#!/usr/bin/python

import json
import logging
import os
import re
import traceback

from db_driver import DB_Driver_REST, DB_Driver_Base
from model.graph import Attr_Diff
from model.graph import Topo_Diff
from neo4j_util import DB_result_set
from neo4j_util import cfmt
import neo4j_util as db_util
from model.model import Link

log = logging.getLogger('rhizi')

class DB_op(object):
    """
    tx wrapped DB operation possibly composing multiple DB queries
    """
    def __init__(self):
        self.statement_set = []
        self.result_set = []
        self.error_set = None
        self.tx_id = None
        self.tx_commit_url = None  # cached from response to tx begin

    def parse_tx_id(self, tx_commit_url):
        m = re.search('/(?P<id>\d+)/commit$', tx_commit_url)
        id_str = m.group('id')
        self.tx_id = int(id_str)

    def add_statement(self, query, query_params={}):
        """
        add a DB query language statement
        @return: statement index (zero based)
        """
        s = db_util.statement_to_REST_form(query, query_params)
        self.statement_set.append(s)
        return len(self.statement_set)

    def __iter__(self):
        """
        iterate over (statement_index, statement, result, error)
        where result & error are mutually exclusive

        note: statement_index is zero based

        TODO: handle partial iteration due to error_set being non-empty
        """
        i = 0
        r_set_len = len(self.result_set)
        for s in self.statement_set:
            r_set = None  # row-set
            if i < r_set_len:  # support partial result recovery
                r_set = DB_result_set(self.result_set[i])
            yield (i, s, r_set)
            i = i + 1

    def parse_multi_statement_response_data(self, data):
        pass

    @property
    def name(self):
        return self.__class__.__name__

    def process_result_set(self):
        """
        DB op can issue complex sets of quries all at once - this helper method
        assists in parsing response data from a single query.
        """
        ret = []
        for _, _, r_set in self:
            for row in r_set:
                for col in row:
                    ret.append(col)
        return ret

class DB_composed_op(DB_op):
    def __init__(self):
        super(DB_composed_op, self).__init__()
        self.sub_op_set = []

    def __assert_false_statement_access(self):
        assert False, "composed_op may not contain statements, only sub-ops"

    def add_statement(self, query, query_params={}):
        self.__assert_false_statement_access()

    def add_sub_op(self, op):
        self.sub_op_set.append(op)

    def __getattribute__(self, attr):
        """
        intercept 'statement_set' attr get
        """
        if attr == 'statement_set':
            self.__assert_false_statement_access()

        return object.__getattribute__(self, attr)

    def __iter__(self):
        """
        iterate over sub_op_set
        """
        for s_op in self.sub_op_set:
            yield s_op

    def process_result_set(self):
        ret = []
        for s_op in self:
            s_result_set = s_op.process_result_set()
            ret.append(s_result_set)
        return ret

class DBO_cypher_query(DB_op):
    """
    freeform cypher query
    """
    def __init__(self, q, q_params={}):
        super(DBO_cypher_query, self).__init__()
        self.add_statement(q, q_params)

class DBO_topo_diff_commit(DB_composed_op):
    """
    commit a Topo_Diff
    """
    def __init__(self, topo_diff):
        super(DBO_topo_diff_commit, self).__init__()

        n_add_map = db_util.meta_attr_list_to_meta_attr_map(topo_diff.node_set_add)
        l_add_map = db_util.meta_attr_list_to_meta_attr_map(topo_diff.link_set_add)
        l_rm_set = topo_diff.link_set_rm
        n_rm_set = topo_diff.node_set_rm

        #
        # [!] order critical
        #
        if len(n_add_map) > 0:
            op = DBO_add_node_set(n_add_map)
            self.add_sub_op(op)

        if len(l_add_map) > 0:
            op = DBO_add_link_set(l_add_map)
            self.add_sub_op(op)

        if len(l_rm_set) > 0:
            op = DBO_rm_link_set(l_rm_set)
            self.add_sub_op(op)

        if len(n_rm_set) > 0:
            op = DBO_rm_node_set(n_rm_set)
            self.add_sub_op(op)

class DBO_attr_diff_commit(DB_op):
    """
    commit a Attr_Diff
    """
    def __init__(self, attr_diff):
        super(DBO_attr_diff_commit, self).__init__()

        for id_attr, n_attr_diff in attr_diff.type__node.items():
            # TODO parameterize multiple attr removal
            r_attr_set = n_attr_diff['__attr_remove']
            w_attr_set = n_attr_diff['__attr_write']

            assert len(r_attr_set) > 0 or len(w_attr_set) > 0

            q_arr = ["match (n {id: {id}}) ",
                     "return n.id, n"]
            q_param_set = {'id': id_attr}

            if len(r_attr_set) > 0:
                stmt_attr_rm = "remove " + ', '.join(['n.' + attr for attr in r_attr_set])
                q_arr.insert(1, stmt_attr_rm)

            if len(w_attr_set) > 0:
                stmt_attr_set = "set n += {attr_set}"
                q_arr.insert(1, stmt_attr_set)
                q_param_set['attr_set'] = w_attr_set

            q = " ".join(q_arr)
            self.add_statement(q, q_param_set)

        for id_attr, n_attr_diff in attr_diff.type__link.items():
            pass  # TODO: handl link attr_diffs

    def process_result_set(self):
        ret = {}
        for _, _, r_set in self:
            for row in r_set:
                n_id, n = [v for v in row]  # we expect a [n_id, n] array
                ret[n_id] = n
        return ret

class DBO_add_node_set(DB_op):
    def __init__(self, node_map):
        """
        DB op: add node set

        @param node_map: node-type to node-set map
        @return: set of new node DB ids
        """
        super(DBO_add_node_set, self).__init__()
        for q, q_param_set in db_util.gen_query_create_from_node_map(node_map):
            self.add_statement(q, q_param_set)

    def process_result_set(self):
        id_set = []
        for _, _, row_set in self:
            for row in row_set:
                for clo in row:
                    id_set.append(clo)

        return id_set

class DBO_add_link_set(DB_op):
    def __init__(self, link_map):
        """
        @param link_map: is a link-type to link-set map - see model.link
        @return: set of new node DB ids
        """
        super(DBO_add_link_set, self).__init__()
        for q, q_params in db_util.gen_query_create_from_link_map(link_map):
            self.add_statement(q, q_params)

    def process_result_set(self):
        id_set = []
        for _, _, r_set in self:
            for row in r_set:
                for col_val in row:
                    id_set.append(col_val)

        return id_set

class DBO_load_node_set_by_DB_id(DB_op):
    def __init__(self, id_set):
        """
        load a set of nodes whose DB id is in id_set

        @param id_set: DB node id set
        @return: loaded node set or an empty set if no match was found
        """
        super(DBO_load_node_set_by_DB_id, self).__init__()
        q = "start n=node({id_set}) return n"
        self.add_statement(q, { 'id_set': id_set})

class DBO_match_node_id_set(DB_op):

    def __init__(self, filter_label=None, filter_attr_map={}):
        """
        match a set of nodes by type / attr_map

        @param filter_label: node type filter
        @param filter_attr_map: is a filter_key to filter_value_set map of
               possible attributes to match against, eg.:
               { 'id':[0,1], 'color: ['red','blue'] }
        @return: a set of node DB id's
        """
        super(DBO_match_node_id_set, self).__init__()

        q = "match (n{filter_label}) {where_clause} return id(n)"
        q = cfmt(q, filter_label="" if not filter_label else ":" + filter_label)
        q = cfmt(q, where_clause=db_util.gen_clause_where_from_filter_attr_map(filter_attr_map))

        q_params = filter_attr_map

        self.add_statement(q, q_params)

class DBO_match_node_set_by_id_attribute(DBO_match_node_id_set):
    def __init__(self, id_set):
        """
        convenience op: load a set of nodes by their 'id' attribute != DB node id
        """
        assert isinstance(id_set, list)

        super(DBO_match_node_set_by_id_attribute, self).__init__(filter_attr_map={'id': id_set})


class DBO_load_link_set(DB_op):
    def __init__(self, link_ptr_set):
        """
        match a set of sets of links by source/target node id attributes

        This class should be instantiated through a static factory function

        @link_ptr_set link pointer set
        @return: a set of loaded links
        """
        super(DBO_load_link_set, self).__init__()

        for l_ptr in link_ptr_set:
            if not l_ptr.src_id:
                q = "match ()-[r]->({id: {dst_id}}) return r"
                q_params = {'dst_id': l_ptr.dst_id}
            elif not l_ptr.dst_id:
                q = "match ({id: {src_id}})-[r]->() return r"
                q_params = {'src_id': l_ptr.src_id}
            else:
                q = "match ({id: {src_id}})-[r]->({id: {dst_id}}) return r"
                q_params = {'src_id': l_ptr.src_id, 'dst_id': l_ptr.dst_id}

            self.add_statement(q, q_params)

    @staticmethod
    def init_from_link_ptr(l_ptr):
        return DBO_load_link_set([l_ptr])

    @staticmethod
    def init_from_link_ptr_set(l_ptr_set):
        return DBO_load_link_set(l_ptr_set)

class DBO_match_link_id_set(DB_op):
    def __init__(self, filter_label=None, filter_attr_map={}):
        """
        load an id-set of links

        @param filter_label: link type filter
        @param filter_attr_map: is a filter_key to filter_value_set map of
               attributes to match link properties against
        @return: a set of loaded link ids
        """
        super(DBO_match_link_id_set, self).__init__()

        q_arr = ['match ()-[r{filter_label} {filter_attr}]->()',
                 'return id(r)'
        ]
        q = ' '.join(q_arr)
        q = cfmt(q, filter_label="" if not filter_label else ":" + filter_label)
        q = cfmt(q, filter_attr=db_util.gen_clause_attr_filter_from_filter_attr_map(filter_attr_map))
        q_params = {k: v[0] for (k, v) in filter_attr_map.items()}  # pass on only first value from each value set

        self.add_statement(q, q_params)

class DBO_rm_node_set(DB_op):
    def __init__(self, id_set, rm_links=False):
        """
        remove node set
        """
        assert len(id_set) > 0, __name__ + ': empty id set'

        super(DBO_rm_node_set, self).__init__()

        if rm_links:
            q_arr = ['match (n)',
                     'where n.id in {id_set}',
                     'optional match (n)-[r]-()',
                     'delete n,r',
                     'return {id_set}'
             ]
        else:
            q_arr = ['match (n)',
                     'where n.id in {id_set}',
                     'delete n',
                     'return {id_set}'
             ]

        q = ' '.join(q_arr)
        q_params = {'id_set': id_set}
        self.add_statement(q, q_params)

class DBO_rm_link_set(DB_op):
    def __init__(self, id_set):
        """
        remove link set

        [!] when removing as a result of node removal, use DBO_rm_node_set 
        along with rm_links=True
        """
        assert len(id_set) > 0, __name__ + ': empty id set'

        super(DBO_rm_link_set, self).__init__()

        q_arr = ['match ()-[r]->()',
                 'where r.id in {id_set}',
                 'delete r',
                 'return {id_set}'
         ]

        q = ' '.join(q_arr)
        q_params = {'id_set': id_set}
        self.add_statement(q, q_params)

class DBO_rz_clone(DB_op):
    def __init__(self, filter_label=None, limit=128):
        """
        clone rhizi

        @return: a dict: {'node_set': n_set,
                          'link_set': l_set }
                 where l_set is a list of (src.id, dst.id, link) tuples
        """
        super(DBO_rz_clone, self).__init__()

        self.limit = limit
        self.skip = 0

        q_arr = ['match (n)' if not filter_label else 'match (n:%s)' % (filter_label),
                 'optional match (n)-[r]->(m)',
                 'with n,r,m',
                 'order by n.id',
                 'skip %d' % (self.skip),
                 'limit %d' % (self.limit),
                 'return n,labels(n),collect([m.id, r, type(r)])']

        q = ' '.join(q_arr)
        self.add_statement(q)

    def process_result_set(self):
        ret_n_set = []
        ret_l_set = []
        for _, _, row_set in self:
            for row in row_set:
                n, n_lbl_set, l_set = row.items()  # see query return statement

                # reconstruct nodes
                assert None != n['id']

                n['__label_set'] = n_lbl_set
                ret_n_set.append(n)

                # reconstruct links from link tuples
                for l_tuple in l_set:
                    assert 3 == len(l_tuple)  # see query return statement

                    if None == l_tuple[0]:  # check if link dst is None
                        # as link matching is optional, collect may yield empty sets
                        continue

                    l = l_tuple[1]
                    l['__src_id'] = n['id']
                    l['__dst_id'] = l_tuple[0]
                    l['__label_set'] = [l_tuple[2]]  # box single value returned by type()

                    ret_l_set.append(l)

        return {'node_set': ret_n_set,
                'link_set': ret_l_set }

class DB_Controller:
    """
    neo4j DB controller
    """
    def __init__(self, config, db_driver_class=None):
        self.config = config
        if not db_driver_class:
            self.db_driver = DB_Driver_REST(self.config.db_base_url)
        else:
            self.db_driver = db_driver_class()
        assert isinstance(self.db_driver, DB_Driver_Base)

    def exec_op(self, op):
        """
        execute operation within a DB transaction
        """
        if isinstance(op, DB_composed_op):
            # construct a list comprehension composed of all sup_op statements
            for s_op in op.sub_op_set:
                self.exec_op(s_op)
            return op.process_result_set()

        try:
            self.db_driver.begin_tx(op)
            self.db_driver.exec_statement_set(op)
            self.db_driver.commit_tx(op)

            ret = op.process_result_set()

            log.debug('exec_op:' + op.name + ': return value: ' + str(ret))
            return ret
        except Exception as e:
            # here we watch for IOExecptions, etc - not db errors
            # these are returned in the db response itself
            log.error(e.message)
            log.error(traceback.print_exc())
            raise e

    def create_db_op(self, f_work, f_cont):
        ret = DB_op(f_work, f_cont)
        return ret

    def exec_cypher_query(self, q):
        """
        @deprecated: use DBO_cypher_query
        """

        # call post and not db_util.post_neo4j to avoid response key errors
        try:
            db_util.post(self.config.db_base_url + '/db/data/cypher', {"query" : q})
        except Exception as e:
            log.error(e.message)
            log.error(traceback.print_exc())
            raise e