# -*- coding: utf-8 -*-
from lxml import etree
from plone.supermodel.debug import parseinfo
from plone.supermodel.interfaces import FIELDSETS_KEY
from plone.supermodel.interfaces import I18N_NAMESPACE
from plone.supermodel.interfaces import IFieldExportImportHandler
from plone.supermodel.interfaces import IFieldMetadataHandler
from plone.supermodel.interfaces import IInvariant
from plone.supermodel.interfaces import ISchemaMetadataHandler
from plone.supermodel.interfaces import ISchemaPolicy
from plone.supermodel.model import Fieldset
from plone.supermodel.model import Model
from plone.supermodel.model import Schema
from plone.supermodel.model import SchemaClass
from plone.supermodel.utils import ns
from zope.component import getUtilitiesFor
from zope.component import getUtility
from zope.component import queryUtility
from zope.dottedname.resolve import resolve
from zope.interface import implementer
from zope.schema import getFields
import linecache
import sys

# Exception

class SupermodelParseError(Exception):

    def __init__(self, orig_exc, fname, element):
        msg = str(orig_exc)

        lineno = None
        if hasattr(orig_exc, 'lineno'):
            lineno = orig_exc.lineno
        elif element is not None:
            lineno = getattr(element, 'sourceline', 'unknown')

        if fname or lineno != 'unknown':
            msg += '\n  File "%s", line %s' % (fname or '<unknown>', lineno)
        if fname and lineno:
            line = linecache.getline(fname, lineno).strip()
            msg += '\n    %s' % line
        self.args = [msg]

# Helper adapters

@implementer(ISchemaPolicy)
class DefaultSchemaPolicy(object):

    def module(self, schemaName, tree):
        return 'plone.supermodel.generated'

    def bases(self, schemaName, tree):
        return ()

    def name(self, schemaName, tree):
        return schemaName


# Algorithm

def parse(source, policy=u""):
    fname = None
    if isinstance(source, basestring):
        fname = source

    try:
        return _parse(source, policy)
    except Exception, e:
        # Re-package the exception as a parse error that will get rendered with
        # the filename and line number of the element that caused the problem.
        # Keep the original traceback so the developer can debug where the problem
        # happened.
        raise SupermodelParseError(e, fname, parseinfo.stack[-1]), None, sys.exc_info()[2]


def _parse(source, policy):
    tree = etree.parse(source)
    root = tree.getroot()

    parseinfo.i18n_domain = root.attrib.get(ns('domain', prefix=I18N_NAMESPACE))

    model = Model()

    handlers = {}
    schema_metadata_handlers = tuple(getUtilitiesFor(ISchemaMetadataHandler))
    field_metadata_handlers = tuple(getUtilitiesFor(IFieldMetadataHandler))

    policy_util = getUtility(ISchemaPolicy, name=policy)

    def readField(fieldElement, schemaAttributes, fieldElements, baseFields):

        # Parse field attributes
        fieldName = fieldElement.get('name')
        fieldType = fieldElement.get('type')

        if fieldName is None or fieldType is None:
            raise ValueError("The attributes 'name' and 'type' are required for each <field /> element")

        handler = handlers.get(fieldType, None)
        if handler is None:
            handler = handlers[fieldType] = queryUtility(IFieldExportImportHandler, name=fieldType)
            if handler is None:
                raise ValueError("Field type %s specified for field %s is not supported" % (fieldType, fieldName, ))

        field = handler.read(fieldElement)

        # Preserve order from base interfaces if this field is an override
        # of a field with the same name in a base interface
        base_field = baseFields.get(fieldName, None)
        if base_field is not None:
            field.order = base_field.order

        # Save for the schema
        schemaAttributes[fieldName] = field
        fieldElements[fieldName] = fieldElement

        return fieldName

    for schema_element in root.findall(ns('schema')):
        parseinfo.stack.append(schema_element)
        schemaAttributes = {}

        schemaName = schema_element.get('name')
        if schemaName is None:
            schemaName = u""

        bases = ()
        baseFields = {}
        based_on = schema_element.get('based-on')
        if based_on is not None:
            bases = tuple([resolve(dotted) for dotted in based_on.split()])
            for base_schema in bases:
                baseFields.update(getFields(base_schema))

        fieldElements = {}

        # Read global fields
        for fieldElement in schema_element.findall(ns('field')):
            parseinfo.stack.append(fieldElement)
            readField(fieldElement, schemaAttributes, fieldElements, baseFields)
            parseinfo.stack.pop()

        # Read invariants, fieldsets and their fields
        invariants = []
        fieldsets = []
        fieldsets_by_name = {}

        for subelement in schema_element:
            parseinfo.stack.append(subelement)

            if subelement.tag == ns('field'):
                readField(subelement, schemaAttributes, fieldElements, baseFields)
            elif subelement.tag == ns('fieldset'):

                fieldset_name = subelement.get('name')
                if fieldset_name is None:
                    raise ValueError(u"Fieldset in schema %s has no name" % (schemaName))

                fieldset = fieldsets_by_name.get(fieldset_name, None)
                if fieldset is None:
                    fieldset_label = subelement.get('label')
                    fieldset_description = subelement.get('description')

                    fieldset = fieldsets_by_name[fieldset_name] = Fieldset(fieldset_name,
                                    label=fieldset_label, description=fieldset_description)
                    fieldsets_by_name[fieldset_name] = fieldset
                    fieldsets.append(fieldset)

                for fieldElement in subelement.findall(ns('field')):
                    parseinfo.stack.append(fieldElement)
                    parsed_fieldName = readField(fieldElement, schemaAttributes, fieldElements, baseFields)
                    if parsed_fieldName:
                        fieldset.fields.append(parsed_fieldName)
                    parseinfo.stack.pop()
            elif subelement.tag == ns('invariant'):
                dotted = subelement.text
                invariant = resolve(dotted)
                if not IInvariant.providedBy(invariant):
                    raise ImportError(
                        u"Invariant functions must provide plone.supermodel.interfaces.IInvariant"
                    )
                invariants.append(invariant)
            parseinfo.stack.pop()

        schema = SchemaClass(name=policy_util.name(schemaName, tree),
                                bases=bases + policy_util.bases(schemaName, tree) + (Schema,),
                                __module__=policy_util.module(schemaName, tree),
                                attrs=schemaAttributes)

        # add invariants to schema as tagged values
        if invariants:
            schema_invariants = schema.queryTaggedValue('invariants', [])
            schema.setTaggedValue('invariants', schema_invariants + invariants)

        # Save fieldsets
        schema.setTaggedValue(FIELDSETS_KEY, fieldsets)

        # Let metadata handlers write metadata
        for handler_name, metadata_handler in field_metadata_handlers:
            for fieldName in schema:
                if fieldName in fieldElements:
                    metadata_handler.read(fieldElements[fieldName], schema, schema[fieldName])

        for handler_name, metadata_handler in schema_metadata_handlers:
            metadata_handler.read(schema_element, schema)

        model.schemata[schemaName] = schema
        parseinfo.stack.pop()

    parseinfo.i18n_domain = None
    return model


__all__ = ('parse', )
