Shell: Tab completes a path on the SD card (#67)

Past the command's name, Tab completes the word being typed as a path: a
folder keeps its slash to go on from, a file completed whole gets a space,
several candidates are listed. Any case typed, the name's own is taken.
After a file command the first slash is understood (`cat no` is /no).
The folder is read on the storage task, bounded to 400 entries looked at
and 24 candidates.

489 host tests (2 new). Checked on the device: a folder, a file inside it,
several candidates, no slash, another case, nothing matching.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

test/test_shell_log/test_shell_log.cpp

@@ -77,6 +77,57 @@ void test_tab_completes_the_first_word() {
     TEST_ASSERT_EQUAL_STRING("n", completeCommand("n", words, matches).c_str());       // and no command starts with n here
 }
 
+void test_a_later_word_is_taken_apart_as_a_path() {
+    PathToComplete p;
+    TEST_ASSERT_FALSE(splitForPath("ls", p));        // still the command
+    TEST_ASSERT_FALSE(splitForPath("rm -r", p));     // a switch
+    TEST_ASSERT_FALSE(splitForPath("irc say he", p));  // not a path, and irc doesn't take one
+    TEST_ASSERT_TRUE(splitForPath("rm -r /notes/sh", p));
+    TEST_ASSERT_EQUAL_STRING("rm -r ", p.head.c_str());
+    TEST_ASSERT_EQUAL_STRING("/notes/", p.folder.c_str());
+    TEST_ASSERT_EQUAL_STRING("sh", p.prefix.c_str());
+    TEST_ASSERT_TRUE(splitForPath("ls /", p));
+    TEST_ASSERT_EQUAL_STRING("/", p.folder.c_str());
+    TEST_ASSERT_EQUAL_STRING("", p.prefix.c_str());
+    TEST_ASSERT_TRUE(splitForPath("cat no", p));  // a file command: the slash is understood
+    TEST_ASSERT_EQUAL_STRING("cat ", p.head.c_str());
+    TEST_ASSERT_EQUAL_STRING("/", p.folder.c_str());
+    TEST_ASSERT_EQUAL_STRING("no", p.prefix.c_str());
+    TEST_ASSERT_TRUE(splitForPath("ls ", p));
+    TEST_ASSERT_EQUAL_STRING("/", p.folder.c_str());
+    TEST_ASSERT_TRUE(splitForPath("gemini get /x", p));  // any word that starts with a slash
+    TEST_ASSERT_TRUE(splitForPath("cp /notes/a.txt /gem", p));  // the second path of two
+    TEST_ASSERT_EQUAL_STRING("cp /notes/a.txt ", p.head.c_str());
+    TEST_ASSERT_EQUAL_STRING("gem", p.prefix.c_str());
+}
+
+void test_tab_completes_a_path() {
+    std::vector<std::string> root = {"captures/", "gemini/", "gnss/", "irc/", "notes/", "updates/", "wifi/", "readme.txt"};
+    std::vector<std::string> matches;
+    PathToComplete p;
+    splitForPath("ls /no", p);
+    TEST_ASSERT_EQUAL_STRING("ls /notes/", completePath(p, root, matches).c_str());  // a folder: its slash, to go on
+    TEST_ASSERT_EQUAL(0, matches.size());
+    splitForPath("cat /re", p);
+    TEST_ASSERT_EQUAL_STRING("cat /readme.txt ", completePath(p, root, matches).c_str());  // a file: done, a space
+    splitForPath("ls /g", p);
+    TEST_ASSERT_EQUAL_STRING("ls /g", completePath(p, root, matches).c_str());  // gemini, gnss: they agree on no more
+    TEST_ASSERT_EQUAL(2, matches.size());
+    TEST_ASSERT_EQUAL_STRING("gemini/", matches[0].c_str());
+    splitForPath("ls /zz", p);
+    TEST_ASSERT_EQUAL_STRING("ls /zz", completePath(p, root, matches).c_str());  // nothing: as it was
+    TEST_ASSERT_EQUAL(0, matches.size());
+    splitForPath("rm -r /NO", p);  // the card doesn't tell cases apart: the name's own case is taken
+    TEST_ASSERT_EQUAL_STRING("rm -r /notes/", completePath(p, root, matches).c_str());
+    std::vector<std::string> notes = {"shopping-list.txt", "Shed.txt", "todo.txt"};
+    splitForPath("cat /notes/sh", p);
+    TEST_ASSERT_EQUAL_STRING("cat /notes/sh", completePath(p, notes, matches).c_str());  // "sh" and "Sh": as far as they agree
+    TEST_ASSERT_EQUAL(2, matches.size());
+    splitForPath("cat /notes/", p);
+    TEST_ASSERT_EQUAL_STRING("cat /notes/", completePath(p, notes, matches).c_str());  // everything fits: the list
+    TEST_ASSERT_EQUAL(3, matches.size());
+}
+
 int main(int, char**) {
     UNITY_BEGIN();
     RUN_TEST(test_lines_arrive_in_pieces);
@@ -84,5 +135,7 @@ int main(int, char**) {
     RUN_TEST(test_the_oldest_lines_go_past_4_kb);
     RUN_TEST(test_command_words_come_from_the_help_text);
     RUN_TEST(test_tab_completes_the_first_word);
+    RUN_TEST(test_a_later_word_is_taken_apart_as_a_path);
+    RUN_TEST(test_tab_completes_a_path);
     return UNITY_END();
 }