"""
Standalone PDF/obrázek náhled — spouští se jako subprocess z extract_patient_info.py.
Argumenty: preview_viewer.py <soubor> [--delete-on-close]
"""
import sys
from pathlib import Path
import tkinter as tk


def main():
    if len(sys.argv) < 2:
        sys.exit(1)

    pdf_path = Path(sys.argv[1])
    delete_on_close = "--delete-on-close" in sys.argv

    try:
        from PIL import Image, ImageTk
        import fitz
    except ImportError as e:
        print(f"[preview_viewer] Chybí knihovna: {e}", file=sys.stderr)
        sys.exit(2)

    suffix = pdf_path.suffix.lower()
    if suffix in (".jpg", ".jpeg", ".png"):
        pil_img = Image.open(pdf_path)
        doc = None
    else:
        doc = fitz.open(str(pdf_path))
        pil_img = None

    root = tk.Tk()
    root.tk.call("encoding", "system", "utf-8")

    sh = root.winfo_screenheight()
    page_count = len(doc) if doc else 1
    current = [0]
    photo_ref = [None]

    def render(n) -> Image.Image:
        if doc is not None:
            page = doc[n]
            zoom = min(700 / page.rect.width, (sh - 150) / page.rect.height)
            pix = page.get_pixmap(matrix=fitz.Matrix(zoom, zoom))
            return Image.frombytes("RGB", (pix.width, pix.height), pix.samples)
        else:
            img = pil_img.copy()
            img.thumbnail((700, sh - 150), Image.LANCZOS)
            return img

    def on_close():
        if doc:
            try:
                doc.close()
            except Exception:
                pass
        if delete_on_close:
            try:
                pdf_path.unlink(missing_ok=True)
            except Exception:
                pass
        root.destroy()

    root.title(pdf_path.stem)
    root.attributes("-topmost", True)
    root.resizable(False, False)
    root.protocol("WM_DELETE_WINDOW", on_close)

    lbl_img = tk.Label(root)
    lbl_img.pack()

    frame_nav = tk.Frame(root)
    frame_nav.pack(pady=4)

    lbl_page = tk.Label(frame_nav, font=("Segoe UI", 9))
    lbl_page.pack(side="left", padx=10)

    def show(n):
        current[0] = n
        img = render(n)
        photo_ref[0] = ImageTk.PhotoImage(img)
        lbl_img.config(image=photo_ref[0])
        lbl_page.config(text=f"Strana {n + 1} / {page_count}")
        btn_prev.config(state="normal" if n > 0 else "disabled")
        btn_next.config(state="normal" if n < page_count - 1 else "disabled")

    btn_prev = tk.Button(frame_nav, text="◄ Předchozí", command=lambda: show(current[0] - 1))
    btn_prev.pack(side="left")
    btn_next = tk.Button(frame_nav, text="Další ►", command=lambda: show(current[0] + 1))
    btn_next.pack(side="left")

    show(0)
    root.update_idletasks()
    sw = root.winfo_screenwidth()
    w = root.winfo_width()
    h = root.winfo_height()
    x = (sw - w) // 2
    root.geometry(f"+{x}+0")

    # Zapiš geometrii do souboru pokud byl předán argument --write-geometry=<cesta>
    import json as _json
    for arg in sys.argv:
        if arg.startswith("--write-geometry="):
            geom_path = Path(arg.split("=", 1)[1])
            geom_path.write_text(_json.dumps({"x": x, "y": 0, "w": w, "h": h}), encoding="utf-8")
            break

    root.lift()
    root.focus_force()
    root.after(100, lambda: root.focus_force())
    root.mainloop()


if __name__ == "__main__":
    main()