import sympy
import numpy as np

__all__ = [
  'read_ltspice_raw'
]

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

  def get_values(self, variable):
    v = [v for v in self.variables if v.expression == variable]
    if len(v) != 1:
        raise Error('Unknown variable: ' + str(variable))
    return self.values[v[0].idx]

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 = {}

  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.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()
    # Skip an extra '\0'
    self.f.seek(pos + 1)
    no_points = int(self.headers['No. Points'])
    no_variables = int(self.headers['No. Variables'])
#    print("variables={}, no_points={}, pos={}".format(no_variables, no_points, pos))
    self.values = vs = np.zeros((no_variables, no_points))
    for p in range(no_points):
      vs[0][p] = np.fromfile(self.f, count=1, dtype='float64')
      pointdata = np.fromfile(self.f, count=no_variables - 1, dtype='float32')
#      print("value={:0=0.15e}".format(vs[0][p]))
      for v in range(1, no_variables):
#        print("p={}, v={}".format(p, v))
#        print("  value={:0=0.15e}".format(pointdata[v - 1]))
        vs[v][p] = pointdata[v - 1]

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

      if len(line) == 0:
        break

      if line[0] == 0:
        line = line[1:]
      if line[-1] == 10:
        line = line[:-1]
#    print("len(line)={}, line={}".format(len(line), str(line)))
      line = str(line, 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

    return LtSpiceRaw(self.variables, self.values)

def read_ltspice_raw(filename):

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