"""
These decorator functions wrap APIs for the simple search server.
"""

import os
from time import time
from datetime import datetime
import numpy as np
from PIL import Image
from flask import request, jsonify
from werkzeug.utils import secure_filename

from app.sql.common import Session

DEFAULT_LIMIT = 30

def api_query(f):
  """Wrap basic API queries with timing"""
  def wrap_api_query(*args, **kwargs):
    start = time()
    query = {}
    kwargs['query'] = query
    results = f(*args, **kwargs)
    query['timing'] = round(time() - start, 2)
    if 'crop' in kwargs['query'] and kwargs['query']['crop'] is None:
      del kwargs['query']['crop']
    else:
      crop = kwargs['query']['crop']
      kwargs['query']['crop'] = {
        'x': crop[0],
        'y': crop[1],
        'w': crop[2],
        'h': crop[3],
      }
    if isinstance(results, list):
      return { 'query': query, 'res': results }
    else:
      return { 'query': query, 'res': results }
  wrap_api_query.__name__ = f.__name__
  return wrap_api_query

def db_session(f):
  """Wrap API queries in a database session object which gets committed"""
  def wrap_db_session(*args, **kwargs):
    session = Session()
    try:
      kwargs['session'] = session
      f(*args, **kwargs)
      session.commit()
    except:
      session.rollback()
      raise
    finally:
      session.close()
  wrap_db_session.__name__ = f.__name__
  return wrap_db_session

def get_offset_and_limit(f):
  """Normalize offset/limit query string params"""
  def wrap_offset(*args, **kwargs):
    kwargs['query']['offset'] = request.args.get('offset', default=0, type=int)
    kwargs['query']['limit'] = request.args.get('limit', default=DEFAULT_LIMIT, type=int)
    x = float(request.args.get('x', default=0.0, type=float))
    y = float(request.args.get('y', default=0.0, type=float))
    w = float(request.args.get('w', default=0.0, type=float))
    h = float(request.args.get('h', default=0.0, type=float))
    if w != 0.0 and h != 0.0:
      kwargs['query']['crop'] = (x, y, w, h,)
    else:
      kwargs['query']['crop'] = None
    return f(*args, **kwargs)
  wrap_offset.__name__ = f.__name__
  return wrap_offset

def store_uploaded_image(param_name, store=False, uploaded_im_path='static/data/uploaded'):
  """Retrive an uploaded image and prepare for processing. Optionally store it to disk."""
  def decorator(f):
    def wrap_uploaded_image(*args, **kwargs):
      if param_name not in request.files:
        raise APIError('No file uploaded')

      file = request.files[param_name]

      # convert string of image data to uint8
      nparr = np.fromstring(file.read(), np.uint8)

      # decode image
      im = Image.fromarray(nparr)
      kwargs['im'] = im

      if store:
        uploaded_im_fn = secure_filename(datetime.now().isoformat() + "_" + file.filename)
        uploaded_im_abspath = os.path.join(uploaded_im_path, uploaded_im_fn)
        uploaded_im_remote_path = os.path.join('/', uploaded_im_path, uploaded_im_fn)
        nparr.tofile(uploaded_im_abspath)
        kwargs['query']['url'] = uploaded_im_remote_path
      return f(*args, **kwargs)
    wrap_uploaded_image.__name__ = f.__name__
    return wrap_uploaded_image
  return decorator

def as_json(f):
  """Output an API query as JSON"""
  def wrap_jsonify(*args, **kwargs):
    return jsonify(f(*args, **kwargs))
  wrap_jsonify.__name__ = f.__name__
  return wrap_jsonify

def exception_handler(f):
  """Handle exceptions caused by the API"""
  def wrapper(*args, **kwargs):
    try:
      return f(*args, **kwargs)
    except Exception as e:
      return {
        "error": True,
        "message": e.message,
        "query": kwargs['query'],
      }
  wrapper.__name__ = f.__name__
  return wrapper

class APIError(Exception):
  def __init__(self, message):
    self.message = message
  def __str__(self):
    return repr(self.message)