from __future__ import annotations

import json
import os
from collections import deque
from datetime import datetime, timezone
from typing import Any

from fastapi import Request

from web.config import settings


def _audit_path() -> str:
    return settings.audit_log_file


def _ensure_parent_dir() -> None:
    parent = os.path.dirname(_audit_path())
    if parent:
        os.makedirs(parent, exist_ok=True)


def _client_ip(request: Request) -> str | None:
    forwarded = request.headers.get("x-forwarded-for")
    if forwarded:
        return forwarded.split(",")[0].strip()
    if request.client:
        return request.client.host
    return None


def _session_identity(session: dict[str, Any]) -> dict[str, Any]:
    return {
        "session_id": session.get("_session_id"),
        "adobe_user_name": session.get("adobe_user_name"),
        "adobe_user_email": session.get("adobe_user_email"),
        "adobe_account_name": session.get("adobe_account_name"),
        "adobe_account_id": session.get("adobe_account_id"),
        "docusign_user_name": session.get("docusign_user_name"),
        "docusign_user_email": session.get("docusign_user_email"),
        "docusign_account_name": session.get("docusign_selected_account_name"),
        "docusign_account_id": session.get("docusign_selected_account_id"),
    }


def request_context(request: Request) -> dict[str, Any]:
    return {
        "path": str(request.url.path),
        "method": request.method,
        "ip": _client_ip(request),
        "user_agent": request.headers.get("user-agent"),
    }


def build_event_with_context(
    context: dict[str, Any],
    session: dict[str, Any],
    action: str,
    details: dict[str, Any] | None = None,
) -> dict[str, Any]:
    event = {
        "timestamp": datetime.now(timezone.utc).isoformat(),
        "action": action,
        "path": context.get("path"),
        "method": context.get("method"),
        "ip": context.get("ip"),
        "user_agent": context.get("user_agent"),
        **_session_identity(session),
    }
    if details:
        event["details"] = details
    return event


def build_event(request: Request, session: dict[str, Any], action: str, details: dict[str, Any] | None = None) -> dict[str, Any]:
    return build_event_with_context(request_context(request), session, action, details)


def log_event(request: Request, session: dict[str, Any], action: str, details: dict[str, Any] | None = None) -> dict[str, Any]:
    event = build_event(request, session, action, details)
    _ensure_parent_dir()
    with open(_audit_path(), "a", encoding="utf-8") as f:
        f.write(json.dumps(event, ensure_ascii=True) + "\n")
    return event


def log_context_event(
    context: dict[str, Any],
    session: dict[str, Any],
    action: str,
    details: dict[str, Any] | None = None,
) -> dict[str, Any]:
    event = build_event_with_context(context, session, action, details)
    _ensure_parent_dir()
    with open(_audit_path(), "a", encoding="utf-8") as f:
        f.write(json.dumps(event, ensure_ascii=True) + "\n")
    return event


def recent_events(limit: int = 100) -> list[dict[str, Any]]:
    path = _audit_path()
    if not os.path.exists(path):
        return []

    lines: deque[str] = deque(maxlen=max(1, min(limit, 500)))
    with open(path, encoding="utf-8") as f:
        for line in f:
            line = line.strip()
            if line:
                lines.append(line)

    events: list[dict[str, Any]] = []
    for line in reversed(lines):
        try:
            item = json.loads(line)
        except json.JSONDecodeError:
            continue
        if isinstance(item, dict):
            events.append(item)
    return events