# Copyright 2013 DEVSIM LLC
#
# SPDX-License-Identifier: Apache-2.0

from devsim.python_packages.model_create import (
    CreateEdgeModel,
    CreateEdgeModelDerivatives,
    InEdgeModelList,
    EnsureEdgeFromNodeModelExists,
)


def CreateBernoulli(device, region):
    """
    Creates the Bernoulli function for Scharfetter Gummel
    """
    #### test for requisite models here
    EnsureEdgeFromNodeModelExists(device, region, "Potential")
    vdiffstr = "(Potential@n0 - Potential@n1)/V_t"
    CreateEdgeModel(device, region, "vdiff", vdiffstr)
    CreateEdgeModel(device, region, "vdiff:Potential@n0", "V_t^(-1)")
    CreateEdgeModel(device, region, "vdiff:Potential@n1", "-vdiff:Potential@n0")
    CreateEdgeModel(device, region, "Bern01", "B(vdiff)")
    CreateEdgeModel(
        device, region, "Bern01:Potential@n0", "dBdx(vdiff) * vdiff:Potential@n0"
    )
    CreateEdgeModel(device, region, "Bern01:Potential@n1", "-Bern01:Potential@n0")
    # identity of Bernoulli functions


#  CreateEdgeModel(device, region, "Bern10",              "Bern01 + vdiff")
#  CreateEdgeModel(device, region, "Bern10:Potential@n0", "Bern01:Potential@n0 + vdiff:Potential@n0")
#  CreateEdgeModel(device, region, "Bern10:Potential@n1", "Bern01:Potential@n1 + vdiff:Potential@n1")


def CreateElectronCurrent(device, region, mu_n):
    """
    Electron current
    """
    EnsureEdgeFromNodeModelExists(device, region, "Potential")
    EnsureEdgeFromNodeModelExists(device, region, "Electrons")
    EnsureEdgeFromNodeModelExists(device, region, "Holes")
    # Make sure the bernoulli functions exist
    if not InEdgeModelList(device, region, "Bern01"):
        CreateBernoulli(device, region)
    #### test for requisite models here
    #  Jn = "ElectronCharge*{0}*EdgeInverseLength*V_t*(Electrons@n1*Bern10 - Electrons@n0*Bern01)".format(mu_n)
    Jn = "ElectronCharge*{0}*EdgeInverseLength*V_t*kahan3(Electrons@n1*Bern01,  Electrons@n1*vdiff,  -Electrons@n0*Bern01)".format(
        mu_n
    )
    #  Jn = "ElectronCharge*{0}*EdgeInverseLength*V_t*((Electrons@n1-Electrons@n0)*Bern01 +  Electrons@n1*vdiff)".format(mu_n)

    CreateEdgeModel(device, region, "ElectronCurrent", Jn)
    for i in ("Electrons", "Potential", "Holes"):
        CreateEdgeModelDerivatives(device, region, "ElectronCurrent", Jn, i)


def CreateHoleCurrent(device, region, mu_p):
    """
    Hole current
    """
    EnsureEdgeFromNodeModelExists(device, region, "Potential")
    EnsureEdgeFromNodeModelExists(device, region, "Holes")
    # Make sure the bernoulli functions exist
    if not InEdgeModelList(device, region, "Bern01"):
        CreateBernoulli(device, region)
    ##### test for requisite models here
    #  Jp ="-ElectronCharge*{0}*EdgeInverseLength*V_t*(Holes@n1*Bern01 - Holes@n0*Bern10)".format(mu_p)
    Jp = "-ElectronCharge*{0}*EdgeInverseLength*V_t*kahan3(Holes@n1*Bern01, -Holes@n0*Bern01, -Holes@n0*vdiff)".format(
        mu_p
    )
    #  Jp ="-ElectronCharge*{0}*EdgeInverseLength*V_t*((Holes@n1 - Holes@n0)*Bern01 - Holes@n0*vdiff)".format(mu_p)
    CreateEdgeModel(device, region, "HoleCurrent", Jp)
    for i in ("Holes", "Potential", "Electrons"):
        CreateEdgeModelDerivatives(device, region, "HoleCurrent", Jp, i)