# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0
"""
This file contains helper functions related to layout.
"""

import os
from urllib.parse import unquote

import chalicelib.settings as msam_settings

import boto3
from boto3.dynamodb.conditions import Key
from botocore.config import Config
from botocore.exceptions import ClientError

# table names generated by CloudFormation
LAYOUT_TABLE_NAME = os.environ["LAYOUT_TABLE_NAME"]

# user-agent config
SOLUTION_ID = os.environ['SOLUTION_ID']
USER_AGENT_EXTRA = {"user_agent_extra": SOLUTION_ID}
MSAM_BOTO3_CONFIG = Config(**USER_AGENT_EXTRA)

# DynamoDB
DYNAMO_RESOURCE = boto3.resource("dynamodb", config=MSAM_BOTO3_CONFIG)


def get_view_layout(view):
    """
    API entry point for retrieving all item positions in a view.
    """
    view = unquote(view)
    items = []
    table_name = LAYOUT_TABLE_NAME
    try:
        table = DYNAMO_RESOURCE.Table(table_name)
        try:
            # get the settings object
            response = table.query(KeyConditionExpression=Key('view').eq(view))
            print(response)
            # return the response or an empty object
            if "Items" in response:
                items = response["Items"]
            print("retrieved")
        except ClientError:
            print("not found")
    except ClientError as error_out:
        # send the exception back in the object
        print(error_out)
        items = {"exception": str(error_out)}
    return items


def set_node_layout(layout_items):
    """
    API entry point for setting nodes in a view. This adds new nodes and overwrites existing nodes. It does not replace the entire set.
    """
    settings = {}
    table_name = LAYOUT_TABLE_NAME
    try:
        table = DYNAMO_RESOURCE.Table(table_name)
        # print(request.json_body)
        # layout_items = request.json_body
        # write to the database in batch
        for item in layout_items:
            table.put_item(Item=item)
        settings = {"message": "saved"}
        print(settings)
    except ClientError as error:
        # send the exception back in the object
        print(error)
        settings = {"exception": str(error)}
    return settings


def delete_node_layout(view, node_id):
    """
    API entry point for removing nodes from a view.
    """
    view = unquote(view)
    node_id = unquote(node_id)
    settings = {}
    table_name = LAYOUT_TABLE_NAME
    try:
        print(view, node_id)
        table = DYNAMO_RESOURCE.Table(table_name)
        table.delete_item(Key={"view": view, "id": node_id})
        settings = {"message": "deleted"}
        print(settings)
    except ClientError as error:
        # send the exception back in the object
        print(error)
        settings = {"exception": str(error)}
    return settings


def has_node(view, node_id):
    """
    API entry point to check presence of nodes in a view.
    """
    view = unquote(view)
    node_id = unquote(node_id)
    table_name = LAYOUT_TABLE_NAME
    try:
        table = DYNAMO_RESOURCE.Table(table_name)
        response = table.get_item(Key={"view": view, "id": node_id})
        # True or False
        return "Item" in response
    except ClientError as error:
        print(error)
        return False


def remove_all_diagrams():
    """
    Delete all diagrams from the database
    """
    try:
        table = DYNAMO_RESOURCE.Table(LAYOUT_TABLE_NAME)
        # empty the value in settings
        msam_settings.put_setting("diagrams", [])
        # empty the channels table
        response = table.scan(ExpressionAttributeNames={
            "#v": "view",
            "#i": "id"
        },
                              ProjectionExpression="#v,#i")
        items = response.get("Items", [])
        while "LastEvaluatedKey" in response:
            response = table.scan(
                ExpressionAttributeNames={
                    "#v": "view",
                    "#i": "id"
                },
                ProjectionExpression="#v,#i",
                ExclusiveStartKey=response["LastEvaluatedKey"])
            items = items + response.get("Items", [])
        for item in items:
            table.delete_item(Key={"view": item["view"], "id": item["id"]})
        response = {"message": "done"}
    except ClientError as client_error:
        print(client_error)
        response = {"message": str(client_error)}
    return response