"""Measure native (M1) simulator throughput on the bundled demo firmware.

Run standalone (from anywhere):

    python3 examples/scripts/sim_bench.py            # untraced baseline
    python3 examples/scripts/sim_bench.py --trace    # baseline + R4 trace overhead

Reports MIPS for a fixed instruction budget -- the budget
``SimClient.continue_(timeout=1.0)`` derives from SIM_IPS = 1e6.  With
``--trace`` a second run enables the exec/access trace and reports the
per-instruction slowdown, so the non-trace path can be checked for regressions.
"""
from __future__ import annotations

import argparse
import sys
import time
from pathlib import Path

ROOT = Path(__file__).resolve().parents[2]
if str(ROOT) not in sys.path:
    sys.path.insert(0, str(ROOT))

import greeneye as ge
from greeneye.errors import RspTimeout
from sim.trace import Trace

DEMO = ROOT / "firmware" / "uproc_demo" / "build" / "uproc_demo.elf"


def measure(budget: int, *, trace: bool = False) -> tuple[int, float]:
    """Run a fixed instruction budget; return (instructions, seconds)."""
    session = ge.launch(kernel=str(DEMO), backend="native", name="sim-bench")
    machine = session.client.machine
    if trace:
        session.client.trace = Trace()  # recorder stays null: nothing is written
    try:
        machine.insns = 0
        started = time.perf_counter()
        try:
            session.client.continue_(timeout=budget / 1_000_000.0)
        except RspTimeout:
            pass  # budget exhausted: the benchmark workload completed
        elapsed = time.perf_counter() - started
        banner = session.target.read_uart().splitlines()
        print(f"uart: {banner[0] if banner else '<empty>'!r}")
        return machine.insns, elapsed
    finally:
        session.close()


def main(argv: list[str] | None = None) -> int:
    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
    parser.add_argument("--budget", type=int, default=1_000_000)
    parser.add_argument("--trace", action="store_true", help="also measure traced throughput")
    parser.add_argument("--trace-budget", type=int, default=200_000)
    args = parser.parse_args(argv)

    insns, elapsed = measure(args.budget)
    mips = insns / elapsed / 1e6 if elapsed else float("inf")
    print(f"native M1: {insns} instructions in {elapsed:.3f}s = {mips:.2f} MIPS (untraced)")

    if args.trace:
        t_insns, t_elapsed = measure(args.trace_budget, trace=True)
        t_mips = t_insns / t_elapsed / 1e6 if t_elapsed else float("inf")
        overhead = (mips / t_mips - 1.0) if t_mips else float("inf")
        print(
            f"native M1 trace: {t_insns} instructions in {t_elapsed:.3f}s = {t_mips:.2f} MIPS "
            f"({overhead * 100:+.1f}% per-instruction vs untraced)"
        )
    return 0


if __name__ == "__main__":
    raise SystemExit(main())