/*
 *  (C) 2009 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */

#define _GNU_SOURCE
#include "darshan-util-config.h"
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>
#include <unistd.h>
#include <inttypes.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>

#include <zlib.h>
#ifdef HAVE_LIBBZ2
#include <bzlib.h>
#endif

#include "darshan-logutils.h"

/* default to a compression buffer size of 4 MiB */
#define DARSHAN_DEF_DECOMP_BUF_SZ (4*1024*1024)

struct darshan_fd_s
{
    int pf;
    int64_t pos;
    char version[8];
    int swap_flag;
    char *exe_mnt_data;
    struct darshan_log_map job_map;
    struct darshan_log_map rec_map;
    struct darshan_log_map mod_map[DARSHAN_MAX_MODS];
};

static int darshan_log_seek(darshan_fd fd, off_t offset);
static int darshan_log_read(darshan_fd fd, void *buf, int len);
static int darshan_log_write(darshan_fd fd, void *buf, int len);
static int darshan_decompress_buffer(char *comp_buf, int comp_buf_sz,
    char *decomp_buf, int *inout_decomp_buf_sz);

/* darshan_log_open()
 *
 * open a darshan log file for reading/writing
 *
 * returns 0 on success, -1 on failure
 */
darshan_fd darshan_log_open(const char *name, const char *mode)
{
    int o_flags;

    /* we only allows "w" or "r" modes, nothing fancy */
    assert(strlen(mode) == 1);
    assert(mode[0] == 'r' || mode[0] == 'w');
    if(mode[0] == 'r')
        o_flags = O_RDONLY;
    else
        o_flags = O_WRONLY;

    darshan_fd tmp_fd = malloc(sizeof(*tmp_fd));
    if(!tmp_fd)
        return(NULL);
    memset(tmp_fd, 0, sizeof(*tmp_fd));

    tmp_fd->pf = open(name, o_flags);
    if(tmp_fd->pf < 0)
    {
        free(tmp_fd);
        return(NULL);
    }

    return(tmp_fd);
}

/* darshan_log_getheader()
 *
 * read the header of the darshan log and set internal data structures
 * NOTE: this function must be called before reading other portions of the log
 *
 * returns 0 on success, -1 on failure
 */
int darshan_log_getheader(darshan_fd fd, struct darshan_header *header)
{
    int i;
    int ret;

    ret = darshan_log_seek(fd, 0);
    if(ret < 0)
    {
        fprintf(stderr, "Error: unable to seek in darshan log file.\n");
        return(ret);
    }

    /* read header from log file */
    ret = darshan_log_read(fd, header, sizeof(*header));
    if(ret < sizeof(*header))
    {
        fprintf(stderr, "Error: invalid darshan log file (failed to read header).\n");
        return(-1);
    }

    /* save the version string */
    strncpy(fd->version, header->version_string, 8);

    if(header->magic_nr == DARSHAN_MAGIC_NR)
    {
        /* no byte swapping needed, this file is in host format already */
        fd->swap_flag = 0;
    }
    else
    {
        /* try byte swapping */
        DARSHAN_BSWAP64(&header->magic_nr);
        if(header->magic_nr == DARSHAN_MAGIC_NR)
        {
            fd->swap_flag = 1;

            /* swap the log map variables in the header */
            DARSHAN_BSWAP64(&header->rec_map.off);
            DARSHAN_BSWAP64(&header->rec_map.len);
            for(i=0;i<DARSHAN_MAX_MODS;i++)
            {
                DARSHAN_BSWAP64(&header->mod_map[i].off);
                DARSHAN_BSWAP64(&header->mod_map[i].len);
            }
        }
        else
        {
            /* otherwise this file is just broken */
            fprintf(stderr, "Error: bad magic number in darshan log file.\n");
            return(-1);
        }
    }

    /* save the mapping of data within log file to this file descriptor */
    fd->job_map.off = sizeof(struct darshan_header);
    fd->job_map.len = header->rec_map.off - fd->job_map.off;
    memcpy(&fd->rec_map, &header->rec_map, sizeof(struct darshan_log_map));
    memcpy(&fd->mod_map, &header->mod_map, DARSHAN_MAX_MODS * sizeof(struct darshan_log_map));

    return(0);
}

/* darshan_log_getjob()
 *
 * read job level metadata from the darshan log file
 *
 * returns 0 on success, -1 on failure
 */
int darshan_log_getjob(darshan_fd fd, struct darshan_job *job)
{
    char *comp_buf;
    char job_buf[DARSHAN_JOB_RECORD_SIZE] = {0};
    int job_buf_sz = DARSHAN_JOB_RECORD_SIZE;
    int ret;

    /* allocate a buffer to store the (compressed) darshan job info */
    comp_buf = malloc(fd->job_map.len);
    if(!comp_buf)
        return(-1);

    ret = darshan_log_seek(fd, fd->job_map.off);
    if(ret < 0)
    {
        fprintf(stderr, "Error: unable to seek in darshan log file.\n");
        free(comp_buf);
        return(ret);
    }

    /* read the job data from the log file */
    ret = darshan_log_read(fd, comp_buf, fd->job_map.len);
    if(ret < fd->job_map.len)
    {
        fprintf(stderr, "Error: invalid darshan log file (failed to read job data).\n");
        free(comp_buf);
        return(-1);
    }

    /* decompress the job data */
    ret = darshan_decompress_buffer(comp_buf, fd->job_map.len,
        job_buf, &job_buf_sz);
    if(ret < 0)
    {
        fprintf(stderr, "Error: unable to decompress darshan job data.\n");
        free(comp_buf);
        return(-1);
    }
    assert(job_buf_sz == DARSHAN_JOB_RECORD_SIZE);
    free(comp_buf);

    memcpy(job, job_buf, sizeof(*job));

    if(fd->swap_flag)
    {
        /* swap bytes if necessary */
        DARSHAN_BSWAP64(&job->uid);
        DARSHAN_BSWAP64(&job->start_time);
        DARSHAN_BSWAP64(&job->end_time);
        DARSHAN_BSWAP64(&job->nprocs);
        DARSHAN_BSWAP64(&job->jobid);
    }

    /* save trailing job data, so exe and mount information can be retrieved later */
    if(!fd->exe_mnt_data)
        fd->exe_mnt_data = malloc(DARSHAN_EXE_LEN+1);
    if(!fd->exe_mnt_data)
        return(-1);
    memcpy(fd->exe_mnt_data, &job_buf[sizeof(*job)], DARSHAN_EXE_LEN+1);

    return(0);
}

int darshan_log_getexe(darshan_fd fd, char *buf)
{
    char *newline;

    /* if the exe/mount info has not been saved yet, read in the job
     * header to get this data.
     */
    if(!fd->exe_mnt_data)
    {
        struct darshan_job job;
        (void)darshan_log_getjob(fd, &job);

        if(!fd->exe_mnt_data)
            return(-1);
    }

    newline = strchr(fd->exe_mnt_data, '\n');

    /* copy over the exe string */
    if(newline)
        memcpy(buf, fd->exe_mnt_data, (newline - fd->exe_mnt_data));

    return (0);
}

/* darshan_log_getmounts()
 * 
 * retrieves mount table information from the log.  Note that mnt_pts and
 * fs_types are arrays that will be allocated by the function and must be
 * freed by the caller.  count will indicate the size of the arrays
 */
int darshan_log_getmounts(darshan_fd fd, char*** mnt_pts,
    char*** fs_types, int* count)
{
    int ret;
    char *pos;
    int array_index = 0;

    /* if the exe/mount info has not been saved yet, read in the job
     * header to get this data.
     */
    if(!fd->exe_mnt_data)
    {
        struct darshan_job job;
        (void)darshan_log_getjob(fd, &job);

        if(!fd->exe_mnt_data)
            return(-1);
    }

    *count = 0;
    pos = fd->exe_mnt_data;
    while((pos = strchr(pos, '\n')) != NULL)
    {
        pos++;
        (*count)++;
    }

    if(*count == 0)
    {
        /* no mount entries present */
        return(0);
    }

    /* allocate output arrays */
    *mnt_pts = malloc((*count)*sizeof(char*));
    assert(*mnt_pts);
    *fs_types = malloc((*count)*sizeof(char*));
    assert(*fs_types);

    /* work backwards through the table and parse each line (except for
     * first, which holds command line information)
     */
    while((pos = strrchr(fd->exe_mnt_data, '\n')) != NULL)
    {
        /* overestimate string lengths */
        (*mnt_pts)[array_index] = malloc(DARSHAN_EXE_LEN);
        assert((*mnt_pts)[array_index]);
        (*fs_types)[array_index] = malloc(DARSHAN_EXE_LEN);
        assert((*fs_types)[array_index]);

        ret = sscanf(++pos, "%s\t%s", (*fs_types)[array_index],
            (*mnt_pts)[array_index]);
        if(ret != 2)
        {
            fprintf(stderr, "Error: poorly formatted mount table in log file.\n");
            return(-1);
        }
        pos--;
        *pos = '\0';
        array_index++;
    }

    return(0);
}

/* darshan_log_gethash()
 *
 * read the hash of records from the darshan log file
 *
 * returns 0 on success, -1 on failure
 */
int darshan_log_gethash(darshan_fd fd, struct darshan_record_ref **hash)
{
    char *comp_buf;
    char hash_buf[DARSHAN_DEF_DECOMP_BUF_SZ] = {0};
    int hash_buf_sz = DARSHAN_DEF_DECOMP_BUF_SZ;
    char *buf_ptr;
    darshan_record_id *rec_id_ptr;
    uint32_t *path_len_ptr;
    char *path_ptr;
    struct darshan_record_ref *ref;
    int ret;

    /* allocate a buffer to store the (compressed, serialized) darshan record hash */
    comp_buf = malloc(fd->rec_map.len);
    if(!comp_buf)
        return(-1);

    ret = darshan_log_seek(fd, fd->rec_map.off);
    if(ret < 0)
    {
        fprintf(stderr, "Error: unable to seek in darshan log file.\n");
        free(comp_buf);
        return(ret);
    }

    /* read the record hash from the log file */
    ret = darshan_log_read(fd, comp_buf, fd->rec_map.len);
    if(ret < fd->rec_map.len)
    {
        fprintf(stderr, "Error: invalid darshan log file (failed to read record hash).\n");
        free(comp_buf);
        return(-1);
    }

    /* decompress the record hash buffer */
    ret = darshan_decompress_buffer(comp_buf, fd->rec_map.len,
        hash_buf, &hash_buf_sz);
    if(ret < 0)
    {
        fprintf(stderr, "Error: unable to decompress darshan job data.\n");
        free(comp_buf);
        return(-1);
    }
    free(comp_buf);

    buf_ptr = hash_buf;
    while(buf_ptr < (hash_buf + hash_buf_sz))
    {
        /* get pointers for each field of this darshan record */
        /* NOTE: darshan record hash serialization method: 
         *          ... darshan_record_id | (uint32_t) path_len | path ...
         */
        rec_id_ptr = (darshan_record_id *)buf_ptr;
        buf_ptr += sizeof(darshan_record_id);
        path_len_ptr = (uint32_t *)buf_ptr;
        buf_ptr += sizeof(uint32_t);
        path_ptr = (char *)buf_ptr;
        buf_ptr += *path_len_ptr;

        if(fd->swap_flag)
        {
            /* we need to sort out endianness issues before deserializing */
            DARSHAN_BSWAP64(rec_id_ptr);
            DARSHAN_BSWAP32(path_len_ptr);
        }

        HASH_FIND(hlink, *hash, rec_id_ptr, sizeof(darshan_record_id), ref);
        if(!ref)
        {
            ref = malloc(sizeof(*ref));
            if(!ref)
            {
                return(-1);
            }
            ref->rec.name = malloc(*path_len_ptr + 1);
            if(!ref->rec.name)
            {
                free(ref);
                return(-1);
            }

            /* set the fields for this record */
            ref->rec.id = *rec_id_ptr;
            memcpy(ref->rec.name, path_ptr, *path_len_ptr);
            ref->rec.name[*path_len_ptr] = '\0';

            /* add this record to the hash */
            HASH_ADD(hlink, *hash, rec.id, sizeof(darshan_record_id), ref);
        }
    }

    return(0);
}

int darshan_log_getmod(darshan_fd fd, darshan_module_id mod_id,
    void **mod_buf, int *mod_buf_sz)
{
    char *comp_buf;
    char *tmp_buf;
    int tmp_buf_sz;
    int ret;
    *mod_buf = NULL;
    *mod_buf_sz = 0;

    if(mod_id < 0 || mod_id >= DARSHAN_MAX_MODS)
    {
        fprintf(stderr, "Error: invalid Darshan module id.\n");
        return(-1);
    }

    if(fd->mod_map[mod_id].len == 0)
    {
        /* this module has no data in the log */
        return(0);
    }

    comp_buf = malloc(fd->mod_map[mod_id].len);
    if(!comp_buf)
        return(-1);

    ret = darshan_log_seek(fd, fd->mod_map[mod_id].off);
    if(ret < 0)
    {
        fprintf(stderr, "Error: unable to seek in darshan log file.\n");
        free(comp_buf);
        return(ret);
    }

    /* read the given module's (compressed) data from the log file */
    ret = darshan_log_read(fd, comp_buf, fd->mod_map[mod_id].len);
    if(ret < fd->mod_map[mod_id].len)
    {
        fprintf(stderr, "Error: invalid darshan log file (failed to read module %s data).\n",
            darshan_module_names[mod_id]);
        free(comp_buf);
        return(-1);
    }

    tmp_buf_sz = DARSHAN_DEF_DECOMP_BUF_SZ;
    tmp_buf = malloc(DARSHAN_DEF_DECOMP_BUF_SZ);
    if(!tmp_buf)
    {
        free(comp_buf);
        return(-1);
    }

    /* decompress this module's data */
    ret = darshan_decompress_buffer(comp_buf, fd->mod_map[mod_id].len, tmp_buf,
        &tmp_buf_sz);
    if(ret < 0)
    {
        fprintf(stderr, "Error: unable to decompress module %s data.\n",
            darshan_module_names[mod_id]);
        free(tmp_buf);
        return(-1);
    }
    free(comp_buf);

    /* pass back the final decompressed data pointer */
    *mod_buf = tmp_buf;
    *mod_buf_sz = tmp_buf_sz;

    return(0);
}

/* TODO: hardcoded for posix -- what can we do generally?
 *       different function for each module and a way to map to this function?
 */
/* TODO: we need bswaps here, too */
int darshan_log_getfile(darshan_fd fd, struct darshan_posix_file *file)
{
    char *comp_buf;
    char hash_buf[DARSHAN_DEF_DECOMP_BUF_SZ] = {0};
    int ret;
    const char* err_string;
    int i;

    if(fd->pos < fd->mod_map[0].off)
    {
        ret = darshan_log_seek(fd, fd->mod_map[0].off);
        if(ret < 0)
        {
            fprintf(stderr, "Error: unable to seek in darshan log file.\n");
            return(ret);
        }
    }

    /* reset file record, so that diff compares against a zero'd out record
     * if file is missing
     */
    memset(file, 0, sizeof(*file));

    ret = darshan_log_read(fd, file, sizeof(*file));
    if(ret == sizeof(*file))
    {
        /* got exactly one, correct size record */
        if(fd->swap_flag)
        {
            /* swap bytes if necessary */
            DARSHAN_BSWAP64(&file->f_id);
            DARSHAN_BSWAP64(&file->rank);
            for(i=0; i<CP_NUM_INDICES; i++)
                DARSHAN_BSWAP64(&file->counters[i]);
            for(i=0; i<CP_F_NUM_INDICES; i++)
                DARSHAN_BSWAP64(&file->fcounters[i]);
        }
        return(1);
    }


    if(ret > 0)
    {
        /* got a short read */
        fprintf(stderr, "Error: invalid file record (too small)\n");
        return(-1);
    }

    if(ret == 0)
    {
        /* hit end of file */
        return(0);
    }

    /* all other errors */
    err_string = strerror(errno);
    fprintf(stderr, "Error: %s\n", err_string);
    return(-1);
}

/* darshan_log_close()
 *
 * close an open darshan file descriptor
 *
 * returns 0 on success, -1 on failure
 */
void darshan_log_close(darshan_fd fd)
{
    if(fd->pf)
        close(fd->pf);

    if(fd->exe_mnt_data)
        free(fd->exe_mnt_data);

    free(fd);
}

/* ******************************************* */

/* return 0 on successful seek to offset, -1 on failure.
 */
static int darshan_log_seek(darshan_fd fd, off_t offset)
{
    off_t ret_off;

    if(fd->pos == offset)
        return(0);

    ret_off = lseek(fd->pf, offset, SEEK_SET);
    if(ret_off == offset)
    {
        fd->pos = offset;
        return(0);
    }

    return(-1);
}

/* return amount written on success, -1 on failure.
 */
static int darshan_log_write(darshan_fd fd, void* buf, int len)
{
    int ret;

    if(fd->pf)
    {
        ret = write(fd->pf, buf, len);
        if(ret > 0)
            fd->pos += ret;
        return(ret);
    }

    return(-1);
}

/* return amount read on success, 0 on EOF, -1 on failure.
 */
static int darshan_log_read(darshan_fd fd, void* buf, int len)
{
    int ret;

    if(fd->pf)
    {
        ret = read(fd->pf, buf, len);
        if(ret > 0)
            fd->pos += ret;
        return(ret);
    }

    return(-1);
}

/* TODO bz2 compression support */
static int darshan_decompress_buffer(char *comp_buf, int comp_buf_sz,
    char *decomp_buf, int *inout_decomp_buf_sz)
{
    int ret;
    int total_out = 0;
    z_stream tmp_stream;

    memset(&tmp_stream, 0, sizeof(tmp_stream));
    tmp_stream.zalloc = Z_NULL;
    tmp_stream.zfree = Z_NULL;
    tmp_stream.opaque = Z_NULL;
    tmp_stream.next_in = comp_buf;
    tmp_stream.avail_in = comp_buf_sz;
    tmp_stream.next_out = decomp_buf;
    tmp_stream.avail_out = *inout_decomp_buf_sz;

    /* initialize the zlib decompression parameters */
    /* TODO: check these parameters? */
    //ret = inflateInit2(&tmp_stream, 31);
    ret = inflateInit(&tmp_stream);
    if(ret != Z_OK)
    {
        return(-1);
    }

    /* while we have not finished consuming all of the compressed input data */
    while(tmp_stream.avail_in)
    {
        if(tmp_stream.avail_out == 0)
        {
            /* We ran out of buffer space for compression.  In theory,
             * we could just alloc more space, but probably just easier
             * to bump up the default size of the output buffer.
             */
            inflateEnd(&tmp_stream);
            return(-1);
        }

        /* decompress data */
        ret = inflate(&tmp_stream, Z_FINISH);
        if(ret != Z_STREAM_END)
        {
            inflateEnd(&tmp_stream);
            return(-1);
        }

        total_out += tmp_stream.total_out;
        if(tmp_stream.avail_in)
            inflateReset(&tmp_stream);
    }
    inflateEnd(&tmp_stream);

    *inout_decomp_buf_sz = total_out;
    return(0);
}

/*
 * Local variables:
 *  c-indent-level: 4
 *  c-basic-offset: 4
 * End:
 *
 * vim: ts=8 sts=4 sw=4 expandtab
 */