#!/usr/bin/python3

from flask import Flask, render_template, send_from_directory, redirect, url_for
from random import choice
from pathlib import Path
from PIL import Image
from time import time
from hashlib import sha256
import click
from shutil import rmtree

import config

app = Flask(__name__)

cache_resolution = (1920, 1080)
cache_dir = Path(config.cachedir) / ("%sx%s" % cache_resolution)


@app.route("/")
def random():
    return render_template("random.html", refresh=config.refresh)


@app.route("/random_image/")
def random_image():
    img_glob = "*jpg"
    imgdir = Path(config.imgdir)
    last_modified_time, last_modified_file = max(
        (f.stat().st_mtime, f) for f in imgdir.glob(img_glob)
    )

    if time() - last_modified_time <= 60:
        selected_image = last_modified_file.relative_to(imgdir)
    else:
        images = list(imgdir.glob(img_glob))
        selected_image = choice(images).relative_to(imgdir)

    return redirect(url_for("image", filename=selected_image))


@app.route("/img/<path:filename>")
def image(filename):
    cache_filename = create_cache_file(filename)

    return send_from_directory(cache_dir, cache_filename)


def rm_cachedir():
    if Path(config.cachedir).exists():
        print("Removing cache dir", config.cachedir)
        rmtree(config.cachedir)


def create_cachedir():
    if not cache_dir.exists():
        print("Creating cache dir", cache_dir)
        cache_dir.mkdir(parents=True)


def create_cache_file(filename):
    create_cachedir()
    cache_file = get_cache_filename(filename)

    if not (cache_dir / cache_file).exists():
        print("Creating cache file", filename)
        img = Image.open(Path(config.imgdir) / filename)
        img.thumbnail(cache_resolution)
        img.save(cache_dir / cache_file, "JPEG")

    return cache_file


def get_cache_filename(filename):
    original_file_path = Path(config.imgdir) / filename
    return sha256(str(original_file_path.resolve()).encode("utf-8")).hexdigest()


def pre_cache_images():
    imgdir = Path(config.imgdir)
    for image_file in sorted(imgdir.glob("*.jpg")):
        create_cache_file(image_file.relative_to(imgdir))


@click.command()
@click.option("--build-cache", is_flag=True, default=False, help="pre-cache images")
@click.option(
    "--clear-cache", is_flag=True, default=False, help="clear cache directory"
)
def run_slider(build_cache, clear_cache):
    if clear_cache:
        rm_cachedir()
    if build_cache:
        pre_cache_images()

    app.run()


if __name__ == "__main__":
    run_slider()