#!/usr/bin/env python3
"""Measure the resource-dependent Behaviours::load portion of client startup.

Build the behaviour_load_profile example in the checkout to be measured first:
    cargo build --release -p horizon-world --example behaviour_load_profile

Run the profiler from the repository root with the matching example binary.
This measures behaviour loading, not time to first rendered frame. With
--cache-dir, the example reads and refreshes the resolved snapshot there, as the
client does with its .horizon-cache folder: the first load of a run builds it
when it is missing, the next loads restore it.
"""
import argparse
import json
import re
import statistics
import subprocess
from pathlib import Path


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--binary", type=Path, default=Path("target/release/examples/behaviour_load_profile"))
    parser.add_argument("--resources", type=Path, default=Path(".local/horizon-client/26.3"))
    parser.add_argument("--cache-dir", type=Path,
                        help="snapshot folder (default: no snapshot, every load is uncached)")
    parser.add_argument("--repeats", type=int, default=5)
    parser.add_argument("--output", type=Path)
    args = parser.parse_args()
    if args.repeats < 1:
        parser.error("--repeats must be at least one")
    samples = []
    for _ in range(args.repeats):
        command = [str(args.binary.resolve()), str(args.resources.resolve())]
        if args.cache_dir:
            command.append(str(args.cache_dir.resolve()))
        run = subprocess.run(command, text=True, capture_output=True, check=True)
        values = {key: float(value) for key, value in
                  re.findall(r"^(registry_ms|behaviours_[0-2]_ms)=([\d.]+)$", run.stderr, re.M)}
        if len(values) != 4:
            raise RuntimeError(f"incomplete profile output: {run.stderr}")
        samples.append(values)
    summary = {key: {"median_ms": round(statistics.median(row[key] for row in samples), 3),
                     "samples_ms": [row[key] for row in samples]}
               for key in samples[0]}
    result = {"scope": "behaviour loader only; not full client startup",
              "binary": str(args.binary), "resources": str(args.resources), "repeats": args.repeats,
              "cache_dir": str(args.cache_dir) if args.cache_dir else None,
              "metrics": summary}
    print(json.dumps(result, indent=2))
    if args.output:
        args.output.parent.mkdir(parents=True, exist_ok=True)
        args.output.write_text(json.dumps(result, indent=2) + "\n")


if __name__ == "__main__":
    main()