import subprocess
import os
import tkinter as tk
from tkinter import filedialog, messagebox, ttk

def compress_pdf(input_pdf, output_pdf, quality="screen"):
    """Compress PDF using Ghostscript without losing much quality."""
    gs_command = [
        "gs", "-sDEVICE=pdfwrite",
        "-dCompatibilityLevel=1.4",
        f"-dPDFSETTINGS=/{quality}",
        "-dNOPAUSE", "-dBATCH",
        f"-sOutputFile={output_pdf}",
        input_pdf
    ]

    try:
        subprocess.run(gs_command, check=True)
        original_size = os.path.getsize(input_pdf) / 1024
        compressed_size = os.path.getsize(output_pdf) / 1024
        reduction = 100 - ((compressed_size / original_size) * 100)

        messagebox.showinfo("Success", f"Compressed PDF saved at:\n{output_pdf}\n"
                                       f"Original: {original_size:.2f} KB\n"
                                       f"Compressed: {compressed_size:.2f} KB\n"
                                       f"Size Reduced: {reduction:.2f}%")

    except subprocess.CalledProcessError as e:
        messagebox.showerror("Error", f"Compression failed: {e}")

def browse_pdf():
    """Select a PDF file."""
    file_path = filedialog.askopenfilename(filetypes=[("PDF Files", "*.pdf")])
    if file_path:
        input_entry.delete(0, tk.END)
        input_entry.insert(0, file_path)

def save_pdf():
    """Select save location for the compressed PDF."""
    output_path = filedialog.asksaveasfilename(defaultextension=".pdf",
                                               filetypes=[("PDF Files", "*.pdf")])
    if output_path:
        output_entry.delete(0, tk.END)
        output_entry.insert(0, output_path)

def start_compression():
    """Start the compression process."""
    input_pdf = input_entry.get()
    output_pdf = output_entry.get()
    quality = quality_var.get()

    if not input_pdf or not output_pdf:
        messagebox.showwarning("Warning", "Please select input and output files.")
        return

    compress_pdf(input_pdf, output_pdf, quality)

# UI
root = tk.Tk()
root.title("PDF Compressor")
root.geometry("400x300")

ttk.Label(root, text="Select PDF File:").pack(pady=2)
input_entry = ttk.Entry(root, width=40)
input_entry.pack(pady=2)
ttk.Button(root, text="Browse", command=browse_pdf).pack(pady=2)

ttk.Label(root, text="Save Compressed PDF As:").pack(pady=2)
output_entry = ttk.Entry(root, width=40)
output_entry.pack(pady=2)
ttk.Button(root, text="Save As", command=save_pdf).pack(pady=2)

ttk.Label(root, text="Compression Quality:").pack(pady=2)
quality_var = tk.StringVar(value="screen")
quality_options = ["screen", "ebook", "printer", "prepress"]
quality_menu = ttk.Combobox(root, textvariable=quality_var, values=quality_options, state="readonly")
quality_menu.pack(pady=2)

ttk.Button(root, text="Compress PDF", command=start_compression).pack(pady=10)

root.mainloop()