git-commit.sh: convert run_status to a C builtin

This creates a new git-runstatus which should do roughly the same thing
as the run_status function from git-commit.sh. Except for color support,
the main focus has been to keep the output identical, so that it can be
verified as correct and then used as a C platform for other improvements to
the status printing code.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/wt-status.c b/wt-status.c
new file mode 100644
index 0000000..ec2c728
--- /dev/null
+++ b/wt-status.c
@@ -0,0 +1,271 @@
+#include "wt-status.h"
+#include "color.h"
+#include "cache.h"
+#include "object.h"
+#include "dir.h"
+#include "commit.h"
+#include "diff.h"
+#include "revision.h"
+#include "diffcore.h"
+
+int wt_status_use_color = 0;
+static char wt_status_colors[][COLOR_MAXLEN] = {
+	"",         /* WT_STATUS_HEADER: normal */
+	"\033[32m", /* WT_STATUS_UPDATED: green */
+	"\033[31m", /* WT_STATUS_CHANGED: red */
+	"\033[31m", /* WT_STATUS_UNTRACKED: red */
+};
+
+static int parse_status_slot(const char *var, int offset)
+{
+	if (!strcasecmp(var+offset, "header"))
+		return WT_STATUS_HEADER;
+	if (!strcasecmp(var+offset, "updated"))
+		return WT_STATUS_UPDATED;
+	if (!strcasecmp(var+offset, "changed"))
+		return WT_STATUS_CHANGED;
+	if (!strcasecmp(var+offset, "untracked"))
+		return WT_STATUS_UNTRACKED;
+	die("bad config variable '%s'", var);
+}
+
+static const char* color(int slot)
+{
+	return wt_status_use_color ? wt_status_colors[slot] : "";
+}
+
+void wt_status_prepare(struct wt_status *s)
+{
+	unsigned char sha1[20];
+	const char *head;
+
+	s->is_initial = get_sha1("HEAD", sha1) ? 1 : 0;
+
+	head = resolve_ref(git_path("HEAD"), sha1, 0);
+	s->branch = head ?
+		    strdup(head + strlen(get_git_dir()) + 1) :
+		    NULL;
+
+	s->reference = "HEAD";
+	s->amend = 0;
+	s->verbose = 0;
+	s->commitable = 0;
+}
+
+static void wt_status_print_header(const char *main, const char *sub)
+{
+	const char *c = color(WT_STATUS_HEADER);
+	color_printf_ln(c, "# %s:", main);
+	color_printf_ln(c, "#   (%s)", sub);
+	color_printf_ln(c, "#");
+}
+
+static void wt_status_print_trailer(void)
+{
+	color_printf_ln(color(WT_STATUS_HEADER), "#");
+}
+
+static void wt_status_print_filepair(int t, struct diff_filepair *p)
+{
+	const char *c = color(t);
+	color_printf(color(WT_STATUS_HEADER), "#\t");
+	switch (p->status) {
+	case DIFF_STATUS_ADDED:
+		color_printf(c, "new file: %s", p->one->path); break;
+	case DIFF_STATUS_COPIED:
+		color_printf(c, "copied: %s -> %s",
+				p->one->path, p->two->path);
+		break;
+	case DIFF_STATUS_DELETED:
+		color_printf_ln(c, "deleted: %s", p->one->path); break;
+	case DIFF_STATUS_MODIFIED:
+		color_printf(c, "modified: %s", p->one->path); break;
+	case DIFF_STATUS_RENAMED:
+		color_printf(c, "renamed: %s -> %s",
+				p->one->path, p->two->path);
+		break;
+	case DIFF_STATUS_TYPE_CHANGED:
+		color_printf(c, "typechange: %s", p->one->path); break;
+	case DIFF_STATUS_UNKNOWN:
+		color_printf(c, "unknown: %s", p->one->path); break;
+	case DIFF_STATUS_UNMERGED:
+		color_printf(c, "unmerged: %s", p->one->path); break;
+	default:
+		die("bug: unhandled diff status %c", p->status);
+	}
+	printf("\n");
+}
+
+static void wt_status_print_updated_cb(struct diff_queue_struct *q,
+		struct diff_options *options,
+		void *data)
+{
+	struct wt_status *s = data;
+	int shown_header = 0;
+	int i;
+	if (q->nr) {
+	}
+	for (i = 0; i < q->nr; i++) {
+		if (q->queue[i]->status == 'U')
+			continue;
+		if (!shown_header) {
+			wt_status_print_header("Updated but not checked in",
+					"will commit");
+			s->commitable = 1;
+			shown_header = 1;
+		}
+		wt_status_print_filepair(WT_STATUS_UPDATED, q->queue[i]);
+	}
+	if (shown_header)
+		wt_status_print_trailer();
+}
+
+static void wt_status_print_changed_cb(struct diff_queue_struct *q,
+                        struct diff_options *options,
+                        void *data)
+{
+	int i;
+	if (q->nr)
+		wt_status_print_header("Changed but not updated",
+				"use git-update-index to mark for commit");
+	for (i = 0; i < q->nr; i++)
+		wt_status_print_filepair(WT_STATUS_CHANGED, q->queue[i]);
+	if (q->nr)
+		wt_status_print_trailer();
+}
+
+void wt_status_print_initial(struct wt_status *s)
+{
+	int i;
+	read_cache();
+	if (active_nr) {
+		s->commitable = 1;
+		wt_status_print_header("Updated but not checked in",
+				"will commit");
+	}
+	for (i = 0; i < active_nr; i++) {
+		color_printf(color(WT_STATUS_HEADER), "#\t");
+		color_printf_ln(color(WT_STATUS_UPDATED), "new file: %s",
+				active_cache[i]->name);
+	}
+	if (active_nr)
+		wt_status_print_trailer();
+}
+
+static void wt_status_print_updated(struct wt_status *s)
+{
+	struct rev_info rev;
+	const char *argv[] = { NULL, NULL, NULL };
+	argv[1] = s->reference;
+	init_revisions(&rev, NULL);
+	setup_revisions(2, argv, &rev, NULL);
+	rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
+	rev.diffopt.format_callback = wt_status_print_updated_cb;
+	rev.diffopt.format_callback_data = s;
+	rev.diffopt.detect_rename = 1;
+	run_diff_index(&rev, 1);
+}
+
+static void wt_status_print_changed(struct wt_status *s)
+{
+	struct rev_info rev;
+	const char *argv[] = { NULL, NULL };
+	init_revisions(&rev, "");
+	setup_revisions(1, argv, &rev, NULL);
+	rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
+	rev.diffopt.format_callback = wt_status_print_changed_cb;
+	rev.diffopt.format_callback_data = s;
+	run_diff_files(&rev, 0);
+}
+
+static void wt_status_print_untracked(const struct wt_status *s)
+{
+	struct dir_struct dir;
+	const char *x;
+	int i;
+	int shown_header = 0;
+
+	memset(&dir, 0, sizeof(dir));
+
+	dir.exclude_per_dir = ".gitignore";
+	x = git_path("info/exclude");
+	if (file_exists(x))
+		add_excludes_from_file(&dir, x);
+
+	read_directory(&dir, ".", "", 0);
+	for(i = 0; i < dir.nr; i++) {
+		/* check for matching entry, which is unmerged; lifted from
+		 * builtin-ls-files:show_other_files */
+		struct dir_entry *ent = dir.entries[i];
+		int pos = cache_name_pos(ent->name, ent->len);
+		struct cache_entry *ce;
+		if (0 <= pos)
+			die("bug in wt_status_print_untracked");
+		pos = -pos - 1;
+		if (pos < active_nr) {
+			ce = active_cache[pos];
+			if (ce_namelen(ce) == ent->len &&
+			    !memcmp(ce->name, ent->name, ent->len))
+				continue;
+		}
+		if (!shown_header) {
+			wt_status_print_header("Untracked files",
+				"use \"git add\" to add to commit");
+			shown_header = 1;
+		}
+		color_printf(color(WT_STATUS_HEADER), "#\t");
+		color_printf_ln(color(WT_STATUS_UNTRACKED), "%.*s",
+				ent->len, ent->name);
+	}
+}
+
+static void wt_status_print_verbose(struct wt_status *s)
+{
+	struct rev_info rev;
+	const char *argv[] = { NULL, NULL, NULL };
+	argv[1] = s->reference;
+	init_revisions(&rev, NULL);
+	setup_revisions(2, argv, &rev, NULL);
+	rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
+	rev.diffopt.detect_rename = 1;
+	run_diff_index(&rev, 1);
+}
+
+void wt_status_print(struct wt_status *s)
+{
+	if (s->branch && strcmp(s->branch, "refs/heads/master"))
+		color_printf_ln(color(WT_STATUS_HEADER),
+			"# On branch %s", s->branch);
+
+	if (s->is_initial) {
+		color_printf_ln(color(WT_STATUS_HEADER), "#");
+		color_printf_ln(color(WT_STATUS_HEADER), "# Initial commit");
+		color_printf_ln(color(WT_STATUS_HEADER), "#");
+		wt_status_print_initial(s);
+	}
+	else {
+		wt_status_print_updated(s);
+		discard_cache();
+	}
+
+	wt_status_print_changed(s);
+	wt_status_print_untracked(s);
+
+	if (s->verbose && !s->is_initial)
+		wt_status_print_verbose(s);
+	if (!s->commitable)
+		printf("%s\n", s->amend ? "# No changes" : "nothing to commit");
+}
+
+int git_status_config(const char *k, const char *v)
+{
+	if (!strcmp(k, "status.color")) {
+		wt_status_use_color = git_config_colorbool(k, v);
+		return 0;
+	}
+	if (!strncmp(k, "status.color.", 13)) {
+		int slot = parse_status_slot(k, 13);
+		color_parse(v, k, wt_status_colors[slot]);
+	}
+	return git_default_config(k, v);
+}