import re, logging
from sqlalchemy.sql.expression import func, and_
from sqlalchemy.sql import select

log = logging.getLogger( __name__ )

# Item-specific information needed to perform tagging.
class ItemTagAssocInfo( object ):
    def __init__( self, item_class, tag_assoc_class, item_id_col ):
        self.item_class = item_class
        self.tag_assoc_class = tag_assoc_class
        self.item_id_col = item_id_col

class TagHandler( object ):
    def __init__( self ):
        # Minimum tag length.
        self.min_tag_len = 2
        # Maximum tag length.
        self.max_tag_len = 255
        # Tag separator.
        self.tag_separators = ',;'
        # Hierarchy separator.
        self.hierarchy_separator = '.'
        # Key-value separator.
        self.key_value_separators = "=:"
        # Initialize with known classes - add to this in subclasses.
        self.item_tag_assoc_info = {}
    def get_tag_assoc_class( self, item_class ):
        """Returns tag association class for item class."""
        return self.item_tag_assoc_info[item_class.__name__].tag_assoc_class
    def get_id_col_in_item_tag_assoc_table( self, item_class ):
        """Returns item id column in class' item-tag association table."""
        return self.item_tag_assoc_info[item_class.__name__].item_id_col
    def get_community_tags( self, trans, item=None, limit=None ):
        """Returns community tags for an item."""
        # Get item-tag association class.
        item_class = item.__class__
        item_tag_assoc_class = self.get_tag_assoc_class( item_class )
        if not item_tag_assoc_class:
            return []
        # Build select statement.
        cols_to_select = [ item_tag_assoc_class.table.c.tag_id, func.count( '*' ) ]
        from_obj = item_tag_assoc_class.table.join( item_class.table ).join( trans.app.model.Tag.table )
        where_clause = ( self.get_id_col_in_item_tag_assoc_table( item_class ) == item.id )
        order_by = [ func.count( "*" ).desc() ]
        group_by = item_tag_assoc_class.table.c.tag_id
        # Do query and get result set.
        query = select( columns=cols_to_select,
                        from_obj=from_obj,
                        whereclause=where_clause,
                        group_by=group_by,
                        order_by=order_by,
                        limit=limit )
        result_set = trans.sa_session.execute( query )
        # Return community tags.
        community_tags = []
        for row in result_set:
            tag_id = row[0]
            community_tags.append( self.get_tag_by_id( trans, tag_id ) )
        return community_tags
    def get_tool_tags( self, trans ):
        result_set = trans.sa_session.execute( select( columns=[ trans.app.model.ToolTagAssociation.table.c.tag_id ],
                                                       from_obj=trans.app.model.ToolTagAssociation.table ).distinct() )

        tags = []
        for row in result_set:
            tag_id = row[0]
            tags.append( self.get_tag_by_id( trans, tag_id ) )
        return tags
    def remove_item_tag( self, trans, user, item, tag_name ):
        """Remove a tag from an item."""
        # Get item tag association.
        item_tag_assoc = self._get_item_tag_assoc( user, item, tag_name )
        # Remove association.
        if item_tag_assoc:
            # Delete association.
            trans.sa_session.delete( item_tag_assoc )
            item.tags.remove( item_tag_assoc )
            return True
        return False
    def delete_item_tags( self, trans, user, item ):
        """Delete tags from an item."""
        # Delete item-tag associations.
        for tag in item.tags:
            trans.sa_session.delete( tag )
        # Delete tags from item.
        del item.tags[:]
    def item_has_tag( self, trans, user, item, tag ):
        """Returns true if item is has a given tag."""
        # Get tag name.
        if isinstance( tag, basestring ):
            tag_name = tag
        elif isinstance( tag, trans.app.model.Tag ):
            tag_name = tag.name
        # Check for an item-tag association to see if item has a given tag.
        item_tag_assoc = self._get_item_tag_assoc( user, item, tag_name )
        if item_tag_assoc:
            return True
        return False
    def apply_item_tag( self, trans, user, item, name, value=None ):
        # Use lowercase name for searching/creating tag.
        lc_name = name.lower()
        # Get or create item-tag association.
        item_tag_assoc = self._get_item_tag_assoc( user, item, lc_name )
        if not item_tag_assoc:
            # Create item-tag association.
            # Create tag; if None, skip the tag (and log error).
            tag = self._get_or_create_tag( trans, lc_name )
            if not tag:
                log.warn( "Failed to create tag with name %s" % lc_name )
                return
            # Create tag association based on item class.
            item_tag_assoc_class = self.get_tag_assoc_class( item.__class__ )
            item_tag_assoc = item_tag_assoc_class()
            # Add tag to association.
            item.tags.append( item_tag_assoc )
            item_tag_assoc.tag = tag
            item_tag_assoc.user = user
        # Apply attributes to item-tag association. Strip whitespace from user name and tag.
        lc_value = None
        if value:
            lc_value = value.lower()
        item_tag_assoc.user_tname = name
        item_tag_assoc.user_value = value
        item_tag_assoc.value = lc_value
        return item_tag_assoc
    def apply_item_tags( self, trans, user, item, tags_str ):
        """Apply tags to an item."""
        # Parse tags.
        parsed_tags = self.parse_tags( tags_str )
        # Apply each tag.
        for name, value in parsed_tags.items():
            self.apply_item_tag( trans, user, item, name, value )
    def get_tags_str( self, tags ):
        """Build a string from an item's tags."""
        # Return empty string if there are no tags.
        if not tags:
            return ""
        # Create string of tags.
        tags_str_list = list()
        for tag in tags:
            tag_str = tag.user_tname
            if tag.value is not None:
                tag_str += ":" + tag.user_value
            tags_str_list.append( tag_str )
        return ", ".join( tags_str_list )
    def get_tag_by_id( self, trans, tag_id ):
        """Get a Tag object from a tag id."""
        return trans.sa_session.query( trans.app.model.Tag ).filter_by( id=tag_id ).first()
    def get_tag_by_name( self, trans, tag_name ):
        """Get a Tag object from a tag name (string)."""
        if tag_name:
            return trans.sa_session.query( trans.app.model.Tag ).filter_by( name=tag_name.lower() ).first()
        return None
    def _create_tag( self, trans, tag_str ):
        """Create a Tag object from a tag string."""
        tag_hierarchy = tag_str.split( self.hierarchy_separator )
        tag_prefix = ""
        parent_tag = None
        for sub_tag in tag_hierarchy:
            # Get or create subtag.
            tag_name = tag_prefix + self._scrub_tag_name( sub_tag )
            tag = trans.sa_session.query( trans.app.model.Tag ).filter_by( name=tag_name).first()
            if not tag:
                tag = trans.app.model.Tag( type=0, name=tag_name )
            # Set tag parent.
            tag.parent = parent_tag
            # Update parent and tag prefix.
            parent_tag = tag
            tag_prefix = tag.name + self.hierarchy_separator
        return tag
    def _get_or_create_tag( self, trans, tag_str ):
        """Get or create a Tag object from a tag string."""
        # Scrub tag; if tag is None after being scrubbed, return None.
        scrubbed_tag_str = self._scrub_tag_name( tag_str )
        if not scrubbed_tag_str:
            return None
        # Get item tag.
        tag = self.get_tag_by_name( trans, scrubbed_tag_str )
        # Create tag if necessary.
        if tag is None:
            tag = self._create_tag( trans, scrubbed_tag_str )
        return tag
    def _get_item_tag_assoc( self, user, item, tag_name ):
        """
        Return ItemTagAssociation object for a user, item, and tag string; returns None if there is
        no such association.
        """
        scrubbed_tag_name = self._scrub_tag_name( tag_name )
        for item_tag_assoc in item.tags:
            if ( item_tag_assoc.user == user ) and ( item_tag_assoc.user_tname == scrubbed_tag_name ):
                return item_tag_assoc
        return None
    def parse_tags( self, tag_str ):
        """
        Returns a list of raw (tag-name, value) pairs derived from a string; method scrubs tag names and values as well.
        Return value is a dictionary where tag-names are keys.
        """
        # Gracefully handle None.
        if not tag_str:
            return dict()
        # Split tags based on separators.
        reg_exp = re.compile( '[' + self.tag_separators + ']' )
        raw_tags = reg_exp.split( tag_str )
        # Extract name-value pairs.
        name_value_pairs = dict()
        for raw_tag in raw_tags:
            nv_pair = self._get_name_value_pair( raw_tag )
            scrubbed_name = self._scrub_tag_name( nv_pair[0] )
            scrubbed_value = self._scrub_tag_value( nv_pair[1] )
            name_value_pairs[scrubbed_name] = scrubbed_value
        return name_value_pairs
    def _scrub_tag_value( self, value ):
        """Scrub a tag value."""
        # Gracefully handle None:
        if not value:
            return None
        # Remove whitespace from value.
        reg_exp = re.compile( '\s' )
        scrubbed_value = re.sub( reg_exp, "", value )
        return scrubbed_value
    def _scrub_tag_name( self, name ):
        """Scrub a tag name."""
        # Gracefully handle None:
        if not name:
            return None
        # Remove whitespace from name.
        reg_exp = re.compile( '\s' )
        scrubbed_name = re.sub( reg_exp, "", name )
        # Ignore starting ':' char.
        if scrubbed_name.startswith( self.hierarchy_separator ):
            scrubbed_name = scrubbed_name[1:]
        # If name is too short or too long, return None.
        if len( scrubbed_name ) < self.min_tag_len or len( scrubbed_name ) > self.max_tag_len:
            return None
        return scrubbed_name
    def _scrub_tag_name_list( self, tag_name_list ):
        """Scrub a tag name list."""
        scrubbed_tag_list = list()
        for tag in tag_name_list:
            scrubbed_tag_list.append( self._scrub_tag_name( tag ) )
        return scrubbed_tag_list
    def _get_name_value_pair( self, tag_str ):
        """Get name, value pair from a tag string."""
        # Use regular expression to parse name, value.
        reg_exp = re.compile( "[" + self.key_value_separators + "]" )
        name_value_pair = reg_exp.split( tag_str )
        # Add empty slot if tag does not have value.
        if len( name_value_pair ) < 2:
            name_value_pair.append( None )
        return name_value_pair

class GalaxyTagHandler( TagHandler ):
    def __init__( self ):
        from galaxy import model
        TagHandler.__init__( self )
        self.item_tag_assoc_info["History"] = ItemTagAssocInfo( model.History,
                                                                model.HistoryTagAssociation,
                                                                model.HistoryTagAssociation.table.c.history_id )
        self.item_tag_assoc_info["HistoryDatasetAssociation"] = \
            ItemTagAssocInfo( model.HistoryDatasetAssociation,
                              model.HistoryDatasetAssociationTagAssociation,
                              model.HistoryDatasetAssociationTagAssociation.table.c.history_dataset_association_id )
        self.item_tag_assoc_info["Page"] = ItemTagAssocInfo( model.Page,
                                                             model.PageTagAssociation,
                                                             model.PageTagAssociation.table.c.page_id )
        self.item_tag_assoc_info["StoredWorkflow"] = ItemTagAssocInfo( model.StoredWorkflow,
                                                                       model.StoredWorkflowTagAssociation,
                                                                       model.StoredWorkflowTagAssociation.table.c.stored_workflow_id )
        self.item_tag_assoc_info["Visualization"] = ItemTagAssocInfo( model.Visualization,
                                                                      model.VisualizationTagAssociation,
                                                                      model.VisualizationTagAssociation.table.c.visualization_id )

class CommunityTagHandler( TagHandler ):
    def __init__( self ):
        from galaxy.webapps.tool_shed import model
        TagHandler.__init__( self )