Make the print_pv() logic hopefully slightly easier to understand.

[remoteglot] / www / js / remoteglot.js

diff --git a/www/js/remoteglot.js b/www/js/remoteglot.js
index cf5fba704f23f826dc4601a27ad68483295d36bc..2e66c82fb03fb406a0ec8180762593501134e836 100644 (file)
--- a/www/js/remoteglot.js
+++ b/www/js/remoteglot.js
@@ -733,35 +733,14 @@ function print_pv(line_num, splicepos, opt_limit, opt_showlast) {
        let pv = display_line.pv;
        let move_num = find_move_num(display_line.start_fen);
        let toplay = find_toplay(display_line.start_fen);
-
-       // Truncate PV at the start if needed.
-       let start_display_move_num = display_line.start_display_move_num;
-       if (start_display_move_num > 0) {
-               pv = pv.slice(start_display_move_num);
-               let to_add = start_display_move_num;
-               if (toplay === 'b') {
-                       ++move_num;
-                       toplay = 'w';
-                       --to_add;
-               }
-               if (to_add % 2 == 1) {
-                       toplay = 'b';
-                       --to_add;
-               }
-               move_num += to_add / 2;
-               if (splicepos !== null && splicepos > 0) {
-                       --splicepos;
-               }
-       }
+       let halfmove_num = move_num * 2 + (toplay === 'w' ? 0 : 1);  // From two, for simplicity.
 
        let ret = document.createDocumentFragment();
-       let in_tb = false;
-       let i = 0;
-       if (opt_limit && opt_showlast && pv.length > opt_limit) {
-               // Truncate the PV at the beginning (instead of at the end).
-               // We assume here that toplay is 'w'. We also assume that if
-               // opt_showlast is set, then it is the history, and thus,
-               // the UI should be to expand the history.
+
+       // Truncate PV at the start if needed.
+       let to_skip = display_line.start_display_move_num;
+       if (opt_limit && opt_showlast && pv.length - to_skip > opt_limit) {
+               // Explicit (UI-visible) truncation from the start, for the history.
                ret.appendChild(document.createTextNode('('));
                let link = document.createElement('a');
                link.className = 'move';
@@ -769,25 +748,37 @@ function print_pv(line_num, splicepos, opt_limit, opt_showlast) {
                link.textContent = '…';
                ret.appendChild(link);
                ret.appendChild(document.createTextNode(') '));
-               i = pv.length - opt_limit;
-               if (i % 2 == 1) {
-                       ++i;
+               to_skip = pv.length - opt_limit;
+               to_skip += to_skip % 2;  // Make sure it starts on a white move.
+       }
+       if (to_skip > 0) {
+               pv = pv.slice(to_skip);
+               halfmove_num += to_skip;
+               if (splicepos !== null) {
+                       splicepos -= to_skip;
+                       if (splicepos < 0) {
+                               splicepos = 0;
+                       }
                }
-               move_num += i / 2;
-       } else if (toplay == 'b' && pv.length > 0) {
-               ret.appendChild(document.createTextNode(move_num + '. … '));
        }
-       for (; i < pv.length; ++i) {
+
+       // The initial move number needs to go before any (TB: …) marker.
+       if (halfmove_num % 2 == 1) {
+               // Black move.
+               ret.appendChild(document.createTextNode((halfmove_num - 1) / 2 + '. … '));
+       } else {
+               // White move.
+               ret.appendChild(document.createTextNode(halfmove_num / 2 + '. '));
+       }
+       let in_tb = false;
+       for (let i = 0; i < pv.length; ++i, ++halfmove_num) {
                let prefix = '';
                if (splicepos === i) {
-                       prefix = '(TB: ';
+                       prefix = '(TB:';
                        in_tb = true;
                }
 
-               if (toplay == 'b' && i == 0) {
-                       ++move_num;
-                       toplay = 'w';
-               } else if (toplay == 'w') {
+               if (halfmove_num % 2 == 0 && i != 0) {
                        if (i > opt_limit && !opt_showlast) {
                                if (in_tb) {
                                        prefix += ')';
@@ -795,12 +786,9 @@ function print_pv(line_num, splicepos, opt_limit, opt_showlast) {
                                ret.appendChild(document.createTextNode(prefix + ' (…)'));
                                return ret;
                        }
-                       prefix += ' ' + move_num + '. ';
-                       ++move_num;
-                       toplay = 'b';
+                       prefix += ' ' + (halfmove_num / 2) + '. ';
                } else {
                        prefix += ' ';
-                       toplay = 'w';
                }
                ret.appendChild(document.createTextNode(prefix));