import json
import datetime

# pull stock data from json files
# timestamps_file = open('timestamps.json', 'r')
# timestamps_file_data = timestamps_file.read()
# timestamps = json.loads(timestamps_file_data)
# timestamps = [datetime.datetime.fromtimestamp(t) for t in timestamps]

# prices_file = open('close_prices.json', 'r')
# prices = json.loads(prices_file.read())

# print('timestamps:\t', timestamps, '\nprices:\t', prices)

# make the line data for the 5 day exponential moving average (EMA)



def interpolate_intersection(intersection_indices, timestamps, prices1, prices2):
    left_index = intersection_indices[0]
    right_index = intersection_indices[1]
    if right_index == -1:
        return timestamps[left_index]
    
    y_1 = prices1[left_index]
    y_2 = prices1[right_index] # first line

    v_1 = prices2[left_index]
    v_2 = prices2[right_index] # second line

    x_1 = 0 # take this as zero the simplify the algebra
    x_diff = timestamps[right_index] - timestamps[left_index] # same for both lines

    # find intersection between those lines
    x_diff = x_diff.total_seconds()
    m_1 = (y_2 - y_1) / x_diff # slope of line 1
    m_2 = (v_2 - v_1) / x_diff

    x_interpolated = (v_1 - y_1) / (m_1 - m_2)
    y_interpolated = m_1 * (x_interpolated) + y_1

    # add back the time we subtracted to make x_1=0
    x_interpolated = datetime.timedelta(seconds = x_interpolated) + timestamps[left_index]
    return (x_interpolated, y_interpolated)



"""
Returns the indices of where two arrays' values intersects
"""
def find_intersections(prices1, prices2, offset=0):
    if len(prices1) != len(prices2):
        print("ERROR IN find_intersections: len of arrs not the same")
        return []
    prev_p1 = prices1[offset]
    prev_p2 = prices2[offset]
    intersection_indices = set()
    for i in range(1 + offset, len(prices1)):
        next_p1 = prices1[i]
        next_p2 = prices2[i]
        # if the sign (negative to positive) changes, then there was an intersection between these pts
        sub_prev = prev_p1 - prev_p2
        sub_next = next_p1 - next_p2

        if (sub_prev > 0 and sub_next < 0) or (sub_prev < 0 and sub_next > 0):
            intersection_indices.add((i-1, i))
        
        if sub_next == 0:
            intersection_indices.add((i, -1))

        prev_p1 = next_p1
        prev_p2 = next_p2
    
    return intersection_indices