photovoter_backend/main.py

from fastapi import FastAPI, File, UploadFile, Depends, BackgroundTasks
from fastapi.responses import JSONResponse
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from fastapi.middleware.cors import CORSMiddleware  # CORS

from secrets import compare_digest
from datetime import datetime
from uuid import uuid4
import sqlite3
import zipfile

# Global settings of this program
# ./config.py
from config import (
    DB_LOCATION,
    DATA_LOCATION,
    DEST_SHRUNK,
    DEST_ORIGINAL,
    CRED_USERNAME,
    CRED_PASSWORD,
)


# our own util for photo upload and processing
from util import import_photos as iph

# Initialization logic
app = FastAPI()
security = HTTPBasic()
iph.check_database(database_path=DB_LOCATION)
con = sqlite3.connect(DB_LOCATION)
con.row_factory = sqlite3.Row
cur = con.cursor()  # NB! single is enough for now, we might require multiple later

origins = [  # CORS
    "*",
]

app.add_middleware(  # CORS
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.get("/new_session", responses={503: {"description": "Unable to initiate session"}})
async def new_session():
    """Start a new session"""
    # add session to the database
    time = datetime.utcnow().replace(microsecond=0).isoformat()
    tries = 3  # something is very wrong with our random, if we miss 3 times
    for i in range(tries):
        try:
            # generate a cookie
            cookie = uuid4().hex
            cur.execute(
                """INSERT INTO sessions(cookie, time)
                            VALUES(:cookie, :time)
                        """,
                {"cookie": cookie, "time": time},
            )
            con.commit()
        except sqlite3.IntegrityError as e:
            if i < tries - 1 and str(e) == "UNIQUE constraint failed: sessions.cookie":
                continue
            elif str(e) == "UNIQUE constraint failed: sessions.cookie":
                return JSONResponse(status_code=503)
            else:
                raise
        break

    # return new session cookie
    return {"cookie": cookie}


@app.get(
    "/next_picture/{cookie}",
    responses={
        204: {"description": "All available images have been appraised"},
        409: {"description": "Uninitiated session"},
    },
)
async def next_picture(cookie: str):
    """Request new picture to rate."""
    # check if the cookie is valid
    cur.execute(
        """SELECT sessionid 
            FROM sessions 
            WHERE cookie = :cookie
            LIMIT 1""",
        {"cookie": cookie},
    )
    sessionid = cur.fetchone()
    if sessionid is None:
        return JSONResponse(status_code=409)

    # take not rated picture from the database
    # do not insert anything in the database yet
    # return this picture

    # SELECT all images EXCEPT images with marks from the current session ->
    # -> SELECT paths for these images
    # FIXME[0]: can this be done better?
    cur.execute(
        """SELECT imgid, resizedpath
                FROM images
                WHERE imgid IN  (SELECT imgid
                                    FROM images
                                    EXCEPT
                                    SELECT imgid
                                    FROM marks
                                    WHERE sessionid = :sessionid)
                LIMIT 1
    """,
        {"sessionid": sessionid["sessionid"]},
    )
    r = cur.fetchone()
    if r is not None:
        return {"picture_id": r["imgid"], "picture_uri": r["resizedpath"]}
    else:
        # All available pics have been voted for by this sessionid
        return JSONResponse(status_code=204)


@app.get(
    "/rate_picture/{cookie}/{picture_id}/{mark}",
    responses={
        406: {"description": "Already appraised"},
        409: {"description": "Uninitiated session"},
    },
)
async def rate_picture(cookie: str, picture_id: int, mark: int):
    """Submit a rating for the picture"""
    # check if the cookie is valid
    cur.execute(
        """SELECT sessionid 
            FROM sessions 
            WHERE cookie = :cookie
            LIMIT 1""",
        {"cookie": cookie},
    )
    sessionid = cur.fetchone()
    if sessionid is None:
        return JSONResponse(status_code=409)

    # add new mark to the session table
    try:
        cur.execute(
            """INSERT INTO marks(imgid, sessionid, mark)
                        VALUES(:imgid,:sessionid,:mark)
                    """,
            {"imgid": picture_id, "sessionid": sessionid["sessionid"], "mark": mark},
        )
        con.commit()
    except sqlite3.IntegrityError as e:
        if str(e) == "UNIQUE constraint failed: marks.imgid, marks.sessionid":
            return JSONResponse(status_code=406)

    return {"status": "success"}


@app.get("/photo_points")
async def photo_points():
    """Get points with the url of a photo and the rate"""
    # assume we always have at least some photos
    # fetch them all
    cur.execute(
        """SELECT images.imgid, resizedpath, GPSLatitude, GPSLongitude, 
                    100*SUM(marks.mark)/COUNT(marks.mark)/MAX(marks.mark)
                FROM images
                LEFT JOIN marks ON images.imgid = marks.imgid
                GROUP BY images.imgid;
        """,  # 100 * SUM(marks.mark)/COUNT(marks.mark)/MAX(marks.mark)
        # is an ad-hoc percentage of likes without know how front end defined like/dislike
        # returns None with no marks (sqlite handles division by 0 gracefully)
    )
    points = cur.fetchall()
    return [
        {
            "id": point["imgid"],
            "url": point["resizedpath"],
            "lon": point["GPSLongitude"],
            "lat": point["GPSLatitude"],
            "rate": point["100*SUM(marks.mark)/COUNT(marks.mark)/MAX(marks.mark)"],
        }
        for point in points
    ]
@app.post(
    "/upload_pictures",
    responses={
        202: {"description": "Archive accepted into processing"},
        401: {"description": "Authentication is required to access this resource"},
        415: {"description": "Cannot process uploaded archive"},
    },
)
async def upload_pictures(
    background_tasks: BackgroundTasks,
    credentials: HTTPBasicCredentials = Depends(security),
    file: UploadFile = File(...),
):
    """Photo upload endpoint"""
    """
    Accepts photo in zip archives with any internal directory structure
    Valid uploads yield 202 status message and process photos in the background
    Non-zip archives yeild 415 error
    Upload is restricted by basic HTTP login, configurable in config.py
    """
    # check authenticity
    correct_username = compare_digest(credentials.username, CRED_USERNAME)
    correct_password = compare_digest(credentials.password, CRED_PASSWORD)
    if not (correct_username and correct_password):
        return JSONResponse(status_code=401)
    # slurp the zip
    if not zipfile.is_zipfile(file.file):
        return JSONResponse(status_code=415)
    # detach from the interface
    # unpack zip
    tasks = BackgroundTasks()
    tasks.add_task(
        unpack_pictures_zip,
        file=file,
        time=datetime.utcnow().replace(microsecond=0).isoformat(),
    )

    # feed the pictures to util/import_photos.py
    return JSONResponse("Accepted", background=tasks)


def unpack_pictures_zip(file: UploadFile, time):
    """
    Unpack and process zip archived photo
    Extract pictures in the DATA_LOCATION/processing
    and feed them to util/import_photos.py
    Walk the nested DATA_LOCATION/processing ourselves
    Uses: DB_LOCATION, DATA_LOCATION
    """
    # we only call this function sporadically, so import here
    import os
    from shutil import rmtree

    print(f"Accepted {file.filename} at {time} into processing")
    processing_path = os.path.join(DATA_LOCATION, "processing" + time)
    os.makedirs(processing_path, exist_ok=True)

    # using private ._file field is a dirty hack, but
    # SpooledTemporaryFile does not implement seekable
    # required by zipfile 'r' mode
    # https://bugs.python.org/issue26175
    with zipfile.ZipFile(file.file._file) as photo_zip:
        problem_files = photo_zip.testzip()
        if problem_files is not None:
            print(f"Errors in {file.filename} from {time} at {problem_files}")
        photo_zip.extractall(path=processing_path)
        photo_zip.close()

    print(f"Start processing {file.filename} from {time}")

    iph.check_database(database_path=DB_LOCATION)
    for (dir, _, _) in os.walk(processing_path):
        iph.run(
            db_location=DB_LOCATION,
            source=os.path.join(dir),
            dest_shrunk=os.path.join(DATA_LOCATION, DEST_SHRUNK),
            dest_original=os.path.join(DATA_LOCATION, DEST_ORIGINAL),
        )

    rmtree(processing_path)

    print(f"Succesfully processed {file.filename} from {time}")