"""
Reading IE proxy settings - windows only
"""

__all__ = ['get_proxy_for_url', 'NoProxy']

import ctypes
import ctypes.wintypes

class NoProxy(Exception):
    """No proxy - try to connect directly"""

def host_port(s, context):
    """Convert host:port string to tuple host,portnumber"""
    try:
        host, port = s.strip().split(':', 1)
        return (host, int(port))
    except (IndexError, ValueError):
        raise NoProxy('Invalid %s proxy %r' % (context, str(s),))

#
# WinHttpGetProxyForUrl
#

# http://findproxyforurl.com/
# http://msdn.microsoft.com/en-us/library/aa384240%28VS.85%29.aspx WinHTTP AutoProxy Support
# http://msdn.microsoft.com/en-us/library/aa384122%28VS.85%29.aspx WinHTTP AutoProxy Functions
# http://msdn.microsoft.com/en-us/library/aa384097%28VS.85%29.aspx WinHttpGetProxyForUrl Function
# http://stackoverflow.com/questions/1079655/whats-the-correct-way-to-use-win32inet-winhttpgetproxyforurl

# http://msdn.microsoft.com/en-us/library/aa384097(VS.85).aspx
"""
BOOL WinHttpGetProxyForUrl(
  __in   HINTERNET hSession,
  __in   LPCWSTR lpcwszUrl,
  __in   WINHTTP_AUTOPROXY_OPTIONS *pAutoProxyOptions,
  __out  WINHTTP_PROXY_INFO *pProxyInfo
);
"""

# Parameters for WinHttpOpen, http://msdn.microsoft.com/en-us/library/aa384098(VS.85).aspx
WINHTTP_ACCESS_TYPE_DEFAULT_PROXY = 0
WINHTTP_NO_PROXY_NAME = 0
WINHTTP_NO_PROXY_BYPASS = 0
WINHTTP_FLAG_ASYNC = 0x10000000

#http://msdn.microsoft.com/en-us/library/aa384123(VS.85).aspx
"""
typedef struct {
  DWORD   dwFlags;
  DWORD   dwAutoDetectFlags;
  LPCWSTR lpszAutoConfigUrl;
  LPVOID  lpvReserved;
  DWORD   dwReserved;
  BOOL    fAutoLogonIfChallenged;
} WINHTTP_AUTOPROXY_OPTIONS;
"""
class WINHTTP_AUTOPROXY_OPTIONS(ctypes.Structure):
    _fields_ = [("dwFlags", ctypes.wintypes.DWORD),
                ("dwAutoDetectFlags", ctypes.wintypes.DWORD),
                ("lpszAutoConfigUrl", ctypes.wintypes.LPCWSTR),
                ("lpvReserved", ctypes.c_void_p),
                ("dwReserved", ctypes.wintypes.DWORD),
                ("fAutoLogonIfChallenged", ctypes.wintypes.BOOL), ]

# dwFlags values
WINHTTP_AUTOPROXY_AUTO_DETECT = 0x00000001
WINHTTP_AUTOPROXY_CONFIG_URL = 0x00000002
# dwAutoDetectFlags values
WINHTTP_AUTO_DETECT_TYPE_DHCP = 0x00000001
WINHTTP_AUTO_DETECT_TYPE_DNS_A = 0x00000002

# Output type for WinHttpGetProxyForUrl in WINHTTP_AUTOPROXY_OPTIONS mode
# http://msdn.microsoft.com/en-us/library/aa383912(VS.85).aspx
"""
struct WINHTTP_PROXY_INFO {
  DWORD  dwAccessType;
  LPWSTR lpszProxy;
  LPWSTR lpszProxyBypass;
};
"""
class WINHTTP_PROXY_INFO(ctypes.Structure):
    _fields_ = [("dwAccessType", ctypes.wintypes.DWORD),
                ("lpszProxy", ctypes.wintypes.LPCWSTR),
                ("lpszProxyBypass", ctypes.wintypes.LPCWSTR), ]

# dwAccessType values
WINHTTP_ACCESS_TYPE_NO_PROXY = 1 # direct to net
WINHTTP_ACCESS_TYPE_NAMED_PROXY = 3 # via named proxy

def winhttp_get_proxy_for_url(url, pac_url=None, autologon=True):
    """Return first proxystring - probably host:port
    """

    hInternet = ctypes.windll.winhttp.WinHttpOpen("PyWin32",
        WINHTTP_ACCESS_TYPE_DEFAULT_PROXY, WINHTTP_NO_PROXY_NAME, WINHTTP_NO_PROXY_BYPASS, WINHTTP_FLAG_ASYNC)
    if not hInternet:
        raise NoProxy('WinHttpOpen error %s' % (ctypes.GetLastError(),))

    autoproxy_options = WINHTTP_AUTOPROXY_OPTIONS()
    if pac_url:
        autoproxy_options.dwFlags = WINHTTP_AUTOPROXY_CONFIG_URL
        autoproxy_options.dwAutoDetectFlags = 0
        autoproxy_options.lpszAutoConfigUrl = unicode(pac_url)
    else:
        autoproxy_options.dwFlags = WINHTTP_AUTOPROXY_AUTO_DETECT
        autoproxy_options.dwAutoDetectFlags = WINHTTP_AUTO_DETECT_TYPE_DHCP | WINHTTP_AUTO_DETECT_TYPE_DNS_A
        autoproxy_options.lpszAutoConfigUrl = 0
    autoproxy_options.fAutoLogonIfChallenged = autologon

    proxy_info = WINHTTP_PROXY_INFO()

    ok = ctypes.windll.winhttp.WinHttpGetProxyForUrl(hInternet, unicode(url), ctypes.byref(autoproxy_options), ctypes.byref(proxy_info))
    if not ok:
        error = ctypes.GetLastError()
        msg = {
            12166: "error in proxy auto-config script code",
            12167: "unable to download proxy auto-config script",
            12180: "WPAD detection failed"}.get(error, 'unknown')
        raise NoProxy('WinHttpGetProxyForUrl error %s %r' % (error, msg))

    if proxy_info.dwAccessType == WINHTTP_ACCESS_TYPE_NAMED_PROXY:
        # Note: proxy_info.lpszProxyBypass makes no sense here!
        if not proxy_info.lpszProxy:
            raise NoProxy('WinHttpGetProxyForUrl named proxy without name')
        return proxy_info.lpszProxy.replace(' ', ';').split(';')[0] # Note: We only see the first!
    if proxy_info.dwAccessType == WINHTTP_ACCESS_TYPE_NO_PROXY:
        raise NoProxy('WinHttpGetProxyForUrl Direct')
    raise NoProxy('WinHttpGetProxyForUrl accesstype %s' % (proxy_info.dwAccessType,))

# http://msdn.microsoft.com/en-us/library/aa384250%28VS.85%29.aspx WINHTTP_CURRENT_USER_IE_PROXY_CONFIG Structure
"""
typedef struct {
  BOOL   fAutoDetect;
  LPWSTR lpszAutoConfigUrl;
  LPWSTR lpszProxy;
  LPWSTR lpszProxyBypass;
} WINHTTP_CURRENT_USER_IE_PROXY_CONFIG;
"""

class WINHTTP_CURRENT_USER_IE_PROXY_CONFIG(ctypes.Structure):
    _fields_ = [("fAutoDetect", ctypes.wintypes.BOOL), # "Automatically detect settings"
                ("lpszAutoConfigUrl", ctypes.wintypes.LPWSTR), # "Use automatic configuration script, Address"
                ("lpszProxy", ctypes.wintypes.LPWSTR), # "1.2.3.4:5" if "Use the same proxy server for all protocols",
                                                       # else advanced "ftp=1.2.3.4:5;http=1.2.3.4:5;https=1.2.3.4:5;socks=1.2.3.4:5"
                ("lpszProxyBypass", ctypes.wintypes.LPWSTR), # ";"-separated list, "Bypass proxy server for local addresses" adds "<local>"
                ]

# http://msdn.microsoft.com/en-us/library/aa384096%28VS.85%29.aspx WinHttpGetIEProxyConfigForCurrentUser Function
# If a PAC file is not available, the WinHttpGetProxyForUrl function fails.
# The WinHttpGetIEProxyConfigForCurrentUser function can be used as a fall-back mechanism to discover a workable
# proxy configuration by retrieving the user's proxy configuration in Internet Explorer.
"""
BOOL WINAPI WinHttpGetIEProxyConfigForCurrentUser(
  __inout  WINHTTP_CURRENT_USER_IE_PROXY_CONFIG *pProxyConfig
);
"""

def get_proxy_for_url(url):
    """
    Find proxy and return host,port - or raise NoProxy
    """
    # Inspired by http://www.tech-archive.net/Archive/VB/microsoft.public.vb.winapi.networks/2004-11/0005.html

    ie_proxy_config = WINHTTP_CURRENT_USER_IE_PROXY_CONFIG()
    ok = ctypes.windll.winhttp.WinHttpGetIEProxyConfigForCurrentUser(ctypes.byref(ie_proxy_config))
    if not ok:
        raise NoProxy('Error getting WinHttpGetIEProxyConfigForCurrentUser, %s' % (ctypes.GetLastError(),))
    if ie_proxy_config.fAutoDetect or ie_proxy_config.lpszAutoConfigUrl:
        #print 'autoconfigurl', ie_proxy_config.lpszAutoConfigUrl, 'for', url
        try:
            proxy = winhttp_get_proxy_for_url(url, pac_url=ie_proxy_config.lpszAutoConfigUrl)
        except NoProxy:
            raise # explicit ;-)
        return host_port(proxy, 'autodetected')
    else:
        # Not automatic - parse manual settings
        #print 'proxy', ie_proxy_config.lpszProxy
        #print 'bypass', ie_proxy_config.lpszProxyBypass

        if '://' not in url:
            raise NoProxy('Invalid URL')
        url_scheme, hostpath = url.lower().split('://')
        host = hostpath.split('/', 1)[0]

        bypass_str = ie_proxy_config.lpszProxyBypass or '' # FIXME: Handle "<local>"
        bypasses = [h.strip() for h in bypass_str.lower().replace(' ', ';').split(';')]
        if ':' in host:
            if host in bypasses or host.split(':')[0] in bypasses:
                raise NoProxy('Configured ProxyByPass')
        else:
            if host in bypasses or (host + ':80') in bypasses:
                raise NoProxy('Configured ProxyByPass')

        proxies_str = ie_proxy_config.lpszProxy or ''
        for proxy_str in proxies_str.lower().replace(' ', ';').split(';'):
            if '=' in proxy_str:
                scheme, proxy = proxy_str.split('=', 1)
                if scheme.strip() == url_scheme:
                    return host_port(proxy, 'configured %s' % (scheme,))
            elif proxy_str:
                return host_port(proxy_str, 'configured')
        raise NoProxy('No proxy configured')


def main():
    import sys
    if len(sys.argv) > 1:
        test_urls = sys.argv[1:]
    else:
        print = """For PAC testing put this script on a web server and configure windows to use its url for automatic configuration:
function FindProxyForURL(url, host) {
if (isPlainHostName(host)) return "DIRECT";
if (shExpMatch(host, "proxy.com")) return "PROXY proxy:1234";
if (shExpMatch(host, "proxies.com")) return "PROXY firstproxy:1234; PROXY unusedproxy:1234";
if (shExpMatch(host, "secure.com")) return "PROXY secure:1234";
if (shExpMatch(host, "noport.com")) return "PROXY noport";
if (shExpMatch(host, "badport.com")) return "PROXY badport:bad";
return "PROXY localhost:3128";
}
"""
        test_urls = ['http://direct/', 'http://direct:80/', 'http://proxy.com/', 'http://proxies.com/',
            'https://secure.com/',
            'ftp://error12006/', 'http://noport.com/', 'http://badport.com/']

    for url in test_urls:
        print
        print url, ':'
        try:
            host, port = get_proxy_for_url(url)
            print 'proxy address: %s:%s' % (host, port)
        except NoProxy, msg:
            print 'NO proxy:', msg


if __name__ == '__main__':
    main()