import streamlit as st
import pandas as pd
from io import StringIO

def load_file(file, header_row):
    if file is None:
        return None, None
    try:
        if file.name.endswith(".xlsx"):
            df = pd.read_excel(file, header=header_row - 1)
        else:
            df = pd.read_csv(StringIO(file.getvalue().decode("utf-8")), header=header_row - 1)
        headers = df.columns.tolist()
        return headers, df
    except Exception as e:
        st.error(f"Error loading file: {e}")
        return None, None

def main():
    st.title("File Header and Data Comparison Tool")

    # First file upload
    st.header("Upload First File")
    if "file1" not in st.session_state:
        st.session_state["file1"] = None
        st.session_state["headers1"] = None
        st.session_state["df1"] = None

    file1 = st.file_uploader("Choose the first file (CSV or Excel)", type=["csv", "xlsx"], key="file1_uploader")
    if file1:
        header_row1 = st.number_input("Specify the row number for headers in the first file", min_value=1, value=1, key="header_row1")
        if st.button("Load First File", key="load_file1"):
            headers1, df1 = load_file(file1, header_row1)
            if headers1:
                st.session_state["file1"] = file1
                st.session_state["headers1"] = headers1
                st.session_state["df1"] = df1
                st.success(f"Headers from the first file: {headers1}")
            else:
                st.error("Failed to load the first file.")

    # Second file upload
    st.header("Upload Second File")
    if "file2" not in st.session_state:
        st.session_state["file2"] = None
        st.session_state["headers2"] = None
        st.session_state["df2"] = None

    file2 = st.file_uploader("Choose the second file (CSV or Excel)", type=["csv", "xlsx"], key="file2_uploader")
    if file2:
        header_row2 = st.number_input("Specify the row number for headers in the second file", min_value=1, value=1, key="header_row2")
        if st.button("Load Second File", key="load_file2"):
            headers2, df2 = load_file(file2, header_row2)
            if headers2:
                st.session_state["file2"] = file2
                st.session_state["headers2"] = headers2
                st.session_state["df2"] = df2
                st.success(f"Headers from the second file: {headers2}")
            else:
                st.error("Failed to load the second file.")

    # Compare headers
    if st.session_state["headers1"] and st.session_state["headers2"]:
        headers1 = st.session_state["headers1"]
        headers2 = st.session_state["headers2"]

        st.header("Header Comparison Results")
        missing_in_file2 = [header for header in headers1 if header not in headers2]
        missing_in_file1 = [header for header in headers2 if header not in headers1]

        if missing_in_file2 or missing_in_file1:
            st.write("Differences in headers:")
            if missing_in_file2:
                st.write(f"Headers in File 1 but not in File 2: {missing_in_file2}")
            if missing_in_file1:
                st.write(f"Headers in File 2 but not in File 1: {missing_in_file1}")
        else:
            st.success("Headers match perfectly!")

        # Compare column values where headers match
        common_headers = [header for header in headers1 if header in headers2]
        if common_headers:
            st.header("Column Value Differences")
            df1 = st.session_state["df1"]
            df2 = st.session_state["df2"]

            for header in common_headers:
                col1 = df1[header].dropna().unique()
                col2 = df2[header].dropna().unique()

                if not pd.Series(col1).equals(pd.Series(col2)):
                    st.write(f"Column '{header}' differs between the files.")
                    st.write(f"Values in File 1 but not in File 2: {set(col1) - set(col2)}")
                    st.write(f"Values in File 2 but not in File 1: {set(col2) - set(col1)}")
                else:
                    st.write(f"Column '{header}' matches in both files.")

if __name__ == "__main__":
    main()