From 33737dd74207d2f7263a3c774cd45b069c1dfa08 Mon Sep 17 00:00:00 2001
From: Oleh Krehel <ohwoeowho@gmail.com>
Date: Thu, 16 Mar 2023 17:56:14 +0100
Subject: [PATCH] Put contexts dict in <script> and reveal them using
 JavaScript

Fixes #1584
---
 coverage/html.py                    | 16 ++++++++++++++-
 coverage/htmlfiles/coverage_html.js | 31 ++++++++++++++++++++++++-----
 coverage/htmlfiles/pyfile.html      | 13 ++++++++----
 3 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/coverage/html.py b/coverage/html.py
index ae09bc37d..0d6f8a24c 100644
--- a/coverage/html.py
+++ b/coverage/html.py
@@ -10,6 +10,8 @@
 import os
 import re
 import shutil
+import json
+from collections import Counter
 
 from dataclasses import dataclass
 from typing import Any, Dict, Iterable, List, Optional, Tuple, TYPE_CHECKING, cast
@@ -367,6 +369,11 @@ def write_html_file(self, ftr: FileToReport, prev_html: str, next_html: str) ->
 
         # Write the HTML page for this file.
         file_data = self.datagen.data_for_file(ftr.fr, ftr.analysis)
+
+        contexts=Counter(c for cline in file_data.lines for c in cline.contexts)
+        context_codes = {y: i for (i, y) in enumerate(x[0] for x in contexts.most_common())}
+        contexts_json = json.dumps({v: k for (k, v) in context_codes.items()}, indent=2)
+
         for ldata in file_data.lines:
             # Build the HTML for the line.
             html_parts = []
@@ -380,6 +387,8 @@ def write_html_file(self, ftr: FileToReport, prev_html: str, next_html: str) ->
                     )
             ldata.html = ''.join(html_parts)
 
+            ldata.context_str = ",".join([str(context_codes[c_context]) for c_context in ldata.context_list])
+
             if ldata.short_annotations:
                 # 202F is NARROW NO-BREAK SPACE.
                 # 219B is RIGHTWARDS ARROW WITH STROKE.
@@ -412,9 +421,14 @@ def write_html_file(self, ftr: FileToReport, prev_html: str, next_html: str) ->
                 )
             ldata.css_class = ' '.join(css_classes) or "pln"
 
+        di = file_data.__dict__
+        if contexts_json == "{}":
+            di["contexts_json"] = None
+        else:
+            di["contexts_json"] = contexts_json
         html_path = os.path.join(self.directory, ftr.html_filename)
         html = self.source_tmpl.render({
-            **file_data.__dict__,
+            **di,
             'prev_html': prev_html,
             'next_html': next_html,
         })
diff --git a/coverage/htmlfiles/coverage_html.js b/coverage/htmlfiles/coverage_html.js
index 1c4eb9881..ff6bd6a0d 100644
--- a/coverage/htmlfiles/coverage_html.js
+++ b/coverage/htmlfiles/coverage_html.js
@@ -595,10 +595,31 @@ coverage.wire_up_sticky_header = function () {
     updateHeader();
 };
 
+coverage.showContexts = function (e) {
+  span = e.target.nextElementSibling.nextElementSibling;
+  span_text = span.textContent;
+
+  if (/^[0-9,]+$/.test(span_text))
+  {
+    span.textContent = "";
+    span_text.split(",").forEach(function(s) {
+      ctx = contexts[s];
+      span.appendChild(document.createTextNode(ctx));
+      span.appendChild(document.createElement("br"));
+    })
+  }
+};
+
 document.addEventListener("DOMContentLoaded", () => {
-    if (document.body.classList.contains("indexfile")) {
-        coverage.index_ready();
-    } else {
-        coverage.pyfile_ready();
-    }
+  cboxes = document.querySelectorAll('[id^=ctxs]')
+  cboxes.forEach(function(cbox) {
+    cbox.addEventListener("click", coverage.showContexts)
+  });
+
+  if (document.body.classList.contains("indexfile")) {
+    coverage.index_ready();
+  } else {
+    coverage.pyfile_ready();
+  }
+
 });
diff --git a/coverage/htmlfiles/pyfile.html b/coverage/htmlfiles/pyfile.html
index 8fcfc660a..1921e1c20 100644
--- a/coverage/htmlfiles/pyfile.html
+++ b/coverage/htmlfiles/pyfile.html
@@ -11,6 +11,13 @@
     {% if extra_css %}
         <link rel="stylesheet" href="{{ extra_css }}" type="text/css">
     {% endif %}
+
+    {% if contexts_json %}
+    <script type="text/javascript">
+      contexts = {{ contexts_json }}
+    </script>
+    {% endif %}
+
     <script type="text/javascript" src="coverage_html.js" defer></script>
 </head>
 <body class="pyfile">
@@ -117,11 +124,9 @@ <h2>
                 {% endif %}
             </span>
             {# Things that should appear below the line. #}
-            {% if line.context_list %}
+            {% if line.context_str %}
                 <span class="ctxs">
-                    {% for context in line.context_list %}
-                        <span>{{context}}</span>
-                    {% endfor %}
+                  {{ line.context_str }}
                 </span>
             {% endif %}
         </p>