From 1d7903ae033eae21a5b2a6b13d247f0c56d25a18 Mon Sep 17 00:00:00 2001
From: Přemysl Janouch <p.janouch@gmail.com>
Date: Thu, 7 May 2015 06:37:50 +0200
Subject: degesch: implement some autocompletion

---
 degesch.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 107 insertions(+), 7 deletions(-)

diff --git a/degesch.c b/degesch.c
index 1e82ee3..54f523e 100644
--- a/degesch.c
+++ b/degesch.c
@@ -5065,7 +5065,7 @@ completion_add_word (struct completion *self, size_t start, size_t end)
 		self->words = xcalloc ((self->words_alloc = 4), sizeof *self->words);
 	if (self->words_len == self->words_alloc)
 		self->words = xrealloc (self->words, (self->words_alloc <<= 1));
-	self->words[self->words_len] = (struct completion_word) { start, end };
+	self->words[self->words_len++] = (struct completion_word) { start, end };
 }
 
 static void
@@ -5098,6 +5098,17 @@ completion_locate (struct completion *self, size_t offset)
 	self->location = i - 1;
 }
 
+static bool
+completion_matches (struct completion *self, int word, const char *pattern)
+{
+	hard_assert (word >= 0 && word < (int) self->words_len);
+	char *text = xstrndup (self->line + self->words[word].start,
+		self->words[word].end - self->words[word].start);
+	bool result = !fnmatch (pattern, text, 0);
+	free (text);
+	return result;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 struct utf8_iter
@@ -5168,16 +5179,105 @@ utf8_common_prefix (const char **vector, size_t len)
 	return prefix;
 }
 
+static void
+complete_command (struct app_context *ctx, struct completion *data,
+	const char *word, struct str_vector *output)
+{
+	(void) ctx;
+	(void) data;
+
+	const char *prefix = "";
+	if (*word == '/')
+	{
+		word++;
+		prefix = "/";
+	}
+
+	for (size_t i = 0; i < N_ELEMENTS (g_command_handlers); i++)
+	{
+		struct command_handler *handler = &g_command_handlers[i];
+		// FIXME: we want an ASCII version
+		if (!strncasecmp (word, handler->name, strlen (word)))
+			str_vector_add_owned (output,
+				xstrdup_printf ("%s%s", prefix, handler->name));
+	}
+}
+
+static void
+complete_option (struct app_context *ctx, struct completion *data,
+	const char *word, struct str_vector *output)
+{
+	(void) data;
+
+	struct str_vector options;
+	str_vector_init (&options);
+
+	// Wildcard expansion is an interesting side-effect
+	char *x = xstrdup_printf ("%s*", word);
+	dump_matching_options (ctx, x, &options);
+	free (x);
+
+	str_vector_add_vector (output, options.vector);
+	str_vector_free (&options);
+}
+
+static void
+complete_nicknames (struct app_context *ctx, struct completion *data,
+	const char *word, struct str_vector *output)
+{
+	// TODO; if (data->location == 0) --> add colons to nicknames
+}
+
 static char **
 complete_word (struct app_context *ctx, struct completion *data,
 	const char *word)
 {
-	// TODO: return a list of matches with the longest common part
-	//   (or a copy of "word" if none) as the first entry
-	// TODO: if there's only one match, don't bother computing the common part
-	char **result = xcalloc (2, sizeof *result);
-	result[0] = xstrdup_printf ("%shue", word);
-	return result;
+	// First figure out what exactly do we need to complete
+	bool try_commands = false;
+	bool try_options = false;
+	bool try_nicknames = false;
+
+	if (data->location == 0 && completion_matches (data, 0, "/*"))
+		try_commands = true;
+	else if (data->location == 1 && completion_matches (data, 0, "/set"))
+		try_options = true;
+	else if (data->location == 1 && completion_matches (data, 0, "/help"))
+		try_commands = try_options = true;
+	else
+		try_nicknames = true;
+
+	struct str_vector words;
+	str_vector_init (&words);
+
+	// Add placeholder
+	str_vector_add_owned (&words, NULL);
+
+	if (try_commands)   complete_command (ctx, data, word, &words);
+	if (try_options)    complete_option (ctx, data, word, &words);
+	if (try_nicknames)  complete_nicknames (ctx, data, word, &words);
+
+	if (words.len == 1)
+	{
+		// Nothing matched
+		str_vector_free (&words);
+		return NULL;
+	}
+
+	if (words.len == 2)
+	{
+		words.vector[0] = words.vector[1];
+		words.vector[1] = NULL;
+	}
+	else
+	{
+		size_t prefix = utf8_common_prefix
+			((const char **) words.vector + 1, words.len - 1);
+		if (!prefix)
+			words.vector[0] = xstrdup (word);
+		else
+			words.vector[0] = xstrndup (words.vector[1], prefix);
+	}
+	return words.vector;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-- 
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