/*  DokuWiki MoaiEditor Watcher.js file
    Version : 0.5a (May 6, 2026)
    Author  : MoaiTools <info@moaitools.org>
    License : GPL 3 (http://www.gnu.org/licenses/gpl.html) */
 
/* This class watches for changes lines in the textarea contents.
   
   It detects deleted and inserted lines. An edited or replaced line is interpreted
   as a deletion folowed by an insertion.

   Handling textarea input events and toolbar button clicks might not be sufficient
   to detect changes. Javascript can change the text without generating any events,
   so unknown plugins might bypass this detection.
   
   This is why we also check regularly if the text has changed even if no user input
   event has been detected. This process is not very cpu intensive even when the page
   is huge (it takes less than 1 ms on a 400 Kb page, which is larger than the largest
   english wikipedia page).
   
   We have a timer class to make these background checks more often if the user has
   interacted recently and less often otherwise (to minimize CPU usage when there is
   no interaction).
*/
MoaiEditor.WatchTextChanges = class {

    constructor(outer) {    
        
        // Arguments
        this.outer = outer;  
        
        // Objects
        this.timer = new MoaiEditor.Timer();
        
        // Intervals
        this.interval = setInterval(this.onInterval.bind(this), 200);
    }
    // ──────────────────────────────────── 
    onInterval() {
    
        // Return if the parent is disabled
        if (!this.outer.enabled)
            return;

        // Return if not enough time has elapsed
        if (!this.timer.due())
            return;

        // Return if the editor is not enabled and ready
        if (!moaiEditor.layoutReady)
            return;
            
        // Check for text changes
        this.checkTextChange();
        
        // Optional debug actions 
        this.debug();
        
    }
    // ──────────────────────────────────── 
    onInput() {
        this.timer.resetPeriod();
        this.timer.restart();
        this.checkTextChange();
    }
    // ──────────────────────────────────── 
    getTextLines() {
        return moaiEditor.layout.textarea.value.split("\n");
    }
    // ──────────────────────────────────── 
    checkTextChange() {
        // Init
        var i;
        const start = Date.now();
        var previous = this.lines;
        var current = this.getTextLines();
        
        // Get shift (delta)
        const shift = current.length - previous.length;
    
        // Walk lines form top to bottom
        for (i=0; i<previous.length; i++) {
            if (current.length <= i)
                break;
            if (previous[i] != current[i])
                break;
        }
        // Return if the text is the same
        if (i == previous.length  &&  shift == 0) {
            return null;
        }
        // First changed line (top to bottom)
        const i0 = i;
    
        // Walk lines form bottom to top and detect the first change
        for (var k=0; k<previous.length; k++) {
            i = previous.length - k - 1;
            var j = current.length - k - 1;
            if (j < 0)
                break;
            if (previous[i] != current[j])
                break;
        }
        // First changed line (bottom to top)
        const i1 = i;
        
        // Calc some values
        var removed = Math.max(0, i1 - i0 + 1);
        if (previous.length == 0) {
            removed = 0;
        }
        var inserted = removed + shift;
        if (inserted < 0) {
            removed -= inserted;
            inserted = 0;
        }
        // Pack the result
        const elapsed = Date.now() - start;
        const data = { num:{keepfirst:i0, remove:removed, insert:inserted}, index:{keeplast: (i0+removed)}, i0:i0, i1:i1, shift:shift, elapsed:elapsed };  
               
        // Store current lines
        this.lines = current;
        
        // Start checking more frequently for changes
        this.timer.resetPeriod();
        
        // Enable "This page is asking you to confirm that you want to leave" popup from: lib/scripts/edit.js
        window.textChanged = true;
        
        // Style the Commit and Cancel buttons
        moaiEditor.buttons.styleExitButtons();
        
        // Inform parent object of the changes
        this.outer.onTextChanged(data); 
    }
    // ──────────────────────────────────── 
    debug() {
        // Placeholder
    }
}; // End Class

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MoaiEditor.Timer = class {

    constructor () {
        this.period = 200;
        this.minPeriod = 200;
        this.maxPeriod = 2000;
        this.inc = 50;
        this.last = Date.now();
    }
    restart () {
        this.last = Date.now();
        this.period += this.inc;
        this.period = Math.min(this.period, this.maxPeriod);
    }
    due () {
        this.debug();
        const elapsed = Date.now() - this.last;
        if (elapsed > this.period) {
            this.restart();
            return true;
        }
        return false;
    }
    set (period) {
        this.period = Math.round(period);
    }
    setMin (period) {
        this.minPeriod = Math.round(period);
    }
    setMax (period) {
        this.minPeriod = Math.round(period);
    }
    setInc (inc) {
        this.inc = inc;
    }
    resetPeriod () {
        this.period = this.minPeriod;
    }
    debug () {
        const line = document.querySelector("#moai__debug div:nth-child(1)");
        if (!line) return;
        const elapsed = '<span style="opacity:0.2">'+(Date.now()-this.last).toString().padStart(4," ")+'</span>';
        const text = "TIMER: "+elapsed+" period:"+this.period+" min:"+this.minPeriod+" max:"+this.maxPeriod;
        line.innerHTML = text;
        line.title = 'Texarea ';
    }
}; // End Class