import os, cStringIO
from model import *
from mtypes import *


c_dbid   = Concept()
c_file   = Concept()
c_image  = Concept()

pathname  = Morphism(c_string, c_file,
                     "A string as the path name of a file.")
strcontent= Morphism(c_string, c_file,
                     "A string with the whole content of a file.")
dbimage   = Morphism(c_dbid,   c_image,
                     "An integer identifier for an image in the database.")
jpegimage = Morphism(c_file,   c_image,
                     "A file containing a JPEG image.")
ppmimage  = Morphism(c_file,   c_image,
                     "A file containing a PPM image.")

show = Operation([c_image, c_none],
                 "Show the given image.")
mul = Operation([c_image, c_image, c_image],
                "Mask the given image (binary 'and' with mask).")


### implementation ###

def show_xv(src):
    os.system('xv "%s"' % src)
show[pathname+jpegimage, 0] = show_xv
# or                         = Operation([c_string, c_none], implement=show_xv)

def mul_and(fn1, fn2):
    return os.popen('./and "%s" "%s"' % (fn1, fn2), 'r')
mul[pathname+ppmimage, pathname+ppmimage, ppmimage] = mul_and

def encode_jpg(src):
    return os.popen('cjpeg "%s"' % src, 'r')
c_image.eq[pathname+ppmimage, jpegimage] = encode_jpg

def decode_jpg(src):
    return os.popen('djpeg "%s"' % src, 'r')
c_image.eq[pathname+jpegimage, ppmimage] = decode_jpg

def binary_open(fn):
    return open(fn, 'rb')
c_file.eq[pathname, 0] = binary_open

## Python 2.3 only
##def make_temp_file(f, hack={}):
##    if f in hack:
##        return hack[f]
##    import tempfile, atexit
##    fd, filename = tempfile.mkstemp()
##    def try_unlink():
##        try:
##            os.unlink(filename)
##        except:
##            pass
##    atexit.register(try_unlink)
##    g = os.fdopen(fd, 'wb')
##    while True:
##        buf = f.read(4096)
##        if not buf: break
##        g.write(buf)
##    g.close()
##    f.close()
##    hack[f] = filename
##    return filename
def make_temp_file(f, hack={}):
    if f in hack:
        return hack[f]
    import tempfile, atexit
    filename = tempfile.mktemp()
    def try_unlink():
        try:
            os.unlink(filename)
        except:
            pass
    atexit.register(try_unlink)
    g = open(filename, 'wb')
    while True:
        buf = f.read(4096)
        if not buf: break
        g.write(buf)
    g.close()
    f.close()
    hack[f] = filename
    return filename
c_file.eq[0, pathname] = make_temp_file

c_file.eq[strcontent, 0] = cStringIO.StringIO

def load_file(f):
    return f.read()
c_file.eq[0, strcontent] = load_file

def db_load(n):
    if os.curdir not in sys.path:
        sys.path.insert(0, os.curdir)
    cwd = os.getcwd()
    try:
        os.chdir('../db')
        import mytest
        return mytest.load(n, djpeg=None)
    finally:
        os.chdir(cwd)
c_image.eq[dbimage, strcontent+jpegimage] = db_load