feat: add spellcheck highlighting support

Introduce optional spellcheck highlighting in the input window using
the Enchant-2 library.

```
/spellcheck on
/spellcheck lang en_US
```

New theme color `input.misspelled`.

Fixes: https://github.com/profanity-im/profanity/issues/183
Signed-off-by: Michael Vetter <jubalh@iodoru.org>

src/ui/console.c

@@ -1270,6 +1270,21 @@ cons_splash_setting(void)
         cons_show("Splash screen (/splash)             : OFF");
 }
 
+void
+cons_spellcheck_setting(void)
+{
+#ifdef HAVE_SPELLCHECK
+    if (prefs_get_boolean(PREF_SPELLCHECK_ENABLE)) {
+        auto_gchar gchar* lang = prefs_get_string(PREF_SPELLCHECK_LANG);
+        cons_show("Spellcheck (/spellcheck)            : ON (%s)", lang);
+    } else {
+        cons_show("Spellcheck (/spellcheck)            : OFF");
+    }
+#else
+    cons_show("Spellcheck (/spellcheck)            : built without spellcheck support");
+#endif
+}
+
 void
 cons_occupants_setting(void)
 {
@@ -1589,6 +1604,7 @@ cons_show_ui_prefs(void)
     cons_beep_setting();
     cons_flash_setting();
     cons_splash_setting();
+    cons_spellcheck_setting();
     cons_winpos_setting();
     cons_wrap_setting();
     cons_time_setting();
@@ -2572,6 +2588,7 @@ cons_theme_properties(void)
     _cons_theme_prop(console, THEME_RECEIPT_SENT, "receipt.sent");
 
     _cons_theme_prop(console, THEME_INPUT_TEXT, "input.text");
+    _cons_theme_prop(console, THEME_INPUT_MISSPELLED, "input.misspelled");
 
     cons_show("");
 }

src/ui/inputwin.c

@@ -50,6 +50,7 @@
 #include "xmpp/roster_list.h"
 #include "xmpp/chat_state.h"
 #include "tools/editor.h"
+#include "tools/spellcheck.h"
 
 static WINDOW* inp_win;
 static int pad_start = 0;
@@ -327,6 +328,8 @@ _inp_write(char* line, int offset)
     getyx(inp_win, y, x);
     col += x;
 
+    gboolean do_spell = prefs_get_boolean(PREF_SPELLCHECK_ENABLE) && (line[0] != '/');
+
     for (size_t i = 0; line[i] != '\0'; i++) {
         char* c = &line[i];
         char retc[PROF_MB_CUR_MAX] = { 0 };
@@ -348,6 +351,47 @@ _inp_write(char* line, int offset)
             i += ch_len - 1;
         }
 
+        if (do_spell) {
+            gunichar uc = g_utf8_get_char(c);
+            if (g_unichar_isalnum(uc) || uc == '\'') {
+                // start of a word
+                size_t start = i - (ch_len - 1);
+                size_t end = start + ch_len;
+                while (line[end] != '\0') {
+                    size_t next_ch_len = mbrlen(&line[end], MB_CUR_MAX, NULL);
+                    if (next_ch_len == (size_t)-2 || next_ch_len == (size_t)-1)
+                        break;
+                    gunichar next_uc = g_utf8_get_char(&line[end]);
+                    if (!g_unichar_isalnum(next_uc) && next_uc != '\'')
+                        break;
+                    end += next_ch_len;
+                }
+
+                char* word = g_strndup(&line[start], end - start);
+                gboolean misspelled = spellcheck_is_misspelled(word);
+                g_free(word);
+
+                if (misspelled) {
+                    wattron(inp_win, theme_attrs(THEME_INPUT_MISSPELLED));
+                }
+
+                // add the word
+                size_t word_pos = start;
+                while (word_pos < end) {
+                    size_t cur_ch_len = mbrlen(&line[word_pos], MB_CUR_MAX, NULL);
+                    waddnstr(inp_win, &line[word_pos], cur_ch_len);
+                    word_pos += cur_ch_len;
+                }
+
+                if (misspelled) {
+                    wattroff(inp_win, theme_attrs(THEME_INPUT_MISSPELLED));
+                }
+
+                i = end - 1;
+                continue;
+            }
+        }
+
         waddnstr(inp_win, c, ch_len);
     }
 

src/ui/ui.h

@@ -284,6 +284,7 @@ void cons_console_setting(void);
 void cons_flash_setting(void);
 void cons_tray_setting(void);
 void cons_splash_setting(void);
+void cons_spellcheck_setting(void);
 void cons_titlebar_setting(void);
 void cons_vercheck_setting(void);
 void cons_occupants_setting(void);