from time import time
from statistics import mean

from fastapi import BackgroundTasks, FastAPI
from fastapi.staticfiles import StaticFiles
from fastapi.responses import FileResponse
from pydantic import BaseModel

from modules.details import rand_details
from modules.inference import generate_image

app = FastAPI(docs_url=None, redoc_url=None)

app.mount("/static", StaticFiles(directory="static"), name="static")

tasks = {}


class NewTask(BaseModel):
    prompt = "покемон"


def get_place_in_queue(task_id):
    queued_tasks = list(task for task in tasks.values()
                        if task["status"] == "queued" or task["status"] == "processing")

    queued_tasks.sort(key=lambda task: task["created_at"])

    queued_task_ids = list(task["task_id"] for task in queued_tasks)

    try:
        return queued_task_ids.index(task_id) + 1
    except:
        return 0


def calculate_eta(task_id):
    total_durations = list(task["completed_at"] - task["started_at"]
                           for task in tasks.values() if "completed_at" in task)

    initial_place_in_queue = tasks[task_id]["initial_place_in_queue"]

    if len(total_durations):
        eta = initial_place_in_queue * mean(total_durations)
    else:
        eta = initial_place_in_queue * 40

    return round(eta, 1)


def process_task(task_id):
    if 'processing' in list(task['status'] for task in tasks.values()):
        return

    tasks[task_id]["status"] = "processing"
    tasks[task_id]["started_at"] = time()

    try:
        tasks[task_id]["value"] = generate_image(tasks[task_id]["prompt"])
    except Exception as ex:
        tasks[task_id]["status"] = "failed"
        tasks[task_id]["error"] = repr(ex)
    else:
        tasks[task_id]["status"] = "completed"
    finally:
        tasks[task_id]["completed_at"] = time()

        queued_tasks = list(task for task in tasks.values() if task["status"] == "queued")

        if queued_tasks:
            print(f"Tasks remaining: {len(queued_tasks)}")
            process_task(queued_tasks[0]["task_id"])


@app.head('/')
@app.get('/')
def index():
    return FileResponse(path="static/index.html", media_type="text/html")


@app.get('/details')
def generate_details():
    return rand_details()


@app.post('/task/create')
def create_task(background_tasks: BackgroundTasks, new_task: NewTask):
    created_at = time()

    task_id = f"{str(created_at)}_{new_task.prompt}"

    tasks[task_id] = {
        "task_id": task_id,
        "created_at": created_at,
        "prompt": new_task.prompt,
        "status": "queued",
        "poll_count": 0,
    }

    tasks[task_id]["initial_place_in_queue"] = get_place_in_queue(task_id)

    background_tasks.add_task(process_task, task_id)

    return tasks[task_id]


@app.get('/task/poll')
def poll_task(task_id: str):
    tasks[task_id]["place_in_queue"] = get_place_in_queue(task_id)
    tasks[task_id]["eta"] = calculate_eta(task_id)
    tasks[task_id]["poll_count"] += 1

    return tasks[task_id]