#!/usr/bin/env python3
"""
Benchmark latency for multiple OpenAI-compatible API groups and models.

Metrics:
- TTFT: time to first non-empty content/reasoning token
- Total latency: time until stream completion
- Output throughput: completion tokens per second when usage is available
- Success rate, median, mean, and p95 across repeated runs

Install:
    pip install -U openai

Security:
    You may store api_key directly in the JSON config, but do not commit
    that config file to Git or share it publicly.

Run:
    python kimi_latency_benchmark.py --config kimi_groups.json --repeats 5 --warmup 1
"""

from __future__ import annotations

import argparse
import csv
import json
import math
import os
import statistics
import sys
import time
from dataclasses import dataclass, asdict
from pathlib import Path
from typing import Any, Iterable

from openai import OpenAI


@dataclass
class RunResult:
    group: str
    model: str
    run_index: int
    is_warmup: bool
    success: bool
    ttft_ms: float | None
    total_ms: float | None
    completion_tokens: int | None
    tokens_per_second: float | None
    output_chars: int
    error: str


def percentile(values: list[float], p: float) -> float | None:
    if not values:
        return None
    ordered = sorted(values)
    index = max(0, min(len(ordered) - 1, math.ceil(p * len(ordered)) - 1))
    return ordered[index]


def mean_or_none(values: list[float]) -> float | None:
    return statistics.mean(values) if values else None


def median_or_none(values: list[float]) -> float | None:
    return statistics.median(values) if values else None


def fmt(value: float | None, digits: int = 1) -> str:
    return "-" if value is None else f"{value:.{digits}f}"


def get_text_from_delta(delta: Any) -> str:
    """Support both normal content and reasoning_content used by some models."""
    pieces: list[str] = []

    content = getattr(delta, "content", None)
    if isinstance(content, str):
        pieces.append(content)

    reasoning = getattr(delta, "reasoning_content", None)
    if isinstance(reasoning, str):
        pieces.append(reasoning)

    return "".join(pieces)


def create_stream(
    client: OpenAI,
    model: str,
    prompt: str,
    max_tokens: int,
    temperature: float,
    extra_body: dict[str, Any] | None,
    include_usage: bool,
):
    kwargs: dict[str, Any] = {
        "model": model,
        "messages": [{"role": "user", "content": prompt}],
        "stream": True,
        "max_tokens": max_tokens,
        "temperature": temperature,
    }
    if extra_body:
        kwargs["extra_body"] = extra_body
    if include_usage:
        kwargs["stream_options"] = {"include_usage": True}
    return client.chat.completions.create(**kwargs)


def benchmark_once(
    client: OpenAI,
    group_name: str,
    model: str,
    run_index: int,
    is_warmup: bool,
    prompt: str,
    max_tokens: int,
    temperature: float,
    extra_body: dict[str, Any] | None,
) -> RunResult:
    start = time.perf_counter()
    first_text_at: float | None = None
    output_parts: list[str] = []
    completion_tokens: int | None = None

    try:
        # First try the standard OpenAI streaming usage option.
        try:
            stream = create_stream(
                client=client,
                model=model,
                prompt=prompt,
                max_tokens=max_tokens,
                temperature=temperature,
                extra_body=extra_body,
                include_usage=True,
            )
        except Exception:
            # Some compatible gateways reject stream_options.
            stream = create_stream(
                client=client,
                model=model,
                prompt=prompt,
                max_tokens=max_tokens,
                temperature=temperature,
                extra_body=extra_body,
                include_usage=False,
            )

        for chunk in stream:
            now = time.perf_counter()

            choices = getattr(chunk, "choices", None) or []
            if choices:
                delta = getattr(choices[0], "delta", None)
                if delta is not None:
                    text = get_text_from_delta(delta)
                    if text:
                        if first_text_at is None:
                            first_text_at = now
                        output_parts.append(text)

            usage = getattr(chunk, "usage", None)
            if usage is not None:
                value = getattr(usage, "completion_tokens", None)
                if isinstance(value, int):
                    completion_tokens = value

        end = time.perf_counter()
        total_s = end - start
        ttft_ms = (
            (first_text_at - start) * 1000
            if first_text_at is not None
            else None
        )
        total_ms = total_s * 1000
        tokens_per_second = (
            completion_tokens / total_s
            if completion_tokens is not None and total_s > 0
            else None
        )

        return RunResult(
            group=group_name,
            model=model,
            run_index=run_index,
            is_warmup=is_warmup,
            success=True,
            ttft_ms=ttft_ms,
            total_ms=total_ms,
            completion_tokens=completion_tokens,
            tokens_per_second=tokens_per_second,
            output_chars=sum(len(x) for x in output_parts),
            error="",
        )

    except Exception as exc:
        end = time.perf_counter()
        return RunResult(
            group=group_name,
            model=model,
            run_index=run_index,
            is_warmup=is_warmup,
            success=False,
            ttft_ms=None,
            total_ms=(end - start) * 1000,
            completion_tokens=None,
            tokens_per_second=None,
            output_chars=0,
            error=f"{type(exc).__name__}: {exc}",
        )


def load_groups(config_path: Path) -> list[dict[str, Any]]:
    data = json.loads(config_path.read_text(encoding="utf-8"))
    if not isinstance(data, list) or not data:
        raise ValueError("配置文件顶层必须是非空 JSON 数组。")

    required = {"name", "base_url", "models"}
    for index, group in enumerate(data):
        if not isinstance(group, dict):
            raise ValueError(f"第 {index + 1} 个分组不是 JSON 对象。")

        missing = required - set(group)
        if missing:
            raise ValueError(
                f"分组 {group.get('name', index + 1)} 缺少字段：{sorted(missing)}"
            )

        if not group.get("api_key") and not group.get("api_key_env"):
            raise ValueError(
                f"分组 {group.get('name', index + 1)} 必须提供 "
                f"api_key 或 api_key_env。"
            )
    return data


def resolve_models(client: OpenAI, value: Any) -> list[str]:
    if value == "auto":
        response = client.models.list()
        return sorted(model.id for model in response.data)

    if isinstance(value, list) and all(isinstance(x, str) for x in value):
        return value

    raise ValueError('models 必须是字符串数组，或字符串 "auto"。')


def write_raw_csv(path: Path, results: Iterable[RunResult]) -> None:
    rows = [asdict(item) for item in results]
    fieldnames = list(RunResult.__annotations__.keys())
    with path.open("w", newline="", encoding="utf-8-sig") as file:
        writer = csv.DictWriter(file, fieldnames=fieldnames)
        writer.writeheader()
        writer.writerows(rows)


def build_summary(results: list[RunResult]) -> list[dict[str, Any]]:
    keys = sorted({(r.group, r.model) for r in results if not r.is_warmup})
    summary: list[dict[str, Any]] = []

    for group, model in keys:
        subset = [
            r for r in results
            if r.group == group and r.model == model and not r.is_warmup
        ]
        successes = [r for r in subset if r.success]
        ttfts = [r.ttft_ms for r in successes if r.ttft_ms is not None]
        totals = [r.total_ms for r in successes if r.total_ms is not None]
        tps_values = [
            r.tokens_per_second
            for r in successes
            if r.tokens_per_second is not None
        ]

        summary.append(
            {
                "group": group,
                "model": model,
                "runs": len(subset),
                "successes": len(successes),
                "success_rate": len(successes) / len(subset) if subset else 0.0,
                "ttft_mean_ms": mean_or_none(ttfts),
                "ttft_median_ms": median_or_none(ttfts),
                "ttft_p95_ms": percentile(ttfts, 0.95),
                "total_mean_ms": mean_or_none(totals),
                "total_median_ms": median_or_none(totals),
                "total_p95_ms": percentile(totals, 0.95),
                "tokens_per_second_mean": mean_or_none(tps_values),
            }
        )

    return summary


def write_summary_csv(path: Path, summary: list[dict[str, Any]]) -> None:
    if not summary:
        return
    with path.open("w", newline="", encoding="utf-8-sig") as file:
        writer = csv.DictWriter(file, fieldnames=list(summary[0].keys()))
        writer.writeheader()
        writer.writerows(summary)


def print_summary(summary: list[dict[str, Any]]) -> None:
    headers = [
        "Group",
        "Model",
        "Success",
        "TTFT median",
        "TTFT p95",
        "Total median",
        "Total p95",
        "Tok/s",
    ]

    rows: list[list[str]] = []
    for row in summary:
        rows.append(
            [
                str(row["group"]),
                str(row["model"]),
                f'{row["successes"]}/{row["runs"]}',
                f'{fmt(row["ttft_median_ms"])} ms',
                f'{fmt(row["ttft_p95_ms"])} ms',
                f'{fmt(row["total_median_ms"])} ms',
                f'{fmt(row["total_p95_ms"])} ms',
                fmt(row["tokens_per_second_mean"], 2),
            ]
        )

    widths = [
        max(len(headers[i]), *(len(row[i]) for row in rows))
        for i in range(len(headers))
    ]

    line = " | ".join(headers[i].ljust(widths[i]) for i in range(len(headers)))
    separator = "-+-".join("-" * width for width in widths)
    print("\n" + line)
    print(separator)
    for row in rows:
        print(" | ".join(row[i].ljust(widths[i]) for i in range(len(headers))))


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="测试多个 API 分组及模型的 TTFT 和完整响应延迟。"
    )
    parser.add_argument(
        "--config",
        default="kimi_groups.json",
        help="分组配置文件路径，默认 kimi_groups.json",
    )
    parser.add_argument(
        "--repeats",
        type=int,
        default=5,
        help="每个模型正式测试次数，默认 5",
    )
    parser.add_argument(
        "--warmup",
        type=int,
        default=1,
        help="每个模型预热次数，不计入汇总，默认 1",
    )
    parser.add_argument(
        "--max-tokens",
        type=int,
        default=64,
        help="最大输出 token 数，默认 64",
    )
    parser.add_argument(
        "--temperature",
        type=float,
        default=0.0,
        help="temperature，默认 0",
    )
    parser.add_argument(
        "--timeout",
        type=float,
        default=120.0,
        help="单次请求超时秒数，默认 120",
    )
    parser.add_argument(
        "--sleep",
        type=float,
        default=0.5,
        help="两次请求间隔秒数，默认 0.5",
    )
    parser.add_argument(
        "--prompt",
        default=(
            "请用一句简短的中文说明什么是大语言模型。"
            "不要使用项目符号，不要超过50个汉字。"
        ),
        help="所有模型使用的固定测试提示词",
    )
    parser.add_argument(
        "--output-prefix",
        default="kimi_latency",
        help="输出文件名前缀，默认 kimi_latency",
    )
    return parser.parse_args()


def main() -> int:
    args = parse_args()
    if args.repeats <= 0 or args.warmup < 0:
        print("repeats 必须大于 0，warmup 不能小于 0。", file=sys.stderr)
        return 2

    config_path = Path(args.config)
    groups = load_groups(config_path)
    all_results: list[RunResult] = []

    for group in groups:
        group_name = str(group["name"])
        api_key = str(group.get("api_key", "")).strip()
        key_env = str(group.get("api_key_env", "")).strip()

        if not api_key and key_env:
            api_key = os.getenv(key_env, "").strip()

        if not api_key:
            source_hint = (
                f"配置中的 api_key 或环境变量 {key_env}"
                if key_env
                else "配置中的 api_key"
            )
            print(
                f"\n[跳过] 分组 {group_name}: 未找到有效 Key，请检查 {source_hint}。",
                file=sys.stderr,
            )
            continue

        client = OpenAI(
            api_key=api_key,
            base_url=str(group["base_url"]).rstrip("/"),
            timeout=args.timeout,
            max_retries=0,  # 避免 SDK 自动重试掩盖真实延迟
        )

        try:
            models = resolve_models(client, group["models"])
        except Exception as exc:
            print(
                f"\n[跳过] 分组 {group_name} 获取模型列表失败："
                f"{type(exc).__name__}: {exc}",
                file=sys.stderr,
            )
            continue

        if not models:
            print(f"\n[跳过] 分组 {group_name} 没有模型。", file=sys.stderr)
            continue

        print(f"\n=== 分组：{group_name}，模型数：{len(models)} ===")
        extra_body = group.get("extra_body")
        total_runs = args.warmup + args.repeats

        for model in models:
            print(f"\n模型：{model}")
            for index in range(total_runs):
                is_warmup = index < args.warmup
                label = "warmup" if is_warmup else f"run {index - args.warmup + 1}"

                result = benchmark_once(
                    client=client,
                    group_name=group_name,
                    model=model,
                    run_index=index + 1,
                    is_warmup=is_warmup,
                    prompt=args.prompt,
                    max_tokens=args.max_tokens,
                    temperature=args.temperature,
                    extra_body=extra_body,
                )
                all_results.append(result)

                if result.success:
                    print(
                        f"  {label:<8} "
                        f"TTFT={fmt(result.ttft_ms)} ms, "
                        f"Total={fmt(result.total_ms)} ms, "
                        f"Tok/s={fmt(result.tokens_per_second, 2)}"
                    )
                else:
                    print(f"  {label:<8} ERROR: {result.error}")

                if args.sleep > 0 and index + 1 < total_runs:
                    time.sleep(args.sleep)

    if not all_results:
        print("\n没有产生测试结果。请检查配置和 API Key。", file=sys.stderr)
        return 1

    raw_path = Path(f"{args.output_prefix}_raw.csv")
    summary_path = Path(f"{args.output_prefix}_summary.csv")

    write_raw_csv(raw_path, all_results)
    summary = build_summary(all_results)
    write_summary_csv(summary_path, summary)
    print_summary(summary)

    print(f"\n原始结果：{raw_path.resolve()}")
    print(f"汇总结果：{summary_path.resolve()}")
    return 0


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