import configparser
import csv
import logging
import os
import shutil
from functools import total_ordering
from pathlib import Path
from typing import MutableMapping, Optional, List, Tuple, Union, Iterator

logger = logging.getLogger(__name__)


@total_ordering
class ObjectType(object):
    def __init__(self, name: str):
        self._name = name
        self._fields = []
        self._objects = {}

    def __eq__(self, o) -> bool:
        other = o  # type: ObjectType
        return isinstance(o, ObjectType) and self._name == other._name

    def __lt__(self, o: object) -> bool:
        if not isinstance(o, ObjectType):
            return True

        other = o  # type: ObjectType
        return self._name < other._name

    def __hash__(self) -> int:
        return self._name.__hash__()

    @property
    def name(self):
        return self._name

    @property
    def fields(self):
        return self._fields

    def index_of(self, field: str, create: bool = False) -> Optional[int]:
        try:
            return self._fields.index(field)
        except ValueError as e:
            if not create:
                return None

            self._fields.append(field)
            return len(self._fields) - 1


class Object(object):
    def __init__(self, ds: "DataSet", ot: ObjectType, key: str):
        self._ds = ds
        self._ot = ot
        self._key = key
        self._data = []

    @property
    def object_type(self):
        return self._ot

    @property
    def key(self):
        return self._key

    def set(self, key: str, value: str) -> "Object":
        if self._ds._frozen:
            raise Exception("This data set is frozen")
        idx = self._ot.index_of(key, create=True)
        self._data.insert(idx, value)

        return self

    def _set_from_object(self, other: "Object"):
        for k in other._ot.fields:
            self.set(k, other.get(k))

    def get(self, key: str) -> Optional[str]:
        idx = self._ot.index_of(key)
        return self._data[idx] if idx is not None and idx < len(self._data) else None

    def get_all(self, *keys: str) -> Optional[List[str]]:
        values = []
        for key in keys:
            idx = self._ot.index_of(key)
            if not idx or idx >= len(self._data):
                return None
            values.append(self._data[idx])
        return values


class DataSet(object):
    def __init__(self, name: Optional[str] = None):
        self._name = name
        self._object_types = {}  # type: MutableMapping[str, ObjectType]
        self._objects_by_type = {}  # type: MutableMapping[ObjectType, MutableMapping[str, Object]]
        self._frozen = False

    @property
    def name(self):
        if not self._name:
            raise Exception("Unnamed data set")
        return self._name

    def __len__(self):
        return sum((len(objects) for objects in self._objects_by_type.values()))

    def freeze(self):
        self._frozen = True

    def _assert_not_frozen(self):
        if self._frozen:
            raise Exception("This data set is frozen")

    def _check_object_type(self, object_type: str, create: bool) -> \
            Optional[Tuple[ObjectType, MutableMapping[str, Object]]]:
        try:
            ot = self._object_types[object_type]
            objects = self._objects_by_type[ot]
            return ot, objects,
        except KeyError:
            if not create:
                return None

            self._assert_not_frozen()

            ot = ObjectType(object_type)
            self._object_types[object_type] = ot
            self._objects_by_type[ot] = objects = {}
            return ot, objects,

    def _check_object(self, object_type: str, key: str, create: bool) -> Optional[Object]:
        t = self._check_object_type(object_type, create)

        if not t:
            return None

        ot, objects = t
        try:
            return objects[key]
        except KeyError:
            self._assert_not_frozen()

            if not create:
                raise Exception("No such type: {}:{}".format(object_type, key))

            o = Object(self, ot, key)
            objects[key] = o
            return o

    def get_object_type(self, object_type: str) -> ObjectType:
        ot, objects = self._check_object_type(object_type, False)

        if not ot:
            raise Exception("No such object type: {}".format(object_type))

        return ot

    def get_object(self, object_type: str, key: str) -> Object:
        o = self._check_object(object_type, key, False)

        if not o:
            raise Exception("No such object: {}:{}".format(object_type, key))

        return o

    def has_object(self, object_type: str, key: str) -> bool:
        t = self._check_object_type(object_type, False)

        if t:
            ot, objects = t
            return key in objects

        return False

    def get_or_create_object(self, object_type: str, key: str) -> Object:
        return self._check_object(object_type, key, True)

    def create_object(self, object_type: str, key: str) -> Object:
        self._assert_not_frozen()

        if self.has_object(object_type, key):
            raise Exception("Object already exist: {}:{}".format(object_type, key))

        return self._check_object(object_type, key, True)

    def items(self) -> Iterator[Object]:
        for objects in self._objects_by_type.values():
            for o in objects.values():
                yield o

    def merge(self, other: "DataSet") -> "DataSet":
        ds = DataSet(self._name)
        for objects in self._objects_by_type.values():
            for o in objects.values():
                ds.create_object(o.object_type.name, o.key)._set_from_object(o)

        for objects in other._objects_by_type.values():
            for o in objects.values():
                ds.get_or_create_object(o.object_type.name, o.key)._set_from_object(o)

        return ds


class DataSetManager(object):
    def __init__(self, basedir: Union[Path, str]):
        self._basedir = Path(basedir)
        self._csv = {}  # type: MutableMapping[str, Tuple[str, Path]]

    def cookie_for_ds(self, ds_name) -> Path:
        try:
            return self._csv[ds_name][1]
        except KeyError:
            return self._basedir / ds_name / "data-set.ini"

    def create_rw(self, name, clean: bool) -> "LazyRwDataSet":
        return LazyRwDataSet(self, name, clean)

    def create_ro(self, inputs: List[str]) -> "LazyRoDataSet":
        return LazyRoDataSet(self, inputs)

    def add_ds(self, ds_type: str, name: str, object_type: str, path: str = None):
        if ds_type == "csv":
            if name in self._csv:
                raise Exception("Data source already exists: {}".format(name))

            self._csv[name] = object_type, Path(path),
        else:
            raise Exception("Unknown data source type: {}".format(ds_type))

    def ds_type(self, name: str):
        return "csv" if name in self._csv else "ini-dir"

    def load(self, name, freeze=False) -> DataSet:
        try:
            object_type, path = self._csv[name]

            if not freeze:
                raise Exception("CSV data sources must be frozen")

            return DataSetManager._load_csv(name, object_type, path, freeze)
        except KeyError:
            return self._load_ini_dir(name, freeze)

    @staticmethod
    def _load_csv(name: str, object_type: str, path: Path, freeze: bool) -> DataSet:
        logger.info("Loading CSV file {}".format(path))
        ds = DataSet(name)

        with open(str(path), newline='') as f:
            r = csv.reader(f)

            header = next(r, None)
            for row in r:
                if len(row) == 0:
                    continue

                key = row[0]

                o = ds.create_object(object_type, key)
                for idx, value in zip(range(0, min(len(row), len(header))), row):
                    o.set(header[idx], value)

        logger.debug("Loaded {} objects".format(len(ds)))
        return ds

    def _load_ini_dir(self, name: str, freeze: bool) -> DataSet:
        ds_dir = Path(name) if Path(name).is_absolute() else self._basedir / name
        ds_dir = ds_dir if ds_dir.is_dir() else ds_dir.parent

        logger.info("Loading DS from '{}'".format(ds_dir))

        ini = self._load_ini(ds_dir / "data-set.ini")
        name = ini.get("data-set", "name")

        ds = DataSet(name)
        count = 0
        for ot_path in ds_dir.glob("*"):
            if not ot_path.is_dir():
                continue

            ot = ot_path.name
            logger.info("  Loading type '{}'".format(ot))
            for o_path in ot_path.glob("*.ini"):
                count += 1

                key = o_path.name[:-4]
                logger.info("    Loading key '{}'".format(key))
                ini = self._load_ini(o_path)
                o = ds.create_object(ot, key)
                for k, v in ini.items("values"):
                    o.set(k, v)

        if freeze:
            ds.freeze()

        logger.info("Loaded {} items".format(count))
        return ds

    def store(self, ds: DataSet):
        ds_dir = self._basedir / ds.name
        items = list(ds.items())
        logger.info("Storing DS '{}' with {} objects to {}".format(ds.name, len(items), ds_dir))

        os.makedirs(ds_dir, exist_ok=True)
        ini = self._blank_ini()
        ini.add_section("data-set")
        ini.set("data-set", "name", ds.name)
        self._store_ini(ini, ds_dir / "data-set.ini")

        for o in items:
            ot = o.object_type
            key = o.key

            ot_dir = ds_dir / ot.name
            os.makedirs(ot_dir, exist_ok=True)
            ini = self._blank_ini()
            ini.add_section("meta")
            ini.set("meta", "type", ot.name)

            ini.add_section("values")
            for k in ot.fields:
                v = o.get(k)
                if v:
                    ini.set("values", k, str(v))
            self._store_ini(ini, ot_dir / "{}.ini".format(key))

    @staticmethod
    def _blank_ini():
        return configparser.ConfigParser(interpolation=None)

    def _load_ini(self, path: Path):
        ini = self._blank_ini()
        if len(ini.read(str(path))) != 1:
            raise IOError("Could not load ini file: {}".format(path))
        return ini

    @staticmethod
    def _store_ini(ini, path):
        with open(path, "w") as f:
            ini.write(f)

    def remove(self, name: str):
        try:
            object_type, path = self._csv[name]
            os.remove(str(path))
        except KeyError:
            shutil.rmtree(self._basedir / name)


class LazyRoDataSet(object):
    def __init__(self, dsm: DataSetManager, inputs):
        self._dsm = dsm
        self._inputs = inputs

    def __enter__(self) -> DataSet:
        # logger.info("enter: name={}, inputs={}".format(self._name, self._inputs))
        ds = DataSet()
        for name in self._inputs:
            ds = ds.merge(self._dsm.load(name, freeze=True))

        ds.freeze()

        self._ds = ds
        return ds

    def __exit__(self, *args):
        return False


class LazyRwDataSet(object):
    def __init__(self, dsm: DataSetManager, name, clean):
        self._dsm = dsm
        self._name = name
        self._clean = clean

    def __enter__(self) -> DataSet:
        cookie = self._dsm.cookie_for_ds(self._name)

        if cookie.exists():
            if not self._clean:
                raise IOError("DataSet already exists: {}, cookie={}".format(self._name, cookie))
            self._dsm.remove(self._name)

        ds = DataSet(self._name)
        self._ds = ds
        return ds

    def __exit__(self, *args):
        self._dsm.store(self._ds)
        return False