/*
 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file filter_common.c Common helper functions for filter input/output. */

#include <sys/types.h>
#include <dirent.h>

#include "para.h"
#include "list.h"
#include "sched.h"
#include "fd.h"
#include "ggo.h"
#include "filter.h"
#include "error.h"
#include "string.h"

/** The array of supported filters. */
struct filter filters[NUM_SUPPORTED_FILTERS] = {FILTER_ARRAY};

/**
 * Call the init function of each supported filter.
 * \sa filter::init
 */
void filter_init(void)
{
	int i;

	FOR_EACH_SUPPORTED_FILTER(i)
		filters[i].init(filters + i);
}

/**
 * Close and destroy a filter callback.
 *
 * \param fcb The filter callback to close.
 *
 * This removes \a fcb from the list of filter callbacks and calls
 * the close callback associated with \a fcb.
 */
static void close_filter_callback(struct filter_callback *fcb)
{
	PARA_NOTICE_LOG("closing filter_callback %p, data: %p\n", fcb, fcb->data);
	list_del(&fcb->node);
	fcb->close(fcb);
}

/**
 * Close all callbacks of a filter node.
 *
 * \param fn The filter node which contains the filter callbacks to be closed.
 *
 * Call close_filter_callback() for each entry in the filter callback list
 * of \a fn.
 */
static void close_callbacks(struct filter_node *fn)
{
	struct filter_callback *fcb, *tmp;

	list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
		PARA_INFO_LOG("closing %s filter callback\n",
			filters[fn->filter_num].name);
		close_filter_callback(fcb);
	}
}

static void call_callbacks(struct filter_node *fn, char *inbuf, size_t inlen,
	char *outbuf, size_t outlen)
{
	struct filter_callback *fcb, *tmp;
	list_for_each_entry_safe(fcb, tmp, &fn->callbacks, node) {
		int ret;
		if (inlen && fcb->input_cb) {
			ret = fcb->input_cb(inbuf, inlen, fcb);
			if (ret < 0) {
				close_filter_callback(fcb);
				continue;
			}
		}
		if (!outlen || !fcb->output_cb)
			continue;
		ret = fcb->output_cb(outbuf, outlen, fcb);
		if (ret < 0)
			close_filter_callback(fcb);
	}
}

/**
 * Call the convert function of each filter.
 *
 * \param s Unused.
 * \param t The task identifying the filter chain.
 *
 * This is the core function of the filter subsystem. It loops over the list of
 * filter nodes determined by \a t and calls the filter's convert function if
 * there is input available for the filter node in question. If the convert
 * function consumed some or all of its input data, all registered input
 * callbacks are called.  Similarly, if a convert function produced output, all
 * registered output callbacks get called.
 *
 * On errors a (negative) error code is stored in t->error.
 *
 * \sa filter_node, filter#convert, filter_callback.
 */
void filter_post_select(__a_unused struct sched *s, struct task *t)
{
	struct filter_chain *fc = container_of(t, struct filter_chain, task);
	struct filter_node *fn;
	char *ib;
	size_t *loaded;
	int i, conv, conv_total = 0;

	if (fc->output_error && *fc->output_error < 0) {
		t->error =  *fc->output_error;
		return;
	}
again:
	ib = *fc->inbufp;
	loaded = fc->in_loaded;
	conv = 0;
	FOR_EACH_FILTER_NODE(fn, fc, i) {
		struct filter *f = filters + fn->filter_num;
		if (fn->loaded < fn->bufsize) {
			size_t size, old_fn_loaded = fn->loaded;
			t->error = f->convert(ib, *loaded, fn);
			if (t->error < 0)
				return;
			size = t->error;
			call_callbacks(fn, ib, size, fn->buf + old_fn_loaded,
				fn->loaded - old_fn_loaded);
			*loaded -= size;
			conv += size + fn->loaded - old_fn_loaded;
			if (*loaded && size)
				memmove(ib, ib + size, *loaded);
		}
		ib = fn->buf;
		loaded = &fn->loaded;
	}
	conv_total += conv;
	if (conv)
		goto again;
	if (*fc->input_error >= 0)
		return;
	if (*fc->out_loaded)
		return;
	if (*fc->in_loaded && conv_total)
		return;
	t->error = -E_FC_EOF;
}

/**
 * Close all filter nodes and their callbacks.
 *
 * \param fc The filter chain to close.
 *
 * For each filter node determined by \a fc, call the close function of each
 * registered filter callback as well as the close function of the
 * corresponding filter.  Free all resources and destroy all callback lists and
 * the filter node list.
 *
 * \sa filter::close, filter_callback::close
 */
void close_filters(struct filter_chain *fc)
{
	struct filter_node *fn;
	int i;

	if (!fc)
		return;
	PARA_NOTICE_LOG("closing filter chain %p\n", fc);
	FOR_EACH_FILTER_NODE(fn, fc, i) {
		struct filter *f = filters + fn->filter_num;
		close_callbacks(fn);
		PARA_INFO_LOG("closing %s filter\n", f->name);
		f->close(fn);
	}
	free(fc->filter_nodes);
}

/*
 * If the filter has a command line parser and options is not NULL, run it.
 * Returns filter_num on success, negative on errors
 */
static int parse_filter_args(int filter_num, char *options, void **conf)
{
	struct filter *f = &filters[filter_num];
	int ret, i, argc = 2;
	char **argv;

//	PARA_DEBUG_LOG("%s, options: %s, parser: %p\n", f->name,
//		options? options : "(none)", f->parse_config);
	if (!f->parse_config)
		return strlen(options)? -E_BAD_FILTER_OPTIONS : filter_num;
//	PARA_DEBUG_LOG("options: %s\n", options);
	argc = split_args(options, &argv, " \t");
//		PARA_DEBUG_LOG("argc = %d, argv[0]: %s\n", argc, argv[0]);
	for (i = argc - 1; i >= 0; i--)
		argv[i + 1] = argv[i];
	argv[0] = para_strdup(f->name);
	argc += 1;
	ret = f->parse_config(argc, argv, conf);
	free(argv[0]);
	free(argv);
	return ret < 0? ret : filter_num;
}

/**
 * Check the filter command line options.
 *
 * \param fa The command line options.
 * \param conf Points to the filter configuration upon successful return.
 *
 * Check if \a fa starts with a the name of a supported filter, followed by
 * a colon. If yes, call the command line parser of that filter.
 *
 * \return On success, the number of the filter is returned and \a conf
 * is initialized to point to the filter configuration determined by \a fa.
 * On errors, a negative value is returned.
 *
 * Note: If \a fa specifies a filter that has no command line parser success is
 * returned, and \a conf is initialized to \p NULL.
 *
 * \sa filter::parse_config
 */
int check_filter_arg(char *fa, void **conf)
{
	int j;

	*conf = NULL;
//	PARA_DEBUG_LOG("arg: %s\n", fa);
	FOR_EACH_SUPPORTED_FILTER(j) {
		const char *name = filters[j].name;
		size_t len = strlen(name);
		char c;
		if (strlen(fa) < len)
			continue;
		if (strncmp(name, fa, len))
			continue;
		c = fa[len];
		if (c && c != ' ')
			continue;
		if (c && !filters[j].parse_config)
			return -E_BAD_FILTER_OPTIONS;
		return parse_filter_args(j, c? fa + len + 1 :
			fa + strlen(fa), conf);
	}
	return -E_UNSUPPORTED_FILTER;
}

void print_filter_helps(int detailed)
{
	int i;

	printf_or_die("\nAvailable filters: \n\t");
	FOR_EACH_SUPPORTED_FILTER(i)
		printf_or_die("%s%s", i? " " : "", filters[i].name);
	printf_or_die("\n\n");

	FOR_EACH_SUPPORTED_FILTER(i) {
		struct filter *f = filters + i;

		if (!f->help.short_help)
			continue;
		printf_or_die("Options for %s:\n", f->name);
		ggo_print_help(&f->help, detailed);
	}

}