import numpy as np

__all__ = [
  'EeError',
  'read_ltspice_raw'
]

class EeError(Exception):
    pass

class LtSpiceRaw(object):
  def __init__(self, variables, values_first, values_rest):
    self.variables = variables
    self.values_first = values_first
    self.values_rest = values_rest

  def get_values(self, variable):
    return self.values[variable.idx]

  def get_variable(self, idx=None, expression=None):
    if idx is not None:
      return self.variables[idx]
    if expression is not None:
      v = [v for v in self.variables if v.expression == expression]
      if len(v) != 1:
          raise Exception('Unknown variable: ' + str(variable))
      return v[0]
    raise Exception('idx or expression must be given')

  def to_pandas(self):
    import pandas
    data = []
    for (i, v) in enumerate(self.values_first):
      data.append(pandas.Series(v, dtype='float64'))

    data = {}
    for (i, v) in enumerate(self.values_first):
      data[self.variables[i].expression] = v

    return pandas.DataFrame(data = data)

class LtSpiceVariable(object):
  def __init__(self, idx, expression, kind):
    self.idx = idx
    self.expression = expression
    self.kind = kind

class LtSpiceReader(object):

  def __init__(self, f):
    self.f = f
    self.mode = 'header'
    self.headers = {}
    self.variables = []
    self.values = []

  def read_header(self, line):
    sep = line.find(':')
    key = line[0:sep]
    value = line[sep + 1:].strip()

#    print("key='{}', value='{}'".format(key, str(value)))

    if key == 'Binary':
      self.set_binary_mode()
    elif key == 'Variables':
      self.no_variables = int(self.headers['No. Variables'])
      self.mode = 'variables'
    else:
      self.headers[key] = value

  def read_variable(self, line):
    parts = line.split('\t')
    idx = int(parts[1])
    expression = parts[2]
    kind = parts[3]
    self.variables.append(LtSpiceVariable(idx, expression, kind))

    if len(self.variables) == self.no_variables:
      self.mode = 'header'

  def set_binary_mode(self):
    self.mode = 'binary'

  def read_binary(self):
    pos = self.f.tell()
    no_points = int(self.headers['No. Points'])
    no_variables = int(self.headers['No. Variables'])

#    print("no_points={}, no_variables={}".format(no_points, no_variables))

    if True:
      self.values = np.zeros((no_variables, no_points), dtype='float32')

      for p in range(no_points):
        self.values[0][p] = np.fromfile(self.f, count=1, dtype='float64')
        row = np.fromfile(self.f, count=no_variables - 1, dtype='float32');
        for v in range(0, len(row)):
            self.values[v + 1][p] = row[v]
    else:
      self.values = np.zeros((no_points, no_variables), dtype='float64')

      for p in range(no_points):
        self.values[p][0] = np.fromfile(self.f, count=1, dtype='float64')
        row = np.fromfile(self.f, count=no_variables - 1, dtype='float32');
        for v in range(0, len(row)):
            self.values[p][v + 1] = row[v]

  def read(self):
    while True:
      line = self.f.readline();

      if len(line) == 0:
        break

      self.f.read(1) # The data is utf16 encoded so read the extra null byte

      # if this wasn't the last line .readline() includes the newline
      if line[-1] == '\n' or line[-1] == 0x0a:
        line = line[:-1]

#      print("len(line)={}, line={}".format(len(line), str(line)))
      line = line.decode(encoding="utf-16")

      if self.mode == 'header':
        self.read_header(line)
      elif self.mode == 'variables':
        self.read_variable(line)

      # The binary data can't be read with readline()
      if self.mode == 'binary':
#        self.f.read()
        self.read_binary()
        break

    if len(self.variables) == 0:
      raise Exception("Something didn't quite work when parsing file, no variables found")

    return LtSpiceRaw(self.variables, self.values, [])

def read_ltspice_raw(filename):

  with open(filename, mode="rb") as f:
    r = LtSpiceReader(f)
    return r.read()