from lxml import etree

from emit import Emit
from param import known_param_fields, known_units
import re

# Emit ArduPilot documentation in an machine readable XML format
class XmlEmit(Emit):
    def __init__(self, *args, **kwargs):
        Emit.__init__(self, *args, **kwargs)
        self.wiki_fname = 'apm.pdef.xml'
        self.f = open(self.wiki_fname, mode='w')
        self.preamble = '''<?xml version="1.0" encoding="utf-8"?>
<!-- Dynamically generated list of documented parameters (generated by param_parse.py) -->
'''
        self.f.write(self.preamble)
        self.paramfile = etree.Element('paramfile')
        self.vehicles = etree.SubElement(self.paramfile, 'vehicles')
        self.libraries = etree.SubElement(self.paramfile, 'libraries')
        self.current_element = self.vehicles

    def close(self):
        # etree.indent(self.paramfile)  # not available on thor, Ubuntu 16.04
        pretty_xml = etree.tostring(self.paramfile, pretty_print=True, encoding='unicode')
        self.f.write(pretty_xml)
        self.f.close()

    def emit_comment(self, s):
        self.f.write("<!-- " + s + " -->")

    def start_libraries(self):
        self.current_element = self.libraries

    def add_xml_subtree_for_param_field(self, param, xml_param, field, new_element_name, item_name):
        '''assumes that "field" is a comma-separated list of items,
        creates a subtree with those elements within'''
        xml_values = etree.SubElement(xml_param, new_element_name)
        values = (param.__dict__[field]).split(',')
        nv_unsorted = {}
        for value in values:
            v = value.split(':')
            if len(v) != 2:
                raise ValueError("Bad value (%s)" % v)
            # i.e. numeric value, string label
            if v[0] in nv_unsorted:
                raise ValueError("%s already exists" % v[0])
            nv_unsorted[v[0]] = v[1]

        all_keys = nv_unsorted.keys()
        if hasattr(param, 'SortValues'):
            sort = getattr(param, 'SortValues').lower()
            zero_at_top = False
            if sort == 'alphabeticalzeroattop':
                zero_at_top = True
            else:
                raise ValueError("Unknown sort (%s)" % sort)

            all_keys = self.sorted_Values_keys(nv_unsorted, zero_at_top=zero_at_top)

        for key in all_keys:
            value = nv_unsorted[key].strip()
            code = key.rstrip().strip()
            xml_value = etree.SubElement(xml_values, item_name, code=code)
            xml_value.text = value

    def sorted_Values_keys(self, nv_pairs, zero_at_top=False):
        '''sorts name/value pairs derived from items in @Values.  Sorts by
        value, with special attention paid to common "Do nothing" values'''
        keys = nv_pairs.keys()
        def sort_key(value):
            description = nv_pairs[value]
            if zero_at_top and value == "0":
                # make sure this item goes at the top of the list:
                return "AAAAAAA"
            return description
        return sorted(keys, key=sort_key)

    def emit(self, g):
        xml_parameters = etree.SubElement(self.current_element, 'parameters', name=g.reference)  # i.e. ArduPlane

        for param in g.params:
            # Begin our parameter node
            if hasattr(param, 'DisplayName'):
                xml_param = etree.SubElement(xml_parameters, 'param', humanName=param.DisplayName, name=param.name)  # i.e. ArduPlane (ArduPlane:FOOPARM)
            else:
                xml_param = etree.SubElement(xml_parameters, 'param', name=param.name)

            if hasattr(param, 'Description'):
                xml_param.set('documentation', param.Description)  # i.e. parameter docs
            if hasattr(param, 'User'):
                xml_param.set('user', param.User)  # i.e. Standard or Advanced

            if hasattr(param, 'Calibration'):
                xml_param.set('calibration', param.Calibration)

            # Add values as chidren of this node
            for field in param.__dict__.keys():
                if not self.should_emit_field(param, field):
                    continue
                if field not in ['name', 'DisplayName', 'Description', 'User', 'SortValues'] and field in known_param_fields:
                    # we emit Bitmask as both a sub-element (so that
                    # consumers don't need to parse the Bimask list),
                    # but also as a text so we don't break existing
                    # implementations.  Contrast with "values", which
                    # is only emitted as a sub-element.
                    if field == 'Bitmask':
                        self.add_xml_subtree_for_param_field(
                            param,
                            xml_param,
                            field='Bitmask',
                            new_element_name='bitmask',
                            item_name='bit',
                        )

                    if field == 'Values' and Emit.prog_values_field.match(param.__dict__[field]):
                        self.add_xml_subtree_for_param_field(
                            param,
                            xml_param,
                            field='Values',
                            new_element_name='values',
                            item_name='value',
                        )

                    elif field == 'Units':
                        abreviated_units = param.__dict__[field]
                        if abreviated_units != '':
                            units = known_units[abreviated_units]   # use the known_units dictionary to convert the abreviated unit into a full textual one
                            xml_field1 = etree.SubElement(xml_param, 'field', name=field)  # i.e. A/s
                            xml_field1.text = abreviated_units
                            xml_field2 = etree.SubElement(xml_param, 'field', name='UnitText')  # i.e. ampere per second
                            xml_field2.text = units
                    else:
                        xml_field = etree.SubElement(xml_param, 'field', name=field)
                        xml_field.text = param.__dict__[field]

            if xml_param.text is None and not len(xml_param):
                xml_param.text = '\n'  # add </param> on next line in case of empty element.