import pandas as pd
import geopandas as gpd
import os
import pyproj
import matplotlib.pyplot as plt
from shapely.geometry import Point

def project_shp(L, wgs84_to_l93, l93_to_wgs84):
    i = 0
    while i < len(df):
        if not df.loc[i, "has_gps"]:
            start = i - 1
            while i < len(df) and not df.loc[i, "has_gps"]:
                i += 1
            end = i

            true_end = None
            for j in range(end, min(end + 2000, len(df))):
                if df.loc[j, "has_gps"] and df.loc[j, "Distance_entre_points_m"] > 0:
                    true_end = j
                    break

            if true_end:
                x_l93, y_l93 = wgs84_to_l93.transform(df.loc[start, "Longitude_WGS"],df.loc[start, "Latitude_WGS"])
                P_start = Point(x_l93, y_l93, )
                dist_start = L.project(P_start)
                
                x_l93, y_l93 = wgs84_to_l93.transform(df.loc[true_end, "Longitude_WGS"],df.loc[true_end, "Latitude_WGS"])
                P_end = Point(x_l93, y_l93)
                dist_end = L.project(P_end)
                
                n = true_end - start - 1
                if n > 0:
                    step = (dist_end - dist_start) / (n + 1)
                    idx = start
                    # dist_temp_cumul = dist_start
                    for k in range(1, n + 1):
                        # dist_temp_cumul += step
                        # df.at[idx, "Distance_cumulee_corrigee"] = dist_temp_cumul

                        try:
                            x_l93, y_l93 = wgs84_to_l93.transform(df.loc[idx, "Longitude_WGS"],df.loc[idx, "Latitude_WGS"])

                            point = Point(x_l93, y_l93)
                            actual_distance = L.project(point)

                            projected_point = L.interpolate(actual_distance + step)
                            
                            x_wgs, y_wgs = l93_to_wgs84.transform(projected_point.x, projected_point.y)
                            
                            df.at[idx + 1, "Latitude_WGS"] = y_wgs
                            df.at[idx + 1, "Longitude_WGS"] = x_wgs
                            
                        except:
                            continue
                        idx += 1
        i += 1


def calcul_distance_cumulee(L, wgs84_to_l93, l93_to_wgs84):
    
    x_l93, y_l93 = wgs84_to_l93.transform(df.loc[0, "Longitude_WGS"],df.loc[0, "Latitude_WGS"])
    df.at[0, "Longitude_Lambert"] = x_l93
    df.at[0, "Latitude_Lambert"] = y_l93
    
    df.at[0, "Distance_Cele"] = L.project(Point(x_l93, y_l93))
    df.at[0, "Distance_Cumulee"] = 0.0
    
    for i in range(1, len(df)):
        x_l93, y_l93 = wgs84_to_l93.transform(df.loc[i, "Longitude_WGS"],df.loc[i, "Latitude_WGS"])
        current_point = Point(x_l93, y_l93)
        df.at[i, "Longitude_Lambert"] = x_l93
        df.at[i, "Latitude_Lambert"] = y_l93
        
        previous_point = Point(wgs84_to_l93.transform(df.loc[i-1, "Longitude_WGS"],df.loc[i-1, "Latitude_WGS"]))
        
        d1 = L.project(previous_point)
        d2 = L.project(current_point)
        dist = d2 - d1        
        df.at[i, "Distance_Cumulee"] =  df.at[i-1, "Distance_Cumulee"] + dist
        

# === PARAMÈTRES ===
in_path = None # TODO
csv_file = "input.csv"
shapefile_name = "célé.shp"

# === 1. Chargement des données
df = pd.read_csv(os.path.join(in_path, csv_file), sep=";")
riv_line = gpd.read_file(os.path.join(in_path, shapefile_name)).to_crs(epsg=2154)
wgs84_to_l93 = pyproj.Transformer.from_crs("EPSG:4326", "EPSG:2154", always_xy=True)
l93_to_wgs84 = pyproj.Transformer.from_crs("EPSG:2154", "EPSG:4326", always_xy=True)

# === 2. Colonnes de travail
df["has_gps"] = df["Longitude_WGS"].notna() & df["Latitude_WGS"].notna()
df["Distance_Cele"] = 0.0

# === 3. Calcul des distances entre points
project_shp(riv_line, wgs84_to_l93, l93_to_wgs84)
calcul_distance_cumulee(riv_line, wgs84_to_l93, l93_to_wgs84)

# Nettoyage
df.drop(columns=["has_gps"], inplace=True)
df.drop(columns=["Distance_entre_points_m"], inplace=True)
df.drop(columns=["Distance_Cele"], inplace=True)


# === 4. Export final
out_path = None # TODO
out_name = "output.csv"
df.to_csv(os.path.join(out_path, out_name), sep=";", index=False, encoding="utf-8")
print("✅ Fichier exporté :", out_name)

# === 5. Visualisation rapide
valid_coords = df[df["Latitude_WGS"].notna() & df["Longitude_WGS"].notna()].copy()
valid_coords["geometry"] = [Point(xy) for xy in zip(valid_coords["Longitude_WGS"], valid_coords["Latitude_WGS"])]
gdf_corr = gpd.GeoDataFrame(valid_coords, geometry="geometry", crs="EPSG:4326")

fig, ax = plt.subplots(figsize=(14, 7))
gdf_corr.plot(ax=ax, color="green", markersize=6, label="Points corrigés v2")
riv_line.to_crs(epsg=4326).plot(ax=ax, edgecolor='black', linewidth=1)

ax.set_title("Carte des points GPS corrigés projetés sur le tracé")
ax.set_xlabel("Longitude")
ax.set_ylabel("Latitude")
ax.legend()
plt.grid(True)
plt.tight_layout()
plt.show()