/*
 * The reader for cgit's config files, which are the main cgitrc, any file
 * it pulls in with an include line, the cgitrc beside a scanned repository,
 * and the cached repolist. A file is a sequence of name=value lines, each
 * handed to a callback that decides what it means, so nothing here knows a
 * single key by name.
 */

#include "cgit.h"
#include "config.h"

#define MAX_INCLUDE_NESTING 8

struct config_origin config_origin;

// The newlines read so far from the file being parsed, which place each entry
// on its line.
static int lines_read;

/*
 * Folds away a carriage return that sits right before a newline so a file
 * saved with DOS line endings parses the same as one saved with Unix endings.
 */
static int next_char(FILE *f)
{
	int c = fgetc(f);

	if (c == '\r') {
		c = fgetc(f);
		if (c != '\n') {
			ungetc(c, f);
			c = '\r';
		}
	}
	if (c == '\n')
		lines_read++;
	return c;
}

static void skip_line(FILE *f)
{
	int c;

	while ((c = next_char(f)) != '\n' && c != EOF)
		;
}

static int next_content_char(FILE *f)
{
	int c = next_char(f);

	for (;;) {
		if (c == EOF)
			return EOF;
		if (c == '#' || c == ';')
			skip_line(f);
		else if (!isspace(c))
			return c;
		c = next_char(f);
	}
}

static int read_entry(FILE *f, struct strbuf *name, struct strbuf *value, int *line)
{
	int c;

	strbuf_reset(value);

	for (;;) {
		c = next_content_char(f);
		if (c == EOF)
			return 0;

		*line = lines_read + 1;
		strbuf_reset(name);
		while (c != '=' && c != '\n' && c != EOF) {
			strbuf_addch(name, c);
			c = next_char(f);
		}
		if (c == EOF)
			return 0;
		// Dropping only the line with no equals sign keeps one typo
		// from hiding the rest of the file.
		if (c != '=')
			continue;

		c = next_char(f);
		while (c != '\n' && c != EOF) {
			strbuf_addch(value, c);
			c = next_char(f);
		}

		return 1;
	}
}

int config_file_parse(const char *filename, config_file_value_fn fn)
{
	static int nesting;
	// An include is parsed from inside a line of the file that names it,
	// which carries on from that line once the include is done.
	struct config_origin outer = config_origin;
	int outer_lines_read = lines_read;
	struct strbuf name = STRBUF_INIT;
	struct strbuf value = STRBUF_INIT;
	struct stat st;
	FILE *f;
	int err = 0;

	// An include line calls back into here, so an include cycle would
	// recurse until the stack gave out.
	if (nesting > MAX_INCLUDE_NESTING)
		return 0;
	if (!(f = fopen(filename, "r")))
		return errno;
	// Git's fopen refuses a directory only where its build defines
	// FREAD_READS_DIRECTORIES, and elsewhere read(2) need not fail on one.
	if (!fstat(fileno(f), &st) && S_ISDIR(st.st_mode)) {
		fclose(f);
		return EISDIR;
	}
	config_origin.file = filename;
	lines_read = 0;
	nesting++;
	while (read_entry(f, &name, &value, &config_origin.line))
		fn(name.buf, value.buf);
	if (ferror(f))
		err = errno;
	nesting--;
	fclose(f);
	config_origin = outer;
	lines_read = outer_lines_read;
	strbuf_release(&name);
	strbuf_release(&value);
	return err;
}

int config_int(const char *name, const char *value)
{
	int number = atoi(value);
	char *end;

	// Space may follow the digits strtol finds, but nothing else.
	strtol(value, &end, 10);
	while (end != value && isspace(*end))
		end++;
	if (end != value && !*end)
		return number;
	// The first line alone, since a git config value can hold a newline
	// that would forge a log line of its own.
	if (config_origin.file)
		fprintf(stderr, "[cgit] Reading %s=%.*s in %s line %d as %d, since it is not a whole number\n",
			name, (int)strcspn(value, "\n"), value, config_origin.file,
			config_origin.line, number);
	else
		fprintf(stderr, "[cgit] Reading %s=%.*s as %d, since it is not a whole number\n",
			name, (int)strcspn(value, "\n"), value, number);
	return number;
}