"""Synthetic one-area frequency response; the RK4 kernel is extracted from the original Lab.
50 Hz, D=1, zero initial deviation and governor output, deficit step at 2 s.
No network, voltage, saturation, deadband, secondary control or protection model.
"""
import math
import time
from frequency_kernel import frequency_values


def run(name, p):
    if name != 'frequency' or set(p) != {'inertia', 'governor', 'deficit', 'droop', 'governor_tau'}:
        raise ValueError('Unknown experiment or parameters')
    for key, low, high in [('inertia', .5, 10), ('deficit', 0, .1),
                           ('droop', .02, .1), ('governor_tau', .1, 2)]:
        value = p[key]
        if type(value) not in (int, float) or not math.isfinite(value) or not low <= value <= high:
            raise ValueError('Parameter out of range: ' + key)
    if type(p['governor']) is not bool:
        raise ValueError('Governor must be boolean')
    start = time.perf_counter()
    t, values = frequency_values(p['inertia'], p['governor'], p['deficit'], p['droop'], p['governor_tau'])
    equilibrium = 50 * (1 - p['deficit'] / (1 + 1 / p['droop'] if p['governor'] else 1))
    return dict(
        metrics=[dict(id='minimum_hz', value=float(min(values)), unit='Hz'),
                 dict(id='end_hz', value=float(values[-1]), unit='Hz'),
                 dict(id='initial_rocof', value=-50 * p['deficit'] / (2 * p['inertia']), unit='Hz/s'),
                 dict(id='equilibrium_hz', value=equilibrium, unit='Hz')],
        series=[dict(id='grid_frequency', x=t.tolist(), y=values.tolist(), x_unit='s', y_unit='Hz'),
                dict(id='nominal_frequency', x=[0, 30], y=[50, 50], x_unit='s', y_unit='Hz')],
        stdout='', provenance=dict(data_type='synthetic', compute_ms=(time.perf_counter()-start)*1000))


if __name__ == '__main__':
    import argparse
    import json
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--parameters', default='{"inertia":2,"governor":true,"deficit":0.05,"droop":0.05,"governor_tau":0.5}')
    args = parser.parse_args()
    print(json.dumps(run('frequency', json.loads(args.parameters)), allow_nan=False))