survey: start pretty printing data in table form

When 'git survey' provides information to the user, this will be presented
in one of two formats: plaintext and JSON. The JSON implementation will be
delayed until the functionality is complete for the plaintext format.

The most important parts of the plaintext format are headers specifying the
different sections of the report and tables providing concreted data.

Create a custom table data structure that allows specifying a list of
strings for the row values. When printing the table, check each column for
the maximum width so we can create a table of the correct size from the
start.

The table structure is designed to be flexible to the different kinds of
output that will be implemented in future changes.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

Documentation/git-survey.adoc

@@ -65,6 +65,13 @@ OUTPUT
 By default, `git survey` will print information about the repository in a
 human-readable format that includes overviews and tables.
 
+References Summary
+~~~~~~~~~~~~~~~~~~
+
+The references summary includes a count of each kind of reference,
+including branches, remote refs, and tags (split by "all" and
+"annotated").
+
 GIT
 ---
 Part of the linkgit:git[1] suite

builtin/survey.c

@@ -7,6 +7,7 @@
 #include "parse-options.h"
 #include "progress.h"
 #include "ref-filter.h"
+#include "strbuf.h"
 #include "strvec.h"
 #include "trace2.h"
 
@@ -80,6 +81,160 @@ static void clear_survey_context(struct survey_context *ctx)
 	strvec_clear(&ctx->refs);
 }
 
+struct survey_table {
+	const char *table_name;
+	struct strvec header;
+	struct strvec *rows;
+	size_t rows_nr;
+	size_t rows_alloc;
+};
+
+#define SURVEY_TABLE_INIT {	\
+	.header = STRVEC_INIT,	\
+}
+
+static void clear_table(struct survey_table *table)
+{
+	strvec_clear(&table->header);
+	for (size_t i = 0; i < table->rows_nr; i++)
+		strvec_clear(&table->rows[i]);
+	free(table->rows);
+}
+
+static void insert_table_rowv(struct survey_table *table, ...)
+{
+	va_list ap;
+	char *arg;
+	ALLOC_GROW(table->rows, table->rows_nr + 1, table->rows_alloc);
+
+	memset(&table->rows[table->rows_nr], 0, sizeof(struct strvec));
+
+	va_start(ap, table);
+	while ((arg = va_arg(ap, char *)))
+		strvec_push(&table->rows[table->rows_nr], arg);
+	va_end(ap);
+
+	table->rows_nr++;
+}
+
+#define SECTION_SEGMENT "========================================"
+#define SECTION_SEGMENT_LEN 40
+static const char *section_line = SECTION_SEGMENT
+				  SECTION_SEGMENT
+				  SECTION_SEGMENT
+				  SECTION_SEGMENT;
+static const size_t section_len = 4 * SECTION_SEGMENT_LEN;
+
+static void print_table_title(const char *name, size_t *widths, size_t nr)
+{
+	size_t width = 3 * (nr - 1);
+
+	for (size_t i = 0; i < nr; i++)
+		width += widths[i];
+
+	if (width > section_len)
+		width = section_len;
+
+	printf("\n%s\n%.*s\n", name, (int)width, section_line);
+}
+
+static void print_row_plaintext(struct strvec *row, size_t *widths)
+{
+	static struct strbuf line = STRBUF_INIT;
+	strbuf_setlen(&line, 0);
+
+	for (size_t i = 0; i < row->nr; i++) {
+		const char *str = row->v[i];
+		size_t len = strlen(str);
+		if (i)
+			strbuf_add(&line, " | ", 3);
+		strbuf_addchars(&line, ' ', widths[i] - len);
+		strbuf_add(&line, str, len);
+	}
+	printf("%s\n", line.buf);
+}
+
+static void print_divider_plaintext(size_t *widths, size_t nr)
+{
+	static struct strbuf line = STRBUF_INIT;
+	strbuf_setlen(&line, 0);
+
+	for (size_t i = 0; i < nr; i++) {
+		if (i)
+			strbuf_add(&line, "-+-", 3);
+		strbuf_addchars(&line, '-', widths[i]);
+	}
+	printf("%s\n", line.buf);
+}
+
+static void print_table_plaintext(struct survey_table *table)
+{
+	size_t *column_widths;
+	size_t columns_nr = table->header.nr;
+	CALLOC_ARRAY(column_widths, columns_nr);
+
+	for (size_t i = 0; i < columns_nr; i++) {
+		column_widths[i] = strlen(table->header.v[i]);
+
+		for (size_t j = 0; j < table->rows_nr; j++) {
+			size_t rowlen = strlen(table->rows[j].v[i]);
+			if (column_widths[i] < rowlen)
+				column_widths[i] = rowlen;
+		}
+	}
+
+	print_table_title(table->table_name, column_widths, columns_nr);
+	print_row_plaintext(&table->header, column_widths);
+	print_divider_plaintext(column_widths, columns_nr);
+
+	for (size_t j = 0; j < table->rows_nr; j++)
+		print_row_plaintext(&table->rows[j], column_widths);
+
+	free(column_widths);
+}
+
+static void survey_report_plaintext_refs(struct survey_context *ctx)
+{
+	struct survey_report_ref_summary *refs = &ctx->report.refs;
+	struct survey_table table = SURVEY_TABLE_INIT;
+
+	table.table_name = _("REFERENCES SUMMARY");
+
+	strvec_push(&table.header, _("Ref Type"));
+	strvec_push(&table.header, _("Count"));
+
+	if (ctx->opts.refs.want_all_refs || ctx->opts.refs.want_branches) {
+		char *fmt = xstrfmt("%"PRIuMAX"", (uintmax_t)refs->branches_nr);
+		insert_table_rowv(&table, _("Branches"), fmt, NULL);
+		free(fmt);
+	}
+
+	if (ctx->opts.refs.want_all_refs || ctx->opts.refs.want_remotes) {
+		char *fmt = xstrfmt("%"PRIuMAX"", (uintmax_t)refs->remote_refs_nr);
+		insert_table_rowv(&table, _("Remote refs"), fmt, NULL);
+		free(fmt);
+	}
+
+	if (ctx->opts.refs.want_all_refs || ctx->opts.refs.want_tags) {
+		char *fmt = xstrfmt("%"PRIuMAX"", (uintmax_t)refs->tags_nr);
+		insert_table_rowv(&table, _("Tags (all)"), fmt, NULL);
+		free(fmt);
+		fmt = xstrfmt("%"PRIuMAX"", (uintmax_t)refs->tags_annotated_nr);
+		insert_table_rowv(&table, _("Tags (annotated)"), fmt, NULL);
+		free(fmt);
+	}
+
+	print_table_plaintext(&table);
+	clear_table(&table);
+}
+
+static void survey_report_plaintext(struct survey_context *ctx)
+{
+	printf("GIT SURVEY for \"%s\"\n", ctx->repo->worktree);
+	printf("-----------------------------------------------------\n");
+	survey_report_plaintext_refs(ctx);
+}
+
 /*
  * After parsing the command line arguments, figure out which refs we
  * should scan.
@@ -318,6 +473,8 @@ int cmd_survey(int argc, const char **argv, const char *prefix, struct repositor
 
 	survey_phase_refs(&ctx);
 
+	survey_report_plaintext(&ctx);
+
 	clear_survey_context(&ctx);
 	return 0;
 }

t/t8100-git-survey.sh

@@ -21,7 +21,23 @@ test_expect_success 'create a semi-interesting repo' '
 
 test_expect_success 'git survey (default)' '
 	git survey >out 2>err &&
-	test_line_count = 0 err
+	test_line_count = 0 err &&
+
+	tr , " " >expect <<-EOF &&
+	GIT SURVEY for "$(pwd)"
+	-----------------------------------------------------
+
+	REFERENCES SUMMARY
+	========================
+	,       Ref Type | Count
+	-----------------+------
+	,       Branches |     1
+	     Remote refs |     0
+	      Tags (all) |     0
+	Tags (annotated) |     0
+	EOF
+
+	test_cmp expect out
 '
 
 test_done