"""Monitor tools: every uptime check, and one check's failures in depth."""
from __future__ import annotations

import json

from sqlalchemy import select

from steward.models.hosts import Host
from steward.models.monitors import MONITOR_TYPE_VALUES, Monitor
from steward.models.users import UserRole
from steward.monitors import service as monitor_svc

from ._shape import (
    age_s, bounded, clamp_limit, db_session, iso, now_utc, pick, redact_url, rnd,
)

_STATES = ("up", "down", "pending", "disabled")


def _state(m: Monitor, latest) -> str:
    if not m.enabled:
        return "disabled"
    if latest is None:
        return "pending"
    return "up" if latest.is_up else "down"


def _tls_days(latest) -> float | None:
    if latest is None or latest.tls_expires_at is None:
        return None
    return rnd((latest.tls_expires_at - now_utc()).total_seconds() / 86400.0, 1)


def _row(m: Monitor, st: dict, host_names: dict[str, str]) -> dict:
    latest = st["latest"]
    return {
        "monitor_id": m.id,
        "monitor_name": m.name,
        "type": m.type,
        "target": redact_url(m.target),
        "host_id": m.host_id,
        "host_name": host_names.get(m.host_id) if m.host_id else None,
        "state": _state(m, latest),
        "down_since": iso(st["down_since"]),
        "down_for_s": age_s(st["down_since"]),
        "last_checked_at": iso(latest.checked_at) if latest else None,
        "response_ms": rnd(latest.response_ms) if latest else None,
        "error": latest.error_msg if latest is not None and not latest.is_up else None,
        "uptime_pct": st["uptime"] or {"24h": None, "7d": None, "30d": None},
        "tls_expires_in_days": _tls_days(latest),
    }


async def _load(db):
    monitors = list((await db.execute(select(Monitor).order_by(Monitor.name))).scalars())
    host_names = dict((await db.execute(select(Host.id, Host.name))).all())
    return monitors, host_names


async def list_monitors(state: str = "", type: str = "", limit: int = 100) -> dict:
    """Every uptime monitor (ping, TCP, DNS, HTTP) with its current state.

    state: "down", "up", "pending" (never checked yet) or "disabled"; empty for all.
    type: "icmp", "tcp", "dns" or "http"; empty for all.
    limit: default 100, max 500.

    Down monitors come first, each with `down_since` (when its current run of
    failures began) and the latest `error`. `uptime_pct` covers 24h/7d/30d;
    `tls_expires_in_days` is set for HTTPS checks. get_monitor shows one
    monitor's configuration and recent failures.
    """
    if state and state not in _STATES:
        raise ValueError(f"state {state!r} is not one of {', '.join(_STATES)}.")
    if type and type not in MONITOR_TYPE_VALUES:
        raise ValueError(f"type {type!r} is not one of {', '.join(MONITOR_TYPE_VALUES)}.")
    limit = clamp_limit(limit, 100, 500)
    async with db_session() as db:
        monitors, host_names = await _load(db)
        if type:
            monitors = [m for m in monitors if m.type == type]
        states = await monitor_svc.monitor_states(db, monitors)
    rows = [_row(m, states[m.id], host_names) for m in monitors]
    if state:
        rows = [r for r in rows if r["state"] == state]
    order = {"down": 0, "pending": 1, "up": 2, "disabled": 3}
    rows.sort(key=lambda r: (order[r["state"]], r["monitor_name"].lower()))
    counts = {s: 0 for s in _STATES}
    for r in rows:
        counts[r["state"]] += 1
    return {"counts": counts, **bounded(rows, limit, key="monitors",
                                        more="Pass a larger `limit`, or filter by `state` or `type`.")}


def _config(m: Monitor) -> dict:
    try:
        cfg = json.loads(m.config_json or "{}")
    except ValueError:
        return {}
    if isinstance(cfg.get("headers"), dict):
        # Header values are often credentials (Authorization, API keys).
        cfg["headers"] = {k: "<redacted>" for k in cfg["headers"]}
    return cfg


async def get_monitor(monitor: str, failures: int = 10) -> dict:
    """One monitor in depth: configuration, current state, uptime and recent failures.

    monitor: the monitor's name (case-insensitive) or id, as list_monitors shows.
    failures: how many of its latest failed checks to return (default 10, max 50),
      newest first, each with its error message.

    `heartbeat` is its last 30 checks oldest-first as a string, "+" up and "-"
    down, to show a flapping check at a glance. Header values in an HTTP
    monitor's configuration are redacted.
    """
    failures = clamp_limit(failures, 10, 50)
    async with db_session() as db:
        monitors, host_names = await _load(db)
        m = pick(monitor, monitors, kind="monitor", list_tool="list_monitors")
        st = (await monitor_svc.monitor_states(db, [m]))[m.id]
        failed = await monitor_svc.recent_failures(db, m.id, failures)
    return {
        **_row(m, st, host_names),
        "check_interval_s": m.check_interval_seconds or None,
        "config": _config(m),
        "heartbeat": "".join("+" if r.is_up else "-" for r in st["recent"]),
        "recent_failures": [
            {
                "checked_at": iso(r.checked_at),
                "age_s": age_s(r.checked_at),
                "error": r.error_msg,
                "status_code": r.status_code,
                "response_ms": rnd(r.response_ms),
            }
            for r in failed
        ],
    }


def register(register_tool) -> None:
    register_tool(list_monitors, role=UserRole.viewer, read_only=True)
    register_tool(get_monitor, role=UserRole.viewer, read_only=True)