# Size of variable arrays:
sizeAlgebraic = 2
sizeStates = 1
sizeConstants = 7
from math import *
from numpy import *

def createLegends():
    legend_states = [""] * sizeStates
    legend_rates = [""] * sizeStates
    legend_algebraic = [""] * sizeAlgebraic
    legend_voi = ""
    legend_constants = [""] * sizeConstants
    legend_voi = "time in component Environment (s)"
    legend_constants[0] = "HR in component Environment (ratepm)"
    legend_constants[5] = "hrf in component Environment (Hz)"
    legend_constants[1] = "PRint in component LVTiming (s)"
    legend_algebraic[0] = "beattime in component LVTiming (s)"
    legend_constants[2] = "Esys in component LVElastanceFunction (elastance)"
    legend_constants[3] = "Edia in component LVElastanceFunction (elastance)"
    legend_constants[4] = "TsK in component LVElastanceFunction (s)"
    legend_constants[6] = "Ts in component LVElastanceFunction (s)"
    legend_algebraic[1] = "E_LV in component LVElastanceFunction (elastance)"
    legend_states[0] = "dummy in component dummy (dimensionless)"
    legend_rates[0] = "d/dt dummy in component dummy (dimensionless)"
    return (legend_states, legend_algebraic, legend_voi, legend_constants)

def initConsts():
    constants = [0.0] * sizeConstants; states = [0.0] * sizeStates;
    constants[0] = 70
    constants[1] = 0.00012
    constants[2] = 5.6
    constants[3] = 0.19
    constants[4] = 0.35
    states[0] = 10
    constants[5] = constants[0]/60.0000
    constants[6] = constants[4]*(power(1.00000*constants[5], 1.0/2))
    return (states, constants)

def computeRates(voi, states, constants):
    rates = [0.0] * sizeStates; algebraic = [0.0] * sizeAlgebraic
    rates[0] = states[0]*-3.00000
    return(rates)

def computeAlgebraic(constants, states, voi):
    algebraic = array([[0.0] * len(voi)] * sizeAlgebraic)
    states = array(states)
    voi = array(voi)
    algebraic[0] = (voi-floor(voi/constants[5])*constants[5])-constants[1]
    algebraic[1] = custom_piecewise([greater_equal(algebraic[0] , 0.00000) & less_equal(algebraic[0] , constants[6]), constants[3]+((constants[2]-constants[3])*(1.00000-cos(( pi*algebraic[0])/constants[6])))/2.00000 , less(algebraic[0] , 1.50000*constants[6]) & greater_equal(algebraic[0] , constants[6]), constants[3]+((constants[2]-constants[3])*(1.00000+cos((2.00000* pi*(algebraic[0]-constants[6]))/constants[6])))/2.00000 , True, constants[3]])
    return algebraic

def custom_piecewise(cases):
    """Compute result of a piecewise function"""
    return select(cases[0::2],cases[1::2])

def solve_model():
    """Solve model with ODE solver"""
    from scipy.integrate import ode
    # Initialise constants and state variables
    (init_states, constants) = initConsts()

    # Set timespan to solve over
    voi = linspace(0, 10, 500)

    # Construct ODE object to solve
    r = ode(computeRates)
    r.set_integrator('vode', method='bdf', atol=1e-06, rtol=1e-06, max_step=1)
    r.set_initial_value(init_states, voi[0])
    r.set_f_params(constants)

    # Solve model
    states = array([[0.0] * len(voi)] * sizeStates)
    states[:,0] = init_states
    for (i,t) in enumerate(voi[1:]):
        if r.successful():
            r.integrate(t)
            states[:,i+1] = r.y
        else:
            break

    # Compute algebraic variables
    algebraic = computeAlgebraic(constants, states, voi)
    return (voi, states, algebraic)

def plot_model(voi, states, algebraic):
    """Plot variables against variable of integration"""
    import pylab
    (legend_states, legend_algebraic, legend_voi, legend_constants) = createLegends()
    pylab.figure(1)
    pylab.plot(voi,vstack((states,algebraic)).T)
    pylab.xlabel(legend_voi)
    pylab.legend(legend_states + legend_algebraic, loc='best')
    pylab.show()

if __name__ == "__main__":
    (voi, states, algebraic) = solve_model()
    plot_model(voi, states, algebraic)