import tkinter as tk
from tkinter import ttk, messagebox
import sqlite3
from pathlib import Path

ROOT = Path(__file__).resolve().parent
DB = ROOT / "address_book.db"

root = tk.Tk()
root.title("Address Book")
root.geometry("620x620")
root.resizable(False, False)

def connect():
    return sqlite3.connect(DB)

def clear_entries():
    f_name.delete(0, tk.END)
    s_name.delete(0, tk.END)
    mob.delete(0, tk.END)
    email.delete(0, tk.END)

def submit():
    values = (
        f_name.get().strip(),
        s_name.get().strip(),
        mob.get().strip(),
        email.get().strip(),
    )

    if not all(values):
        messagebox.showwarning("Missing data", "Please fill in all four fields.")
        return

    conn = connect()
    c = conn.cursor()
    c.execute(
        """
        INSERT INTO address_book (f_name, s_name, mob, email)
        VALUES (?, ?, ?, ?)
        """,
        values,
    )
    conn.commit()
    conn.close()

    clear_entries()
    search()

def search():
    conn = connect()
    c = conn.cursor()
    c.execute("""
        SELECT f_name, s_name, mob, email, oid
        FROM address_book
        ORDER BY oid
    """)
    records = c.fetchall()
    conn.close()

    output.delete("1.0", tk.END)

    if not records:
        output.insert(tk.END, "No records found.")
        return

    for record in records:
        output.insert(
            tk.END,
            f"OID: {record[4]} | "
            f"{record[0]} {record[1]} | "
            f"Mobile: {record[2]} | "
            f"Email: {record[3]}\n"
        )

def delete_rec():
    oid = id_no.get().strip()

    if not oid.isdigit():
        messagebox.showwarning("Invalid OID", "Enter a valid numeric OID.")
        return

    conn = connect()
    c = conn.cursor()
    c.execute("DELETE FROM address_book WHERE oid = ?", (int(oid),))
    deleted = c.rowcount
    conn.commit()
    conn.close()

    id_no.delete(0, tk.END)

    if deleted:
        messagebox.showinfo("Deleted", f"Record {oid} was deleted.")
    else:
        messagebox.showwarning("Not found", f"No record with OID {oid} exists.")

    search()

def update_rec():
    oid = id_no.get().strip()
    column = update_column.get()
    value = update_value.get().strip()

    allowed_columns = {
        "First Name": "f_name",
        "Surname": "s_name",
        "Mobile": "mob",
        "Email": "email",
    }

    if not oid.isdigit():
        messagebox.showwarning("Invalid OID", "Enter a valid numeric OID.")
        return

    if not value:
        messagebox.showwarning("Missing value", "Enter the new value.")
        return

    # The column name cannot be passed as a normal SQL parameter,
    # so only a value from this fixed whitelist is allowed.
    db_column = allowed_columns[column]

    conn = connect()
    c = conn.cursor()

    sql = "UPDATE address_book SET {} = ? WHERE oid = ?".format(db_column)
    c.execute(sql, (value, int(oid)))
    updated = c.rowcount

    conn.commit()
    conn.close()

    if updated:
        messagebox.showinfo(
            "Updated",
            f"Record {oid} was updated successfully."
        )
        id_no.delete(0, tk.END)
        update_value.delete(0, tk.END)
        search()
    else:
        messagebox.showwarning(
            "Not found",
            f"No record with OID {oid} exists."
        )

# Create database/table if it does not already exist.
conn = connect()
c = conn.cursor()
c.execute("""
CREATE TABLE IF NOT EXISTS address_book (
    f_name TEXT,
    s_name TEXT,
    mob TEXT,
    email TEXT
)
""")
conn.commit()
conn.close()

# ---------- GUI ----------
tk.Label(root, text="First Name").grid(row=0, column=0, sticky="e", padx=8, pady=6)
f_name = tk.Entry(root, width=35)
f_name.grid(row=0, column=1, padx=8, pady=6)

tk.Label(root, text="Surname").grid(row=1, column=0, sticky="e", padx=8, pady=6)
s_name = tk.Entry(root, width=35)
s_name.grid(row=1, column=1, padx=8, pady=6)

tk.Label(root, text="Mobile").grid(row=2, column=0, sticky="e", padx=8, pady=6)
mob = tk.Entry(root, width=35)
mob.grid(row=2, column=1, padx=8, pady=6)

tk.Label(root, text="Email").grid(row=3, column=0, sticky="e", padx=8, pady=6)
email = tk.Entry(root, width=35)
email.grid(row=3, column=1, padx=8, pady=6)

tk.Button(root, text="Save", command=submit, width=14).grid(
    row=4, column=0, padx=8, pady=10
)
tk.Button(root, text="Display all", command=search, width=14).grid(
    row=4, column=1, sticky="w", padx=8, pady=10
)

tk.Label(root, text="Enter OID").grid(row=5, column=0, sticky="e", padx=8, pady=6)
id_no = tk.Entry(root, width=35)
id_no.grid(row=5, column=1, padx=8, pady=6)

tk.Button(root, text="Delete", command=delete_rec, width=14).grid(
    row=6, column=0, padx=8, pady=8
)

tk.Label(root, text="Update field").grid(row=7, column=0, sticky="e", padx=8, pady=6)
update_column = ttk.Combobox(
    root,
    values=("First Name", "Surname", "Mobile", "Email"),
    state="readonly",
    width=32,
)
update_column.current(0)
update_column.grid(row=7, column=1, padx=8, pady=6)

tk.Label(root, text="New value").grid(row=8, column=0, sticky="e", padx=8, pady=6)
update_value = tk.Entry(root, width=35)
update_value.grid(row=8, column=1, padx=8, pady=6)

tk.Button(root, text="Update", command=update_rec, width=14).grid(
    row=9, column=0, columnspan=2, pady=8
)

output = tk.Text(root, width=72, height=13, wrap="word")
output.grid(row=10, column=0, columnspan=2, padx=10, pady=12)

search()
root.mainloop()