import json
import copy
import subprocess
from collections import Counter

from fatcat_openapi_client import ApiClient, Editgroup
from fatcat_openapi_client.rest import ApiException
from fatcat_tools.transforms import entity_from_dict, entity_to_dict


class EntityCleaner:
    """
    API for individual jobs:

        # record iterators sees
        push_record(record)
        finish()

        # provided helpers
        self.api
        self.get_editgroup_id()
        counts({'lines', 'skip', 'merged', 'updated'})

        # implemented per-task
        try_merge(idents, primary=None) -> int (entities updated)

    This class is pretty similar to EntityImporter, but isn't subclassed.
    """

    def __init__(self, api, entity_type, **kwargs):

        eg_extra = kwargs.get('editgroup_extra', dict())
        eg_extra['git_rev'] = eg_extra.get('git_rev',
            subprocess.check_output(["git", "describe", "--always"]).strip()).decode('utf-8')
        eg_extra['agent'] = eg_extra.get('agent', 'fatcat_tools.EntityCleaner')

        self.api = api
        self.entity_type = entity_type
        self.dry_run_mode = kwargs.get('dry_run_mode', True)
        self.edit_batch_size = kwargs.get('edit_batch_size', 50)
        self.editgroup_description = kwargs.get('editgroup_description', "Generic Entity Cleaner Bot")
        self.editgroup_extra = eg_extra
        self.reset()
        self.ac = ApiClient()

        if self.dry_run_mode:
            print("Running in dry-run mode!")

    def reset(self):
        self.counts = Counter({'lines': 0, 'cleaned': 0, 'updated': 0})
        self._edit_count = 0
        self._editgroup_id = None
        self._entity_queue = []
        self._idents_inflight = []

    def push_record(self, record):
        """
        Intended to be called by "pusher" class (which could be pulling from
        JSON file, Kafka, whatever).

        Input is expected to be an entity in JSON-like dict form.

        Returns nothing.
        """
        self.counts['lines'] += 1
        if (not record):
            self.counts['skip-null'] += 1
            return

        entity = entity_from_dict(record, self.entity_type, api_client=self.ac)

        if entity.state != 'active':
            self.counts['skip-inactive'] += 1
            return

        cleaned = self.clean_entity(copy.deepcopy(entity))
        if entity == cleaned:
            self.counts['skip-clean'] += 1
            return
        else:
            self.counts['cleaned'] += 1

        if self.dry_run_mode:
            entity_dict = entity_to_dict(entity, api_client=self.ac)
            print(json.dumps(entity_dict))
            return

        if entity.ident in self._idents_inflight:
            raise ValueError("Entity already part of in-process update: {}".format(entity.ident))

        updated = self.try_update(cleaned)
        if updated:
            self.counts['updated'] += updated
            self._edit_count += updated
            self._idents_inflight.append(entity.ident)

        if self._edit_count >= self.edit_batch_size:
            self.api.accept_editgroup(self._editgroup_id)
            self._editgroup_id = None
            self._edit_count = 0
            self._idents_inflight = []
        return

    def clean_entity(self, entity):
        """
        Mutates entity in-place and returns it
        """
        # implementations should fill this in
        raise NotImplementedError

    def try_update(self, entity):
        """
        Returns edit count (number of entities updated).

        If >= 1, does not need to update self.counts. If no entities updated,
        do need to update counts internally.
        """
        # implementations should fill this in
        raise NotImplementedError

    def finish(self):
        if self._edit_count > 0:
            self.api.accept_editgroup(self._editgroup_id)
            self._editgroup_id = None
            self._edit_count = 0
            self._idents_inflight = []

        return self.counts

    def get_editgroup_id(self):

        if not self._editgroup_id:
            eg = self.api.create_editgroup(
                Editgroup(
                    description=self.editgroup_description,
                    extra=self.editgroup_extra))
            self._editgroup_id = eg.editgroup_id

        return self._editgroup_id