#!/usr/bin/env python3

import os
import shutil
import re
import yaml

from operator import itemgetter

from jinja2 import Environment, PackageLoader, select_autoescape
from PIL import Image, ExifTags
from dotenv import load_dotenv

from configuration import SITE_TITLE, SITE_AUTHOR, SITE_AUTHOR_WEBSITE, THEME


# Load env var from .env file
load_dotenv(dotenv_path=".env")


PICTURES_DIR_NAME = "photos"
OUTPUT_DIR_NAME = "output"

# Configure YAML to accept environment variables in metadata files
# Based on https://stackoverflow.com/a/27232341 solution
pattern = re.compile(r"^ENV\[\'(.*)\'\]$")
yaml.add_implicit_resolver("!pathex", pattern, Loader=yaml.SafeLoader)


def pathex_constructor(loader, node):
    value = loader.construct_scalar(node)
    env_var, = pattern.match(value).groups()
    return os.getenv(env_var)


yaml.add_constructor("!pathex", pathex_constructor, yaml.SafeLoader)


def list_galleries_in(path):
    gallery_dirs = [f for f in os.scandir(path) if f.is_dir()]
    for gallery_dir in gallery_dirs:
        metadata = {}
        metadata_path = os.path.join(gallery_dir.path, "metadata.yml")
        if os.path.exists(metadata_path):
            with open(metadata_path, "r") as metadata_file:
                metadata = yaml.safe_load(metadata_file)

        private = False
        url = f"{gallery_dir.name}.html"
        output_path = gallery_dir.name
        password = metadata.get("password", None)
        if password:
            private = True
            url = f"{gallery_dir.name}-{password}.html"
            output_path = f"{output_path}-{password}"

        photos = list(list_photos_in(gallery_dir, output_path))
        if len(photos) == 0:
            continue
        photos.sort(key=itemgetter("name"))

        # Try to get cover from metadata, if it doesn't exist, take one by
        # default.
        cover_photo = None
        cover_name = metadata.get("cover")
        if cover_name:
            cover_photo = find_photo(photos, cover_name)
        if cover_photo is None:
            cover_index = (len(gallery_dir.name) + 42) % len(photos)
            cover_photo = photos[cover_index]

        gallery = {
            "name": metadata.get("name", gallery_dir.name),
            "path": gallery_dir.path,
            "output_path": output_path,
            "url": url,
            "num_photos": len(photos),
            "photos": photos,
            "cover_photo": cover_photo,
            "private": private,
        }
        yield gallery


def find_photo(photos, photo_name):
    for photo in photos:
        if photo["name"] == photo_name:
            return photo
    return None


def list_photos_in(gallery_dir, gallery_output_path):
    photo_files = [
        f for f in os.scandir(gallery_dir) if re.match(".+\.jpg", f.name, re.I)
    ]
    for photo_file in photo_files:
        url = os.path.join(gallery_output_path, photo_file.name)
        thumb_url = os.path.join(gallery_output_path, f"thumb_{photo_file.name}")
        photo = {
            "name": photo_file.name,
            "path": photo_file.path,
            "url": url,
            "thumb_url": thumb_url,
        }
        yield photo


def generate_output_dir():
    output_path = os.path.join(os.curdir, OUTPUT_DIR_NAME)
    if not os.path.isdir(output_path):
        os.mkdir(output_path)
    return output_path


def generate_style(output_path):
    style_path = os.path.join(os.curdir, THEME, "style")
    style_output_path = os.path.join(output_path, "style")
    if os.path.isdir(style_output_path):
        shutil.rmtree(style_output_path)
    shutil.copytree(style_path, style_output_path)


def generate_index(output_path, galleries):
    index_path = os.path.join(output_path, "index.html")

    theme_path = os.path.join(os.curdir, THEME)
    jinja_env = Environment(
        loader=PackageLoader("boop", theme_path), autoescape=select_autoescape(["html"])
    )
    index_template = jinja_env.get_template("index.html.j2")

    with open(index_path, "w") as index_file:
        index_file.write(
            index_template.render(
                galleries=galleries,
                site_title=SITE_TITLE,
                site_author=SITE_AUTHOR,
                site_author_website=SITE_AUTHOR_WEBSITE,
            )
        )


def generate_gallery(output_path, gallery):
    generate_gallery_index(output_path, gallery)
    generate_gallery_photos(output_path, gallery)


def generate_gallery_index(output_path, gallery):
    gallery_index_path = os.path.join(output_path, gallery["url"])

    theme_path = os.path.join(os.curdir, THEME)
    jinja_env = Environment(
        loader=PackageLoader("boop", theme_path), autoescape=select_autoescape(["html"])
    )
    gallery_template = jinja_env.get_template("gallery.html.j2")

    with open(gallery_index_path, "w") as gallery_file:
        gallery_file.write(
            gallery_template.render(
                gallery=gallery,
                site_title=SITE_TITLE,
                site_author=SITE_AUTHOR,
                site_author_website=SITE_AUTHOR_WEBSITE,
            )
        )


def generate_gallery_photos(output_path, gallery):
    gallery_output_path = os.path.join(output_path, gallery["output_path"])
    if not os.path.isdir(gallery_output_path):
        os.mkdir(gallery_output_path)

    for photo in gallery["photos"]:
        photo_output_path = os.path.join(output_path, photo["url"])
        if not os.path.exists(photo_output_path):
            shutil.copyfile(photo["path"], photo_output_path)

        thumb_output_path = os.path.join(output_path, photo["thumb_url"])
        if not os.path.exists(thumb_output_path):
            generate_thumb_file(thumb_output_path, photo)


def generate_thumb_file(output_path, photo):
    orientation_key = get_orientation_exif_key()
    size = (440, 264)

    with Image.open(photo["path"]) as image:
        # First, make sure image is correctly oriented
        exif = image._getexif()
        if exif[orientation_key] == 3:
            image = image.rotate(180, expand=True)
        elif exif[orientation_key] == 6:
            image = image.rotate(270, expand=True)
        elif exif[orientation_key] == 8:
            image = image.rotate(90, expand=True)

        w, h = image.size
        if w > size[0] and h > size[1]:
            # If the original file is larger in width AND height, we resize
            # first the image to the lowest size accepted (both width and
            # height stays greater or equal to requested size).
            # E.g. 1200x900 is resized to 440x330
            #      1200x600 is resized to 528x264
            if size[0] / size[1] <= w / h:
                w = int(max(size[1] * w / h, 1))
                h = 264
            else:
                h = int(max(size[0] * h / w, 1))
                w = 440
            new_size = (w, h)

            image.draft(None, new_size)
            image = image.resize(new_size, Image.BICUBIC)

        # We now have an image with at least w = 440 OR h = 264 (unless one of
        # the size is smaller). But the image can still be larger than
        # requested size, so we have to crop the image in the middle.
        crop_box = None
        if w > size[0]:
            left = (w - size[0]) / 2
            right = left + size[0]
            crop_box = (left, 0, right, h)
        elif h > size[1]:
            upper = (h - size[1]) / 2
            lower = upper + size[1]
            crop_box = (0, upper, w, lower)
        if crop_box is not None:
            image = image.crop(crop_box)

        # And we save the final image.
        image.save(output_path)


def get_orientation_exif_key():
    for (key, tag) in ExifTags.TAGS.items():
        if tag == "Orientation":
            return key


def main():
    print("Loading galleries... ", end="")
    pictures_folder = os.path.join(os.curdir, PICTURES_DIR_NAME)
    galleries = list(list_galleries_in(pictures_folder))
    if len(galleries) == 0:
        print(f"No galleries found in {pictures_folder}")
        return
    galleries.sort(key=itemgetter("name"))
    print(f"{len(galleries)} galleries found.")

    print("Generating output folder... ", end="")
    output_path = generate_output_dir()
    print("✔️")
    print("Generating style folder... ", end="")
    generate_style(output_path)
    print("✔️")
    print("Generating index file... ", end="")
    generate_index(output_path, galleries)
    print("✔️")
    for gallery in galleries:
        print(f"Generating {gallery['name']} gallery ({gallery['url']})... ", end="")
        generate_gallery(output_path, gallery)
        print("✔️")
    print("Galleries generated 🎉")


if __name__ == "__main__":
    main()