import georinex as gr
import matplotlib.pyplot as plt
import numpy as np
from datetime import datetime
import pandas as pd

# Read the RINEX file
rinex_file = '96813390_small.24O'
data = gr.load(rinex_file)

# Get available GPS satellites, start with 'G'
available_sats = [sv for sv in data.sv.values if sv.startswith('G')]

# Extract GPS pseudorange data
gps_data = data.sel(sv=available_sats)
# For now, get only the C1C pseudorange data
c1c_data = gps_data['C1C'].dropna(dim='sv', how='all')

# Convert time index to datetime
times = c1c_data.time.values
satellites = c1c_data.sv.values

# Create the plot
plt.figure(figsize=(15, 10))

# Plot each satellite's pseudorange
for sat in satellites:
    sat_data = c1c_data.sel(sv=sat)
    valid_data = sat_data.dropna(dim='time')
    
    if len(valid_data) > 0:  # Only plot if we have valid data
        plt.plot(valid_data.time, valid_data.values, 
                 label=sat, marker='.',
                 linestyle='-', markersize=2)

# Customize the plot
plt.title('GPS Pseudorange Measurements (C1C)', fontsize=14)
plt.xlabel('Time (UTC)', fontsize=12)
plt.ylabel('Pseudorange', fontsize=12)
plt.grid(True, linestyle='--', alpha=0.7)
plt.legend(bbox_to_anchor=(1.05, 1), loc='upper left')
plt.tight_layout()

# Rotate x-axis labels for better readability
plt.xticks(rotation=45)

# Show the plot
plt.show()

# Print some basic statistics
print("\nBasic Statistics for GPS Pseudorange Measurements:")
print("Number of GPS satellites observed:", len(satellites))
print("Observation period:", times[0], "to", times[-1])
print("\nPseudorange ranges for each satellite:")
for sat in satellites:
    sat_data = c1c_data.sel(sv=sat).dropna(dim='time')
    if len(sat_data) > 0:
        print(f"{sat}: {sat_data.min().values:.2f} - {sat_data.max().values:.2f} meters")

# Optionally, print available satellites
print("\nAvailable GPS satellites:", available_sats)