/* ====================================================================
 * The Apache Software License, Version 1.1
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 * reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
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 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 *    not be used to endorse or promote products derived from this
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 * 5. Products derived from this software may not be called "Apache",
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

#ifndef APR_HOOKS_H
#define APR_HOOKS_H

#include "apu.h"
/* For apr_array_header_t */
#include "apr_tables.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @package Apache hooks functions
 */

#define APR_DECLARE_EXTERNAL_HOOK(ns,link,ret,name,args) \
typedef ret ns##_HOOK_##name##_t args; \
link##_DECLARE(void) ns##_hook_##name(ns##_HOOK_##name##_t *pf, \
                                      const char * const *aszPre, \
                                      const char * const *aszSucc, int nOrder); \
link##_DECLARE(ret) ns##_run_##name args; \
typedef struct ns##_LINK_##name##_t \
    { \
    ns##_HOOK_##name##_t *pFunc; \
    const char *szName; \
    const char * const *aszPredecessors; \
    const char * const *aszSuccessors; \
    int nOrder; \
    } ns##_LINK_##name##_t;

#define APR_HOOK_STRUCT(members) \
static struct { members } _hooks;

#define APR_HOOK_LINK(name) \
    apr_array_header_t *link_##name;

#define APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
link##_DECLARE(void) ns##_hook_##name(ns##_HOOK_##name##_t *pf,const char * const *aszPre, \
                                      const char * const *aszSucc,int nOrder) \
    { \
    ns##_LINK_##name##_t *pHook; \
    if(!_hooks.link_##name) \
	{ \
	_hooks.link_##name=apr_array_make(apr_global_hook_pool,1,sizeof(ns##_LINK_##name##_t)); \
	apr_hook_sort_register(#name,&_hooks.link_##name); \
	} \
    pHook=apr_array_push(_hooks.link_##name); \
    pHook->pFunc=pf; \
    pHook->aszPredecessors=aszPre; \
    pHook->aszSuccessors=aszSucc; \
    pHook->nOrder=nOrder; \
    pHook->szName=apr_current_hooking_module; \
    if(apr_debug_module_hooks) \
	apr_show_hook(#name,aszPre,aszSucc); \
    }

/**
 * Implement a hook that has no return code, and therefore runs all of the
 * registered functions
 * @param ns The namespace prefix of the hook functions
 * @param link The linkage declaration prefix of the hook
 * @param name The name of the hook
 * @param args_decl The declaration of the arguments for the hook
 * @param args_used The names for the arguments for the hook
 * @deffunc void APR_IMPLEMENT_EXTERNAL_HOOK_VOID(ns, link, name, args_decl, args_use)
 * @tip The link prefix FOO corresponds to FOO_DECLARE() macros, which
 * provide export linkage from the module that IMPLEMENTs the hook, and
 * import linkage from external modules that link to the hook's module.
 */
#define APR_IMPLEMENT_EXTERNAL_HOOK_VOID(ns,link,name,args_decl,args_use) \
APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
link##_DECLARE(void) ns##_run_##name args_decl \
    { \
    ns##_LINK_##name##_t *pHook; \
    int n; \
\
    if(!_hooks.link_##name) \
	return; \
\
    pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
	pHook[n].pFunc args_use; \
    }

/* FIXME: note that this returns ok when nothing is run. I suspect it should
   really return decline, but that breaks Apache currently - Ben
*/
/**
 * Implement a hook that runs until one of the functions returns something
 * other than OK or DECLINE
 * @param ns The namespace prefix of the hook functions
 * @param link The linkage declaration prefix of the hook
 * @param name The name of the hook
 * @param args_decl The declaration of the arguments for the hook
 * @param args_used The names for the arguments for the hook
 * @deffunc int APR_IMPLEMENT_EXTERNAL_HOOK_RUN_ALL(ns, link, name, args_decl, args_use)
 * @tip The link prefix FOO corresponds to FOO_DECLARE() macros, which
 * provide export linkage from the module that IMPLEMENTs the hook, and
 * import linkage from external modules that link to the hook's module.
 */
#define APR_IMPLEMENT_EXTERNAL_HOOK_RUN_ALL(ns,link,ret,name,args_decl,args_use,ok,decline) \
APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
link##_DECLARE(ret) ns##_run_##name args_decl \
    { \
    ns##_LINK_##name##_t *pHook; \
    int n; \
    ret rv; \
\
    if(!_hooks.link_##name) \
	return ok; \
\
    pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
	{ \
	rv=pHook[n].pFunc args_use; \
\
	if(rv != ok && rv != decline) \
	    return rv; \
	} \
    return ok; \
    }


/**
 * Implement a hook that runs until the first function returns something
 * other than the value of decline
 * @param ns The namespace prefix of the hook functions
 * @param link The linkage declaration prefix of the hook
 * @param name The name of the hook
 * @param args_decl The declaration of the arguments for the hook
 * @param args_used The names for the arguments for the hook
 * @deffunc int APR_IMPLEMENT_HOOK_RUN_FIRST(ns, link, name, args_decl, args_use, decline)
 * @tip The link prefix FOO corresponds to FOO_DECLARE() macros, which
 * provide export linkage from the module that IMPLEMENTs the hook, and
 * import linkage from external modules that link to the hook's module.
 */
#define APR_IMPLEMENT_EXTERNAL_HOOK_RUN_FIRST(ns,link,ret,name,args_decl,args_use,decline) \
APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
link##_DECLARE(ret) ns##_run_##name args_decl \
    { \
    ns##_LINK_##name##_t *pHook; \
    int n; \
    ret rv; \
\
    if(!_hooks.link_##name) \
	return decline; \
\
    pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
    for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
	{ \
	rv=pHook[n].pFunc args_use; \
\
	if(rv != decline) \
	    return rv; \
	} \
    return decline; \
    }

     /* Hook orderings */
#define APR_HOOK_REALLY_FIRST	(-10)
#define APR_HOOK_FIRST		0
#define APR_HOOK_MIDDLE		10
#define APR_HOOK_LAST		20
#define APR_HOOK_REALLY_LAST	30

/**
 * The global pool used to allocate any memory needed by the hooks.
 * @defvar apr_pool_t *apr_global_hook_pool
 */ 
extern APU_DECLARE_DATA apr_pool_t *apr_global_hook_pool;

/**
 * A global variable to determine if debugging information about the
 * hooks functions should be printed
 * @defvar apr_pool_t *apr_debug_module_hooks
 */ 
extern APU_DECLARE_DATA int apr_debug_module_hooks;

/**
 * The name of the module that is currently registering a function
 * @defvar apr_pool_t *apr_current_hooking_module
 */ 
extern APU_DECLARE_DATA const char *apr_current_hooking_module;

/**
 * Register a hook function to be sorted
 * @param szHookName The name of the Hook the function is registered for
 * @param aHooks The array which stores all of the functions for this hook
 * @deffunc void apr_hook_sort_register(const char *szHookName, apr_array_header_t **aHooks)
 */
APU_DECLARE(void) apr_hook_sort_register(const char *szHookName, 
                                        apr_array_header_t **aHooks);
/**
 * Sort all of the registerd functions for a given hook
 * @deffunc void apr_sort_hooks(void)
 */
APU_DECLARE(void) apr_sort_hooks(void);

/**
 * Print all of the information about the current hook.  This is used for
 * debugging purposes.
 * @param szName The name of the hook
 * @param aszPre All of the functions in the predecessor array
 * @param aszSucc All of the functions in the successor array
 * @deffunc void apr_show_hook(const char *szName, const char *const *aszPre, const char *const *aszSucc)
 */
APU_DECLARE(void) apr_show_hook(const char *szName,const char * const *aszPre,
                               const char * const *aszSucc);

/**
 * Remove all currently registered functions.
 * @deffunc void apr_hook_deregister_all(void)
 */
APU_DECLARE(void) apr_hook_deregister_all(void);

#ifdef __cplusplus
}
#endif

#endif /* APR_HOOKS_H */