#!/usr/bin/env python3
"""Generate a side-by-side comparison of vLLM+MTP speculative decoding and vLLM default.

Usage:
    python3 compare.py --mtp <mtp_result_root> --default <default_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 main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--mtp", type=Path, required=True)
    parser.add_argument("--default", type=Path, required=True)
    parser.add_argument("-o", "--output", type=Path, default=Path("comparison.md"))
    args = parser.parse_args()

    mtp_data = load_result(args.mtp)
    default_data = load_result(args.default)

    by_scenario = defaultdict(dict)
    for data in (mtp_data, default_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("# vLLM+MTP speculative decoding vs vLLM default on DeepSeek-V4-Flash (H200, TP=8)\n\n")
        f.write("## Summary\n\n")
        f.write("- Model: `/data/models/DeepSeek-V4-Flash`\n")
        f.write("- Hardware: 8x NVIDIA H200 143GB\n")
        f.write("- Tensor Parallelism: 8\n")
        f.write("- Benchmark client: `sglang.bench_serving --backend vllm`\n")
        f.write("- Default: no speculative decoding\n")
        f.write("- MTP: `--speculative-config '{\\\"method\\\":\\\"mtp\\\",\\\"num_speculative_tokens\\\":1}'` (official DeepSeek-V4 recipe)\n\n")

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

        for scenario_name in sorted(by_scenario.keys()):
            for backend in ("vllm-mtp", "vllm-default"):
                s = by_scenario[scenario_name].get(backend)
                if s is None:
                    continue
                cfg = s["config"]
                m = s["metrics"]
                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']['mean']:.2f} | {m['ttft_ms']['p95']:.2f} | {m['ttft_ms']['p99']:.2f} | "
                    f"{m['tpot_ms']['mean']:.2f} | {m['tpot_ms']['p99']:.2f} | "
                    f"{m['e2e_ms']['mean']:.2f} |\n"
                )

        f.write("\n## Notes\n\n")
        f.write("- TTFT mean/P95/P99 are the main focus for verifying MTP's impact on time-to-first-token.\n")
        f.write("- Mean TPOT and E2E are included to check whether speculative decoding pays back after first token.\n")

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


if __name__ == "__main__":
    main()