# XML-database conversion

import re

import traceback

from xml.dom import Node

import exc

import sql

import strings

import util

import xml_dom

def name_of(node): return re.sub(r'^.*\.', r'', node.tagName)

ptr_suffix = '_id'

def is_ptr(node_name): return node_name.lower().endswith(ptr_suffix)

def ptr_type_guess(node_name):

    assert is_ptr(node_name)

    return node_name[:-len(ptr_suffix)]

def ptr_target(node):

    assert is_ptr(name_of(node))

    return xml_dom.first_elem(node)

def find_by_name(node, name):

    for parent in xml_dom.NodeParentIter(node):

        if name_of(parent) == name: return parent

        else:

            for child in xml_dom.NodeElemIter(parent):

                child_name = name_of(child)

                if is_ptr(child_name):

                    target = ptr_target(child)

                    if target.tagName == name: return target

                elif child_name == name: return child

    return None

def get(db, node, limit=None, start=None):

    def pkey(table): return sql.pkey(db, table)

    node = node.firstChild

    table = name_of(node)

    pkey_ = pkey(table)

    fields = []

    conds = {}

    for child in xml_dom.NodeElemIter(node):

        child_name = name_of(child)

        if xml_dom.is_empty(child): fields.append(child_name)

        elif xml_dom.is_text(child): conds[child_name] = xml_dom.value(child)

        else: raise Exception('Joins not supported yet')

    id_ = xml_dom.get_id(node)

    if id_ != None: conds[pkey(table)] = id_ # replace any existing pkey value

    if fields == []: fields.append(pkey_)

    return sql.select(db, table, fields, conds, limit, start)

def put(db, node, row_ct_ref=None, on_error=exc.raise_, pool=None,

    store_ids=False, parent_id=None):

    '''store_ids enables searching the tree for missing fields'''

    def pkey(table): return sql.pkey(db, table, True)

    def put_(node, parent_id=None):

        args = (db, node, row_ct_ref, on_error, pool, store_ids, parent_id)

        if parent_id != None and pool != None: pool.apply_async(put, args)

        else: return put(*args)

    def on_error_(e):

        exc.add_msg(e, 'node:\n'+str(node))

        on_error(e)

    table = name_of(node)

    try: pkey_ = pkey(table)

    except sql.DatabaseErrors, e: on_error_(e); return None

    row = {}

    children = []

    # Divide children into fields and children with fkeys to parent

    for child in xml_dom.NodeElemIter(node):

        child_name = name_of(child)

        if xml_dom.is_empty(child): row[child_name] = None

        elif xml_dom.is_text(child):

            row[child_name] = strings.to_unicode(xml_dom.value(child))

        elif is_ptr(child_name): row[child_name] = put_(ptr_target(child))

        else: children.append(child)

    try: del row[pkey_]

    except KeyError: pass

    # Add fkey to parent

    if parent_id != None:

        parent_ptr = node.getAttribute('fkey')

        if parent_ptr == '': parent_ptr = pkey(name_of(node.parentNode))

        row[parent_ptr] = parent_id

    # Insert node

    try:

        for try_num in xrange(2):

            try:

                id_ = sql.put(db, table, row, pkey_, row_ct_ref)

                if store_ids: xml_dom.set_id(node, id_)

                break

            except sql.NullValueException, e:

                col = e.cols[0]

                if try_num > 0: raise # exception still raised after retry

                if store_ids and is_ptr(col):

                    # Search for required column in ancestors and their children

                    target = find_by_name(node, ptr_type_guess(col))

                    if target == None: raise

                    row[col] = xml_dom.get_id(target)

                else: raise

    except sql.DatabaseErrors, e: on_error_(e); return None

    # Insert children with fkeys to parent

    for child in children: put_(child, id_)

    return id_

def put_table(db, node, table, commit=False, row_ct_ref=None,

    table_is_esc=False):

    '''

    @param node The XML tree that transforms the input to the output. Similar to

        put()'s node param, but with the input column name prefixed by "$" in

        place of the column value.

    @param commit Whether to commit after each query

    '''

    import sys; sys.stderr.write(str(node))

    if commit: db.db.commit()

    raise NotImplementedError('By-column optimization not available yet')