import argparse
import pymupdf

import tkinter
from tkinter import ttk
from PIL import Image, ImageTk

CURRENT_PAGE = 0


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("file")
    args = parser.parse_args()

    doc: pymupdf.Document
    with pymupdf.open(args.file) as doc:
        toc = doc.get_toc()

        def toc_entry_for_page(page_num: int) -> str:
            last_title = ""
            for lvl, t, p in toc:
                if (p - 1) > page_num:
                    return last_title
                if (p - 1) == page_num:
                    return t
                last_title = t

        root = tkinter.Tk()
        frm = ttk.Frame(root, padding=10)
        frm.grid()

        page_title = ttk.Label(frm)
        page_title.grid(column=1, row=0)

        page_view = ttk.Label(frm)
        page_view.grid(column=1, row=1)

        def load_page(page_num: int):
            page = doc[page_num]
            pix = page.get_pixmap()

            mode = "RGBA" if pix.alpha else "RGB"
            img = Image.frombytes(mode, [pix.width, pix.height], pix.samples)
            img = ImageTk.PhotoImage(img)
            page_view.configure(image=img)
            page_view.image = img

            page_title.configure(text=toc_entry_for_page(page_num))

        def next_page():
            global CURRENT_PAGE
            CURRENT_PAGE += 1
            load_page(CURRENT_PAGE)

        def previous_page():
            global CURRENT_PAGE
            CURRENT_PAGE -= 1
            load_page(CURRENT_PAGE)

        ttk.Button(frm, text="Previous", command=previous_page).grid(column=0, row=1)
        ttk.Button(frm, text="Next", command=next_page).grid(column=2, row=1)

        load_page(CURRENT_PAGE)

        root.mainloop()


if __name__ == "__main__":
    main()