import asyncio
import io
import mimetypes
import urllib.parse
from pathlib import PurePosixPath
from urllib.parse import unquote
from wsgiref.handlers import format_date_time

import av
import av.datasets
import fitz  # PyMuPDF
from av.streams import SideData
from PIL import Image
from sanic import Blueprint, empty, raw
from sanic.exceptions import NotFound
from sanic.log import logger

from cista import config
from cista.util.filename import sanitize

bp = Blueprint("preview", url_prefix="/preview")


@bp.get("/<path:path>")
async def preview(req, path):
    """Preview a file"""
    maxsize = int(req.args.get("px", 1024))
    maxzoom = float(req.args.get("zoom", 2.0))
    quality = int(req.args.get("q", 40))
    rel = PurePosixPath(sanitize(unquote(path)))
    path = config.config.path / rel
    stat = path.lstat()
    etag = config.derived_secret(
        "preview", rel, stat.st_mtime_ns, quality, maxsize, maxzoom
    ).hex()
    savename = PurePosixPath(path.name).with_suffix(".webp")
    headers = {
        "etag": etag,
        "last-modified": format_date_time(stat.st_mtime),
        "cache-control": "max-age=604800, immutable"
        + ("" if config.config.public else ", private"),
        "content-type": "image/webp",
        "content-disposition": f"inline; filename*=UTF-8''{urllib.parse.quote(savename.as_posix())}",
    }
    if req.headers.if_none_match == etag:
        # The client has it cached, respond 304 Not Modified
        return empty(304, headers=headers)

    if not path.is_file():
        raise NotFound("File not found")

    img = await asyncio.get_event_loop().run_in_executor(
        req.app.ctx.threadexec, dispatch, path, quality, maxsize, maxzoom
    )
    return raw(img, headers=headers)


def dispatch(path, quality, maxsize, maxzoom):
    if path.suffix.lower() in (".pdf", ".xps", ".epub", ".mobi"):
        return process_pdf(path, quality=quality, maxsize=maxsize, maxzoom=maxzoom)
    if mimetypes.guess_type(path.name)[0].startswith("video/"):
        return process_video(path, quality=quality, maxsize=maxsize)
    return process_image(path, quality=quality, maxsize=maxsize)


def process_image(path, *, maxsize, quality):
    img = Image.open(path)
    w, h = img.size
    img.thumbnail((min(w, maxsize), min(h, maxsize)))
    # Fix rotation based on EXIF data
    try:
        rotate_values = {3: 180, 6: 270, 8: 90}
        orientation = img._getexif().get(274)
        if orientation in rotate_values:
            logger.debug(f"Rotating preview {path} by {rotate_values[orientation]}")
            img = img.rotate(rotate_values[orientation], expand=True)
    except AttributeError:
        ...
    except Exception as e:
        logger.error(f"Error rotating preview image: {e}")
    # Save as webp
    imgdata = io.BytesIO()
    img.save(imgdata, format="webp", quality=quality, method=4)
    return imgdata.getvalue()


def process_pdf(path, *, maxsize, maxzoom, quality, page_number=0):
    pdf = fitz.open(path)
    page = pdf.load_page(page_number)
    w, h = page.rect[2:4]
    zoom = min(maxsize / w, maxsize / h, maxzoom)
    mat = fitz.Matrix(zoom, zoom)
    pix = page.get_pixmap(matrix=mat)
    return pix.pil_tobytes(format="webp", quality=quality, method=4)


def process_video(path, *, maxsize, quality):
    with av.open(str(path)) as container:
        stream = container.streams.video[0]
        rot = stream.side_data and stream.side_data.get(SideData.DISPLAYMATRIX) or 0
        stream.codec_context.skip_frame = "NONKEY"
        container.seek(container.duration // 8)
        img = next(container.decode(stream)).to_image()
        del stream

    img.thumbnail((maxsize, maxsize))
    imgdata = io.BytesIO()
    if rot:
        img = img.rotate(rot, expand=True)
    img.save(imgdata, format="webp", quality=quality, method=4)
    del img

    return imgdata.getvalue()