AWS: Implement diffing of solutions

cms/server/admin/handlers/__init__.py

@@ -79,7 +79,8 @@
     SubmissionHandler, \
     SubmissionCommentHandler, \
     SubmissionOfficialStatusHandler, \
-    SubmissionFileHandler
+    SubmissionFileHandler, \
+    SubmissionDiffHandler
 from .task import \
     AddTaskHandler, \
     TaskHandler, \
@@ -215,12 +216,13 @@
     (r"/submission/([0-9]+)(?:/([0-9]+))?/comment", SubmissionCommentHandler),
     (r"/submission/([0-9]+)(?:/([0-9]+))?/official", SubmissionOfficialStatusHandler),
     (r"/submission_file/([0-9]+)", SubmissionFileHandler),
+    (r"/submission_diff/([0-9]+)/([0-9]+)", SubmissionDiffHandler),
 
     # User tests
 
     (r"/user_test/([0-9]+)(?:/([0-9]+))?", UserTestHandler),
     (r"/user_test_file/([0-9]+)", UserTestFileHandler),
-    
+
     # The following prefixes are handled by WSGI middlewares:
     # * /rpc, defined in cms/io/web_service.py
     # * /static, defined in cms/io/web_service.py

cms/server/admin/handlers/submission.py

@@ -26,7 +26,9 @@
 
 """
 
+import json
 import logging
+import difflib
 
 from cms.db import Dataset, File, Submission
 from cms.grading.languagemanager import get_language
@@ -88,6 +90,89 @@ def get(self, file_id):
         self.fetch(digest, "text/plain", real_filename)
 
 
+class SubmissionDiffHandler(BaseHandler):
+    """Shows a diff between two submissions.
+    """
+    @require_permission(BaseHandler.AUTHENTICATED)
+    def get(self, old_id, new_id):
+        sub_old = Submission.get_from_id(old_id, self.sql_session)
+        sub_new = Submission.get_from_id(new_id, self.sql_session)
+
+        self.set_header("Content-type", "application/json; charset=utf-8")
+        resp = {
+            'message': None,
+            'files': []
+        }
+
+        if sub_old is None or sub_new is None:
+            missing_id = old_id if sub_old is None else new_id
+            resp['message'] = f"Submission ID {missing_id} not found."
+            self.write(json.dumps(resp))
+            return
+
+        if sub_old.task_id == sub_new.task_id:
+            files_to_compare = sub_old.task.submission_format
+            old_files = sub_old.files
+            new_files = sub_new.files
+        elif len(sub_old.files) == 1 and len(sub_new.files) == 1:
+            old_file = list(sub_old.files.values())[0]
+            old_files = {"submission.%l": old_file}
+            new_file = list(sub_new.files.values())[0]
+            new_files = {"submission.%l": new_file}
+            files_to_compare = ["submission.%l"]
+        else:
+            resp['message'] = "Cannot compare submissions: they are for " \
+                "different tasks and have more than 1 file."
+            self.write(json.dumps(resp))
+            return
+
+        result_files = []
+        for fname in files_to_compare:
+            if ".%l" in fname:
+                if sub_old.language == sub_new.language and sub_old.language is not None:
+                    ext = get_language(sub_old.language).source_extension
+                else:
+                    ext = ".txt"
+                real_fname = fname.replace(".%l", ext)
+            else:
+                real_fname = fname
+
+            def get_file(x, which):
+                if fname not in x:
+                    return None, f"File not present in {which} submission"
+                digest = x[fname].digest
+                file_bin = self.service.file_cacher.get_file_content(digest)
+                if len(file_bin) > 1000000:
+                    return None, f"{which} file is too big to diff".capitalize()
+                file_lines = file_bin.decode(errors='replace').splitlines()
+                if len(file_lines) > 5000:
+                    return None, f"{which} file has too many lines to diff".capitalize()
+                return file_lines, None
+
+            old_content, old_status = get_file(old_files, "old")
+            if old_status:
+                result_files.append({"fname": real_fname, "status": old_status})
+                continue
+            new_content, new_status = get_file(new_files, "new")
+            if new_status:
+                result_files.append({"fname": real_fname, "status": new_status})
+                continue
+
+            if old_content == new_content:
+                result_files.append({"fname": real_fname, "status": "No changes"})
+            else:
+                diff_iter = difflib.unified_diff(old_content, new_content, lineterm='')
+                # skip the "---" and "+++" lines.
+                next(diff_iter)
+                next(diff_iter)
+                diff = '\n'.join(diff_iter)
+
+                result_files.append({"fname": real_fname, "diff": diff})
+
+        resp['files'] = result_files
+        self.write(json.dumps(resp))
+
+
 class SubmissionCommentHandler(BaseHandler):
     """Called when the admin comments on a submission.
 

cms/server/admin/static/aws_style.css

@@ -742,3 +742,10 @@ a.button-link {
 a.button-link:hover {
     background-color: #EEF3EA;
 }
+
+th.diff-only, td.diff-only {
+    display: none;
+}
+table.diff-open th.diff-only, table.diff-open td.diff-only {
+    display: table-cell;
+}

cms/server/admin/static/aws_utils.js

@@ -91,6 +91,25 @@ document.addEventListener('keydown', function(event) {
     }
 });
 
+CMS.AWSUtils.filename_to_lang = function(file_name) {
+    // TODO: update if adding a new language to cms
+    // (need to also update the prism bundle then)
+    var extension_to_lang = {
+        'cs': 'csharp',
+        'cpp': 'cpp',
+        'c': 'c',
+        'h': 'c',
+        'go': 'go',
+        'hs': 'haskell',
+        'java': 'java',
+        'js': 'javascript',
+        'php': 'php',
+        'py': 'python',
+        'rs': 'rust',
+    }
+    var file_ext = file_name.split('.').pop();
+    return extension_to_lang[file_ext] || file_ext;
+}
 
 /**
  * This is called when we receive file content, or an error message.
@@ -114,23 +133,7 @@ CMS.AWSUtils.prototype.file_received = function(response, error) {
             this.display_subpage(elements);
             return;
         }
-        // TODO: update if adding a new language to cms
-        // (need to also update the prism bundle then)
-        var extension_to_lang = {
-            'cs': 'csharp',
-            'cpp': 'cpp',
-            'c': 'c',
-            'h': 'c',
-            'go': 'go',
-            'hs': 'haskell',
-            'java': 'java',
-            'js': 'javascript',
-            'php': 'php',
-            'py': 'python',
-            'rs': 'rust',
-        }
-        var file_ext = file_name.split('.').pop();
-        var lang_name = extension_to_lang[file_ext] || file_ext;
+        var lang_name = CMS.AWSUtils.filename_to_lang(file_name);
 
         elements.push($('<h1>').text(file_name));
         elements.push($('<a>').text("Download").prop("href", url));
@@ -903,3 +906,70 @@ CMS.AWSUtils.prototype.render_markdown_preview = function(target) {
         },
     });
 }
+
+/**
+ * Handlers for diffing submissions.
+ */
+
+/**
+ * Shows/hides the diff radio buttons when opening/closing the diff section.
+ */
+CMS.AWSUtils.prototype.update_diffchooser = function() {
+    var el = document.getElementById("diffchooser");
+    if(el.open) {
+        $("#submissions_table").addClass("diff-open");
+    } else {
+        $("#submissions_table").removeClass("diff-open");
+    }
+}
+
+/**
+ * Updates the submission ID inputs when clicking diff radio buttons.
+ */
+CMS.AWSUtils.prototype.update_diff_ids = function(ev) {
+    var name = ev.target.name;
+    var sub_id = ev.target.dataset.submission;
+    if(name == "diff-radio-old") {
+        $("#diff-old-input").val(sub_id);
+    } else {
+        $("#diff-new-input").val(sub_id);
+    }
+}
+
+/**
+ * Renders a diff that was received from the server.
+ */
+CMS.AWSUtils.prototype.show_diff = function(response, error) {
+    if(error !== null) {
+        this.display_subpage([$('<p>').text('Error: ' + error)]);
+        return;
+    }
+    var elements = [];
+    if(response.message !== null) {
+        elements.push($('<p>').text(response.message));
+    }
+    for(let x of response.files) {
+        elements.push($('<h2>').text(x.fname));
+        if('status' in x) {
+            elements.push($('<p>').text(x.status));
+            continue;
+        }
+        var lang_name = CMS.AWSUtils.filename_to_lang(x.fname);
+        var codearea = $('<code>').text(x.diff)
+            .addClass('language-diff-' + lang_name)
+            .addClass('diff-highlight');
+        elements.push($('<pre>').append(codearea));
+    }
+    this.display_subpage(elements);
+    Prism.highlightAllUnder(document.getElementById('subpage_content'));
+}
+
+/**
+ * Called when "Diff" button is clicked, requests the diff from the server.
+ */
+CMS.AWSUtils.prototype.do_diff = function() {
+    var old_id = $("#diff-old-input").val();
+    var new_id = $("#diff-new-input").val();
+    var show_diff = this.bind_func(this, this.show_diff);
+    this.ajax_request(this.url("submission_diff", old_id, new_id), null, show_diff);
+}