from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

from caffe2.python import core
import caffe2.python.hypothesis_test_util as hu

from hypothesis import given
import hypothesis.strategies as st

import copy
from functools import partial
import math
import numpy as np


class TestLearningRate(hu.HypothesisTestCase):
    @given(**hu.gcs_cpu_only)
    def test_alter_learning_rate_op(self, gc, dc):
        iter = np.random.randint(low=1, high=1e5, size=1)
        active_period = int(np.random.randint(low=1, high=1e3, size=1))
        inactive_period = int(np.random.randint(low=1, high=1e3, size=1))
        base_lr = float(np.random.random(1))

        def ref(iter):
            iter = float(iter)
            reminder = iter % (active_period + inactive_period)
            if reminder < active_period:
                return (np.array(base_lr), )
            else:
                return (np.array(0.), )

        op = core.CreateOperator(
            'LearningRate',
            'iter',
            'lr',
            policy="alter",
            active_first=True,
            base_lr=base_lr,
            active_period=active_period,
            inactive_period=inactive_period
        )

        self.assertReferenceChecks(gc, op, [iter], ref)

    @given(**hu.gcs_cpu_only)
    def test_hill_learning_rate_op(self, gc, dc):
        iter = np.random.randint(low=1, high=1e5, size=1)

        num_iter = int(np.random.randint(low=1e2, high=1e3, size=1))
        start_multiplier = 1e-4
        gamma = 1.0
        power = 0.5
        end_multiplier = 1e-2
        base_lr = float(np.random.random(1))

        def ref(iter):
            iter = float(iter)
            if iter < num_iter:
                lr = start_multiplier + (
                    1.0 - start_multiplier
                ) * iter / num_iter
            else:
                iter -= num_iter
                lr = math.pow(1.0 + gamma * iter, -power)
                lr = max(lr, end_multiplier)
            return (np.array(base_lr * lr), )

        op = core.CreateOperator(
            'LearningRate',
            'data',
            'out',
            policy="hill",
            base_lr=base_lr,
            num_iter=num_iter,
            start_multiplier=start_multiplier,
            gamma=gamma,
            power=power,
            end_multiplier=end_multiplier,
        )
        self.assertReferenceChecks(gc, op, [iter], ref)

    @given(gc=hu.gcs['gc'],
            min_num_iter=st.integers(min_value=10, max_value=20),
            max_num_iter=st.integers(min_value=50, max_value=100))
    def test_composite_learning_rate_op(self, gc, min_num_iter, max_num_iter):
        np.random.seed(65535)
        # Generate the iteration numbers for sub policy
        # The four sub policies are as follows:
        # 1. exp; 2. step; 3. fix; 4. exp
        num_lr_policy = 4
        iter_nums = np.random.randint(
            low=min_num_iter, high=max_num_iter, size=num_lr_policy)
        accu_iter_num = copy.deepcopy(iter_nums)
        for i in range(1, num_lr_policy):
            accu_iter_num[i] += accu_iter_num[i - 1]
        total_iter_nums = accu_iter_num[-1]

        policy_lr_scale = np.random.uniform(low=2.0, high=2.0, size=num_lr_policy)

        # args for StepLRPolicy
        step_size = np.random.randint(low=2, high=min_num_iter // 2)
        step_gamma = np.random.random()
        # args for ExpLRPolicy
        exp_gamma = np.random.random()
        # common args
        base_lr = 0.1

        # StepLRPolicy
        def step_lr(iter, lr_scale):
            return math.pow(step_gamma, iter // step_size) * lr_scale

        # ExpLRPolicy
        def exp_lr(iter, lr_scale):
            return math.pow(exp_gamma, iter) * lr_scale

        # FixedLRPolicy
        def fixed_lr(iter, lr_scale):
            return lr_scale

        # test one sub policy case
        def one_policy_check_ref(iter, lr_scale):
            iter = int(iter)
            exp_lr_val = exp_lr(iter, lr_scale=lr_scale)
            return (np.array(base_lr * exp_lr_val), )

        op = core.CreateOperator(
            'LearningRate',
            'data',
            'out',
            policy='composite',
            sub_policy_num_iters=iter_nums[:1],
            sub_policy_0_lr_scale=policy_lr_scale[0],
            sub_policy_0_policy='exp',
            sub_policy_0_gamma=exp_gamma,
            base_lr=base_lr,
        )
        for iter_idx in range(1, total_iter_nums + 1):
            self.assertReferenceChecks(
                gc, op, [np.asarray([iter_idx])],
                partial(one_policy_check_ref, lr_scale=policy_lr_scale[0]))

        # all the case with all four sub policies
        def all_sub_policy_check_ref(iter, lr_scale):
            assert iter <= accu_iter_num[3]
            if iter <= accu_iter_num[0]:
                lr = exp_lr(iter, lr_scale=lr_scale)
            elif iter <= accu_iter_num[1]:
                lr = step_lr(iter, lr_scale=lr_scale)
            elif iter <= accu_iter_num[2]:
                lr = fixed_lr(iter, lr_scale=lr_scale)
            else:
                lr = exp_lr(iter, lr_scale=lr_scale)
            return (np.array(base_lr * lr), )

        op = core.CreateOperator(
            'LearningRate',
            'data',
            'out',
            policy='composite',
            sub_policy_num_iters=iter_nums,
            sub_policy_0_policy='exp',
            sub_policy_0_lr_scale=policy_lr_scale[0],
            sub_policy_0_gamma=exp_gamma,
            sub_policy_1_policy='step',
            sub_policy_1_lr_scale=policy_lr_scale[1],
            sub_policy_1_stepsize=step_size,
            sub_policy_1_gamma=step_gamma,
            sub_policy_2_policy='fixed',
            sub_policy_2_lr_scale=policy_lr_scale[2],
            sub_policy_3_policy='exp',
            sub_policy_3_gamma=exp_gamma,
            sub_policy_3_lr_scale=policy_lr_scale[3],
            base_lr=base_lr,
        )

        iter_policy = 0
        for iter_idx in range(1, total_iter_nums + 1):
            if iter_idx > accu_iter_num[iter_policy]:
                iter_policy += 1
            self.assertReferenceChecks(
                gc, op, [np.asarray([iter_idx])],
                partial(all_sub_policy_check_ref,
                        lr_scale=policy_lr_scale[iter_policy])
            )


if __name__ == "__main__":
    import unittest
    unittest.main()
