"""
Agent / LLM 诊断日志：耗时、输入输出规模、截断预览。

- **详情**（prompt 预览 / hash / 响应预览）：仅在 ``LOG_LEVEL`` 为 ``TRACE`` / ``DEBUG`` 时通过 ``logger.debug`` 输出。
- **摘要**（单行：耗时、字符数、operation 名）：当 ``LOG_AGENT_VERBOSE=1`` 时通过 ``logger.info`` 输出，
  便于生产环境在不把全局日志调到 DEBUG 的情况下排查 Agent 性能与路径。

生产/预发建议 ``LOG_LEVEL=INFO``；需看 Agent 耗时与规模时可设 ``LOG_AGENT_VERBOSE=1``，无需长期 DEBUG。

敏感内容：DEBUG 下会记录用户相关文本；``AGENT_LOG_MAX_CHARS=0`` 时预览不截断（完整输出，慎用）。

配置（节选）：``AGENT_LOG_OMIT_SYSTEM_MESSAGE_BODY``（默认 true）省略聊天 System 正文，仅打 len+sha12；
``AGENT_LOG_JSON_PROMPT_PREFIX_CHARS`` + ``AGENT_LOG_JSON_PROMPT_PREFIX_ONLY_IF_LEN_GT`` 在 DEBUG 下跳过
超长单段 ``*.prompt`` 的前缀再预览；
``AGENT_LOG_PROMPT_MODE=hash_only`` 时 ``*.prompt`` 仅输出 sha12 + 长度，无正文；
``AGENT_LOG_PROMPT_DEDUP=1`` 时同一 label 连续相同全文则跳过重复行。
"""

from __future__ import annotations

import hashlib
import threading
import time
from contextlib import contextmanager
from typing import Any, Iterator

from opentelemetry import trace
from opentelemetry.trace import Status, StatusCode

from app.core.config import settings
from app.core.telemetry import get_tracer
from app.core.runtime_constants import agent_log_defaults

_dedup_lock = threading.Lock()
_last_prompt_sha256_by_label: dict[str, str] = {}


def _payload_sha256_hex(text: str) -> str:
    return hashlib.sha256(text.encode("utf-8", errors="replace")).hexdigest()


def _payload_sha12(text: str) -> str:
    return _payload_sha256_hex(text)[:12]


def agent_verbose_enabled() -> bool:
    """是否输出含 prompt/response 等 DEBUG 级详情。"""
    raw = (settings.log_level or "INFO").strip().upper()
    return raw in ("TRACE", "DEBUG")


def agent_summary_enabled() -> bool:
    """是否输出单行 INFO 摘要（耗时、规模等），不依赖全局 DEBUG。"""
    if agent_verbose_enabled():
        return True
    return bool(agent_log_defaults.agent_verbose)


def truncate_for_log(text: str | None, *, max_chars: int | None = None) -> str:
    """截断过长文本，避免日志爆量。max_chars / AGENT_LOG_MAX_CHARS 为 0 表示不截断。"""
    if text is None:
        return ""
    max_c = max_chars if max_chars is not None else agent_log_defaults.max_chars
    s = str(text)
    if max_c <= 0 or len(s) <= max_c:
        return s
    return s[:max_c] + f"... [truncated total_len={len(s)}]"


def log_agent_detail(
    logger: Any,
    message: str,
    *args: Any,
) -> None:
    """DEBUG 级详情（含预览时先判断 ``agent_verbose_enabled()``）。"""
    if agent_verbose_enabled():
        logger.debug(message, *args)


def log_agent_summary(
    logger: Any,
    message: str,
    *args: Any,
) -> None:
    """INFO 级单行摘要（``LOG_AGENT_VERBOSE`` 或 DEBUG 全局时启用）。"""
    if agent_summary_enabled():
        logger.info(message, *args)


@contextmanager
def agent_span(
    logger: Any,
    operation: str,
    **context: Any,
) -> Iterator[None]:
    """
    记录一段 Agent/LLM 调用的起止与耗时。
    - DEBUG：输出 context 与起止。
    - INFO（仅 ``LOG_AGENT_VERBOSE``）：仅输出结束行含 duration_ms。
    """
    t0 = time.perf_counter()
    ctx = " ".join(f"{k}={v!r}" for k, v in context.items())
    if agent_verbose_enabled():
        logger.debug("agent_span_start {} {}", operation, ctx)

    def _log_end(ms: float) -> None:
        if agent_verbose_enabled():
            logger.debug("agent_span_end {} duration_ms={:.2f} {}", operation, ms, ctx)
        elif agent_log_defaults.agent_verbose:
            logger.info("agent_span {} duration_ms={:.2f} {}", operation, ms, ctx)

    if settings.otel_enabled:
        tracer = get_tracer("app.agent")
        with tracer.start_as_current_span(
            "agent.operation",
            attributes={"agent.operation": operation},
        ) as span:
            failed = False
            try:
                yield
            except Exception:
                failed = True
                if span.is_recording():
                    span.set_status(Status(StatusCode.ERROR))
                raise
            finally:
                ms = (time.perf_counter() - t0) * 1000
                if span.is_recording():
                    span.set_attribute("agent.duration_ms", round(ms, 2))
                    if not failed:
                        span.set_status(Status(StatusCode.OK))
                _log_end(ms)
        return

    try:
        yield
    finally:
        _log_end((time.perf_counter() - t0) * 1000)


def log_agent_payload(
    logger: Any,
    label: str,
    text: str | None,
    *,
    max_chars: int | None = None,
) -> None:
    """在 DEBUG 下记录文本长度与截断预览（*.prompt 可 hash_only / 去重）。"""
    if not agent_verbose_enabled():
        return
    raw = text or ""
    total_len = len(raw)
    digest = _payload_sha256_hex(raw)
    sha12 = digest[:12]

    is_prompt = label.endswith(".prompt")
    if is_prompt and agent_log_defaults.prompt_dedup:
        with _dedup_lock:
            if _last_prompt_sha256_by_label.get(label) == digest:
                logger.debug(
                    "agent_payload_skipped label={} reason=same_as_previous sha12={} total_len={}",
                    label,
                    sha12,
                    total_len,
                )
                return
            _last_prompt_sha256_by_label[label] = digest

    preview_source = raw
    extra_note = ""
    if (
        is_prompt
        and agent_log_defaults.json_prompt_prefix_chars > 0
        and total_len > agent_log_defaults.json_prompt_prefix_only_if_len_gt
    ):
        skip = agent_log_defaults.json_prompt_prefix_chars
        preview_source = raw[skip:]
        extra_note = f" skipped_prefix_chars={skip}"

    mode = (agent_log_defaults.prompt_mode or "preview").strip().lower()
    if is_prompt and mode == "hash_only":
        logger.debug(
            "agent_payload label={} total_len={} sha12={} mode=hash_only{}",
            label,
            total_len,
            sha12,
            extra_note,
        )
        return

    preview = truncate_for_log(preview_source, max_chars=max_chars)
    logger.debug(
        "agent_payload {} total_len={}{} sha12={} preview={}",
        label,
        total_len,
        extra_note,
        sha12,
        preview,
    )