// ReplayPlayer drives xterm.js playback of recorded session events.
function ReplayPlayer(containerId, sessionId) {
    this.terminal = new Terminal({
        cols: 80,
        rows: 24,
        convertEol: true,
        disableStdin: true,
        theme: {
            background: '#000000',
            foreground: '#ffffff'
        }
    });
    this.terminal.open(document.getElementById(containerId));

    this.sessionId = sessionId;
    this.events = [];
    this.index = 0;
    this.speed = 1;
    this.timers = [];
    this.playing = false;

    // Fetch events immediately.
    var self = this;
    fetch('/api/sessions/' + sessionId + '/events')
        .then(function(r) { return r.json(); })
        .then(function(data) {
            self.events = data.events || [];
        });
}

ReplayPlayer.prototype.play = function() {
    if (this.playing) return;
    if (this.events.length === 0) return;
    this.playing = true;
    this._schedule();
};

ReplayPlayer.prototype.pause = function() {
    this.playing = false;
    for (var i = 0; i < this.timers.length; i++) {
        clearTimeout(this.timers[i]);
    }
    this.timers = [];
};

ReplayPlayer.prototype.reset = function() {
    this.pause();
    this.index = 0;
    this.terminal.reset();
};

ReplayPlayer.prototype.setSpeed = function(speed) {
    this.speed = speed;
    if (this.playing) {
        this.pause();
        this.play();
    }
};

ReplayPlayer.prototype._schedule = function() {
    var self = this;
    var baseT = this.index < this.events.length ? this.events[this.index].t : 0;

    for (var i = this.index; i < this.events.length; i++) {
        (function(idx) {
            var evt = self.events[idx];
            var delay = (evt.t - baseT) / self.speed;
            var timer = setTimeout(function() {
                if (!self.playing) return;
                // Only write output events (d=1) to terminal; input is echoed in output.
                if (evt.d === 1) {
                    var raw = atob(evt.data);
                    self.terminal.write(raw);
                }
                self.index = idx + 1;
                if (self.index >= self.events.length) {
                    self.playing = false;
                }
            }, delay);
            self.timers.push(timer);
        })(i);
    }
};