import pandas as pd
import geopandas as gpd
from shapely.geometry import Point
import numpy as np
import pyproj
import math
import sys

# Function to convert WGS84 to Lambert 93 for the entire DataFrame
def convert_to_lambert93(row, transf):
    if(math.isnan(row[x_col]) or math.isnan(row[y_col])):
        x, y = transf.transform(row[x_inter_col], row[y_inter_col])
        row[x_inter_col] = x
        row[y_inter_col] = y
    return row

def point_position_on_line(pt):
    return line.project(pt)

# Load CSV
df = pd.read_csv(sys.argv[1], encoding='UTF-8', on_bad_lines='skip', delimiter=';')

x_col = sys.argv[4]
y_col = sys.argv[5]

x_inter_col = sys.argv[6]
y_inter_col = sys.argv[7]

df[x_col] = pd.to_numeric(df[x_col], errors='coerce')
df[y_col] = pd.to_numeric(df[y_col], errors='coerce')

# Load shapefile (must contain LineString)
line_gdf = gpd.read_file(sys.argv[2])
line = line_gdf.union_all()  # merge if multiple lines

# Create geometry
df['geometry'] = df.apply(
    lambda row: Point(row[x_col], row[y_col]) if not pd.isna(row[x_col]) and not pd.isna(row[y_col]) else None,
    axis=1
)

# Get position
df['distance_on_line'] = df['geometry'].apply(lambda g: line.project(g) if g else np.nan)

# Interpolate
df['distance_on_line'] = df['distance_on_line'].interpolate(method='linear', limit_direction='both')

# Create interpolated points
df['geometry'] = df['distance_on_line'].apply(lambda d: line.interpolate(d))

# Start with original values
df[x_inter_col] = df[x_col]
df[y_inter_col] = df[y_col]

# Update only missing ones
df.loc[df[x_col].isna(), x_inter_col] = df.loc[df[x_col].isna(), 'geometry'].apply(lambda g: g.x)
df.loc[df[y_col].isna(), y_inter_col] = df.loc[df[y_col].isna(), 'geometry'].apply(lambda g: g.y)


# Load CSV and shape
df = pd.read_csv("in/raw.csv", delimiter=';', encoding='utf-8')
df[x_col] = pd.to_numeric(df[x_col], errors='coerce')
df[y_col] = pd.to_numeric(df[y_col], errors='coerce')

# Load the shapefile (must be a LineString)
line = gpd.read_file("in/célé.shp").unary_union  # Merge multiple lines if needed

# Assign geometry to known points
df['geometry'] = df.apply(
    lambda r: Point(r[x_col], r[y_col]) if pd.notna(r[x_col]) else None,
    axis=1
)

# Compute the position of known points along the line
df['distance_on_line'] = df['geometry'].apply(lambda g: line.project(g) if g else np.nan)

# Interpolate missing distances (ensures every point has a valid position)
df['distance_on_line'] = df['distance_on_line'].interpolate(method='linear', limit_direction='both')

# Interpolate new coordinates from the reference shape
df['geometry'] = df['distance_on_line'].apply(lambda d: line.interpolate(d) if pd.notna(d) else None)
df[x_inter_col] = df['geometry'].apply(lambda g: g.x if g else np.nan)
df[y_inter_col] = df['geometry'].apply(lambda g: g.y if g else np.nan)

# Apply the conversion to the entire DataFrame row-wise
wgs84 = pyproj.CRS("EPSG:4326")
lambert93 = pyproj.CRS("EPSG:2154")
transformer = pyproj.Transformer.from_crs(wgs84, lambert93, always_xy=True)

df = df.apply(lambda row : convert_to_lambert93(row, transformer), axis=1)

# Save fixed CSV
df.to_csv(sys.argv[3], sep=';', index=False)