from otree.api import (
    models, widgets, BaseConstants, BaseSubsession, BaseGroup, BasePlayer,
    Currency as c, currency_range
)
import random

doc = """
This is a task that requires real effort from participants.
Subjects are shown images of text.
Subjects are required to translate the text into a number and type it into the entry field.
The quality of a subject's transcription is measured by the
<a href="http://en.wikipedia.org/wiki/Levenshtein_distance">Levenshtein distance</a>.
"""


def levenshtein(a, b):
    """Calculates the Levenshtein distance between a and b."""
    n, m = len(a), len(b)
    if n > m:
        # Make sure n <= m, to use O(min(n,m)) space
        a, b = b, a
        n, m = m, n

    current = range(n + 1)
    for i in range(1, m + 1):
        previous, current = current, [i] + [0] * n
        for j in range(1, n + 1):
            add, delete = previous[j] + 1, current[j - 1] + 1
            change = previous[j - 1]
            if a[j - 1] != b[i - 1]:
                change = change + 1
            current[j] = min(add, delete, change)

    return current[n]


def distance_and_ok(transcribed_text, reference_text, max_error_rate):
    error_threshold = len(reference_text) * max_error_rate
    distance = levenshtein(transcribed_text, reference_text)
    ok = distance <= error_threshold
    return distance, ok


class Constants(BaseConstants):
    name_in_url = 'real_effort'
    players_per_group = None

    reference_texts = [
        "24552046495527",
        "665580712165"
        "3142508056"
        "2865885056",
    ]

    num_rounds = len(reference_texts)

    allowed_error_rates = [0, 0, 0, 0]


class Subsession(BaseSubsession):
    pass


class Group(BaseGroup):
    pass


class Player(BasePlayer):
    transcribed_text = models.LongStringField()
    levenshtein_distance = models.IntegerField()