'''
This module contains the high-level webservice logic such as the Flask setup
and the Flask endpoints.
'''
import sys
import logging
import argparse

from flask import Flask, jsonify, request
from flask.ext.sqlalchemy import SQLAlchemy
from flask.ext.script import Manager
from flask.ext.migrate import Migrate, MigrateCommand

from accounting.storage import Storage
from accounting.storage.ledgercli import Ledger
from accounting.storage.sql import SQLStorage
from accounting.transport import AccountingEncoder, AccountingDecoder
from accounting.exceptions import AccountingException
from accounting.decorators import jsonify_exceptions


app = Flask('accounting')
app.config.from_pyfile('config.py')

storage = Storage()

if isinstance(storage, SQLStorage):
    # TODO: Move migration stuff into SQLStorage
    db = storage.db
    migrate = Migrate(app, db)

    manager = Manager(app)
    manager.add_command('db', MigrateCommand)


@app.before_request
def init_ledger():
    '''
    :py:meth:`flask.Flask.before_request`-decorated method that initializes an
    :py:class:`accounting.Ledger` object.
    '''
    global ledger
    #ledger = Ledger(ledger_file=app.config['LEDGER_FILE'])


# These will convert output from our internal classes to JSON and back
app.json_encoder = AccountingEncoder
app.json_decoder = AccountingDecoder


@app.route('/')
def index():
    ''' Hello World! '''
    return 'Hello World!'


@app.route('/transaction', methods=['GET'])
def transaction_get():
    '''
    Returns the JSON-serialized output of :meth:`accounting.Ledger.reg`
    '''
    return jsonify(transactions=storage.get_transactions())

@app.route('/transaction/<string:transaction_id>', methods=['POST'])
@jsonify_exceptions
def transaction_update(transaction_id=None):
    if transaction_id is None:
        raise AccountingException('The transaction ID cannot be None.')

    transaction = request.json['transaction']

    if transaction.id is not None and not transaction.id == transaction_id:
        raise AccountingException('The transaction data has an ID attribute and'
                                  ' it is not the same ID as in the path')
    elif transaction.id is None:
        transaction.id = transaction_id

    storage.update_transaction(transaction)

    return jsonify(status='OK')


@app.route('/transaction', methods=['POST'])
@jsonify_exceptions
def transaction_post():
    '''
    REST/JSON endpoint for transactions.

    Current state:

    Takes a POST request with a ``transactions`` JSON payload and writes it to
    the ledger file.

    Requires the ``transactions`` payload to be __type__-annotated:

    .. code-block:: json

        {
          "transactions": [
            {
              "__type__": "Transaction",
              "date": "2013-01-01",
              "payee": "Kindly T. Donor",
              "postings": [
                {
                  "__type__": "Posting",
                  "account": "Income:Foo:Donation",
                  "amount": {
                    "__type__": "Amount",
                    "amount": "-100",
                    "symbol": "$"
                  }
                },
                {
                  "__type__": "Posting",
                  "account": "Assets:Checking",
                  "amount": {
                    "__type__": "Amount",
                    "amount": "100",
                    "symbol": "$"
                  }
                }
              ]
            }
        }

    becomes::

        2013-01-01 Kindly T. Donor
          Income:Foo:Donation                                         $ -100
          Assets:Checking                                              $ 100
    '''
    transactions = request.json.get('transactions')

    if not transactions:
        raise AccountingException('No transaction data provided')

    for transaction in transactions:
        storage.add_transaction(transaction)

    return jsonify(status='OK')


def main(argv=None):
    prog = __name__
    if argv is None:
        prog = sys.argv[0]
        argv = sys.argv[1:]

    parser = argparse.ArgumentParser(prog=prog)
    parser.add_argument('-v', '--verbosity',
                        default='INFO',
                        help=('Filter logging output. Possible values:' +
                              ' CRITICAL, ERROR, WARNING, INFO, DEBUG'))

    global storage
    storage = Ledger(app=app)

    args = parser.parse_args(argv)

    logging.basicConfig(level=getattr(logging, args.verbosity, 'INFO'))

    app.run(host=app.config['HOST'], port=app.config['PORT'])

if __name__ == '__main__':
    main()