"""
TensorFlow SavedModel predictor base class.
Loads and runs inference on TensorFlow SavedModel format.
"""

import logging
import numpy as np

try:
	import tensorflow as tf
	# Limit GPU memory growth
	gpus = tf.config.experimental.list_physical_devices('GPU')
	if gpus:
		for gpu in gpus:
			tf.config.experimental.set_memory_growth(gpu, True)
except ImportError:
	tf = None
	logging.warning('TensorFlow not available')


class TensorFlowPredictor:
	"""Base class for TensorFlow SavedModel predictors."""

	def __init__(self, model_path, device='gpu'):
		if tf is None:
			raise ImportError('TensorFlow is required for this predictor')

		self.device = device
		self.model = self._load_model(model_path)
		logging.info('TensorFlow SavedModel loaded: %s', model_path)

	def _load_model(self, model_path):
		"""Load SavedModel from directory."""
		return tf.saved_model.load(model_path)

	def preprocess(self, images):
		"""
		Preprocess images before inference.
		Override in subclass.
		"""
		raise NotImplementedError

	def postprocess(self, outputs):
		"""
		Postprocess model outputs.
		Override in subclass.
		"""
		raise NotImplementedError

	def predict(self, streams, **kwargs):
		"""
		Run prediction on input streams.
		Override in subclass.
		"""
		raise NotImplementedError


class KerasPredictor:
	"""Base class for Keras model predictors (for .h5 or SavedModel)."""

	def __init__(self, model_path, device='gpu'):
		if tf is None:
			raise ImportError('TensorFlow is required for this predictor')

		self.device = device
		self.model = self._load_model(model_path)
		logging.info('Keras model loaded: %s', model_path)

	def _load_model(self, model_path):
		"""Load Keras model."""
		return tf.keras.models.load_model(model_path, compile=False)

	def preprocess(self, images):
		raise NotImplementedError

	def postprocess(self, outputs):
		raise NotImplementedError

	def predict(self, streams, **kwargs):
		raise NotImplementedError