#ifndef _CHUNK_H_
#define _CHUNK_H_
#include "first.h"

#include "buffer.h"
#include "array.h"
#include "fdlog.h"

/* both should be way smaller than SSIZE_MAX :) */
#define MAX_READ_LIMIT  (256*1024)
#define MAX_WRITE_LIMIT (256*1024)

typedef struct chunk_file_view {
	char    *mptr; /* base pointer of mmap'ed area */
	off_t    mlen; /* length of mmap'ed area */
	off_t    foff; /* offset from the start of the file */
	int    refcnt;
} chunk_file_view;

typedef struct chunk {
	struct chunk *next;
	enum { MEM_CHUNK, FILE_CHUNK } type;

	buffer *mem; /* either the storage of the mem-chunk or the name of the file */

	/* the size of the chunk is either:
	 * - mem-chunk: buffer_string_length(chunk::mem) - c->offset
	 * - file-chunk: chunk::file.length - c->offset
	 */
	off_t offset;

	struct {
		/* filechunk */
		off_t  length; /* end pos + 1 in file (octets to send: file.length - c->offset) */

		int    fd;
		uint8_t is_temp; /* file is temporary and will be deleted if on cleanup */
		uint8_t busy;    /* file chunk not in page cache; reading might block */
		uint8_t flagmask;/* (internal; used with preadv2() RWF_NOWAIT) */
	  #if defined(HAVE_MMAP) || defined(_WIN32) /*(see local sys-mmap.h)*/
		chunk_file_view *view;
	  #endif
		void *ref;
		void(*refchg)(void *, int);
	} file;
} chunk;

typedef struct chunkqueue {
	chunk *first;
	chunk *last;

	off_t bytes_in, bytes_out;

	off_t upload_temp_file_size;
	unsigned int tempdir_idx;
} chunkqueue;

ssize_t chunk_file_pread (int fd, void *buf, size_t count, off_t offset);

/* attempts non-blocking preadv2 RWF_NOWAIT on Linux, else chunk_file_pread() */
ssize_t chunk_file_pread_chunk (chunk *c, void *buf, size_t count);

__attribute_returns_nonnull__
buffer * chunk_buffer_acquire(void);

void chunk_buffer_release(buffer *b);

__attribute_nonnull__()
void chunk_buffer_yield(buffer *b);

size_t chunk_buffer_prepare_append (buffer *b, size_t sz);

void chunkqueue_chunk_pool_clear(void);
void chunkqueue_chunk_pool_free(void);

__attribute_returns_nonnull__
chunkqueue *chunkqueue_init(chunkqueue *cq);

__attribute_cold__
void chunkqueue_set_chunk_size (size_t sz);

__attribute_cold__
void chunkqueue_set_tempdirs_default_reset (void);

__attribute_cold__
void chunkqueue_set_tempdirs_default (const array *tempdirs, off_t upload_temp_file_size);

void chunkqueue_set_tempdirs(chunkqueue * restrict cq, off_t upload_temp_file_size);

__attribute_cold__
const char *chunkqueue_env_tmpdir(void);

void chunkqueue_append_file(chunkqueue * restrict cq, const buffer * restrict fn, off_t offset, off_t len); /* copies "fn" */
void chunkqueue_append_file_fd(chunkqueue * restrict cq, const buffer * restrict fn, int fd, off_t offset, off_t len); /* copies "fn" */
void chunkqueue_append_mem(chunkqueue * restrict cq, const char * restrict mem, size_t len); /* copies memory */
void chunkqueue_append_mem_min(chunkqueue * restrict cq, const char * restrict mem, size_t len); /* copies memory */

__attribute_nonnull__()
void chunkqueue_append_buffer(chunkqueue * restrict cq, buffer * restrict mem); /* may reset "mem" */

__attribute_nonnull__()
void chunkqueue_append_chunkqueue(chunkqueue * restrict cq, chunkqueue * restrict src);

__attribute_returns_nonnull__
buffer * chunkqueue_prepend_buffer_open_sz(chunkqueue *cq, size_t sz);

__attribute_returns_nonnull__
buffer * chunkqueue_prepend_buffer_open(chunkqueue *cq);

void chunkqueue_prepend_buffer_commit(chunkqueue *cq);

__attribute_returns_nonnull__
buffer * chunkqueue_append_buffer_open_sz(chunkqueue *cq, size_t sz);

__attribute_returns_nonnull__
buffer * chunkqueue_append_buffer_open(chunkqueue *cq);

void chunkqueue_append_buffer_commit(chunkqueue *cq);

int chunkqueue_append_mem_to_tempfile(chunkqueue * restrict cq, const char * restrict mem, size_t len, log_error_st * const restrict errh);

#ifdef HAVE_SPLICE
ssize_t chunkqueue_append_splice_pipe_tempfile(chunkqueue * restrict cq, int fd, unsigned int len, log_error_st * restrict errh);
ssize_t chunkqueue_append_splice_sock_tempfile(chunkqueue * restrict cq, int fd, unsigned int len, log_error_st * restrict errh);
__attribute_cold__
void chunkqueue_internal_pipes(int init);
#else
#define chunkqueue_internal_pipes(init) do { } while (0)
#endif

/* functions to handle buffers to read into: */
/* obtain/reserve memory in chunkqueue at least len (input) size,
 * return pointer to memory with len (output) available for use
 * modifying the chunkqueue invalidates the memory area.
 * should always be followed by chunkqueue_get_memory(),
 *  even if nothing was read.
 * pass 0 in len for mem at least half of chunk_buf_sz
 */
__attribute_returns_nonnull__
char * chunkqueue_get_memory(chunkqueue * restrict cq, size_t * restrict len);
/* commit len bytes of mem obtained from chunkqueue_get_memory() */
void chunkqueue_use_memory(chunkqueue * restrict cq, chunk *ckpt, size_t len);
void chunkqueue_update_file(chunkqueue * restrict cq, chunk *c, off_t len);

/* mark first "len" bytes as written (incrementing chunk offsets)
 * and remove finished chunks
 */
void chunkqueue_mark_written(chunkqueue *cq, off_t len);

void chunkqueue_remove_finished_chunks(chunkqueue *cq);

__attribute_cold__
void chunkqueue_remove_empty_chunks(chunkqueue *cq);

void chunkqueue_steal(chunkqueue * restrict dest, chunkqueue * restrict src, off_t len);
int chunkqueue_steal_with_tempfiles(chunkqueue * restrict dest, chunkqueue * restrict src, off_t len, log_error_st * const restrict errh);
void chunkqueue_append_cq_range (chunkqueue *dst, const chunkqueue *src, off_t offset, off_t len);

int chunk_open_file_chunk(chunk * restrict c, log_error_st * restrict errh);

void chunkqueue_compact_mem_offset(chunkqueue *cq);
void chunkqueue_compact_mem(chunkqueue *cq, size_t clen);

void chunkqueue_small_resp_optim (chunkqueue * restrict cq);

ssize_t chunkqueue_write_chunk (int fd, chunkqueue * restrict cq, log_error_st * restrict errh);
ssize_t chunkqueue_write_chunk_to_pipe (int fd, chunkqueue * restrict cq, log_error_st * restrict errh);

int chunkqueue_peek_data (chunkqueue *cq, char **data, uint32_t *dlen, log_error_st * restrict errh, int nowait);
int chunkqueue_read_data (chunkqueue *cq, char *data, uint32_t dlen, log_error_st * restrict errh);

chunk * chunkqueue_read_squash (chunkqueue * restrict cq, log_error_st * restrict errh);

__attribute_pure__
__attribute_nonnull__()
static inline off_t chunkqueue_length(const chunkqueue *cq);
static inline off_t chunkqueue_length(const chunkqueue *cq) {
	return cq->bytes_in - cq->bytes_out;
}

__attribute_cold__
void chunkqueue_free(chunkqueue *cq);

void chunkqueue_reset(chunkqueue *cq);

__attribute_pure__
__attribute_nonnull__()
static inline int chunkqueue_is_empty(const chunkqueue *cq);
static inline int chunkqueue_is_empty(const chunkqueue *cq) {
	return NULL == cq->first;
}

const chunk_file_view * chunkqueue_chunk_file_viewadj (chunk *c, off_t n, log_error_st * restrict errh);

__attribute_pure__
__attribute_nonnull__()
static inline char *
chunk_file_view_dptr (const chunk_file_view * const cfv, off_t offset);
static inline char *
chunk_file_view_dptr (const chunk_file_view * const cfv, off_t offset)
{
    return cfv->mptr - cfv->foff + offset;
}

__attribute_pure__
__attribute_nonnull__()
static inline off_t
chunk_file_view_dlen (const chunk_file_view * const cfv, off_t offset);
static inline off_t
chunk_file_view_dlen (const chunk_file_view * const cfv, off_t offset)
{
    return cfv->mlen + cfv->foff - offset;
}

static inline const chunk_file_view *
chunkqueue_chunk_file_view (chunk * const c, const off_t n, log_error_st * const restrict errh);
static inline const chunk_file_view *
chunkqueue_chunk_file_view (chunk * const c, const off_t n, log_error_st * const restrict errh)
{
    /*assert(c->type == FILE_CHUNK);*/
  #if defined(HAVE_MMAP) || defined(_WIN32) /*(see local sys-mmap.h)*/
    /* mmap buffer if offset is outside old mmap area or not mapped at all */
    const chunk_file_view * const restrict cfv = c->file.view;
    if (NULL == cfv
        ? c->file.length - c->offset >= 131072 /* TBD: min chunk size to mmap */
        : (c->offset - cfv->foff < 0
           || chunk_file_view_dlen(cfv, c->offset) < (n ? n : 1)))
        return chunkqueue_chunk_file_viewadj(c, n, errh);
    return cfv;
  #else
    UNUSED(c);
    UNUSED(n);
    UNUSED(errh);
    return NULL;
  #endif
}

#endif