#ifndef __IMAP_MESSAGE_CACHE_H
#define __IMAP_MESSAGE_CACHE_H

/* IMAP message cache. Caches are mailbox-specific and must be cleared
   if UID validity changes. Also if message data may have changed,
   imap_msgcache_close() must be called.

   Caching is mostly done to avoid parsing the same message multiple times
   when client fetches the message in parts.
*/

#include "message-parser.h"

typedef enum {
	IMAP_CACHE_BODY			= 0x01,
	IMAP_CACHE_BODYSTRUCTURE	= 0x02,
	IMAP_CACHE_ENVELOPE		= 0x04,

	IMAP_CACHE_MESSAGE_OPEN		= 0x08,
	IMAP_CACHE_MESSAGE_PART		= 0x10,
	IMAP_CACHE_MESSAGE_HDR_SIZE	= 0x20,
	IMAP_CACHE_MESSAGE_BODY_SIZE	= 0x40
} ImapCacheField;

typedef struct {
	/* Open mail for reading. */
	IOBuffer *(*open_mail)(void *context);
	/* Rewind input buffer to beginning, possibly closing the old buffer
	   if it can't directly be rewinded. */
	IOBuffer *(*inbuf_rewind)(IOBuffer *inbuf, void *context);

	/* Returns field if it's already cached, or NULL. */
	const char *(*get_cached_field)(ImapCacheField field, void *context);
	/* Returns MessagePart if it's already cached, or NULL. */
	MessagePart *(*get_cached_parts)(Pool pool, void *context);
} ImapMessageCacheIface;

typedef struct _ImapMessageCache ImapMessageCache;

ImapMessageCache *imap_msgcache_alloc(ImapMessageCacheIface *iface);
void imap_msgcache_clear(ImapMessageCache *cache);
void imap_msgcache_free(ImapMessageCache *cache);

/* Open the specified message. virtual_header/body_size may be 0
   if it's not known. */
void imap_msgcache_open(ImapMessageCache *cache, unsigned int uid,
			ImapCacheField fields,
			uoff_t virtual_header_size, uoff_t virtual_body_size,
			void *context);

/* Close the IOBuffer for opened message. */
void imap_msgcache_close(ImapMessageCache *cache);

/* Returns the field from cache, or NULL if it's not cached. */
const char *imap_msgcache_get(ImapMessageCache *cache, ImapCacheField field);

/* Returns the root MessagePart for message, or NULL if failed. */
MessagePart *imap_msgcache_get_parts(ImapMessageCache *cache);

/* Returns TRUE if successful. If inbuf is not NULL, it's set to point to
   beginning of message, or to beginning of message body if hdr_size is NULL. */
int imap_msgcache_get_rfc822(ImapMessageCache *cache, IOBuffer **inbuf,
			     MessageSize *hdr_size, MessageSize *body_size);

/* Returns TRUE if successful. *inbuf is set to point to the first non-skipped
   character. size is set to specify the full size of message. */
int imap_msgcache_get_rfc822_partial(ImapMessageCache *cache,
				     uoff_t virtual_skip,
				     uoff_t max_virtual_size,
				     int get_header, MessageSize *size,
				     IOBuffer **inbuf);

/* Returns TRUE if successful. *inbuf is set to point to beginning of
   message. */
int imap_msgcache_get_data(ImapMessageCache *cache, IOBuffer **inbuf);

#endif