/*
 * Copyright (C) 2007 Martin Willi
 * Hochschule fuer Technik Rapperswil
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * $Id: enumerator.c 3589 2008-03-13 14:14:44Z martin $
 */

#include "enumerator.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <dirent.h>
#include <errno.h>

#include <debug.h>

/**
 * Implementation of enumerator_create_empty().enumerate
 */
static bool enumerate_empty(enumerator_t *enumerator, ...)
{
	return FALSE;
}

/**
 * See header
 */
enumerator_t* enumerator_create_empty()
{
	enumerator_t *this = malloc_thing(enumerator_t);
	this->enumerate = enumerate_empty;
	this->destroy = (void*)free;
	return this;
}

/**
 * Enumerator implementation for directory enumerator
 */
typedef struct {
	/** implements enumerator_t */
	enumerator_t public;
	/** directory handle */
	DIR *dir;
	/** absolute path of current file */
	char full[PATH_MAX];
	/** where directory part of full ends and relative file gets written */
	char *full_end;
} dir_enum_t;

/**
 * Implementation of enumerator_create_directory().destroy
 */
static void destroy_dir_enum(dir_enum_t *this)
{
	closedir(this->dir);
	free(this);
}

/**
 * Implementation of enumerator_create_directory().enumerate
 */
static bool enumerate_dir_enum(dir_enum_t *this, char **relative,
							   char **absolute, struct stat *st)
{
	struct dirent *entry = readdir(this->dir);
	size_t len, remaining;
	
	if (!entry)
	{
		return FALSE;
	}
	if (streq(entry->d_name, ".") || streq(entry->d_name, ".."))
	{
		return enumerate_dir_enum(this, relative, absolute, st);
	}
	if (relative)
	{
		*relative = entry->d_name;
	}
	if (absolute || st)
	{	
		remaining = sizeof(this->full) - (this->full_end - this->full);
		len = snprintf(this->full_end, remaining, "%s", entry->d_name);
		if (len < 0 || len >= remaining)
		{
			DBG1("buffer too small to enumerate file '%s'", entry->d_name);
			return FALSE;
		}
		if (absolute)
		{
			*absolute = this->full;
		}
		if (st)
		{
			if (stat(this->full, st))
			{
				DBG1("stat() on '%s' failed: %s", this->full, strerror(errno));
				return FALSE;
			}
		}
	}
	return TRUE;
}

/**
 * See header
 */
enumerator_t* enumerator_create_directory(char *path)
{
	size_t len;
	dir_enum_t *this = malloc_thing(dir_enum_t);
	this->public.enumerate = (void*)enumerate_dir_enum;
	this->public.destroy = (void*)destroy_dir_enum;
	
	if (*path == '\0')
	{
		path = "./";
	}
	len = snprintf(this->full, sizeof(this->full)-1, "%s", path);
	if (len < 0 || len >= sizeof(this->full)-1)
	{
		DBG1("path string %s too long", path);
		free(this);
		return NULL;
	}
	/* append a '/' if not already done */
	if (this->full[len-1] != '/')
	{
		this->full[len++] = '/';
		this->full[len] = '\0';
	}
	this->full_end = &this->full[len];
	
	this->dir = opendir(path);
	if (this->dir == NULL)
	{
		DBG1("opening directory %s failed: %s", path, strerror(errno));
		free(this);
		return NULL;
	}
	return &this->public;
}

/**
 * enumerator for nested enumerations
 */
typedef struct {
	/* implements enumerator_t */
	enumerator_t public;
	/* outer enumerator */
	enumerator_t *outer;
	/* inner enumerator */
	enumerator_t *inner;
	/* constructor for inner enumerator */
	enumerator_t *(*create_inner)(void *outer, void *data);
	/* data to pass to constructor above */
	void *data;
	/* destructor for data */
	void (*destroy_data)(void *data);
} nested_enumerator_t;


/**
 * Implementation of enumerator_create_nested().enumerate()
 */
static bool enumerate_nested(nested_enumerator_t *this, void *v1, void *v2,
							 void *v3, void *v4, void *v5)
{
	while (TRUE)
	{
		while (this->inner == NULL)
		{	
			void *outer;
			
			if (!this->outer->enumerate(this->outer, &outer))
			{
				return FALSE;
			}
			this->inner = this->create_inner(outer, this->data);
		}
		if (this->inner->enumerate(this->inner, v1, v2, v3, v4, v5))
		{
			return TRUE;
		}
		this->inner->destroy(this->inner);
		this->inner = NULL;
	}
}

/**
 * Implementation of enumerator_create_nested().destroy()
 **/
static void destroy_nested(nested_enumerator_t *this)
{
	if (this->destroy_data)
	{
		this->destroy_data(this->data);
	}
	DESTROY_IF(this->inner);
	this->outer->destroy(this->outer);
	free(this);
}

/**
 * See header
 */
enumerator_t *enumerator_create_nested(enumerator_t *outer,
					enumerator_t *(inner_constructor)(void *outer, void *data),
					void *data, void (*destroy_data)(void *data))
{
	nested_enumerator_t *enumerator = malloc_thing(nested_enumerator_t);
	
	enumerator->public.enumerate = (void*)enumerate_nested;
	enumerator->public.destroy = (void*)destroy_nested;
	enumerator->outer = outer;
	enumerator->inner = NULL;
	enumerator->create_inner = (void*)inner_constructor;
	enumerator->data = data;
	enumerator->destroy_data = destroy_data;
	
	return &enumerator->public;
}

/**
 * enumerator for filtered enumerator
 */
typedef struct {
	enumerator_t public;
	enumerator_t *unfiltered;
	void *data;
	bool (*filter)(void *data, ...);
	void (*destructor)(void *data);
} filter_enumerator_t;

/**
 * Implementation of enumerator_create_filter().destroy
 */
void destroy_filter(filter_enumerator_t *this)
{
	if (this->destructor)
	{
		this->destructor(this->data);
	}
	this->unfiltered->destroy(this->unfiltered);
	free(this);
}

/**
 * Implementation of enumerator_create_filter().enumerate
 */
bool enumerate_filter(filter_enumerator_t *this, void *o1, void *o2,
					  void *o3, void *o4, void *o5)
{
	void *i1, *i2, *i3, *i4, *i5;

	while (this->unfiltered->enumerate(this->unfiltered, &i1, &i2, &i3, &i4, &i5))
	{
		if (this->filter(this->data, &i1, o1, &i2, o2, &i3, o3, &i4, o4, &i5, o5))
		{
			return TRUE;
		}
	}
	return FALSE;
}

/**
 * see header
 */
enumerator_t *enumerator_create_filter(enumerator_t *unfiltered,
									   bool (*filter)(void *data, ...),
									   void *data, void (*destructor)(void *data))
{
	filter_enumerator_t *this = malloc_thing(filter_enumerator_t);
	
	this->public.enumerate = (void*)enumerate_filter;
	this->public.destroy = (void*)destroy_filter;
	this->unfiltered = unfiltered;
	this->filter = filter;
	this->data = data;
	this->destructor = destructor;
	
	return &this->public;
}

/**
 * enumerator for cleaner enumerator
 */
typedef struct {
	enumerator_t public;
	enumerator_t *wrapped;
	void (*cleanup)(void *data);
	void *data;
} cleaner_enumerator_t;

/**
 * Implementation of enumerator_create_cleanup().destroy
 */
static void destroy_cleaner(cleaner_enumerator_t *this)
{
	this->cleanup(this->data);
	this->wrapped->destroy(this->wrapped);
	free(this);
}

/**
 * Implementation of enumerator_create_cleaner().enumerate
 */
static bool enumerate_cleaner(cleaner_enumerator_t *this, void *v1, void *v2,
							  void *v3, void *v4, void *v5)
{
	return this->wrapped->enumerate(this->wrapped, v1, v2, v3, v4, v5);
}

/**
 * see header
 */
enumerator_t *enumerator_create_cleaner(enumerator_t *wrapped,
										void (*cleanup)(void *data), void *data)
{
	cleaner_enumerator_t *this = malloc_thing(cleaner_enumerator_t);
	
	this->public.enumerate = (void*)enumerate_cleaner;
	this->public.destroy = (void*)destroy_cleaner;
	this->wrapped = wrapped;
	this->cleanup = cleanup;
	this->data = data;
	
	return &this->public;
}

/**
 * enumerator for single enumerator
 */
typedef struct {
	enumerator_t public;
	void *item;
	void (*cleanup)(void *item);
	bool done;
} single_enumerator_t;

/**
 * Implementation of enumerator_create_single().destroy
 */
static void destroy_single(single_enumerator_t *this)
{
	if (this->cleanup)
	{
		this->cleanup(this->item);
	}
	free(this);
}

/**
 * Implementation of enumerator_create_single().enumerate
 */
static bool enumerate_single(single_enumerator_t *this, void **item)
{
	if (this->done)
	{
		return FALSE;
	}
	*item = this->item;
	this->done = TRUE;
	return TRUE;
}

/**
 * see header
 */
enumerator_t *enumerator_create_single(void *item, void (*cleanup)(void *item))
{
	single_enumerator_t *this = malloc_thing(single_enumerator_t);
	
	this->public.enumerate = (void*)enumerate_single;
	this->public.destroy = (void*)destroy_single;
	this->item = item;
	this->cleanup = cleanup;
	this->done = FALSE;
	
	return &this->public;
}