import os
import nixio as nix
from enum import Enum


class ItemDescriptor():
    
    def __init__(self, name=None, id=None, type=None, value=None, definition=None, block_id=None, entity_type=None) -> None:
        super().__init__()
        self.name = name
        self.type = type
        self.id = id
        self.block_id= block_id
        self.definition = definition
        self.value = value
        self.entity_type = entity_type


class NodeType(Enum):
     Root = "root"
     Section = "section"
     Block = "block"
     DataArray = "data_array"
     DataFrame = "data_frame"
     Property = "property"
     Dimension = "dimension"
     Source = "source"
     Tag = "tag"
     MultiTag = "multi_tag"
     Group = "group"
     Feature="feature"


class Singleton(type):
    _instances = {}
    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]

class EntityBuffer():

    def __init__(self) -> None:
        super().__init__()
        self._buffer = {}
    
    def put(self, entity):
        if not hasattr(entity, "id"):
            return
        id = entity.id
        if id not in self._buffer.keys():
            self._buffer[id] = entity
    
    def has(self, id):
        return id in self._buffer.keys()
    
    def get(self, id):
        if self.has(id):
            return self._buffer[id]
        else:
            return None
    
    def clear(self):
        self._buffer.clear()


class FileHandler(metaclass=Singleton):
    
    def __init__(self) -> None:
        super().__init__()
        self._filename = None
        self._nix_file = None
        self._file_requests = []
        self._entity_buffer = EntityBuffer()
    
    def open(self, filename):
        """[summary]

        Args:
            filename ([type]): [description]
        """
        self.close()
      
        if not os.path.exists(filename):
            return False, "File %s could not be found!" % filename
        try:
            self._nix_file = nix.File.open(filename, nix.FileMode.ReadOnly)
            self._filename = filename
            return True, "Successfully opened file %s." % filename.split(os.sep)[-1]
        except RuntimeError as e:
            return False, "Failed to open file %s! \n Error message is: %s" % (filename, e)
        except OSError as e:
            return False, "Failed to open file %s! \n Error message is: %s\n Probably no nix file?!" % (filename, e)

    def close(self):
        # TODO check if there are any pending file requests!
        if self._nix_file is not None and self._nix_file.is_open():
            self._nix_file.close()
            self._nix_file = None
            self._file_requests = []
            self._entity_buffer.clear()

    def file_descriptor(self):
        
        return ItemDescriptor()

    @property
    def is_valid(self):
        return self._nix_file is not None and self._nix_file.is_open()
    
    @property
    def filename(self):
        return self._filename

    def request_metadata(self, root_id=None, depth=1):
        """[summary]

        Args:
            root_id ([type], optional): [description]. Defaults to None.
            depth (int, optional): [description]. Defaults to 1.
        """
        def get_subsections(section):
            sub_sections = []
            for s in section.sections:
                self._entity_buffer.put(s)
                sub_sections.append(ItemDescriptor(s.name, s.id, s.type, definition=s.definition, entity_type=NodeType.Section))
            return sub_sections
        
        def get_properties(section):
            props = []
            for p in section.props:
                value = "unset"
                props.append(ItemDescriptor(p.name, p.id, value=value, entity_type=NodeType.Property))
            return props

        sections = []
        properties = []
        if root_id is None:
            sections = get_subsections(self._nix_file)
        else:
            fs = self._entity_buffer.get(root_id)
            if fs is None:
                found_section = self._nix_file.find_sections(lambda s: s.id == root_id)
                fs = found_section[0] if len(found_section) > 0 else None
            if fs is None:
                return sections, properties
            sections.extend(get_subsections(fs))
            properties.extend(get_properties(fs))
        return sections, properties

    def _entity_info(self, entities, block_id, entity_type):
        infos = []
        for e in entities:
            self._entity_buffer.put(e)
            itd = ItemDescriptor(e.name, e.id, e.type, definition=e.definition, entity_type=entity_type, block_id=block_id)
            infos.append(itd)
            # TODO set the value to something meaningful for the various entity types
        return infos

    def request_blocks(self):
        return self._entity_info(self._nix_file.blocks, None, NodeType.Block)

    def get_block(self, id):
        b = b = self._entity_buffer.get(id)
        if not b:
            b = self._nix_file.blocks[id]
        return b
    
    def request_data_arrays(self, block_id):
        b = self.get_block(block_id)
        return self._entity_info(b.data_arrays, block_id, NodeType.DataArray)

    def request_tags(self, block_id):
        b = self.get_block(block_id)
        tags = self._entity_info(b.tags, block_id, NodeType.Tag)
        tags.extend(self._entity_info(b.multi_tags, block_id, NodeType.MultiTag))
        return tags

    def request_references(self, block_id, tag_id, is_mtag):
        b = self.get_block(block_id)
        t = self._entity_buffer.get(tag_id)
        if t is None:
            if is_mtag:
                t = b.multi_tags[tag_id]
            else:
                t = b.tags[tag_id]
        return self._entity_info(t.references, block_id, NodeType.DataArray)

    def request_features(self, block_id, tag_id, is_mtag):
        b = self.get_block(block_id)
        t = self._entity_buffer.get(tag_id)
        if t is None:
            if is_mtag:
                t = b.multi_tags[tag_id]
            else:
                t = b.tags[tag_id]
        feats = []
        for f in t.features:
            itd = ItemDescriptor(f.data.name, f.id, f.link_type, definition=f.data.definition, block_id=block_id, entity_type=NodeType.Feature)
            feats.append(itd)
        return feats

    def request_dimensions(self, block_id, array_id):
        da = self._entity_buffer.get(array_id)
        if da is None:
            b = self.get_block(block_id)
            da = b.data_arrays[array_id]
        dimensions = []
        for i, d in enumerate(da.dimensions):
            dim_name = "%i. dim: %s" % (i+1, d.label if hasattr(d, "label") else "")
            dim_type= "%s %s" % (d.dimension_type, "dimension")
            dimensions.append(ItemDescriptor(dim_name, type=dim_type, entity_type=NodeType.Dimension, block_id=block_id))
        return dimensions

    def request_data_frames(self, block_id):
        if self._nix_file.version[1] >= 2:
            b = self.get_block(block_id)
            return self._entity_info(b.data_frames, block_id, NodeType.DataFrame)
        return []

    def request_groups(self, block_id):
        b = self.get_block(block_id)
        return self._entity_info(b.groups, block_id, NodeType.Group)

    def request_sources(self, block_id, parent_source_id=None):
        def get_subsources(src):
            sub_sources = []
            for s in src.sources:
                self._entity_buffer.put(s)
                sub_sources.append(ItemDescriptor(s.name, s.id, s.type, definition=s.definition, entity_type=NodeType.Source))
            return sub_sources
        b = self.get_block(block_id)
        if parent_source_id is None:
            return self._entity_info(b.sources, block_id, NodeType.Source)
        else:
            srcs = b.find_sources(lambda s: s.id == parent_source_id)
            sources = []
            for src in srcs:
                sources.extend(get_subsources(src))
            return sources