detect transitions - Connections on dynamic
    // targets get destroyed during list re-evaluation, losing the signal
    property Timer _statePoll: Timer {
        interval: 250
        running: root.players.length > 0
        repeat: true
        onTriggered: root._checkStates()
    }

    function _checkStates() {
        const prevWas = _wasPlaying;
        const nextWas = {};

        for (let i = 0; i < players.length; i++) {
            const p = players[i];
            const identity = p.identity ?? "";
            const isPlaying = p.playbackState === MprisPlaybackState.Playing;
            nextWas[identity] = isPlaying;

            if (isPlaying && !prevWas[identity]) {
                // This player just started playing
                const times = Object.assign({}, _lastPlayedTime);
                times[identity] = Date.now();
                _lastPlayedTime = times;

                // Always switch to the newly playing player
                if (player !== p) {
                    playerIdx = i;
                    _selectedIdentity = identity;
                }
            }
        }

        // Check if current player just paused
        const curIdentity = player?.identity ?? "";
        if (prevWas[curIdentity] && !nextWas[curIdentity]) {
            _switchToPlaying();
        }

        _wasPlaying = nextWas;
    }

    function _switchToPlaying() {
        let best = -1;
        let bestTime = 0;
        for (let i = 0; i < players.length; i++) {
            if (players[i].playbackState === MprisPlaybackState.Playing) {
                const t = _lastPlayedTime[players[i].identity ?? ""] || 0;
                if (best < 0 || t > bestTime) {
                    best = i;
                    bestTime = t;
                }
            }
        }
        if (best >= 0) {
            playerIdx = best;
            _selectedIdentity = players[best].identity ?? "";
        }
    }

    function _switchToBest() {
        let best = -1;
        let bestTime = 0;
        let bestPlaying = -1;
        let bestPlayingTime = 0;

        for (let i = 0; i < players.length; i++) {
            const identity = players[i].identity ?? "";
            const t = _lastPlayedTime[identity] || 0;
            if (players[i].playbackState === MprisPlaybackState.Playing) {
                if (bestPlaying < 0 || t > bestPlayingTime) {
                    bestPlaying = i;
                    bestPlayingTime = t;
                }
            }
            if (best < 0 || t > bestTime) {
                best = i;
                bestTime = t;
            }
        }

        const chosen = bestPlaying >= 0 ? bestPlaying : (best >= 0 ? best : 0);
        playerIdx = chosen;
        if (players[chosen])
            _selectedIdentity = players[chosen].identity ?? "";
    }

    function switchPlayer(idx) {
        playerIdx = idx;
        if (players[idx])
            _selectedIdentity = players[idx].identity ?? "";
    }
}