import unittest
import numpy as np
from op_test import OpTest

SIGMOID_THRESHOLD_MIN = -40.0
SIGMOID_THRESHOLD_MAX = 13.0
EXP_MAX_INPUT = 40.0


def identity(x):
    return x


def sigmoid(x):
    y = np.copy(x)
    y[x < SIGMOID_THRESHOLD_MIN] = SIGMOID_THRESHOLD_MIN
    y[x > SIGMOID_THRESHOLD_MAX] = SIGMOID_THRESHOLD_MAX
    return 1. / (1. + np.exp(-y))


def tanh(x):
    y = -2. * x
    y[y > EXP_MAX_INPUT] = EXP_MAX_INPUT
    return (2. / (1. + np.exp(y))) - 1.


def relu(x):
    return np.maximum(x, 0)


def lstm(
        input,  # T x 4D
        lod,  # 1 x N
        h0=None,  # N x D
        c0=None,  # N x D
        w_h=None,  # D x 4D
        w_b=None,  # 1 x 4D
        w_c=None,  # 1 x 3D
        is_reverse=False,
        gate_act=None,
        cell_act=None,
        cand_act=None):
    def _step(x, w_h, w_c, h_pre, c_pre, gate_act, cell_act, cand_act):
        g = np.dot(h_pre, w_h)  # 1 x 4D
        g = g + x
        g = np.reshape(g, (1, g.size))
        c_tmp, g_i, g_f, g_o = np.split(g, 4, axis=1)
        if w_c is None:
            g_i = gate_act(g_i)  # 1 x D
            g_f = gate_act(g_f)  # 1 x D
        else:
            w_ic, w_fc, w_oc = np.split(w_c, 3, axis=1)
            g_i = gate_act(g_i + w_ic * c_pre)  # 1 x D
            g_f = gate_act(g_f + w_fc * c_pre)  # 1 x D
        c = g_f * c_pre + g_i * cand_act(c_tmp)  # 1 x D

        if w_c is None:
            g_o = gate_act(g_o)  # 1 x D
        else:
            _, _, w_oc = np.split(w_c, 3, axis=1)
            g_o = gate_act(g_o + w_oc * c)  # 1 x D
        h = g_o * cell_act(c)
        bg = np.concatenate((cand_act(c_tmp), g_i, g_f, g_o), axis=1)
        return h, c, bg

    offset = lod[0]
    batch_size = len(offset) - 1
    hidden = []
    cell = []
    gate = []
    if w_b is not None:
        input = input + np.tile(w_b, (offset[-1], 1))
    for i in range(batch_size):
        # compute one sequence
        seq_len = offset[i + 1] - offset[i]
        x = input[offset[i]:offset[i + 1], :]
        h_pre = h0[i]  # 1 x D
        c_pre = c0[i]  # 1 x D
        for j in range(seq_len):
            # compute one step
            h_pre, c_pre, g_pre = _step(x[j], w_h, w_c, h_pre, c_pre, gate_act,
                                        cell_act, cand_act)
            hidden.append(h_pre.flatten())
            cell.append(c_pre.flatten())
            gate.append(g_pre.flatten())

    hidden = np.array(hidden).astype("float64")
    cell = np.array(cell).astype("float64")
    gate = np.array(gate).astype("float64")
    assert gate.shape == input.shape
    assert hidden.shape == (input.shape[0], input.shape[1] / 4)
    assert cell.shape == (input.shape[0], input.shape[1] / 4)
    return hidden, cell, gate


class LstmUnitTest(OpTest):
    def set_data(self):
        D = 4
        #lod = [[0, 2, 6, 9]]
        lod = [[0, 1]]
        shape = (1, D)

        x = np.random.normal(size=(1, 4 * D)).astype("float64")
        h0 = np.zeros((4, D)).astype("float64")
        c0 = np.zeros((4, D)).astype("float64")
        w = np.random.normal(size=(D, 4 * D)).astype("float64")
        b = np.random.normal(size=(1, 7 * D)).astype("float64")

        w_b = b[:, 0:4 * D]
        w_c = b[:, 4 * D:]
        #h, c, g = lstm(x, lod, h0, c0, w, w_b, w_c, False, sigmoid, tanh, tanh)
        h, c, g = lstm(x, lod, h0, c0, w, w_b, w_c, False, identity, identity,
                       identity)

        g_sort = np.zeros_like(x)
        #idx = [2,6,0,3,7,1,4,8,5]
        #for i, j in enumerate(idx):
        #  g_sort[i, :] = g[j, :]

        self.inputs = {
            'Input': (x, lod),
            'H0': h0,
            'C0': c0,
            'Weight': w,
            'Bias': b
        }
        self.outputs = {'Hidden': h, 'Cell': c, 'BatchGate': g_sort}
        self.attrs = {
            'usePeepholes': True,
            'isReverse': False,
            'gateActivation': 'linear',
            'cellActivation': 'linear',
            'candidateActivation': 'linear'
        }

    def setUp(self):
        self.set_data()
        self.op_type = "lstm"

    def test_check_output(self):
        self.check_output()


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