#ifndef H_HEADER_METHOD
#define H_HEADER_METHOD

/** \ingroup header
 * \file rpmdb/header_method.h
 * Header method prototypes
 */

#include <header.h>

/** \ingroup header
 * Create new (empty) header instance.
 * @return		header
 */
typedef
Header (*HDRnew) (void);

/** \ingroup header
 * Dereference a header instance.
 * @param h		header
 * @return		NULL always
 */
typedef
Header (*HDRfree) (Header h);

/** \ingroup header
 * Reference a header instance.
 * @param h		header
 * @return		referenced header instance
 */
typedef
Header (*HDRlink) (Header h);

/** \ingroup header
 * Dereference a header instance.
 * @param h		header
 * @return		NULL always
 */
typedef
Header (*HDRunlink) (Header h);

/** \ingroup header
 * Sort tags in header.
 * @todo Eliminate from API.
 * @param h		header
 */
typedef
void (*HDRsort) (Header h);

/** \ingroup header
 * Restore tags in header to original ordering.
 * @todo Eliminate from API.
 * @param h		header
 */
typedef
void (*HDRunsort) (Header h);

/** \ingroup header
 * Return size of on-disk header representation in bytes.
 * @param h		header
 * @param magicp	include size of 8 bytes for (magic, 0)?
 * @return		size of on-disk header
 */
typedef
unsigned int (*HDRsizeof) (Header h, enum hMagic magicp);

/** \ingroup header
 * Convert header to on-disk representation.
 * @param h		header (with pointers)
 * @return		on-disk header blob (i.e. with offsets)
 */
typedef
void * (*HDRunload) (Header h);

/** \ingroup header
 * Convert header to on-disk representation, and then reload.
 * This is used to insure that all header data is in one chunk.
 * @param h		header (with pointers)
 * @param tag		region tag
 * @return		on-disk header (with offsets)
 */
typedef
Header (*HDRreload) (Header h, int tag);

/** \ingroup header
 * Duplicate a header.
 * @param h		header
 * @return		new header instance
 */
typedef
Header (*HDRcopy) (Header h);

/** \ingroup header
 * Convert header to in-memory representation.
 * @param uh		on-disk header blob (i.e. with offsets)
 * @return		header
 */
typedef
Header (*HDRload) (void * uh);

/** \ingroup header
 * Make a copy and convert header to in-memory representation.
 * @param uh		on-disk header blob (i.e. with offsets)
 * @return		header
 */
typedef
Header (*HDRcopyload) (const void * uh);

/** \ingroup header
 * Read (and load) header from file handle.
 * @param fd		file handle
 * @param magicp	read (and verify) 8 bytes of (magic, 0)?
 * @return		header (or NULL on error)
 */
typedef
Header (*HDRread) (FD_t fd, enum hMagic magicp);

/** \ingroup header
 * Write (with unload) header to file handle.
 * @param fd		file handle
 * @param h		header
 * @param magicp	prefix write with 8 bytes of (magic, 0)?
 * @return		0 on success, 1 on error
 */
typedef
int (*HDRwrite) (FD_t fd, Header h, enum hMagic magicp);

/** \ingroup header
 * Check if tag is in header.
 * @param h		header
 * @param tag		tag
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRisentry) (Header h, int32_t tag);  

/** \ingroup header
 * Free data allocated when retrieved from header.
 * @param h		header
 * @param data		address of data (or NULL)
 * @param type		type of data (or -1 to force free)
 * @return		NULL always
 */
typedef
void * (*HDRfreetag) (Header h,
		const void * data, rpmTagType type);

/** \ingroup header
 * Retrieve tag value.
 * Will never return RPM_I18NSTRING_TYPE! RPM_STRING_TYPE elements with
 * RPM_I18NSTRING_TYPE equivalent entries are translated (if HEADER_I18NTABLE
 * entry is present).
 *
 * @param h		header
 * @param tag		tag
 * @retval type		address of tag value data type (or NULL)
 * @retval p		address of pointer to tag value(s) (or NULL)
 * @retval c		address of number of values (or NULL)
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRget) (Header h, int32_t tag,
			hTYP_t type,
			void ** p,
			hCNT_t c);

/** \ingroup header
 * Retrieve tag value using header internal array.
 * Get an entry using as little extra RAM as possible to return the tag value.
 * This is only an issue for RPM_STRING_ARRAY_TYPE.
 *
 * @param h		header
 * @param tag		tag
 * @retval type		address of tag value data type (or NULL)
 * @retval p		address of pointer to tag value(s) (or NULL)
 * @retval c		address of number of values (or NULL)
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRgetmin) (Header h, int32_t tag,
			hTYP_t type,
			hPTR_t * p,
			hCNT_t c);

/** \ingroup header
 * Add tag to header.
 * Duplicate tags are okay, but only defined for iteration (with the
 * exceptions noted below). While you are allowed to add i18n string
 * arrays through this function, you probably don't mean to. See
 * headerAddI18NString() instead.
 *
 * @param h		header
 * @param tag		tag
 * @param type		tag value data type
 * @param p		pointer to tag value(s)
 * @param c		number of values
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRadd) (Header h, int32_t tag, int32_t type, const void * p, int32_t c);

/** \ingroup header
 * Append element to tag array in header.
 * Appends item p to entry w/ tag and type as passed. Won't work on
 * RPM_STRING_TYPE. Any pointers into header memory returned from
 * headerGetEntryMinMemory() for this entry are invalid after this
 * call has been made!
 *
 * @param h		header
 * @param tag		tag
 * @param type		tag value data type
 * @param p		pointer to tag value(s)
 * @param c		number of values
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRappend) (Header h, int32_t tag, int32_t type, const void * p, int32_t c);

/** \ingroup header
 * Add or append element to tag array in header.
 * @todo Arg "p" should have const.
 * @param h		header
 * @param tag		tag
 * @param type		tag value data type
 * @param p		pointer to tag value(s)
 * @param c		number of values
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRaddorappend) (Header h, int32_t tag, int32_t type, const void * p, int32_t c);

/** \ingroup header
 * Add locale specific tag to header.
 * A NULL lang is interpreted as the C locale. Here are the rules:
 * \verbatim
 *	- If the tag isn't in the header, it's added with the passed string
 *	   as new value.
 *	- If the tag occurs multiple times in entry, which tag is affected
 *	   by the operation is undefined.
 *	- If the tag is in the header w/ this language, the entry is
 *	   *replaced* (like headerModifyEntry()).
 * \endverbatim
 * This function is intended to just "do the right thing". If you need
 * more fine grained control use headerAddEntry() and headerModifyEntry().
 *
 * @param h		header
 * @param tag		tag
 * @param string	tag value
 * @param lang		locale
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRaddi18n) (Header h, int32_t tag, const char * string,
                const char * lang);

/** \ingroup header
 * Modify tag in header.
 * If there are multiple entries with this tag, the first one gets replaced.
 * @param h		header
 * @param tag		tag
 * @param type		tag value data type
 * @param p		pointer to tag value(s)
 * @param c		number of values
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRmodify) (Header h, int32_t tag, int32_t type, const void * p, int32_t c);

/** \ingroup header
 * Delete tag in header.
 * Removes all entries of type tag from the header, returns 1 if none were
 * found.
 *
 * @param h		header
 * @param tag		tag
 * @return		0 on success, 1 on failure (INCONSISTENT)
 */
typedef
int (*HDRremove) (Header h, int32_t tag);

/** \ingroup header
 * Return formatted output string from header tags.
 * The returned string must be free()d.
 *
 * @param h		header
 * @param fmt		format to use
 * @param tags		array of tag name/value pairs
 * @param extensions	chained table of formatting extensions.
 * @retval errmsg	error message (if any)
 * @return		formatted output string (malloc'ed)
 */
typedef
char * (*HDRsprintf) (Header h, const char * fmt,
		     const struct headerTagTableEntry_s * tags,
		     const struct headerSprintfExtension_s * extensions,
		     errmsg_t * errmsg);

/** \ingroup header
 * Duplicate tag values from one header into another.
 * @param headerFrom	source header
 * @param headerTo	destination header
 * @param tagstocopy	array of tags that are copied
 */
typedef
void (*HDRcopytags) (Header headerFrom, Header headerTo, hTAG_t tagstocopy);

/** \ingroup header
 * Destroy header tag iterator.
 * @param hi		header tag iterator
 * @return		NULL always
 */
typedef
HeaderIterator (*HDRfreeiter) (HeaderIterator hi);

/** \ingroup header
 * Create header tag iterator.
 * @param h		header
 * @return		header tag iterator
 */
typedef
HeaderIterator (*HDRinititer) (Header h);

/** \ingroup header
 * Return next tag from header.
 * @param hi		header tag iterator
 * @retval tag		address of tag
 * @retval type		address of tag value data type
 * @retval p		address of pointer to tag value(s)
 * @retval c		address of number of values
 * @return		1 on success, 0 on failure
 */
typedef
int (*HDRnextiter) (HeaderIterator hi,
		hTAG_t tag,
		hTYP_t type,
		hPTR_t * p,
		hCNT_t c);

/** \ingroup header
 * Header method vectors.
 */
typedef struct HV_s * HV_t;
struct HV_s {
    HDRlink	hdrlink;
    HDRunlink	hdrunlink;
    HDRfree	hdrfree;
    HDRnew	hdrnew;
    HDRsort	hdrsort;
    HDRunsort	hdrunsort;
    HDRsizeof	hdrsizeof;
    HDRunload	hdrunload;
    HDRreload	hdrreload;
    HDRcopy	hdrcopy;
    HDRload	hdrload;
    HDRcopyload	hdrcopyload;
    HDRread	hdrread;
    HDRwrite	hdrwrite;
    HDRisentry	hdrisentry;
    HDRfreetag	hdrfreetag;
    HDRget	hdrget;
    HDRgetmin	hdrgetmin;
    HDRadd	hdradd;
    HDRappend	hdrappend;
    HDRaddorappend hdraddorappend;
    HDRaddi18n	hdraddi18n;
    HDRmodify	hdrmodify;
    HDRremove	hdrremove;
    HDRsprintf	hdrsprintf;
    HDRcopytags	hdrcopytags;
    HDRfreeiter	hdrfreeiter;
    HDRinititer	hdrinititer;
    HDRnextiter	hdrnextiter;
    void *	hdrvecs;
    void *	hdrdata;
    int		hdrversion;
};

#endif  /* H_HEADER_METHOD */