/*  DokuWiki MoaiEditor Match_headers.js file
    Version : 0.5a (May 6, 2026)
    Author  : MoaiTools <info@moaitools.org>
    License : GPL 3 (http://www.gnu.org/licenses/gpl.html) */

MoaiEditor.MatchHeaders = class {

    constructor(outer) {
        
        // Arguments
        this.outer = outer;
        
        // Variables        
        this.nodes = [];            // Array of header nodes in the html      {i, text, type, handle, matchline}
        this.candidates = [];       // Array of candidate lines               {i, text, type, linenum}
    }
    // ┌───────────────────────────────────┐
    // │ Public                            │
    // └───────────────────────────────────┘
    
    findAll () {
        
        
        // Find all header matches
        for (let node of this.nodes) {
            // Find the line
            const line = this.findMatch(node);
            // Update the header array (for header clicks and table of contents)
            node.matchline = line;
            // Append to the matches array (for synchonized scrolling)
            if (line !== null)
                this.outer.matches.add (node.type, node.handle, line, line, 'header');
        }
    }
    // ────────────────────────────────────
    findMatch (node) {

        // Check for similar headers
        var matches = [];
        for (let candidate of this.candidates) 
            if (this.same(node, candidate))
                matches.push(candidate);
        // If there are no matches return null
        if (matches.length == 0)
            return null;
        // If there is just one match, return the line number
        if (matches.length == 1)
            return matches[0].linenum;
        // If there is more than one match, check if one of them has the same neighbors
        var maxScore = -1;
        var bestMatch = null;
        for (let candidate of matches) {
            const score = this.neighborsScore(node, candidate);
            if (score > maxScore) {
                maxScore = score;
                bestMatch = candidate;
            }
        }
        return bestMatch.linenum;
    }
    // ────────────────────────────────────
    parseText (lines) {
        this.candidates = [];
        var i = 0;
        var l = -1;
        // Iterarate every line of text
        for (let line of lines) {
            l += 1;
            // Continue if it's not a header line
            const header = this.isHeader(line);
            if (!header)
                continue;
            // Otherwise store the header
            this.candidates.push({
                i       : i,
                type    : header.type,
                text    : header.text,
                linenum : l,
            });
            // Increment index
            i += 1;
        }
    }
    // ┌───────────────────────────────────┐
    // │ Private                           │
    // └───────────────────────────────────┘
    
    neighborsScore (node, candidate) {
    
        var d = 1;
        var score = 0;
        var idx_node = node.i;
        var idx_text = candidate.i;
        while (true) {
            // Left neighbors
            var leftNodeNeighbor = this.getNeighbor(this.nodes, idx_node-d);
            var leftTextNeighbor = this.getNeighbor(this.candidates, idx_text-d);
            if (this.same(leftNodeNeighbor, leftTextNeighbor))
                score += 1;
            // Right neighbors
            var rightNodeNeighbor = this.getNeighbor(this.nodes, idx_node+d);
            var rightTextNeighbor = this.getNeighbor(this.candidates, idx_text+d);
            if (this.same(rightNodeNeighbor, rightTextNeighbor))
                score += 1; 
            // Exit condition
            if (score % 2 != 0  ||  leftNodeNeighbor === null   ||  rightNodeNeighbor === null)
                break;
            // Increment distance
            d += 1;
        }
        return score/(2*d);
    }
    // ────────────────────────────────────
    same (node, candidate) {
        if (node === null  &&  candidate === null)
            return true;
        if (node === null  ||  candidate === null)
            return false;
        if (node.type != candidate.type)
            return false;
        if (node.text != candidate.text)
            return false;
        return true;
    }
    // ──────────────────────────────────── 
    getNeighbor (array, idx) {    
        if (idx < 0  ||  idx > array.length-1)
            return null;
        return array[idx];
    }
    // ──────────────────────────────────── 
    isHeader (line) {
    
        // Fail if the line does not include '=='
        if (line.search("==") == -1)
            return null;
        // Fail if the line starts with two or more spaces
        if (line.substr(0,2) == '  ')
            return null;
        // Fail if the trimmed line does not end in '=='
        if (line.trim().slice(-2) != '==')
            return null;
        // Search all sequences of two or more '='
        let regex = /(={2,})/gd;
        let matches = [...line.matchAll(regex)];
        // Fail if we have less than two sequences
        if (matches.length < 2)
            return null;
        // Extract the content of the header (inner part)
        var first = matches[0];
        var last  = matches.at(-1);
        var pos_start = first.indices[0][1];
        var pos_end   = last.index;
        var content = line.substring(pos_start, pos_end);
        var text = content.trim();
        // Fail if the content is empty (or whitespace)
        if (text.length == 0)
            return null;
        // Determine the type of header (h1, h2, etc)
        var len = first.indices[0][1] - first.indices[0][0];
        var type;
        if (len < 6)
            type = ['H5','H4','H3','H2'][len-2];
        else
            type = 'H1';
        // Return the data
        return {
            type         : type,
            text         : text,
            content      : content,
            contentStart : pos_start,
            contentEnd   : pos_end
        };
    }
}; // End Class