'''
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 accounting import Ledger
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')

ledger = None

@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('/balance')
def balance_report():
    '''
    Returns the JSON-serialized result of :meth:`accounting.Ledger.bal`
    '''
    report_data = ledger.bal()

    return jsonify(balance_report=report_data)

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

@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:
        ledger.add_transaction(transaction)

    return jsonify(foo='bar')


@app.route('/parse-json', methods=['POST'])
def parse_json():
    r'''
    Parses a __type__-annotated JSON payload and debug-logs the decoded version
    of it.

    Example:

    .. code-block:: bash

        wget http://127.0.0.1:5000/balance -O balance.json
        curl -X POST -H 'Content-Type: application/json' -d @balance.json \
            http://127.0.0.1/parse-json
        # Logging output (linebreaks added for clarity)
        # DEBUG:accounting:json data: {'balance_report':
        #    [<Account "None" [
        #        <Amount $ 0>, <Amount KARMA 0>]
        #        [<Account "Assets" [
        #            <Amount $ 50>, <Amount KARMA 10>]
        #            [<Account "Assets:Checking" [
        #                <Amount $ 50>] []>,
        #             <Account "Assets:Karma Account" [
        #                <Amount KARMA 10>] []>]>,
        #         <Account "Expenses" [
        #            <Amount $ 500>]
        #            [<Account "Expenses:Blah" [
        #                <Amount $ 250>]
        #                [<Account "Expenses:Blah:Hosting" [
        #                    <Amount $ 250>] []>]>,
        #             <Account "Expenses:Foo" [
        #                <Amount $ 250>] [
        #                <Account "Expenses:Foo:Hosting" [
        #                    <Amount $ 250>] []>]>]>,
        #         <Account "Income" [
        #            <Amount $ -550>,
        #            <Amount KARMA -10>]
        #            [<Account "Income:Donation" [
        #                <Amount $ -50>] []>,
        #             <Account "Income:Foo" [
        #                <Amount $ -500>]
        #                [<Account "Income:Foo:Donation" [
        #                    <Amount $ -500>] []>]>,
        #             <Account "Income:Karma" [
        #             <Amount KARMA -10>] []>]>]>]}
    '''
    app.logger.debug('json data: %s', request.json)
    return jsonify(foo='bar')


@app.route('/register')
def register_report():
    '''
    Returns the JSON-serialized output of :py:meth:`accounting.Ledger.reg`
    '''
    report_data = ledger.reg()

    return jsonify(register_report=report_data)


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'))

    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()