import asyncio
import asyncpg
import os
import jinja2
from starlette.applications import Starlette
from starlette.responses import HTMLResponse, UJSONResponse, PlainTextResponse
from starlette.routing import Route
from random import randint
from operator import itemgetter
from urllib.parse import parse_qs


READ_ROW_SQL = 'SELECT "randomnumber", "id" FROM "world" WHERE id = $1'
WRITE_ROW_SQL = 'UPDATE "world" SET "randomnumber"=$1 WHERE id=$2'
ADDITIONAL_ROW = [0, 'Additional fortune added at request time.']



async def setup_database():
    global connection_pool
    connection_pool = await asyncpg.create_pool(
        user=os.getenv('PGUSER', 'benchmarkdbuser'),
        password=os.getenv('PGPASS', 'benchmarkdbpass'),
        database='hello_world',
        host='tfb-database',
        port=5432
    )


def load_fortunes_template():
    path = os.path.join('templates', 'fortune.html')
    with open(path, 'r') as template_file:
        template_text = template_file.read()
        return jinja2.Template(template_text)


def get_num_queries(request):
    try:
        query_string = request['query_string']
        query_count = int(parse_qs(query_string)[b'queries'][0])
    except (KeyError, IndexError, ValueError):
        return 1

    if query_count < 1:
        return 1
    if query_count > 500:
        return 500
    return query_count


connection_pool = None
sort_fortunes_key = itemgetter(1)
template = load_fortunes_template()
loop = asyncio.get_event_loop()
loop.run_until_complete(setup_database())


async def single_database_query(request):
    row_id = randint(1, 10000)

    async with connection_pool.acquire() as connection:
        number = await connection.fetchval(READ_ROW_SQL, row_id)

    return UJSONResponse({'id': row_id, 'randomNumber': number})


async def multiple_database_queries(request):
    num_queries = get_num_queries(request)
    row_ids = [randint(1, 10000) for _ in range(num_queries)]
    worlds = []

    async with connection_pool.acquire() as connection:
        statement = await connection.prepare(READ_ROW_SQL)
        for row_id in row_ids:
            number = await statement.fetchval(row_id)
            worlds.append({'id': row_id, 'randomNumber': number})

    return UJSONResponse(worlds)


async def fortunes(request):
    async with connection_pool.acquire() as connection:
        fortunes = await connection.fetch('SELECT * FROM Fortune')

    fortunes.append(ADDITIONAL_ROW)
    fortunes.sort(key=sort_fortunes_key)
    content = template.render(fortunes=fortunes)
    return HTMLResponse(content)


async def database_updates(request):
    num_queries = get_num_queries(request)
    updates = [(randint(1, 10000), randint(1, 10000)) for _ in range(num_queries)]
    worlds = [{'id': row_id, 'randomNumber': number} for row_id, number in updates]

    async with connection_pool.acquire() as connection:
        statement = await connection.prepare(READ_ROW_SQL)
        for row_id, number in updates:
            await statement.fetchval(row_id)
        await connection.executemany(WRITE_ROW_SQL, updates)

    return UJSONResponse(worlds)


routes = [
    Route('/json', UJSONResponse({'message': 'Hello, world!'})),
    Route('/db', single_database_query),
    Route('/queries', multiple_database_queries),
    Route('/fortunes', fortunes),
    Route('/updates', database_updates),
    Route('/plaintext', PlainTextResponse(b'Hello, world!')),
]

app = Starlette(routes=routes)