"""
Minimal proxy to a GEOS C dynamic library, which is system dependant

Two environment variables influence this module: GEOS_LIBRARY_PATH and/or
GEOS_CONFIG.

If GEOS_LIBRARY_PATH is set to a path to a GEOS C shared library, this is
used. Otherwise GEOS_CONFIG can be set to a path to `geos-config`. If
`geos-config` is already on the PATH environment variable, then it will
be used to help better guess the name for the GEOS C dynamic library.
"""

from ctypes import CDLL, cdll, c_void_p, c_char_p
from ctypes.util import find_library
import os
import logging
import re
import subprocess
import sys


# Add message handler to this module's logger
log = logging.getLogger(__name__)
ch = logging.StreamHandler()
log.addHandler(ch)

if 'all' in sys.warnoptions:
    # show GEOS messages in console with: python -W all
    log.setLevel(logging.DEBUG)


# The main point of this module is to load a dynamic library to this variable
lgeos = None

# First try: use GEOS_LIBRARY_PATH environment variable
if 'GEOS_LIBRARY_PATH' in os.environ:
    geos_library_path = os.environ['GEOS_LIBRARY_PATH']
    try:
        lgeos = CDLL(geos_library_path)
    except:
        log.warn('cannot open shared object from GEOS_LIBRARY_PATH: %s',
                 geos_library_path)
    if lgeos:
        if hasattr(lgeos, 'GEOSversion'):
            log.debug('found GEOS C library using GEOS_LIBRARY_PATH')
        else:
            raise OSError(
                'shared object GEOS_LIBRARY_PATH is not a GEOS C library: '
                + str(geos_library_path))

# Second try: use GEOS_CONFIG environment variable
if 'GEOS_CONFIG' in os.environ:
    geos_config = os.environ['GEOS_CONFIG']
    log.debug('geos_config: %s', geos_config)
else:
    geos_config = 'geos-config'


def get_geos_config(option):
    '''Get configuration option from the `geos-config` development utility

    Path to utility is set with a module-level `geos_config` variable, which
    can be changed or unset.
    '''
    geos_config = globals().get('geos_config')
    if not geos_config or not isinstance(geos_config, str):
        raise OSError('Path to geos-config is not set')
    try:
        stdout, stderr = subprocess.Popen(
            [geos_config, option],
            stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()
    except OSError as ex:
        # e.g., [Errno 2] No such file or directory
        raise OSError(
            'Could not find geos-config %r: %s' % (geos_config, ex))
    if stderr and not stdout:
        raise ValueError(stderr.strip())
    if sys.version_info[0] >= 3:
        result = stdout.decode('ascii').strip()
    else:
        result = stdout.strip()
    log.debug('%s %s: %r', geos_config, option, result)
    return result

# Now try and use the utility to load from `geos-config --clibs` with
# some magic smoke to guess the other parts of the library name
try:
    clibs = get_geos_config('--clibs')
except OSError:
    geos_config = None
if not lgeos and geos_config:
    base = ''
    name = 'geos_c'
    for item in clibs.split():
        if item.startswith("-L"):
            base = item[2:]
        elif item.startswith("-l"):
            name = item[2:]
    # Now guess the actual library name using a list of possible formats
    if sys.platform == 'win32':
        # Unlikely, since geos-config is a shell script, but you never know...
        fmts = ['{name}.dll']
    elif sys.platform == 'darwin':
        fmts = ['lib{name}.dylib', '{name}.dylib', '{name}.framework/{name}']
    elif os.name == 'posix':
        fmts = ['lib{name}.so', 'lib{name}.so.1']
    guesses = []
    for fmt in fmts:
        lib_name = fmt.format(name=name)
        geos_library_path = os.path.join(base, lib_name)
        try:
            lgeos = CDLL(geos_library_path)
            break
        except:
            guesses.append(geos_library_path)
    if lgeos:
        if hasattr(lgeos, 'GEOSversion'):
            log.debug('found GEOS C library using geos-config')
        else:
            raise OSError(
                'shared object found by geos-config is not a GEOS C library: '
                + str(geos_library_path))
    else:
        log.warn("cannot open shared object from '%s --clibs': %r",
                 geos_config, clibs)
        log.warn("there were %d guess(es) for this path:\n\t%s",
                 len(guesses), '\n\t'.join(guesses))


# Platform-specific attempts, and build `free` object

def load_dll(libname, fallbacks=None):
    lib = find_library(libname)
    dll = None
    if lib is not None:
        try:
            log.debug("Trying `CDLL(%s)`", lib)
            dll = CDLL(lib)
        except OSError:
            log.warn("Failed `CDLL(%s)`", lib)
            pass

    if not dll and fallbacks is not None:
        for name in fallbacks:
            try:
                log.debug("Trying `CDLL(%s)`", name)
                dll = CDLL(name)
            except OSError:
                # move on to the next fallback
                log.warn("Failed `CDLL(%s)`", name)
                pass

    if dll:
        log.debug("Library path: %r", lib or name)
        log.debug("DLL: %r", dll)
        return dll
    else:
        # No shared library was loaded. Raise OSError.
        raise OSError(
            "Could not find library {0} or load any of its variants {1}".format(
                libname, fallbacks or []))


if sys.platform.startswith('linux'):
    if not lgeos:
        lgeos = load_dll('geos_c',
                         fallbacks=['libgeos_c.so.1', 'libgeos_c.so'])
    free = load_dll('c').free
    free.argtypes = [c_void_p]
    free.restype = None

elif sys.platform == 'darwin':
    if not lgeos:
        if hasattr(sys, 'frozen'):
            # .app file from py2app
            alt_paths = [os.path.join(os.environ['RESOURCEPATH'],
                         '..', 'Frameworks', 'libgeos_c.dylib')]
        else:
            alt_paths = [
                # The Framework build from Kyng Chaos
                "/Library/Frameworks/GEOS.framework/Versions/Current/GEOS",
                # macports
                '/opt/local/lib/libgeos_c.dylib',
            ]
        lgeos = load_dll('geos_c', fallbacks=alt_paths)

    free = load_dll('c', fallbacks=['/usr/lib/libc.dylib']).free
    free.argtypes = [c_void_p]
    free.restype = None

elif sys.platform == 'win32':
    if not lgeos:
        try:
            egg_dlls = os.path.abspath(
                os.path.join(os.path.dirname(__file__), "DLLs"))
            wininst_dlls = os.path.abspath(os.__file__ + "../../../DLLs")
            original_path = os.environ['PATH']
            os.environ['PATH'] = "%s;%s;%s" % \
                (egg_dlls, wininst_dlls, original_path)
            lgeos = CDLL("geos.dll")
        except (ImportError, WindowsError, OSError):
            raise

    def free(m):
        try:
            cdll.msvcrt.free(m)
        except WindowsError:
            # TODO: http://web.archive.org/web/20070810024932/
            #     + http://trac.gispython.org/projects/PCL/ticket/149
            pass

elif sys.platform == 'sunos5':
    if not lgeos:
        lgeos = load_dll('geos_c',
                         fallbacks=['libgeos_c.so.1', 'libgeos_c.so'])
    free = CDLL('libc.so.1').free
    free.argtypes = [c_void_p]
    free.restype = None

else:  # other *nix systems
    if not lgeos:
        lgeos = load_dll('geos_c',
                         fallbacks=['libgeos_c.so.1', 'libgeos_c.so'])
    free = load_dll('c', fallbacks=['libc.so.6']).free
    free.argtypes = [c_void_p]
    free.restype = None

# TODO: what to do with 'free'? It isn't used.


def _geos_version():
    # extern const char GEOS_DLL *GEOSversion();
    GEOSversion = lgeos.GEOSversion
    GEOSversion.restype = c_char_p
    GEOSversion.argtypes = []
    # #define GEOS_CAPI_VERSION "@VERSION@-CAPI-@CAPI_VERSION@"
    geos_version_string = GEOSversion()
    if sys.version_info[0] >= 3:
        geos_version_string = geos_version_string.decode('ascii')

    res = re.findall(r'(\d+)\.(\d+)\.(\d+)', geos_version_string)
    assert len(res) == 2, res
    geos_version = tuple(int(x) for x in res[0])
    capi_version = tuple(int(x) for x in res[1])

    return geos_version_string, geos_version, capi_version

geos_version_string, geos_version, geos_capi_version = _geos_version()
