[PATCH 12/30] survey: start pretty printing data in table form

["Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>]

From: Derrick Stolee <stolee@gmail.com>

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>
---
 builtin/survey.c      | 175 ++++++++++++++++++++++++++++++++++++++++++
 t/t8100-git-survey.sh |  17 +++-
 2 files changed, 191 insertions(+), 1 deletion(-)

diff --git a/builtin/survey.c b/builtin/survey.c
index 1b4fe591e59..b2104e84d61 100644
--- a/builtin/survey.c
+++ b/builtin/survey.c
@@ -5,6 +5,7 @@
 #include "parse-options.h"
 #include "progress.h"
 #include "ref-filter.h"
+#include "strbuf.h"
 #include "strvec.h"
 #include "trace2.h"
 
@@ -27,10 +28,16 @@ static struct survey_refs_wanted default_ref_options = {
 	.want_all_refs = 1,
 };
 
+enum survey_format {
+	SURVEY_PLAINTEXT = 0,
+	SURVEY_JSON = 1,
+};
+
 struct survey_opts {
 	int verbose;
 	int show_progress;
 	struct survey_refs_wanted refs;
+	enum survey_format format;
 };
 
 struct survey_report_ref_summary {
@@ -78,6 +85,161 @@ 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++;
+}
+
+static void print_table_title(const char *name, size_t *widths, size_t nr)
+{
+	static struct strbuf lines = STRBUF_INIT;
+	size_t width = 0;
+	strbuf_setlen(&lines, 0);
+
+	strbuf_addch(&lines, ' ');
+	strbuf_addstr(&lines, name);
+	strbuf_addch(&lines, '\n');
+
+	for (size_t i = 0; i < nr; i++) {
+		if (i)
+			width += 3;
+		width += widths[i];
+	}
+	strbuf_addchars(&lines, '=', width);
+	printf("%s\n", lines.buf);
+}
+
+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);
+}
+
+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"", 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"", 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"", refs->tags_nr);
+		insert_table_rowv(&table, _("Tags (all)"), fmt, NULL);
+		free(fmt);
+		fmt = xstrfmt("%"PRIuMAX"", 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);
+}
+
+static void survey_report_json(struct survey_context *ctx)
+{
+	/* TODO. */
+}
+
 /*
  * After parsing the command line arguments, figure out which refs we
  * should scan.
@@ -312,6 +474,19 @@ int cmd_survey(int argc, const char **argv, const char *prefix)
 
 	survey_phase_refs(&ctx);
 
+	switch (ctx.opts.format) {
+	case SURVEY_PLAINTEXT:
+		survey_report_plaintext(&ctx);
+		break;
+
+	case SURVEY_JSON:
+		survey_report_json(&ctx);
+		break;
+
+	default:
+		BUG("Undefined format");
+	}
+
 	clear_survey_context(&ctx);
 	return 0;
 }
diff --git a/t/t8100-git-survey.sh b/t/t8100-git-survey.sh
index 5903c90cb57..a57f6ca7a59 100755
--- a/t/t8100-git-survey.sh
+++ b/t/t8100-git-survey.sh
@@ -21,7 +21,22 @@ test_expect_success 'creat 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 &&
+
+	cat >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
-- 
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