"""
Pi - calculate pi over time via the monte carlo method. idea borrowed from #linode
Copyright (C) 2010  Brian S. Stephan

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""

import math
import random
import sqlite3

from extlib import irclib

from Module import Module

class Pi(Module):
    """
    Use the Monte Carlo method to approximate pi. Each time this method is called,
    it calculates a random point inside a square on the xy plane. If that point also
    falls within a circle bound within that square, it is added to the count of points
    inside. Over time, 4 * count_inside / count approaches pi.

    Idea from #linode on OFTC. Code from http://www.eveandersson.com/pi/monte-carlo-circle
    """

    def db_init(self):
        """
        Initialize database tables.
        """

        # init the database if pi table doesn't exist
        version = self.db_module_registered(self.__class__.__name__)
        if version == None:
            # create tables
            db = self.get_db()
            try:
                db.execute('''
                    CREATE TABLE pi_log (
                        id INTEGER PRIMARY KEY AUTOINCREMENT,
                        count_inside INTEGER NOT NULL,
                        count_total INTEGER NOT NULL,
                        time TEXT DEFAULT CURRENT_TIMESTAMP
                    )
                    ''')
                db.execute('''
                    CREATE VIEW pi_latest_pi AS
                        SELECT count_inside, count_total
                        FROM pi_log
                        ORDER BY id DESC
                    ''')
                db.execute('INSERT INTO drbotzo_modules VALUES (?,?)', (self.__class__.__name__, 1))
                db.commit()
            except sqlite3.Error as e:
                db.rollback()
                print("sqlite error: " + str(e))
                raise

    def do(self, connection, event, nick, userhost, replypath, what, admin_unlocked):
        if what == "pi":
            db = self.get_db()
            try:
                cur = db.cursor()
                pi_data = cur.execute('SELECT * FROM pi_latest_pi')
                datum = pi_data.fetchone()

                if datum == None:
                    count_inside    = 0
                    count           = 0
                else:
                    # load values
                    count_inside    = datum['count_inside']
                    count           = datum['count_total']

                x = random.random()
                y = random.random()
                inside = False
                d = math.hypot(x,y)
                if d < 1:
                    inside = True
                    count_inside += 1
                count += 1
                pi = 4.0 * count_inside / count

                cur.execute('INSERT INTO pi_log (count_inside, count_total) VALUES (?,?)', (count_inside, count))
                db.commit()
            except sqlite3.Error as e:
                db.rollback()
                return self.reply(connection, replypath, "sqlite error: " + str(e))

            return self.reply(connection, replypath, "({0:.10f}, {1:.10f}) is {2}within the circle. pi is {5:.10f}. (i:{3:d} p:{4:d})".format(x, y, "" if inside else "not ", count_inside, count, pi));

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