#ifndef _WIMLIB_RESOURCE_H
#define _WIMLIB_RESOURCE_H

#include "wimlib/callback.h"
#include "wimlib/file_io.h"
#include "wimlib/list.h"
#include "wimlib/sha1.h"
#include "wimlib/types.h"

struct wim_lookup_table_entry;
struct wim_image_metadata;

/* Specification of a resource in a WIM file.
 *
 * If a `struct wim_lookup_table_entry' lte has
 * (lte->resource_location == RESOURCE_IN_WIM), then lte->wim_res_spec points to
 * an instance of this structure.
 *
 * Normally, there is a one-to-one correspondence between WIM lookup table
 * entries ("streams", each of which may be the contents of a file, for example)
 * and WIM resources.  However, WIM resources with the
 * WIM_RESHDR_FLAG_PACKED_STREAMS flag set may actually contain multiple streams
 * compressed together.  */
struct wim_resource_spec {
	/* The WIM containing this resource.  @wim->in_fd is expected to be a
	 * file descriptor to the underlying WIM file, opened for reading.  */
	WIMStruct *wim;

	/* The offset, in bytes, from the start of WIM file at which this
	 * resource starts.  */
	u64 offset_in_wim;

	/* The size of this resource in the WIM file.  For compressed resources
	 * this is the compressed size, including overhead such as the chunk
	 * table.  */
	u64 size_in_wim;

	/* The number of bytes of uncompressed data this resource decompresses
	 * to.  */
	u64 uncompressed_size;

	/* The list of streams this resource contains.  */
	struct list_head stream_list;

	/* Flags for this resource (WIM_RESHDR_FLAG_*).  */
	u32 flags : 8;

	/* [wimlib extension] This flag will be set if the WIM is pipable.  In
	 * such cases, the resource will be in a slightly different format if it
	 * is compressed.  */
	u32 is_pipable : 1;

	/* Temporary flag.  */
	u32 raw_copy_ok : 1;
};

/* On-disk version of a WIM resource header.  */
struct wim_reshdr_disk {
	/* Size of the resource as it appears in the WIM file (possibly
	 * compressed).  */
	u8 size_in_wim[7];

	/* Zero or more of the WIM_RESHDR_FLAG_* flags.  These indicate, for
	 * example, whether the resource is compressed or not.  */
	u8 flags;

	/* Offset of the resource from the start of the WIM file, in bytes.  */
	le64 offset_in_wim;

	/* Uncompressed size of the resource, in bytes.  */
	le64 uncompressed_size;
} _packed_attribute;

/* In-memory version of a WIM resource header (`struct wim_reshdr_disk').  */
struct wim_reshdr {
	u64 size_in_wim : 56;
	u64 flags : 8;
	u64 offset_in_wim;
	u64 uncompressed_size;
};

/* Flags for the `flags' field of WIM resource headers (`struct wim_reshdr').
 */

/* Unknown meaning; may be intended to indicate spaces in the WIM that are free
 * to overwrite.  Currently ignored by wimlib.  */
#define WIM_RESHDR_FLAG_FREE            0x01

/* The resource is a metadata resource for a WIM image, or is the lookup table
 * or XML data for the WIM.  */
#define WIM_RESHDR_FLAG_METADATA        0x02

/* The resource is compressed using the WIM's default compression type and uses
 * the regular chunk table format.  */
#define WIM_RESHDR_FLAG_COMPRESSED	0x04

/* Unknown meaning; may be intended to indicate a partial stream.  Currently
 * ignored by wimlib.  */
#define WIM_RESHDR_FLAG_SPANNED         0x08

/* The resource is packed in a special format that may contain multiple
 * underlying streams, or this resource entry represents a stream packed into
 * one such resource.  When resources have this flag set, the WIM version number
 * should be WIM_VERSION_PACKED_STREAMS.  */
#define WIM_RESHDR_FLAG_PACKED_STREAMS	0x10

/* Magic number in the 'uncompressed_size' field of the resource header that
 * identifies the main entry for a pack.  */
#define WIM_PACK_MAGIC_NUMBER		0x100000000ULL

/* Returns true if the specified WIM resource is compressed, using either the
 * original chunk table layout or the alternate layout for resources that may
 * contain multiple packed streams.  */
static inline bool
resource_is_compressed(const struct wim_resource_spec *rspec)
{
	return (rspec->flags & (WIM_RESHDR_FLAG_COMPRESSED |
				WIM_RESHDR_FLAG_PACKED_STREAMS));
}

static inline void
copy_reshdr(struct wim_reshdr *dest, const struct wim_reshdr *src)
{
	memcpy(dest, src, sizeof(struct wim_reshdr));
}

static inline void
zero_reshdr(struct wim_reshdr *reshdr)
{
	memset(reshdr, 0, sizeof(struct wim_reshdr));
}

extern void
wim_res_hdr_to_spec(const struct wim_reshdr *reshdr, WIMStruct *wim,
		    struct wim_resource_spec *rspec);

extern void
wim_res_spec_to_hdr(const struct wim_resource_spec *rspec,
		    struct wim_reshdr *reshdr);

extern void
get_wim_reshdr(const struct wim_reshdr_disk *disk_reshdr,
	       struct wim_reshdr *reshdr);

void
put_wim_reshdr(const struct wim_reshdr *reshdr,
	       struct wim_reshdr_disk *disk_reshdr);

/* Alternate chunk table format for resources with
 * WIM_RESHDR_FLAG_PACKED_STREAMS set.  */
struct alt_chunk_table_header_disk {
	/* Uncompressed size of the resource in bytes.  */
	le64 res_usize;

	/* Number of bytes each compressed chunk decompresses into, except
	 * possibly the last which decompresses into the remainder.  This
	 * overrides the chunk size specified by the WIM header.  */
	le32 chunk_size;

	/* Compression format used for compressed chunks:
	 * 0 = None
	 * 1 = LZX
	 * 2 = XPRESS
	 * 3 = LZMS
	 *
	 * This overrides the compression type specified by the WIM header.  */
	le32 compression_format;

	/* This header is directly followed by a table of compressed sizes of
	 * the chunks (4 bytes per entry).  */
} _packed_attribute;

/* Functions to read streams  */

extern int
read_partial_wim_stream_into_buf(const struct wim_lookup_table_entry *lte,
				 size_t size, u64 offset, void *buf);

extern int
read_full_stream_into_buf(const struct wim_lookup_table_entry *lte, void *buf);

extern int
read_full_stream_into_alloc_buf(const struct wim_lookup_table_entry *lte,
				void **buf_ret);

extern int
wim_reshdr_to_data(const struct wim_reshdr *reshdr,
		   WIMStruct *wim, void **buf_ret);

extern int
skip_wim_stream(struct wim_lookup_table_entry *lte);

/*
 * Type of callback function for beginning to read a stream.
 *
 * @lte:
 *	Stream that is about to be read.
 *
 * @is_partial_res:
 *	Set to true if the stream is just one of several being read from a
 *	single pack and therefore would be extra expensive to read
 *	independently.
 *
 * @ctx:
 *	User-provided context.
 *
 * Must return 0 on success, a positive error code on failure, or the special
 * value BEGIN_STREAM_STATUS_SKIP_STREAM to indicate that the stream should not
 * be read, and read_stream_list() should continue on to the next stream
 * (without calling @consume_chunk or @end_stream).
 */
typedef int (*read_stream_list_begin_stream_t)(struct wim_lookup_table_entry *lte,
					       bool is_partial_res,
					       void *ctx);

#define BEGIN_STREAM_STATUS_SKIP_STREAM	-1

/*
 * Type of callback function for finishing reading a stream.
 *
 * @lte:
 *	Stream that has been fully read, or stream that started being read but
 *	could not be fully read due to a read error.
 *
 * @status:
 *	0 if reading the stream was successful; otherwise a nonzero error code
 *	that specifies the return status.
 *
 * @ctx:
 *	User-provided context.
 */
typedef int (*read_stream_list_end_stream_t)(struct wim_lookup_table_entry *lte,
					     int status,
					     void *ctx);


/* Callback functions and contexts for read_stream_list().  */
struct read_stream_list_callbacks {

	/* Called when a stream is about to be read.  */
	read_stream_list_begin_stream_t begin_stream;

	/* Called when a chunk of data has been read.  */
	consume_data_callback_t consume_chunk;

	/* Called when a stream has been fully read.  A successful call to
	 * @begin_stream will always be matched by a call to @end_stream.  */
	read_stream_list_end_stream_t end_stream;

	/* Parameter passed to @begin_stream.  */
	void *begin_stream_ctx;

	/* Parameter passed to @consume_chunk.  */
	void *consume_chunk_ctx;

	/* Parameter passed to @end_stream.  */
	void *end_stream_ctx;
};

/* Flags for read_stream_list()  */
#define VERIFY_STREAM_HASHES		0x1
#define COMPUTE_MISSING_STREAM_HASHES	0x2
#define STREAM_LIST_ALREADY_SORTED	0x4

extern int
read_stream_list(struct list_head *stream_list,
		 size_t list_head_offset,
		 const struct read_stream_list_callbacks *cbs,
		 int flags);

/* Functions to extract streams.  */

extern int
extract_stream(struct wim_lookup_table_entry *lte,
	       u64 size,
	       consume_data_callback_t extract_chunk,
	       void *extract_chunk_arg);

extern int
extract_stream_to_fd(struct wim_lookup_table_entry *lte,
		     struct filedes *fd, u64 size);

extern int
extract_full_stream_to_fd(struct wim_lookup_table_entry *lte,
			  struct filedes *fd);

extern int
extract_chunk_to_fd(const void *chunk, size_t size, void *_fd_p);

/* Miscellaneous stream functions.  */

extern int
sha1_stream(struct wim_lookup_table_entry *lte);

/* Functions to read/write metadata resources.  */

extern int
read_metadata_resource(WIMStruct *wim,
		       struct wim_image_metadata *image_metadata);

extern int
write_metadata_resource(WIMStruct *wim, int image, int write_resource_flags);

/* Definitions specific to pipable WIM resources.  */

/* Arbitrary number to begin each stream in the pipable WIM, used for sanity
 * checking.  */
#define PWM_STREAM_MAGIC 0x2b9b9ba2443db9d8ULL

/* Header that precedes each resource in a pipable WIM.  */
struct pwm_stream_hdr {
	le64 magic;			/* +0   */
	le64 uncompressed_size;		/* +8   */
	u8 hash[SHA1_HASH_SIZE];	/* +16  */
	le32 flags;			/* +36  */
					/* +40  */
} _packed_attribute;

/* Extra flag for the @flags field in `struct pipable_wim_stream_hdr': Indicates
 * that the SHA1 message digest of the stream has not been calculated.
 * Currently only used for the XML data.  */
#define PWM_RESHDR_FLAG_UNHASHED         0x100

/* Header that precedes each chunk of a compressed resource in a pipable WIM.
 */
struct pwm_chunk_hdr {
	le32 compressed_size;
} _packed_attribute;

#endif /* _WIMLIB_RESOURCE_H */