#include <bh/internal/file.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>

static const bh_io_table_t bh_file_table = {
    (int (*)(struct bh_io_s *, int)) bh_file_open_base,
    (void (*)(struct bh_io_s *)) bh_file_close_base,
    (int (*)(struct bh_io_s *)) bh_file_is_open_base,
    (size_t (*)(struct bh_io_s *, char *, size_t)) bh_file_read_base,
    (size_t (*)(struct bh_io_s *, const char *, size_t)) bh_file_write_base,
    (void (*)(struct bh_io_s *)) bh_file_flush_base,
    (int (*)(struct bh_io_s *, bh_off_t, int)) bh_file_seek_base,
    (bh_off_t (*)(struct bh_io_s *)) bh_file_size_base,
    (bh_off_t (*)(struct bh_io_s *)) bh_file_tell_base,
    (bh_off_t (*)(struct bh_io_s *)) bh_file_available_base,
    (void (*)(struct bh_io_s *)) bh_file_clear_base,
    (void (*)(struct bh_io_s *)) bh_file_destroy_base
};

bh_file_t *bh_file_new(const char *path)
{
    bh_file_t *result;

    /* Allocate and initialize file structure */
    result = malloc(sizeof(*result));
    if (result && bh_file_init(result, path))
    {
        /* Something went wrong - free allocated memory */
        free(result);
        result = NULL;
    }

    return result;
}

int bh_file_init(bh_file_t *file,
                 const char *path)
{
    /* Ensure that path is not empty */
    if (!path)
        return BH_INVALID;

    /* Initialize underlying io object */
    bh_io_init(&file->base, &bh_file_table, 1);

    /* Initialize file io object */
    file->handle = -1;
    file->mode = 0;
    file->path = strdup(path);

    return BH_OK;
}

void bh_file_destroy_base(bh_file_t *file)
{
    /* Close the file */
    bh_file_close(file);
    free(file->path);
    bh_io_destroy_base(&file->base);
}

int bh_file_open_base(bh_file_t *file,
                      int mode)
{
    /* Set open mode for 0666 permisions */
    mode_t open_mode = (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
    int open_flags = 0;

    /* Check if file is already opened */
    if (file->handle != -1)
        return BH_OK;

    /* Determine read/write flags */
    if (mode & BH_IO_READ_WRITE)
        open_flags |= O_RDWR;
    else if (mode & BH_IO_READ)
        open_flags |= O_RDONLY;
    else if (mode & BH_IO_WRITE)
        open_flags |= O_WRONLY;
    else
        return BH_INVALID;

    /* Determine open mode */
    switch (mode & (BH_IO_CREATE | BH_IO_OPEN))
    {
    default:
    case 0:            open_flags |= O_CREAT;          break;
    case BH_IO_CREATE: open_flags |= O_CREAT | O_EXCL; break;
    case BH_IO_OPEN:   /* Do nothing */                break;
    }

    if (mode & BH_IO_APPEND)
        open_flags |= O_APPEND;

    if (mode & BH_IO_TRUNCATE)
        open_flags |= O_TRUNC;

    /* Open file */
    file->handle = open(file->path, open_flags, open_mode);

    /* Check for errors */
    if (file->handle == -1)
    {
        switch (errno)
        {
        case EEXIST: return BH_FOUND;
        case ENOENT: return BH_NOT_FOUND;
        default: return BH_ERROR;
        }
    }

    return BH_OK;
}

void bh_file_close_base(bh_file_t *file)
{
    /* Close file if it's open */
    if (file->handle != -1)
        close(file->handle);

    /* Set handle to invalid value */
    file->handle = -1;
}

int bh_file_is_open_base(bh_file_t *file)
{
    /* If handle is not -1 - then file is open */
    return file->handle != -1;
}

size_t bh_file_read_base(bh_file_t *file,
                         char *data,
                         size_t size)
{
    ssize_t readed;

    /* Check if file is open */
    if (file->handle == -1)
    {
        /* Error occured - set error bit */
        file->base.flags |= BH_IO_ERROR;
        return 0;
    }

    /* Read data from file */
    readed = read(file->handle, data, size);
    if (readed < 0)
    {
        /* Error occured - set error bit */
        file->base.flags |= BH_IO_ERROR;
        return 0;
    }

    /* Check for end of file */
    if (!readed)
        file->base.flags |= BH_IO_EOF;
    else
        file->base.flags &= ~BH_IO_EOF;

    /* Return number of readed bytes */
    return readed;
}

size_t bh_file_write_base(bh_file_t *file,
                          const char *data,
                          size_t size)
{
    ssize_t written;

    /* Check if file is open */
    if (file->handle == -1)
    {
        /* Error occured - set error bit */
        file->base.flags |= BH_IO_ERROR;
        return 0;
    }

    /* Write data to file */
    written = write(file->handle, data, size);
    if (written < 0)
    {
        /* Error occured - set error bit */
        file->base.flags |= BH_IO_ERROR;
        return 0;
    }

    /* Check for end of file */
    if (!written)
        file->base.flags |= BH_IO_EOF;
    else
        file->base.flags &= ~BH_IO_EOF;

    /* Return number of written bytes */
    return written;
}

void bh_file_flush_base(bh_file_t *file)
{
    /* Check if file is open */
    if (file->handle == -1)
        return;

    /* Signal OS to flush data from the internal buffers */
    fsync(file->handle);
}

int bh_file_seek_base(bh_file_t *file,
                      bh_off_t pos,
                      int dir)
{
    /* Check if file is open */
    if (file->handle == -1)
        return BH_ERROR;

    /* Seek to desired location */
    if (lseek(file->handle, pos, dir) == -1)
        return BH_ERROR;

    return BH_OK;
}

bh_off_t bh_file_size_base(bh_file_t *file)
{
    struct stat sb;

    /* Check if file is open */
    if (file->handle == -1)
        return -1;

    /* Get file size from the OS */
    if (fstat(file->handle, &sb))
        return -1;

    return sb.st_size;
}

bh_off_t bh_file_tell_base(bh_file_t *file)
{
    /* Check if file is open */
    if (file->handle == -1)
        return -1;

    /* Get current file position */
    return lseek(file->handle, 0, SEEK_CUR);
}

bh_off_t bh_file_available_base(bh_file_t *file)
{
    /* Get available bytes for reading */
    return bh_file_size_base(file) - bh_file_tell_base(file);
}

void bh_file_clear_base(bh_file_t *file)
{
    file->base.flags &= ~BH_IO_ERROR;
}