/*
 * 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

/*
 * 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';
		}
	}
	return c;
}

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

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

	strbuf_reset(value);

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

		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;
	struct strbuf name = STRBUF_INIT;
	struct strbuf value = STRBUF_INIT;
	FILE *f;

	// An include line calls back into here, so an include cycle would
	// recurse until the stack gave out.
	if (nesting > MAX_INCLUDE_NESTING)
		return -1;
	if (!(f = fopen(filename, "r")))
		return -1;
	nesting++;
	while (read_entry(f, &name, &value))
		fn(name.buf, value.buf);
	nesting--;
	fclose(f);
	strbuf_release(&name);
	strbuf_release(&value);
	return 0;
}