import os
import re
import json
import copy

from .exceptions import (
    SchemaTemplateMissingKeys,
    SchemaDuplicatedEnvGroupKeys
)

try:
    STRING_TYPE = basestring
except Exception:
    STRING_TYPE = str

WRAPPER_TYPES = ["form", "collapsible-wrap"]
NOT_SET = type("NOT_SET", (), {"__bool__": lambda obj: False})()
OVERRIDE_VERSION = 1

template_key_pattern = re.compile(r"(\{.*?[^{0]*\})")


def _fill_schema_template_data(
    template, template_data, required_keys=None, missing_keys=None
):
    first = False
    if required_keys is None:
        first = True
        required_keys = set()
        missing_keys = set()

        _template = []
        default_values = {}
        for item in template:
            if isinstance(item, dict) and "__default_values__" in item:
                default_values = item["__default_values__"]
            else:
                _template.append(item)
        template = _template

        for key, value in default_values.items():
            if key not in template_data:
                template_data[key] = value

    if not template:
        output = template

    elif isinstance(template, list):
        output = []
        for item in template:
            output.append(_fill_schema_template_data(
                item, template_data, required_keys, missing_keys
            ))

    elif isinstance(template, dict):
        output = {}
        for key, value in template.items():
            output[key] = _fill_schema_template_data(
                value, template_data, required_keys, missing_keys
            )

    elif isinstance(template, STRING_TYPE):
        # TODO find much better way how to handle filling template data
        for replacement_string in template_key_pattern.findall(template):
            key = str(replacement_string[1:-1])
            required_keys.add(key)
            if key not in template_data:
                missing_keys.add(key)
                continue

            value = template_data[key]
            if replacement_string == template:
                # Replace the value with value from templates data
                # - with this is possible to set value with different type
                template = value
            else:
                # Only replace the key in string
                template = template.replace(replacement_string, value)
        output = template

    else:
        output = template

    if first and missing_keys:
        raise SchemaTemplateMissingKeys(missing_keys, required_keys)

    return output


def _fill_schema_template(child_data, schema_collection, schema_templates):
    template_name = child_data["name"]
    template = schema_templates.get(template_name)
    if template is None:
        if template_name in schema_collection:
            raise KeyError((
                "Schema \"{}\" is used as `schema_template`"
            ).format(template_name))
        raise KeyError("Schema template \"{}\" was not found".format(
            template_name
        ))

    # Default value must be dictionary (NOT list)
    # - empty list would not add any item if `template_data` are not filled
    template_data = child_data.get("template_data") or {}
    if isinstance(template_data, dict):
        template_data = [template_data]

    output = []
    for single_template_data in template_data:
        try:
            filled_child = _fill_schema_template_data(
                template, single_template_data
            )

        except SchemaTemplateMissingKeys as exc:
            raise SchemaTemplateMissingKeys(
                exc.missing_keys, exc.required_keys, template_name
            )

        for item in filled_child:
            filled_item = _fill_inner_schemas(
                item, schema_collection, schema_templates
            )
            if filled_item["type"] == "schema_template":
                output.extend(_fill_schema_template(
                    filled_item, schema_collection, schema_templates
                ))
            else:
                output.append(filled_item)
    return output


def _fill_inner_schemas(schema_data, schema_collection, schema_templates):
    if schema_data["type"] == "schema":
        raise ValueError("First item in schema data can't be schema.")

    children_key = "children"
    object_type_key = "object_type"
    for item_key in (children_key, object_type_key):
        children = schema_data.get(item_key)
        if not children:
            continue

        if object_type_key == item_key:
            if not isinstance(children, dict):
                continue
            children = [children]

        new_children = []
        for child in children:
            child_type = child["type"]
            if child_type == "schema":
                schema_name = child["name"]
                if schema_name not in schema_collection:
                    if schema_name in schema_templates:
                        raise KeyError((
                            "Schema template \"{}\" is used as `schema`"
                        ).format(schema_name))
                    raise KeyError(
                        "Schema \"{}\" was not found".format(schema_name)
                    )

                filled_child = _fill_inner_schemas(
                    schema_collection[schema_name],
                    schema_collection,
                    schema_templates
                )

            elif child_type == "schema_template":
                for filled_child in _fill_schema_template(
                    child, schema_collection, schema_templates
                ):
                    new_children.append(filled_child)
                continue

            else:
                filled_child = _fill_inner_schemas(
                    child, schema_collection, schema_templates
                )

            new_children.append(filled_child)

        if item_key == object_type_key:
            if len(new_children) != 1:
                raise KeyError((
                    "Failed to fill object type with type: {} | name {}"
                ).format(
                    child_type, str(child.get("name"))
                ))
            new_children = new_children[0]

        schema_data[item_key] = new_children
    return schema_data


# TODO reimplement logic inside entities
def validate_environment_groups_uniquenes(
    schema_data, env_groups=None, keys=None
):
    is_first = False
    if env_groups is None:
        is_first = True
        env_groups = {}
        keys = []

    my_keys = copy.deepcopy(keys)
    key = schema_data.get("key")
    if key:
        my_keys.append(key)

    env_group_key = schema_data.get("env_group_key")
    if env_group_key:
        if env_group_key not in env_groups:
            env_groups[env_group_key] = []
        env_groups[env_group_key].append("/".join(my_keys))

    children = schema_data.get("children")
    if not children:
        return

    for child in children:
        validate_environment_groups_uniquenes(
            child, env_groups, copy.deepcopy(my_keys)
        )

    if is_first:
        invalid = {}
        for env_group_key, key_paths in env_groups.items():
            if len(key_paths) > 1:
                invalid[env_group_key] = key_paths

        if invalid:
            raise SchemaDuplicatedEnvGroupKeys(invalid)


def validate_schema(schema_data):
    validate_environment_groups_uniquenes(schema_data)


def get_gui_schema(subfolder, main_schema_name):
    dirpath = os.path.join(
        os.path.dirname(__file__),
        "schemas",
        subfolder
    )
    loaded_schemas = {}
    loaded_schema_templates = {}
    for root, _, filenames in os.walk(dirpath):
        for filename in filenames:
            basename, ext = os.path.splitext(filename)
            if ext != ".json":
                continue

            filepath = os.path.join(root, filename)
            with open(filepath, "r") as json_stream:
                try:
                    schema_data = json.load(json_stream)
                except Exception as exc:
                    raise ValueError((
                        "Unable to parse JSON file {}\n{}"
                    ).format(filepath, str(exc)))
            if isinstance(schema_data, list):
                loaded_schema_templates[basename] = schema_data
            else:
                loaded_schemas[basename] = schema_data

    main_schema = _fill_inner_schemas(
        loaded_schemas[main_schema_name],
        loaded_schemas,
        loaded_schema_templates
    )
    validate_schema(main_schema)
    return main_schema


def get_studio_settings_schema():
    return get_gui_schema("system_schema", "schema_main")


def get_project_settings_schema():
    return get_gui_schema("projects_schema", "schema_main")


class OverrideStateItem:
    """Object used as item for `OverrideState` enum.

    Used object to be able use exact object comparison and value comparisons.
    """
    values = set()

    def __init__(self, value, name):
        self.name = name
        if value in self.__class__.values:
            raise ValueError(
                "Implementation bug: Override State with same value as other."
            )
        self.__class__.values.add(value)
        self.value = value

    def __repr__(self):
        return "<object {}> {} {}".format(
            self.__class__.__name__, self.value, self.name
        )

    def __eq__(self, other):
        """Defines behavior for the equality operator, ==."""
        if isinstance(other, OverrideStateItem):
            return self.value == other.value
        return self.value == other

    def __gt__(self, other):
        """Defines behavior for the greater-than operator, >."""
        if isinstance(other, OverrideStateItem):
            return self.value > other.value
        return self.value > other

    def __lt__(self, other):
        """Defines behavior for the less-than operator, <."""
        if isinstance(other, OverrideStateItem):
            return self.value < other.value
        return self.value < other

    def __le__(self, other):
        """Defines behavior for the less-than-or-equal-to operator, <=."""
        if isinstance(other, OverrideStateItem):
            return self.value == other.value or self.value < other.value
        return self.value == other or self.value < other

    def __ge__(self, other):
        """Defines behavior for the greater-than-or-equal-to operator, >=."""
        if isinstance(other, OverrideStateItem):
            return self.value == other.value or self.value > other.value
        return self.value == other or self.value > other


class OverrideState:
    """Enumeration of override states.

    Each state have unique value.

    Currently has 4 states:
    - NOT_DEFINED - Initial state will raise an error if want to access
        anything in entity.
    - DEFAULTS - Entity cares only about default values. It is not
        possible to set higher state if any entity does not have filled
        default value.
    - STUDIO - First layer of overrides. Hold only studio overriden values
        that are applied on top of defaults.
    - PROJECT - Second layer of overrides. Hold only project overrides that are
        applied on top of defaults and studio overrides.
    """
    NOT_DEFINED = OverrideStateItem(-1, "Not defined")
    DEFAULTS = OverrideStateItem(0, "Defaults")
    STUDIO = OverrideStateItem(1, "Studio overrides")
    PROJECT = OverrideStateItem(2, "Project Overrides")