import time
import calendar

from PLC.Timestamp import Timestamp
from PLC.Faults import *
from PLC.Parameter import Parameter


class Row(dict):
    """
    Representation of a row in a database table. To use, optionally
    instantiate with a dict of values. Update as you would a
    dict. Commit to the database with sync().
    """

    # Set this to the name of the table that stores the row.
    # e.g. table_name = "nodes"
    table_name = None

    # Set this to the name of the primary key of the table. It is
    # assumed that the this key is a sequence if it is not set when
    # sync() is called.
    # e.g. primary_key="node_id"
    primary_key = None

    # Set this to the names of tables that reference this table's
    # primary key.
    join_tables = []

    # Set this to a dict of the valid fields of this object and their
    # types. Not all fields (e.g., joined fields) may be updated via
    # sync().
    fields = {}

    # The name of the view that extends objects with tags
    # e.g. view_tags_name = "view_node_tags"
    view_tags_name = None

    # Set this to the set of tags that can be returned by the Get function
    tags = {}

    def __init__(self, api, fields = {}):
        dict.__init__(self, fields)
        self.api = api
        # run the class_init initializer once
        cls=self.__class__
        if not hasattr(cls,'class_inited'):
            cls.class_init (api)
            cls.class_inited=True # actual value does not matter

    def validate(self):
        """
        Validates values. Will validate a value with a custom function
        if a function named 'validate_[key]' exists.
        """

        # Warn about mandatory fields
        mandatory_fields = self.api.db.fields(self.table_name, notnull = True, hasdef = False)
        for field in mandatory_fields:
            if field not in self or self[field] is None:
                raise PLCInvalidArgument(field + " must be specified and cannot be unset in class %s"%self.__class__.__name__)

        # Validate values before committing
        for key, value in self.items():
            if value is not None and hasattr(self, 'validate_' + key):
                validate = getattr(self, 'validate_' + key)
                self[key] = validate(value)

    def separate_types(self, items):
        """
        Separate a list of different typed objects.
        Return a list for each type (ints, strs and dicts)
        """

        if isinstance(items, (list, tuple, set)):
            ints = [x for x in items if isinstance(x, int)]
            strs = [x for x in items if isinstance(x, str)]
            dicts = [x for x in items if isinstance(x, dict)]
            return (ints, strs, dicts)
        else:
            raise PLCInvalidArgument("Can only separate list types")


    def associate(self, *args):
        """
        Provides a means for high level api calls to associate objects
        using low level calls.
        """

        if len(args) < 3:
            raise PLCInvalidArgumentCount("auth, field, value must be specified")
        elif hasattr(self, 'associate_' + args[1]):
            associate = getattr(self, 'associate_'+args[1])
            associate(*args)
        else:
            raise PLCInvalidArguemnt("No such associate function associate_%s" % args[1])

    def validate_timestamp (self, timestamp):
        return Timestamp.sql_validate(timestamp)

    def add_object(self, classobj, join_table, columns = None):
        """
        Returns a function that can be used to associate this object
        with another.
        """

        def add(self, obj, columns = None, commit = True):
            """
            Associate with the specified object.
            """

            # Various sanity checks
            assert isinstance(self, Row)
            assert self.primary_key in self
            assert join_table in self.join_tables
            assert isinstance(obj, classobj)
            assert isinstance(obj, Row)
            assert obj.primary_key in obj
            assert join_table in obj.join_tables

            # By default, just insert the primary keys of each object
            # into the join table.
            if columns is None:
                columns = {self.primary_key: self[self.primary_key],
                           obj.primary_key: obj[obj.primary_key]}

            params = []
            for name, value in columns.items():
                params.append(self.api.db.param(name, value))

            self.api.db.do("INSERT INTO %s (%s) VALUES(%s)" % \
                           (join_table, ", ".join(columns), ", ".join(params)),
                           columns)

            if commit:
                self.api.db.commit()

        return add

    add_object = classmethod(add_object)

    def remove_object(self, classobj, join_table):
        """
        Returns a function that can be used to disassociate this
        object with another.
        """

        def remove(self, obj, commit = True):
            """
            Disassociate from the specified object.
            """

            assert isinstance(self, Row)
            assert self.primary_key in self
            assert join_table in self.join_tables
            assert isinstance(obj, classobj)
            assert isinstance(obj, Row)
            assert obj.primary_key in obj
            assert join_table in obj.join_tables

            self_id = self[self.primary_key]
            obj_id = obj[obj.primary_key]

            self.api.db.do("DELETE FROM %s WHERE %s = %s AND %s = %s" % \
                           (join_table,
                            self.primary_key, self.api.db.param('self_id', self_id),
                            obj.primary_key, self.api.db.param('obj_id', obj_id)),
                           locals())

            if commit:
                self.api.db.commit()

        return remove

    remove_object = classmethod(remove_object)

    # convenience: check in dict (self.fields or self.tags) that a key is writable
    @staticmethod
    def is_writable (key,value,dict):
        # if not mentioned, assume it's writable (e.g. deleted ...)
        if key not in dict: return True
        # if mentioned but not linked to a Parameter object, idem
        if not isinstance(dict[key], Parameter): return True
        # if not marked ro, it's writable
        if not dict[key].ro: return True
        return False

    def db_fields(self, obj = None):
        """
        Return only those fields that can be set or updated directly
        (i.e., those fields that are in the primary table (table_name)
        for this object, and are not marked as a read-only Parameter.
        """

        if obj is None:
            obj = self

        db_fields = self.api.db.fields(self.table_name)
        return dict ( [ (key, value) for (key, value) in list(obj.items())
                        if key in db_fields and
                        Row.is_writable(key, value, self.fields) ] )

    def tag_fields (self, obj=None):
        """
        Return the fields of obj that are mentioned in tags
        """
        if obj is None: obj=self

        return dict ( [ (key,value) for (key,value) in obj.items()
                        if key in self.tags and Row.is_writable(key,value,self.tags) ] )

    # takes as input a list of columns, sort native fields from tags
    # returns 2 dicts and one list : fields, tags, rejected
    @classmethod
    def parse_columns (cls, columns):
        (fields,tags,rejected)=({},{},[])
        for column in columns:
            if column in cls.fields: fields[column]=cls.fields[column]
            elif column in cls.tags: tags[column]=cls.tags[column]
            else: rejected.append(column)
        return (fields,tags,rejected)

    # compute the 'accepts' part of a method, from a list of column names, and a fields dict
    # use exclude=True to exclude the column names instead
    # typically accepted_fields (Node.fields,['hostname','model',...])
    @staticmethod
    def accepted_fields (update_columns, fields_dict, exclude=False):
        result={}
        for (k,v) in fields_dict.items():
            if (not exclude and k in update_columns) or (exclude and k not in update_columns):
                result[k]=v
        return result

    # filter out user-provided fields that are not part of the declared acceptance list
    # keep it separate from split_fields for simplicity
    # typically check_fields (<user_provided_dict>,{'hostname':Parameter(str,...),'model':Parameter(..)...})
    @staticmethod
    def check_fields (user_dict, accepted_fields):
# avoid the simple, but silent, version
#        return dict ([ (k,v) for (k,v) in user_dict.items() if k in accepted_fields ])
        result={}
        for (k,v) in list(user_dict.items()):
            if k in accepted_fields: result[k]=v
            else: raise PLCInvalidArgument ('Trying to set/change unaccepted key %s'%k)
        return result

    # given a dict (typically passed to an Update method), we check and sort
    # them against a list of dicts, e.g. [Node.fields, Node.related_fields]
    # return is a list that contains n+1 dicts, last one has the rejected fields
    @staticmethod
    def split_fields (fields, dicts):
        result=[]
        for x in dicts: result.append({})
        rejected={}
        for (field,value) in fields.items():
            found=False
            for i in range(len(dicts)):
                candidate_dict=dicts[i]
                if field in list(candidate_dict.keys()):
                    result[i][field]=value
                    found=True
                    break
            if not found: rejected[field]=value
        result.append(rejected)
        return result

    ### class initialization : create tag-dependent cross view if needed
    @classmethod
    def tagvalue_view_name (cls, tagname):
        return "tagvalue_view_%s_%s"%(cls.primary_key,tagname)

    @classmethod
    def tagvalue_view_create_sql (cls,tagname):
        """
        returns a SQL sentence that creates a view named after the primary_key and tagname,
        with 2 columns
        (*) column 1: primary_key
        (*) column 2: actual tag value, renamed into tagname
        """

        if not cls.view_tags_name:
            raise Exception('WARNING: class %s needs to set view_tags_name'%cls.__name__)

        table_name=cls.table_name
        primary_key=cls.primary_key
        view_tags_name=cls.view_tags_name
        tagvalue_view_name=cls.tagvalue_view_name(tagname)
        return 'CREATE OR REPLACE VIEW %(tagvalue_view_name)s ' \
            'as SELECT %(table_name)s.%(primary_key)s,%(view_tags_name)s.value as "%(tagname)s" ' \
            'from %(table_name)s right join %(view_tags_name)s using (%(primary_key)s) ' \
            'WHERE tagname = \'%(tagname)s\';'%locals()

    @classmethod
    def class_init (cls,api):
        cls.tagvalue_views_create (api)

    @classmethod
    def tagvalue_views_create (cls,api):
        if not cls.tags: return
        for tagname in list(cls.tags.keys()):
            api.db.do(cls.tagvalue_view_create_sql (tagname))
        api.db.commit()

    def __eq__(self, y):
        """
        Compare two objects.
        """

        # Filter out fields that cannot be set or updated directly
        # (and thus would not affect equality for the purposes of
        # deciding if we should sync() or not).
        x = self.db_fields()
        y = self.db_fields(y)
        return dict.__eq__(x, y)

    # validate becomes optional on sept. 2010
    # we find it useful to use DeletePerson on duplicated entries
    def sync(self, commit = True, insert = None, validate=True):
        """
        Flush changes back to the database.
        """

        # Validate all specified fields
        if validate: self.validate()

        # Filter out fields that cannot be set or updated directly
        db_fields = self.db_fields()

        # Parameterize for safety
        keys = list(db_fields.keys())
        values = [self.api.db.param(key, value) for (key, value) in list(db_fields.items())]

        # If the primary key (usually an auto-incrementing serial
        # identifier) has not been specified, or the primary key is the
        # only field in the table, or insert has been forced.
        if self.primary_key not in self or \
           keys == [self.primary_key] or \
           insert is True:

            # If primary key id is a serial int and it isnt included, get next id
            if (self.fields[self.primary_key].type is int
                    and self.primary_key not in self):
                pk_id = self.api.db.next_id(self.table_name, self.primary_key)
                self[self.primary_key] = pk_id
                db_fields[self.primary_key] = pk_id
                keys = list(db_fields.keys())
                values = [self.api.db.param(key, value) for (key, value) in list(db_fields.items())]
            # Insert new row
            sql = "INSERT INTO %s (%s) VALUES (%s)" % \
                  (self.table_name, ", ".join(keys), ", ".join(values))
        else:
            # Update existing row
            columns = ["%s = %s" % (key, value) for (key, value) in zip(keys, values)]
            sql = "UPDATE {} SET {} WHERE {} = {}"\
                  .format(self.table_name,
                          ", ".join(columns),
                          self.primary_key,
                          self.api.db.param(self.primary_key, self[self.primary_key]))

        self.api.db.do(sql, db_fields)

        if commit:
            self.api.db.commit()

    def delete(self, commit = True):
        """
        Delete row from its primary table, and from any tables that
        reference it.
        """

        assert self.primary_key in self

        for table in self.join_tables + [self.table_name]:
            if isinstance(table, tuple):
                key = table[1]
                table = table[0]
            else:
                key = self.primary_key

            sql = "DELETE FROM %s WHERE %s = %s" % \
                  (table, key,
                   self.api.db.param(self.primary_key, self[self.primary_key]))

            self.api.db.do(sql, self)

        if commit:
            self.api.db.commit()

class Table(list):
    """
    Representation of row(s) in a database table.
    """

    def __init__(self, api, classobj, columns = None):
        self.api = api
        self.classobj = classobj
        self.rows = {}

        if columns is None:
            columns = classobj.fields
            tag_columns={}
        else:
            (columns,tag_columns,rejected) = classobj.parse_columns(columns)
            if not columns and not tag_columns:
                raise PLCInvalidArgument("No valid return fields specified for class %s"%classobj.__name__)
            if rejected:
                raise PLCInvalidArgument("unknown column(s) specified %r in %s"%(rejected,classobj.__name__))

        self.columns = columns
        self.tag_columns = tag_columns

    def sync(self, commit = True):
        """
        Flush changes back to the database.
        """

        for row in self:
            row.sync(commit)

    def selectall(self, sql, params = None):
        """
        Given a list of rows from the database, fill ourselves with
        Row objects.
        """

        for row in self.api.db.selectall(sql, params):
            obj = self.classobj(self.api, row)
            self.append(obj)

    def dict(self, key_field = None):
        """
        Return ourself as a dict keyed on key_field.
        """

        if key_field is None:
            key_field = self.classobj.primary_key

        return dict([(obj[key_field], obj) for obj in self])