#!/usr/bin/env python3
"""Generate a side-by-side comparison of SGLang and vLLM results.

Usage:
    python3 compare.py --sglang <sglang_result_root> --vllm <vllm_result_root> \
        [--output comparison.md]
"""
import argparse
import json
from collections import defaultdict
from pathlib import Path


def load_result(result_root: Path) -> dict:
    path = result_root / "results.json"
    with open(path, "r", encoding="utf-8") as f:
        return json.load(f)


def slo_status(ttft_p95_ms: float, tpot_mean_ms: float, ttft_limit_ms: float = 3000.0, tpot_limit_ms: float = 50.0) -> str:
    ttft_ok = ttft_p95_ms < ttft_limit_ms
    tpot_ok = tpot_mean_ms < tpot_limit_ms
    if ttft_ok and tpot_ok:
        return "✅"
    if ttft_ok or tpot_ok:
        return "⚠️"
    return "❌"


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--sglang", type=Path, required=True)
    parser.add_argument("--vllm", type=Path, required=True)
    parser.add_argument("-o", "--output", type=Path, default=Path("comparison.md"))
    parser.add_argument("--ttft-limit", type=float, default=3000.0)
    parser.add_argument("--tpot-limit", type=float, default=50.0)
    args = parser.parse_args()

    sglang_data = load_result(args.sglang)
    vllm_data = load_result(args.vllm)

    model = sglang_data.get("metadata", {}).get("model", "unknown")
    hardware = sglang_data.get("metadata", {}).get("hardware", "unknown")

    by_scenario = defaultdict(dict)
    for data in (sglang_data, vllm_data):
        backend = data["metadata"]["engine"]
        for s in data.get("scenarios", []):
            key = s["name"]
            by_scenario[key][backend] = s

    with open(args.output, "w", encoding="utf-8") as f:
        f.write(f"# SGLang vs vLLM ({hardware})\n\n")
        f.write("## Summary\n\n")
        f.write(f"- Model: `{model}`\n")
        f.write(f"- Hardware: {hardware}\n")
        f.write("- Benchmark client: `sglang.bench_serving`\n")
        f.write(f"- SLO reference: TTFT P95 < {args.ttft_limit}ms, TPOT mean < {args.tpot_limit}ms\n\n")

        f.write("## Side-by-side results\n\n")
        f.write("| Scenario | Backend | Conc | Input | Output | Req/s | OutTok/s | TTFT P95(ms) | TTFT P99(ms) | TPOT Mean(ms) | TPOT P95(ms) | TPOT P99(ms) | E2E P99(ms) | SLO |\n")
        f.write("|---|---|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|\n")

        for scenario_name in sorted(by_scenario.keys()):
            for backend in ("sglang", "vllm"):
                s = by_scenario[scenario_name].get(backend)
                if s is None:
                    continue
                cfg = s["config"]
                m = s["metrics"]
                status = slo_status(m["ttft_ms"]["p95"], m["tpot_ms"]["mean"], args.ttft_limit, args.tpot_limit)
                f.write(
                    f"| {scenario_name} | {backend} | {cfg['concurrency']} | {cfg['input_len']} | {cfg['output_len']} | "
                    f"{m['request_throughput']:.2f} | {m['output_token_throughput']:.2f} | "
                    f"{m['ttft_ms']['p95']:.2f} | {m['ttft_ms']['p99']:.2f} | "
                    f"{m['tpot_ms']['mean']:.2f} | {m['tpot_ms']['p95']:.2f} | {m['tpot_ms']['p99']:.2f} | "
                    f"{m['e2e_ms']['p99']:.2f} | {status} |\n"
                )

        f.write("\n## Notes\n\n")
        f.write("- SLO check uses TTFT P95 and TPOT mean.\n")
        f.write("- A ⚠️ indicates one of the two metrics is out of target; ❌ indicates both are out.\n")

    print(f"Wrote comparison to {args.output}")


if __name__ == "__main__":
    main()