"""Module for generic files endpoints."""
import traceback
from pathlib import Path

from flask import request, jsonify, Blueprint, current_app as app

from .chunks import chunk_name, chunks_directory

files = Blueprint("files", __name__)

@files.route("/upload/resumable", methods=["GET"])
def resumable_upload_get():
    """Used for checking whether **ALL** chunks have been uploaded."""
    fileid = request.args.get("resumableIdentifier", type=str) or ""
    filename = request.args.get("resumableFilename", type=str) or ""
    chunk = request.args.get("resumableChunkNumber", type=int) or 0
    if not(fileid or filename or chunk):
        return jsonify({
            "message": "At least one required query parameter is missing.",
            "error": "BadRequest",
            "statuscode": 400
        }), 400

    if Path(chunks_directory(fileid),
            chunk_name(filename, chunk)).exists():
        return "OK"

    return jsonify({
            "message": f"Chunk {chunk} was not found.",
            "error": "NotFound",
            "statuscode": 404
        }), 404


def __merge_chunks__(targetfile: Path, chunkpaths: tuple[Path, ...]) -> Path:
    """Merge the chunks into a single file."""
    with open(targetfile, "ab") as _target:
        for chunkfile in chunkpaths:
            with open(chunkfile, "rb") as _chunkdata:
                _target.write(_chunkdata.read())

            chunkfile.unlink()
    return targetfile


@files.route("/upload/resumable", methods=["POST"])
def resumable_upload_post():
    """Do the actual chunks upload here."""
    _totalchunks = request.form.get("resumableTotalChunks", type=int) or 0
    _chunk = request.form.get("resumableChunkNumber", default=1, type=int)
    _uploadfilename = request.form.get(
        "resumableFilename", default="", type=str) or ""
    _fileid = request.form.get(
        "resumableIdentifier", default="", type=str) or ""
    _targetfile = Path(app.config["UPLOAD_FOLDER"], _fileid)

    if _targetfile.exists():
        return jsonify({
            "message": (
                "A file with a similar unique identifier has previously been "
                "uploaded and possibly is/has being/been processed."),
            "error": "BadRequest",
            "statuscode": 400
        }), 400

    try:
        chunks_directory(_fileid).mkdir(exist_ok=True, parents=True)
        request.files["file"].save(Path(chunks_directory(_fileid),
                                        chunk_name(_uploadfilename, _chunk)))

        # Check whether upload is complete
        chunkpaths = tuple(
            Path(chunks_directory(_fileid), chunk_name(_uploadfilename, _achunk))
            for _achunk in range(1, _totalchunks+1))
        if all(_file.exists() for _file in chunkpaths):
            # merge_files and clean up chunks
            __merge_chunks__(_targetfile, chunkpaths)
            chunks_directory(_fileid).rmdir()
            return jsonify({
                "uploaded-file": _targetfile.name,
                "message": "File was uploaded successfully!",
                "statuscode": 200
            }), 200
        return jsonify({
            "message": "Some chunks were not uploaded!",
            "error": "ChunksUploadError",
            "error-description": "Some chunks were not uploaded!"
        })
    except Exception as exc:# pylint: disable=[broad-except]
        msg = "Error processing uploaded file chunks."
        app.logger.error(msg, exc_info=True, stack_info=True)
        return jsonify({
            "message": msg,
            "error": type(exc).__name__,
            "error-description": " ".join(str(arg) for arg in exc.args),
            "error-trace": traceback.format_exception(exc)
        }), 500