/*
 * Copyright 2005-2017 ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 *
 * In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
 * virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
 */

/*
 *
 * Description: file pool
 *
 */

#include "grib_api_internal.h"
#define GRIB_MAX_OPENED_FILES 200

#if GRIB_PTHREADS
static pthread_once_t once  = PTHREAD_ONCE_INIT;
static pthread_mutex_t mutex1 = PTHREAD_MUTEX_INITIALIZER;

static void init() {
    pthread_mutexattr_t attr;
    pthread_mutexattr_init(&attr);
    pthread_mutexattr_settype(&attr,PTHREAD_MUTEX_RECURSIVE);
    pthread_mutex_init(&mutex1,&attr);
    pthread_mutexattr_destroy(&attr);

}
#elif GRIB_OMP_THREADS
static int once = 0;
static omp_nest_lock_t mutex1;

static void init()
{
    GRIB_OMP_CRITICAL(lock_grib_filepool_c)
    {
        if (once == 0)
        {
            omp_init_nest_lock(&mutex1);
            once = 1;
        }
    }
}
#endif

static short next_id=0;

/* Note: A fast cut-down version of strcmp which does NOT return -1 */
/* 0 means input strings are equal and 1 means not equal */
GRIB_INLINE static int grib_inline_strcmp(const char* a,const char* b)
{
    if (*a != *b) return 1;
    while((*a!=0 && *b!=0) &&  *(a) == *(b) ) {a++;b++;}
    return (*a==0 && *b==0) ? 0 : 1;
}

static grib_file_pool file_pool= {
        0,                    /* grib_context* context;*/
        0,                    /* grib_file* first;*/
        0,                    /* grib_file* current; */
        0,                    /* size_t size;*/
        0,                    /* int number_of_opened_files;*/
        GRIB_MAX_OPENED_FILES /* int max_opened_files; */
};

void grib_file_pool_clean()
{
    grib_file *file,*next;

    if (!file_pool.first) return;

    file=file_pool.first;
    while(file) {
        next=file->next;
        grib_file_delete(file);
        file=next;
    }
}

static void grib_file_pool_change_id()
{
    grib_file *file;

    if (!file_pool.first) return;

    file=file_pool.first;
    while(file) {
        file->id+=1000;
        file=file->next;
    }
}

static grib_file* grib_read_file(grib_context *c,FILE* fh,int *err)
{
    short marker=0;
    short id=0;
    grib_file* file;
    *err = grib_read_short(fh,&marker);
    if(!marker) return NULL;

    file=(grib_file*)grib_context_malloc_clear(c,sizeof(grib_file));
    file->buffer=0;
    file->name=grib_read_string(c,fh,err);
    if (*err) return NULL;

    *err=grib_read_short(fh,&id);
    file->id=id;
    if (*err) return NULL;

    file->next=grib_read_file(c,fh,err);
    if (*err) return NULL;

    return file;
}

static int grib_write_file(FILE *fh,grib_file* file)
{
    int err=0;

    if (!file)
        return grib_write_null_marker(fh);

    err=grib_write_not_null_marker(fh);
    if (err) return err;

    err=grib_write_string(fh,file->name);
    if (err) return err;

    err=grib_write_short(fh,(short)file->id);
    if (err) return err;

    return grib_write_file(fh,file->next);
}

grib_file* grib_file_pool_get_files()
{
    return file_pool.first;
}

int grib_file_pool_read(grib_context* c,FILE* fh)
{
    int err=0;
    short marker=0;
    grib_file* file;

    if (!c) c=grib_context_get_default();

    err = grib_read_short(fh,&marker);
    if(!marker) {
        grib_context_log(c,GRIB_LOG_ERROR,
                "Unable to find file information in index file\n");
        return GRIB_INVALID_FILE;
    }

    grib_file_pool_change_id();
    file=file_pool.first;

    while (file->next)
        file=file->next;

    file->next=grib_read_file(c,fh,&err);
    if (err) return err;

    return GRIB_SUCCESS;
}

int grib_file_pool_write(FILE* fh)
{
    int err=0;
    if (!file_pool.first)
        return grib_write_null_marker(fh);

    err=grib_write_not_null_marker(fh);
    if (err) return err;

    return grib_write_file(fh,file_pool.first);
}

grib_file* grib_file_open(const char* filename, const char* mode,int* err)
{
    grib_file *file=0,*prev=0;
    int same_mode=0;
    int is_new=0;
    GRIB_MUTEX_INIT_ONCE(&once,&init);

    if (!file_pool.context) file_pool.context=grib_context_get_default();

    if (file_pool.current && !grib_inline_strcmp(filename,file_pool.current->name)) {
        file=file_pool.current;
    } else {
        GRIB_MUTEX_LOCK(&mutex1);
        file=file_pool.first;
        while (file) {
            if (!grib_inline_strcmp(filename,file->name)) break;
            prev=file;
            file=file->next;
        }
        if (!file) {
            is_new=1;
            file=grib_file_new(file_pool.context,filename,err);
            if (prev) prev->next=file;
            file_pool.current=file;
            if (!prev) file_pool.first=file;
            file_pool.size++;
        }
        GRIB_MUTEX_UNLOCK(&mutex1);
    }

    if (file->mode) same_mode=grib_inline_strcmp(mode,file->mode) ? 0 : 1;
    if (file->handle && same_mode) {
        *err=0;
        return file;
    }

    GRIB_MUTEX_LOCK(&mutex1);
    if (!same_mode && file->handle) {
        /*printf("========== mode=%s file->mode=%s\n",mode,file->mode);*/
        fclose(file->handle);
    }

    if (!file->handle) {
        /*printf("-- opening file %s %s\n",file->name,mode);*/
        if (!is_new && *mode == 'w') {
            /* fprintf(stderr,"++++ opening %s as append\n",file->name); */
            file->handle = fopen(file->name,"a");
        } else {
            file->handle = fopen(file->name,mode);
            /* fprintf(stderr,"++++ opening %s as mode\n",file->name); */
        }

        file->mode=strdup(mode);
        if (!file->handle) {
            grib_context_log(file->context,GRIB_LOG_PERROR,"grib_file_open: cannot open file %s",file->name);
            *err=GRIB_IO_PROBLEM;
            GRIB_MUTEX_UNLOCK(&mutex1);
            return NULL;
        }
        if (file_pool.context->io_buffer_size) {
#ifdef POSIX_MEMALIGN
            if (posix_memalign((void**)&(file->buffer),sysconf(_SC_PAGESIZE),file_pool.context->io_buffer_size) ) {
                grib_context_log(file->context,GRIB_LOG_FATAL,"posix_memalign unable to allocate io_buffer\n");
            }
#else
            file->buffer = (void*)malloc(file_pool.context->io_buffer_size);
            if (!file->buffer) {
                grib_context_log(file->context,GRIB_LOG_FATAL,"Unable to allocate io_buffer\n");
            }
#endif
            setvbuf(file->handle,file->buffer,_IOFBF,file_pool.context->io_buffer_size);
        }

        file_pool.number_of_opened_files++;
    }

    GRIB_MUTEX_UNLOCK(&mutex1);
    return file;
}

void grib_file_pool_delete_file(grib_file* file) {
    grib_file* prev=NULL;
    GRIB_MUTEX_INIT_ONCE(&once,&init);
    GRIB_MUTEX_LOCK(&mutex1);

    if (file==file_pool.first) {
        file_pool.first=file->next;
        file_pool.current=file->next;
    } else {

        prev=file_pool.first;
        file_pool.current=file_pool.first;
        while (prev) {
            if (prev->next==file) break;
            prev=prev->next;
        }
        Assert(prev);
        prev->next=file->next;
    }

    if (file->handle) {
        file_pool.number_of_opened_files--;
    }
    grib_file_delete(file);
    GRIB_MUTEX_UNLOCK(&mutex1);

}

void grib_file_close(const char* filename, int force, int* err)
{
    grib_file* file=NULL;
    grib_context* context = grib_context_get_default();

    /* Performance: keep the files open to avoid opening and closing files when writing the output. */
    /* So only call fclose() when too many files are open. */
    /* Also see ECC-411 */
    int do_close = (file_pool.number_of_opened_files > context->file_pool_max_opened_files);
    if (force == 1) do_close=1; /* Can be overridden with the force argument */

    if ( do_close ) {
        /*printf("+++++++++++++ closing file %s (n=%d)\n",filename, file_pool.number_of_opened_files);*/
        GRIB_MUTEX_INIT_ONCE(&once,&init);
        GRIB_MUTEX_LOCK(&mutex1);
        file=grib_get_file(filename,err);
        if (file->handle) {
            if (fclose(file->handle) != 0) {
                *err=GRIB_IO_PROBLEM;
            }
            if (file->buffer) {
                free(file->buffer);
                file->buffer=0;
            }
            file->handle=NULL;
            file_pool.number_of_opened_files--;
        }
        GRIB_MUTEX_UNLOCK(&mutex1);
    }
}

void grib_file_close_all(int *err)
{
    grib_file* file = NULL;
    if (!file_pool.first) return;

    GRIB_MUTEX_INIT_ONCE(&once,&init);
    GRIB_MUTEX_LOCK(&mutex1);

    file = file_pool.first;
    while (file) {
        if (file->handle) {
            if (fclose(file->handle) != 0) {
                *err=GRIB_IO_PROBLEM;
            }
            file->handle=NULL;
        }
        file = file->next;
    }

    GRIB_MUTEX_UNLOCK(&mutex1);
}

grib_file* grib_get_file(const char* filename,int* err)
{
    grib_file* file=NULL;

    if (file_pool.current->name && !grib_inline_strcmp(filename,file_pool.current->name)) {
        return file_pool.current;
    }

    file=file_pool.first;
    while (file) {
        if (!grib_inline_strcmp(filename,file->name)) break;
        file=file->next;
    }
    if (!file) file=grib_file_new(0,filename,err);

    return file;
}

grib_file* grib_find_file(short id)
{
    grib_file* file=NULL;

    if (file_pool.current->name && id==file_pool.current->id) {
        return file_pool.current;
    }

    file=file_pool.first;
    while (file) {
        if (id==file->id) break;
        file=file->next;
    }

    return file;
}

grib_file* grib_file_new(grib_context* c, const char* name, int* err)
{
    grib_file* file;

    if (!c) c=grib_context_get_default( );

    file=(grib_file*)grib_context_malloc_clear( c,sizeof(grib_file));

    if (!file) {
        grib_context_log(c,GRIB_LOG_ERROR,"grib_file_new: unable to allocate memory");
        *err=GRIB_OUT_OF_MEMORY;
        return NULL;
    }
    GRIB_MUTEX_INIT_ONCE(&once,&init);

    file->name=strdup(name);
    file->id=next_id;

    GRIB_MUTEX_LOCK(&mutex1);
    next_id++;
    GRIB_MUTEX_UNLOCK(&mutex1);

    file->mode=0;
    file->handle=0;
    file->refcount=0;
    file->context=c;
    file->next=0;
    file->buffer=0;
    return file;
}

void grib_file_delete(grib_file* file)
{
    {
        if (!file) return;
    }
    GRIB_MUTEX_INIT_ONCE(&once,&init);
    GRIB_MUTEX_LOCK(&mutex1);
    /* GRIB-803: cannot call fclose yet! Causes crash */
    /* TODO: Set handle to NULL in filepool too */
#if 0
    if (file->handle) {
        if (fclose(file->handle) != 0) {
            perror(file->name);
        }
    }
#endif
    if (file->name) free(file->name);
    if (file->mode) free(file->mode);

    if (file->buffer) {
        free(file->buffer);
    }
    grib_context_free(file->context,file);
    file=NULL;
    GRIB_MUTEX_UNLOCK(&mutex1);
}
