"""
Get interface description of GRASS commands

Based on gui/wxpython/gui_modules/menuform.py

Usage:

::

    from grass.script import task as gtask
    gtask.command_info('r.info')

(C) 2011 by the GRASS Development Team
This program is free software under the GNU General Public
License (>=v2). Read the file COPYING that comes with GRASS
for details.

.. sectionauthor:: Martin Landa <landa.martin gmail.com>
"""
import re
import sys
import string

if sys.version_info.major == 3:
    unicode = str

try:
    import xml.etree.ElementTree as etree
except ImportError:
    import elementtree.ElementTree as etree # Python <= 2.4
from xml.parsers import expat  # TODO: works for any Python?
# Get the XML parsing exceptions to catch. The behavior chnaged with Python 2.7
# and ElementTree 1.3.
if hasattr(etree, 'ParseError'):
    ETREE_EXCEPTIONS = (etree.ParseError, expat.ExpatError)
else:
    ETREE_EXCEPTIONS = (expat.ExpatError)

from .utils import encode, decode, split
from .core import *


class grassTask:
    """This class holds the structures needed for filling by the parser

    Parameter blackList is a dictionary with fixed structure, eg.

    ::

        blackList = {'items' : {'d.legend' : { 'flags' : ['m'], 'params' : [] }},
                     'enabled': True}

    :param str path: full path
    :param blackList: hide some options in the GUI (dictionary)
    """
    def __init__(self, path=None, blackList=None):
        self.path = path
        self.name = _('unknown')
        self.params = list()
        self.description = ''
        self.label = ''
        self.flags = list()
        self.keywords = list()
        self.errorMsg = ''
        self.firstParam = None
        if blackList:
            self.blackList = blackList
        else:
            self.blackList = {'enabled': False, 'items': {}}

        if path is not None:
            try:
                processTask(tree=etree.fromstring(get_interface_description(path)),
                            task=self)
            except ScriptError as e:
                self.errorMsg = e.value

            self.define_first()

    def define_first(self):
        """Define first parameter

        :return: name of first parameter
        """
        if len(self.params) > 0:
            self.firstParam = self.params[0]['name']

        return self.firstParam

    def get_error_msg(self):
        """Get error message ('' for no error)
        """
        return self.errorMsg

    def get_name(self):
        """Get task name
        """
        if sys.platform == 'win32':
            name, ext = os.path.splitext(self.name)
            if ext in ('.py', '.sh'):
                return name
            else:
                return self.name

        return self.name

    def get_description(self, full=True):
        """Get module's description

        :param bool full: True for label + desc
        """
        if self.label:
            if full:
                return self.label + ' ' + self.description
            else:
                return self.label
        else:
            return self.description

    def get_keywords(self):
        """Get module's keywords
        """
        return self.keywords

    def get_list_params(self, element='name'):
        """Get list of parameters

        :param str element: element name
        """
        params = []
        for p in self.params:
            params.append(p[element])

        return params

    def get_list_flags(self, element='name'):
        """Get list of flags

        :param str element: element name
        """
        flags = []
        for p in self.flags:
            flags.append(p[element])

        return flags

    def get_param(self, value, element='name', raiseError=True):
        """Find and return a param by name

        :param value: param's value
        :param str element: element name
        :param bool raiseError: True for raise on error
        """
        for p in self.params:
            val = p.get(element, None)
            if val is None:
                continue
            if isinstance(val, (list, tuple)):
                if value in val:
                    return p
            elif isinstance(val, (bytes, unicode)):
                if p[element][:len(value)] == value:
                    return p
            else:
                if p[element] == value:
                    return p

        if raiseError:
            raise ValueError(_("Parameter element '%(element)s' not found: '%(value)s'") % \
                { 'element' : element, 'value' : value })
        else:
            return None

    def get_flag(self, aFlag):
        """Find and return a flag by name

        Raises ValueError when the flag is not found.

        :param str aFlag: name of the flag
        """
        for f in self.flags:
            if f['name'] == aFlag:
                return f
        raise ValueError(_("Flag not found: %s") % aFlag)

    def get_cmd_error(self):
        """Get error string produced by get_cmd(ignoreErrors = False)

        :return: list of errors
        """
        errorList = list()
        # determine if suppress_required flag is given
        for f in self.flags:
            if f['value'] and f['suppress_required']:
                return errorList

        for p in self.params:
            if not p.get('value', '') and p.get('required', False):
                if not p.get('default', ''):
                    desc = p.get('label', '')
                    if not desc:
                        desc = p['description']
                    errorList.append(_("Parameter '%(name)s' (%(desc)s) is missing.") % \
                                     {'name': p['name'], 'desc': encode(desc)})

        return errorList

    def get_cmd(self, ignoreErrors=False, ignoreRequired=False,
                ignoreDefault=True):
        """Produce an array of command name and arguments for feeding
        into some execve-like command processor.

        :param bool ignoreErrors: True to return whatever has been built so
                                  far, even though it would not be a correct
                                  command for GRASS
        :param bool ignoreRequired: True to ignore required flags, otherwise
                                    '@<required@>' is shown
        :param bool ignoreDefault: True to ignore parameters with default values
        """
        cmd = [self.get_name()]

        suppress_required = False
        for flag in self.flags:
            if flag['value']:
                if len(flag['name']) > 1:  # e.g. overwrite
                    cmd += ['--' + flag['name']]
                else:
                    cmd += ['-' + flag['name']]
                if flag['suppress_required']:
                    suppress_required = True
        for p in self.params:
            if p.get('value', '') == '' and p.get('required', False):
                if p.get('default', '') != '':
                    cmd += ['%s=%s' % (p['name'], p['default'])]
                elif ignoreErrors and not suppress_required and not ignoreRequired:
                    cmd += ['%s=%s' % (p['name'], _('<required>'))]
            elif p.get('value', '') == '' and p.get('default', '') != '' and not ignoreDefault:
                cmd += ['%s=%s' % (p['name'], p['default'])]
            elif p.get('value', '') != '' and \
                    (p['value'] != p.get('default', '') or not ignoreDefault):
                # output only values that have been set, and different from defaults
                cmd += ['%s=%s' % (p['name'], p['value'])]

        errList = self.get_cmd_error()
        if ignoreErrors is False and errList:
            raise ValueError('\n'.join(errList))

        return cmd

    def get_options(self):
        """Get options
        """
        return {'flags': self.flags, 'params': self.params}

    def has_required(self):
        """Check if command has at least one required parameter
        """
        for p in self.params:
            if p.get('required', False):
                return True

        return False

    def set_param(self, aParam, aValue, element='value'):
        """Set param value/values.
        """
        try:
            param = self.get_param(aParam)
        except ValueError:
            return

        param[element] = aValue

    def set_flag(self, aFlag, aValue, element='value'):
        """Enable / disable flag.
        """
        try:
            param = self.get_flag(aFlag)
        except ValueError:
            return

        param[element] = aValue

    def set_options(self, opts):
        """Set flags and parameters

        :param opts list of flags and parameters"""
        for opt in opts:
            if opt[0] ==  '-':  # flag
                self.set_flag(opt.lstrip('-'), True)
            else:  # parameter
                key, value = opt.split('=', 1)
                self.set_param(key, value)


class processTask:
    """A ElementTree handler for the --interface-description output,
    as defined in grass-interface.dtd. Extend or modify this and the
    DTD if the XML output of GRASS' parser is extended or modified.

    :param tree: root tree node
    :param task: grassTask instance or None
    :param blackList: list of flags/params to hide

    :return: grassTask instance
    """
    def __init__(self, tree, task=None, blackList=None):
        if task:
            self.task = task
        else:
            self.task = grassTask()
        if blackList:
            self.task.blackList = blackList

        self.root = tree

        self._process_module()
        self._process_params()
        self._process_flags()
        self.task.define_first()

    def _process_module(self):
        """Process module description
        """
        self.task.name = self.root.get('name', default='unknown')

        # keywords
        for keyword in self._get_node_text(self.root, 'keywords').split(','):
            self.task.keywords.append(keyword.strip())

        self.task.label = self._get_node_text(self.root, 'label')
        self.task.description = self._get_node_text(self.root, 'description')

    def _process_params(self):
        """Process parameters
        """
        for p in self.root.findall('parameter'):
            # gisprompt
            node_gisprompt = p.find('gisprompt')
            gisprompt = False
            age = element = prompt = None
            if node_gisprompt is not None:
                gisprompt = True
                age = node_gisprompt.get('age', '')
                element = node_gisprompt.get('element', '')
                prompt = node_gisprompt.get('prompt', '')

            # value(s)
            values = []
            values_desc = []
            node_values = p.find('values')
            if node_values is not None:
                for pv in node_values.findall('value'):
                    values.append(self._get_node_text(pv, 'name'))
                    desc = self._get_node_text(pv, 'description')
                    if desc:
                        values_desc.append(desc)

            # keydesc
            key_desc = []
            node_key_desc = p.find('keydesc')
            if node_key_desc is not None:
                for ki in node_key_desc.findall('item'):
                    key_desc.append(ki.text)

            if p.get('multiple', 'no') == 'yes':
                multiple = True
            else:
                multiple = False
            if p.get('required', 'no') == 'yes':
                required = True
            else:
                required = False

            if self.task.blackList['enabled'] and \
                    self.task.name in self.task.blackList['items'] and \
                    p.get('name') in self.task.blackList['items'][self.task.name].get('params', []):
                hidden = True
            else:
                hidden = False

            self.task.params.append( {
                "name"           : p.get('name'),
                "type"           : p.get('type'),
                "required"       : required,
                "multiple"       : multiple,
                "label"          : self._get_node_text(p, 'label'),
                "description"    : self._get_node_text(p, 'description'),
                'gisprompt'      : gisprompt,
                'age'            : age,
                'element'        : element,
                'prompt'         : prompt,
                "guisection"     : self._get_node_text(p, 'guisection'),
                "guidependency"  : self._get_node_text(p, 'guidependency'),
                "default"        : self._get_node_text(p, 'default'),
                "values"         : values,
                "values_desc"    : values_desc,
                "value"          : '',
                "key_desc"       : key_desc,
                "hidden"         : hidden
                })

    def _process_flags(self):
        """Process flags
        """
        for p in self.root.findall('flag'):
            if self.task.blackList['enabled'] and \
                    self.task.name in self.task.blackList['items'] and \
                    p.get('name') in self.task.blackList['items'][self.task.name].get('flags', []):
                hidden = True
            else:
                hidden = False

            if p.find('suppress_required') is not None:
                suppress_required = True
            else:
                suppress_required = False

            self.task.flags.append( {
                    "name"              : p.get('name'),
                    "label"             : self._get_node_text(p, 'label'),
                    "description"       : self._get_node_text(p, 'description'),
                    "guisection"        : self._get_node_text(p, 'guisection'),
                    "suppress_required" : suppress_required,
                    "value"             : False,
                    "hidden"            : hidden
                    } )

    def _get_node_text(self, node, tag, default=''):
        """Get node text"""
        p = node.find(tag)
        if p is not None:
            res = ' '.join(p.text.split())
            return res

        return default

    def get_task(self):
        """Get grassTask instance"""
        return self.task


def convert_xml_to_utf8(xml_text):
    # enc = locale.getdefaultlocale()[1]

    # modify: fetch encoding from the interface description text(xml)
    # e.g. <?xml version="1.0" encoding="GBK"?>
    pattern = re.compile(b'<\?xml[^>]*\Wencoding="([^"]*)"[^>]*\?>')
    m = re.match(pattern, xml_text)
    if m is None:
        return xml_text.encode("utf-8") if xml_text else None
    #
    enc = m.groups()[0]

    # modify: change the encoding to "utf-8", for correct parsing
    xml_text_utf8 = xml_text.decode(enc.decode('ascii')).encode("utf-8")
    p = re.compile(b'encoding="' + enc + b'"', re.IGNORECASE)
    xml_text_utf8 = p.sub(b'encoding="utf-8"', xml_text_utf8)

    return xml_text_utf8


def get_interface_description(cmd):
    """Returns the XML description for the GRASS cmd (force text encoding to
    "utf-8").

    The DTD must be located in $GISBASE/gui/xml/grass-interface.dtd,
    otherwise the parser will not succeed.

    :param cmd: command (name of GRASS module)
    """
    try:
        p = Popen([cmd, '--interface-description'], stdout=PIPE,
                  stderr=PIPE)
        cmdout, cmderr = p.communicate()

        # TODO: do it better (?)
        if not cmdout and sys.platform == 'win32':
            # we in fact expect pure module name (without extension)
            # so, lets remove extension
            if cmd.endswith('.py'):
                cmd = os.path.splitext(cmd)[0]

            if cmd == 'd.rast3d':
                sys.path.insert(0, os.path.join(os.getenv('GISBASE'),
                                                'gui', 'scripts'))

            p = Popen([sys.executable, get_real_command(cmd),
                       '--interface-description'],
                      stdout=PIPE, stderr=PIPE)
            cmdout, cmderr = p.communicate()

            if cmd == 'd.rast3d':
                del sys.path[0]  # remove gui/scripts from the path

        if p.returncode != 0:
            raise ScriptError(_("Unable to fetch interface description for command '<{cmd}>'."
                                "\n\nDetails: <{det}>").format(cmd=cmd, det=decode(cmderr)))

    except OSError as e:
        raise ScriptError(_("Unable to fetch interface description for command '<{cmd}>'."
                            "\n\nDetails: <{det}>").format(cmd=cmd, det=e))

    desc = convert_xml_to_utf8(cmdout)
    desc = desc.replace(b'grass-interface.dtd',
                        os.path.join(os.getenv('GISBASE'), 'gui', 'xml',
                                     'grass-interface.dtd').encode('utf-8'))
    return desc


def parse_interface(name, parser=processTask, blackList=None):
    """Parse interface of given GRASS module

    The *name* is either GRASS module name (of a module on path) or
    a full or relative path to an executable.

    :param str name: name of GRASS module to be parsed
    :param parser:
    :param blackList:
    """
    try:
        tree = etree.fromstring(get_interface_description(name))
    except ETREE_EXCEPTIONS as error:
        raise ScriptError(_("Cannot parse interface description of"
            "<{name}> module: {error}").format(name=name, error=error))
    task = parser(tree, blackList=blackList).get_task()
    # if name from interface is different than the originally
    # provided name, then the provided name is likely a full path needed
    # to actually run the module later
    # (processTask uses only the XML which does not contain the original
    # path used to execute the module)
    if task.name != name:
        task.path = name
    return task


def command_info(cmd):
    """Returns meta information for any GRASS command as dictionary
    with entries for description, keywords, usage, flags, and
    parameters, e.g.

    >>> command_info('g.tempfile') # doctest: +NORMALIZE_WHITESPACE
    {'keywords': ['general', 'support'], 'params': [{'gisprompt': False,
    'multiple': False, 'name': 'pid', 'guidependency': '', 'default': '',
    'age': None, 'required': True, 'value': '', 'label': '', 'guisection': '',
    'key_desc': [], 'values': [], 'values_desc': [], 'prompt': None,
    'hidden': False, 'element': None, 'type': 'integer', 'description':
    'Process id to use when naming the tempfile'}], 'flags': [{'description':
    "Dry run - don't create a file, just prints it's file name", 'value':
    False, 'label': '', 'guisection': '', 'suppress_required': False,
    'hidden': False, 'name': 'd'}, {'description': 'Print usage summary',
    'value': False, 'label': '', 'guisection': '', 'suppress_required': False,
    'hidden': False, 'name': 'help'}, {'description': 'Verbose module output',
    'value': False, 'label': '', 'guisection': '', 'suppress_required': False,
    'hidden': False, 'name': 'verbose'}, {'description': 'Quiet module output',
    'value': False, 'label': '', 'guisection': '', 'suppress_required': False,
    'hidden': False, 'name': 'quiet'}], 'description': "Creates a temporary
    file and prints it's file name.", 'usage': 'g.tempfile pid=integer [--help]
    [--verbose] [--quiet]'}

    >>> command_info('v.buffer')
    ['vector', 'geometry', 'buffer']

    :param str cmd: the command to query
    """
    task = parse_interface(cmd)
    cmdinfo = {}

    cmdinfo['description'] = task.get_description()
    cmdinfo['keywords'] = task.get_keywords()
    cmdinfo['flags'] = flags = task.get_options()['flags']
    cmdinfo['params'] = params = task.get_options()['params']

    usage = task.get_name()
    flags_short = list()
    flags_long = list()
    for f in flags:
        fname = f.get('name', 'unknown')
        if len(fname) > 1:
            flags_long.append(fname)
        else:
            flags_short.append(fname)

    if len(flags_short) > 1:
        usage += ' [-' + ''.join(flags_short) + ']'

    for p in params:
        ptype = ','.join(p.get('key_desc', []))
        if not ptype:
            ptype = p.get('type', '')
        req = p.get('required', False)
        if not req:
            usage += ' ['
        else:
            usage += ' '
        usage += p['name'] + '=' + ptype
        if p.get('multiple', False):
            usage += '[,' + ptype + ',...]'
        if not req:
            usage += ']'

    for key in flags_long:
        usage += ' [--' + key + ']'

    cmdinfo['usage'] = usage

    return cmdinfo

def cmdtuple_to_list(cmd):
    """Convert command tuple to list.

    :param tuple cmd: GRASS command to be converted

    :return: command in list
    """
    cmdList = []
    if not cmd:
        return cmdList

    cmdList.append(cmd[0])

    if 'flags' in cmd[1]:
        for flag in cmd[1]['flags']:
            cmdList.append('-' + flag)
    for flag in ('help', 'verbose', 'quiet', 'overwrite'):
        if flag in cmd[1] and cmd[1][flag] is True:
            cmdList.append('--' + flag)

    for k, v in cmd[1].items():
        if k in ('flags', 'help', 'verbose', 'quiet', 'overwrite'):
            continue
        if ' ' in v:
            v = '"%s"' % v
        cmdList.append('%s=%s' % (k, v))

    return cmdList

def cmdlist_to_tuple(cmd):
    """Convert command list to tuple for run_command() and others

    :param list cmd: GRASS command to be converted

    :return: command as tuple
    """
    if len(cmd) < 1:
        return None

    dcmd = {}
    for item in cmd[1:]:
        if '=' in item: # params
            key, value = item.split('=', 1)
            dcmd[str(key)] = value.replace('"', '')
        elif item[:2] == '--': # long flags
            flag = item[2:]
            if flag in ('help', 'verbose', 'quiet', 'overwrite'):
                dcmd[str(flag)] = True
        elif len(item) == 2 and item[0] == '-': # -> flags
            if 'flags' not in dcmd:
                dcmd['flags'] = ''
            dcmd['flags'] += item[1]
        else: # unnamed parameter
            module = parse_interface(cmd[0])
            dcmd[module.define_first()] = item

    return (cmd[0], dcmd)

def cmdstring_to_tuple(cmd):
    """Convert command string to tuple for run_command() and others

    :param str cmd: command to be converted

    :return: command as tuple
    """
    return cmdlist_to_tuple(split(cmd))
