# Standard library imports.
from pathlib import Path
from math    import ceil

# External library imports.
import filetype

# Django imports.
from django.http      import HttpResponseNotFound
from django.conf      import settings
from django.shortcuts import (render,
                              redirect)

# Project imports.
from .utils import make_thumbnail

###########################################################################################
# CONSTANTS.                                                                              #
###########################################################################################

CELLS_PER_ROW   = 7
ROWS_PER_PAGE   = 4
IMAGES_PER_PAGE = CELLS_PER_ROW * ROWS_PER_PAGE

###########################################################################################
# View functions.                                                                         #
###########################################################################################

def gallery_view(request, path = None):
    """
    Shows a list of subdirectories and image files inside the given path.
    The path should be inside the GALLERY_ROOT path, otherwise a 404 error will be thrown.
    """

    def list2rows(lst, cells = CELLS_PER_ROW):
        rows = []
        i = 0
        while i < len(lst):
            row = []
            for c in range(cells):
                try:
                    row.append(lst[i + c])
                except:
                    pass
            rows.append(row)
            i += cells
        return rows

    full_path = settings.GALLERY_ROOT.joinpath(path) if path is not None else settings.GALLERY_ROOT

    if full_path.exists():
        if full_path.is_dir():
            subdirs    = sorted([i for i in full_path.iterdir() if i.is_dir()])
            images     = sorted([i for i in full_path.iterdir() if i.is_file() and filetype.is_image(str(i))])
            img_data   = []
            num_pages  = ceil((len(images) / CELLS_PER_ROW) / ROWS_PER_PAGE)

            try:
                page = int(request.GET.get('page', 1))
            except ValueError:
                page = 1

            page_offset = IMAGES_PER_PAGE * (page - 1)

            for image in images[page_offset : page_offset + IMAGES_PER_PAGE]:
                make_thumbnail(image)

                img_context = {
                    'path': image.name,
                    'name': image.name,
                    'thumbnail': '/thumbs/' + path + '/' + image.name if path is not None else '/thumbs/' + image.name
                } 

                img_data.append(img_context)

            print(page)

            context = {
                'path':      path,
                'subdirs':   list2rows(subdirs),
                'images':    list2rows(img_data),
                'pages':     range(1, num_pages + 1),
                'num_files': len(images),
                'page':      page,
                'prev_page': page - 1,
                'next_page': page + 1,
                'num_pages': num_pages
            }

            return render(request, 'gallery_view.html', context)

        else:
            image     = Path('/imgs/').joinpath(path)
            img_dir   = settings.GALLERY_ROOT.joinpath(path).parent
            images    = sorted([i.name for i in img_dir.iterdir() if i.is_file() and filetype.is_image(str(i))])
            index     = images.index(image.name)
            previous  = index - 1 if index > 0 else None
            following = index + 1 if index < len(images) - 1 else None

            context = {
                'image_path': image,
                'prev': images[previous] if previous is not None else None,
                'next': images[following] if following is not None else None
            }

            return render(request, 'image_view.html', context)

    else:
        return HttpResponseNotFound('Not found')