#!/usr/bin/env python3
'''
Handle API requests to the database
'''

import json
import sqlite3
from os import path

DATABASE = '/usr/local/www/mocha-server/mocha.db'
if not path.exists(DATABASE):
    DATABASE = 'mocha.db'

# TODO: Add fetching of top N users by score
# TODO: Add ability to store and retrieve avatars (as image files?)

def fetch_users(user_ids):
    '''
    Gets a list of users searching by name.
    This can also easily be done by user_id.
    '''
    conn = sqlite3.connect(DATABASE)
    conn.row_factory = sqlite3.Row
    cursor = conn.cursor()
    output = []
    for user_id in user_ids:
        cursor.execute('select * from users where user_id=(?)', (user_id, ))
        output += cursor.fetchall()

    output = json.dumps([dict(row) for row in output])
    conn.commit()
    conn.close()

    if output == '[]':
        output = None

    return output


def get_top_n(search_parameter, desc, num):
    '''
    In progress.
    Currently the query seems to work, but returning a dict does not
    preserve order.

    Store an orderd id list and put that in the json?

    Alternatively, sort on the client-side.
    '''
    conn = sqlite3.connect(DATABASE)
    conn.row_factory = sqlite3.Row
    cursor = conn.cursor()
    if desc:
        cursor.execute('select * from users order by ? desc limit ?',
                       (search_parameter, num))
    else:
        cursor.execute('select * from users order by ? asc limit ?',
                       (search_parameter, num))

    output = cursor.fetchall()
    # print(output)

    output = json.dumps([dict(row) for row in output])
    conn.commit()
    conn.close()

    if output == '[]':
        output = None

    return output


# add new parameters as needed
def update_row(_user_id, _updated_username):
    '''
    WIP.
    Will add a new user.
    '''
    print()


def insert_row(user_id, username):
    '''
    Inserts a row for a NEW user with given parameters
    This may work better with AUTOINCREMENT to avoid arbitrary ids and
    duplicates.

    Alternatively, use randomized unique IDs.
    '''

    conn = sqlite3.connect(DATABASE)
    conn.row_factory = sqlite3.Row
    cursor = conn.cursor()
    cursor.execute('insert into users values (?,?)', (user_id, username))
    conn.commit()
    conn.close()


def fetch_user(user_id):
    '''
    Returns a JSON object containing the requested user
    Also can return a list of all users if user_id == '*'
    '''
    conn = sqlite3.connect(DATABASE)
    conn.row_factory = sqlite3.Row
    cursor = conn.cursor()
    if user_id != '*':  # must use (?), (item,) format
        cursor.execute('SELECT * FROM users WHERE user_id=(?)', (user_id, ))
    else:
        cursor.execute('SELECT * FROM users')

    output = cursor.fetchall()
    output = json.dumps([dict(row) for row in output])
    conn.commit()
    conn.close()

    if output == '[]':
        output = None

    return output


def fetch_top_n(num):
    '''
    Retrieves the top n users by score.
    '''
    output = get_top_n('score', True, num)
    return output


def process_request(uri):
    '''
    Handles the API endpoint.
    Currently supports:
        -   /mocha/users/{user_id}      Returns JSON of the specified user
        -   /mocha/users/*              Returns JSON list of all users
    '''
    parts = uri.split('/')[1:]
    assert parts[0] == 'mocha'

    output = None

    if parts[1] == 'users' and len(parts) > 2:
        if ',' in parts[2]:
            output = fetch_users(parts[2].split(','))
        else:
            output = fetch_user(parts[2])
    elif parts[1] == 'top' and len(parts) > 2:
        output = fetch_top_n(parts[2])
    else:
        output = None

    return output


def application(environ, start_response):
    '''
    mod_wsgi entry point
    '''
    status = '200 OK'
    output = process_request(environ['REQUEST_URI'])

    if output is None:
        status = '404 Not Found'
        output = ''

    output = output.encode('UTF-8')

    response_headers = [('Content-type', 'application/json'),
                        ('Content-Length', str(len(output)))]

    start_response(status, response_headers)

    return [output]


if __name__ == '__main__':
    print(fetch_users(['1', '2', '3']))


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