from flask import Flask, request, jsonify, g
import sqlite3

make_table = r'''
CREATE TABLE IF NOT EXISTS counters
(counter_name TEXT PRIMARY KEY, counter_value INTEGER)
'''

add_counter = r'''
INSERT INTO counters
VALUES(?, ?)
'''

get_all_counters = r'''
SELECT * FROM counters;
'''

increment_counter = r'''
UPDATE counters
SET counter_value = (SELECT counter_value FROM counters WHERE counter_name = ?) + 1
WHERE counter_name = ?
'''

decrement_counter = r'''
UPDATE counters
SET counter_value = (SELECT counter_value FROM counters WHERE counter_name = ?) - 1
WHERE counter_name = ?
'''



app = Flask(__name__)

def get_db():
    db = getattr(g, "_database", None)

    if db is None:
        db = g._database = sqlite3.connect("counters.db")
        db.execute(make_table)

    return db

def get_all_counters_as_dict():
    cursor = get_db().execute(get_all_counters)
    all_counters = cursor.fetchall()

    print(all_counters)

    return {counter[0]:counter[1] for counter in all_counters}

def add_counter_to_db(counter_name, counter_initial_value):
    cursor = get_db().execute(add_counter, [counter_name, counter_initial_value])
    get_db().commit()

def modify_counter_in_db(counter_name, increment):
    if increment:
        get_db().execute(increment_counter, [counter_name, counter_name])
    else:
        get_db().execute(decrement_counter, [counter_name, counter_name])

    get_db().commit()

@app.route("/counters", methods=['GET', 'POST'])
def handle_counters_endpoint():
    if request.method == 'GET':
        response_dict = {
            'all_counters': get_all_counters_as_dict()
        }
        return jsonify(response_dict), 200
    elif request.method == 'POST':
        if request.content_type == 'application/json':
            body = request.get_json()

            if not "new_counter_name" in body.keys() or not "new_counter_starting_value" in body.keys():
                error_response = {
                    'status': 'ERROR',
                    'reason': 'Body for posting to /counters endpoint must contain both new_counter_name and new_counter_starting_value',
                    'input_body': body
                }
                return jsonify(error_response), 400

            add_counter_to_db(request.get_json()['new_counter_name'], request.get_json()['new_counter_starting_value'])
            return jsonify({'status': 'OK'}), 200
        else:
            error_response = {
                'status': 'ERROR',
                'reason': 'Content Type for endpoint /counters must be application/json'
            }
            return jsonify(error_response), 400

@app.route("/counters/<counter_name>", methods=['GET'])
def handle_counters_subcounter_endpoint(counter_name):
    all_counters = get_all_counters_as_dict()
    if not counter_name in all_counters.keys():
        error_response = {
            'status': 'ERROR',
            'reason': 'Counter name {counter} does not exist'.format(counter=counter_name)
        }
        return jsonify(error_response), 404
    
    data_response = {
        'counter_name': counter_name,
        'counter_value': all_counters[counter_name]
    }

    return jsonify(data_response), 200

@app.route("/counters/<counter_name>/increment", methods=['POST'])
def handle_counters_subcounter_increment(counter_name):
    all_counters = get_all_counters_as_dict()

    if not counter_name in all_counters.keys():
        error_response = {
            'status': 'ERROR',
            'reason': 'Counter name {counter} does not exist'.format(counter=counter_name)
        }
        return jsonify(error_response), 404
    
    data_response = {
        'counter_name': counter_name,
        'old_value': all_counters[counter_name],
        'new_value': all_counters[counter_name] + 1
    }

    modify_counter_in_db(counter_name, True)

    return jsonify(data_response), 200

@app.route("/counters/<counter_name>/decrement", methods=['POST'])
def handle_counters_subcounter_decrement(counter_name):
    all_counters = get_all_counters_as_dict()

    if not counter_name in all_counters.keys():
        error_response = {
            'status': 'ERROR',
            'reason': 'Counter name {counter} does not exist'.format(counter=counter_name)
        }
        return jsonify(error_response), 404
    
    data_response = {
        'counter_name': counter_name,
        'old_value': all_counters[counter_name],
        'new_value': all_counters[counter_name] - 1
    }

    modify_counter_in_db(counter_name, False)

    return jsonify(data_response), 200
    
@app.teardown_appcontext
def close_connection(exception):
    db = getattr(g, '_database', None)

    if db is not None:
        db.close()  

if __name__ == '__main__':
    app.run(debug=True)