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/command/cmd_ac.c

@@ -43,6 +43,7 @@
 static char* _sub_autocomplete(ProfWin* window, const char* const input, gboolean previous);
 static char* _notify_autocomplete(ProfWin* window, const char* const input, gboolean previous);
 static char* _theme_autocomplete(ProfWin* window, const char* const input, gboolean previous);
+static char* _spellcheck_autocomplete(ProfWin* window, const char* const input, gboolean previous);
 static char* _autoaway_autocomplete(ProfWin* window, const char* const input, gboolean previous);
 static char* _autoconnect_autocomplete(ProfWin* window, const char* const input, gboolean previous);
 static char* _account_autocomplete(ProfWin* window, const char* const input, gboolean previous);
@@ -138,6 +139,7 @@ static Autocomplete autoconnect_ac;
 static Autocomplete wintitle_ac;
 static Autocomplete theme_ac;
 static Autocomplete theme_load_ac;
+static Autocomplete spellcheck_ac;
 static Autocomplete account_ac;
 static Autocomplete account_set_ac;
 static Autocomplete account_clear_ac;
@@ -298,6 +300,7 @@ static Autocomplete* all_acs[] = {
     &autoconnect_ac,
     &wintitle_ac,
     &theme_ac,
+    &spellcheck_ac,
     &account_ac,
     &account_set_ac,
     &account_clear_ac,
@@ -563,6 +566,10 @@ cmd_ac_init(void)
     autocomplete_add(theme_ac, "colours");
     autocomplete_add(theme_ac, "properties");
 
+    autocomplete_add(spellcheck_ac, "on");
+    autocomplete_add(spellcheck_ac, "off");
+    autocomplete_add(spellcheck_ac, "lang");
+
     autocomplete_add(disco_ac, "info");
     autocomplete_add(disco_ac, "items");
 
@@ -1748,6 +1755,16 @@ cmd_ac_complete_filepath(const char* const input, char* const startstr, gboolean
     return autocomplete_param_with_ac(input, startstr, filepath_ac, TRUE, previous);
 }
 
+static char*
+_spellcheck_autocomplete(ProfWin* window, const char* const input, gboolean previous)
+{
+    char* result = NULL;
+
+    result = autocomplete_param_with_ac(input, "/spellcheck", spellcheck_ac, TRUE, previous);
+
+    return result;
+}
+
 static char*
 _cmd_ac_complete_params(ProfWin* window, const char* const input, gboolean previous)
 {
@@ -1767,6 +1784,11 @@ _cmd_ac_complete_params(ProfWin* window, const char* const input, gboolean previ
         }
     }
 
+    result = _spellcheck_autocomplete(window, input, previous);
+    if (result) {
+        return result;
+    }
+
     // autocomplete nickname in chat rooms
     if (window->type == WIN_MUC) {
         ProfMucWin* mucwin = (ProfMucWin*)window;

src/command/cmd_defs.c

@@ -1451,6 +1451,22 @@ static const struct cmd_t command_defs[] = {
               { "on|off", "Enable or disable splash logo." })
     },
 
+    { CMD_PREAMBLE("/spellcheck",
+                   parse_args, 1, 2, &cons_spellcheck_setting)
+      CMD_MAINFUNC(cmd_spellcheck)
+      CMD_TAGS(
+              CMD_TAG_UI)
+      CMD_SYN(
+              "/spellcheck on|off",
+              "/spellcheck lang <locale>")
+      CMD_DESC(
+              "Enable or disable spellchecking, or set the language.")
+      CMD_ARGS(
+              { "on|off", "Enable or disable spellchecking." },
+              { "list", "List available dictionaries recognized by Enchant." },
+              { "lang <locale>", "Set the spellcheck language (en_US)." })
+    },
+
     { CMD_PREAMBLE("/autoconnect",
                    parse_args, 1, 2, &cons_autoconnect_setting)
       CMD_MAINFUNC(cmd_autoconnect)

src/command/cmd_funcs.c

@@ -54,6 +54,7 @@
 #include "tools/plugin_download.h"
 #include "tools/bookmark_ignore.h"
 #include "tools/editor.h"
+#include "tools/spellcheck.h"
 #include "plugins/plugins.h"
 #include "ui/inputwin.h"
 #include "ui/ui.h"
@@ -6560,6 +6561,37 @@ cmd_splash(ProfWin* window, const char* const command, gchar** args)
     return TRUE;
 }
 
+gboolean
+cmd_spellcheck(ProfWin* window, const char* const command, gchar** args)
+{
+#ifdef HAVE_SPELLCHECK
+    if (g_strcmp0(args[0], "on") == 0) {
+        prefs_set_boolean(PREF_SPELLCHECK_ENABLE, TRUE);
+        cons_show("Spellcheck enabled.");
+    } else if (g_strcmp0(args[0], "off") == 0) {
+        prefs_set_boolean(PREF_SPELLCHECK_ENABLE, FALSE);
+        cons_show("Spellcheck disabled.");
+    } else if (g_strcmp0(args[0], "lang") == 0) {
+        if (args[1] == NULL) {
+            cons_bad_cmd_usage(command);
+        } else {
+            if (spellcheck_set_lang(args[1])) {
+                prefs_set_string(PREF_SPELLCHECK_LANG, args[1]);
+                cons_show("Spellcheck language set to: %s", args[1]);
+            } else {
+                cons_show("Failed to set spellcheck language to: %s. Is the dictionary installed?", args[1]);
+            }
+        }
+    } else {
+        cons_bad_cmd_usage(command);
+    }
+#else
+    cons_show("Profanity was built without spellcheck support.");
+#endif
+
+    return TRUE;
+}
+
 gboolean
 cmd_autoconnect(ProfWin* window, const char* const command, gchar** args)
 {

src/command/cmd_funcs.h

@@ -103,6 +103,7 @@ gboolean cmd_bookmark_ignore(ProfWin* window, const char* const command, gchar**
 gboolean cmd_roster(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_software(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_splash(ProfWin* window, const char* const command, gchar** args);
+gboolean cmd_spellcheck(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_states(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_status_get(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_status_set(ProfWin* window, const char* const command, gchar** args);