# steward/core/settings.py
"""DB-backed application settings.

Keys use dotted notation (e.g. "smtp.host").
Values are JSON-encoded in the DB.

Usage in create_app() (before event loop):
    from steward.core.settings import load_settings_sync
    settings = load_settings_sync(db_url)

Usage at runtime (inside async handlers):
    from steward.core.settings import get_setting, set_setting
    async with app.db_sessionmaker() as session:
        value = await get_setting(session, "smtp.host")
        await set_setting(session, "smtp.host", "mail.example.com")
"""
from __future__ import annotations
import asyncio
import json
import logging
from datetime import datetime, timezone
from typing import Any

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from steward.models.settings import AppSetting

logger = logging.getLogger(__name__)

_DEFAULT_WEBHOOK_TEMPLATE = (
    '{"content": "**{{ alert.state }}** — {{ alert.resource }} — '
    '{{ alert.rule_name }} ({{ alert.metric }} = {{ alert.value }})"}'
)

# All recognised settings and their defaults.
# Plugin settings are stored as "plugin.<name>" and handled separately.
DEFAULTS: dict[str, Any] = {
    # General — external URL for install scripts, share links, alert deep-links.
    # Empty = fall back to the current request's Host header.
    "general.public_base_url": "",
    "session.lifetime_hours": 8,
    "data.retention_days": 90,
    "monitors.poll_interval_seconds": 60,
    "smtp.host": "",
    "smtp.port": 587,
    "smtp.tls": True,
    "smtp.username": "",
    "smtp.password": "",
    "smtp.recipients": [],
    "webhook.url": "",
    "webhook.template": _DEFAULT_WEBHOOK_TEMPLATE,
    "ansible.sources": [],
    # Ansible credentials — global, used by every run (manual + alert-triggered).
    # ssh_private_key/become/vault are encrypted at rest (see SECRET_KEYS).
    "ansible.ssh_private_key": "",
    "ansible.become_password": "",
    "ansible.vault_password": "",
    # Public half of the managed keypair — non-secret, displayed so it can be
    # sprayed onto hosts (provisioning installs it into ~steward/.ssh).
    "ansible.ssh_public_key": "",
    # Default SSH login for steady-state runs — the dedicated account
    # provisioning creates. Acts as a floor (--user); a target's ansible_user
    # or a per-run bootstrap override still wins.
    "ansible.ssh_user": "steward",
    "ansible.host_key_checking": False,
    # Max simultaneous playbook runs; extra runs queue. Applied at app start.
    "ansible.max_concurrent_runs": 3,
    "ping.threshold.good_ms": 50,
    "ping.threshold.warn_ms": 200,
    # Degraded/critical cutoffs for metric coloring (warn=amber, crit=red).
    # cpu/mem/disk/load are percentages (load is load-per-core %); temp in °C.
    # uptime is "higher is better" so its warn/crit are floors. Ping latency
    # reuses ping.threshold.good_ms/warn_ms above.
    "thresholds.cpu_warn": 80, "thresholds.cpu_crit": 90,
    "thresholds.mem_warn": 80, "thresholds.mem_crit": 90,
    "thresholds.disk_warn": 80, "thresholds.disk_crit": 90,
    "thresholds.load_warn": 80, "thresholds.load_crit": 100,
    "thresholds.temp_warn": 70, "thresholds.temp_crit": 85,
    "thresholds.uptime_warn": 99.0, "thresholds.uptime_crit": 95.0,
    # Docker time-series retention (rule 25 — tunable, no restart). Raw 30s
    # samples are heavy, so keep a short raw window then roll up to hourly
    # averages kept much longer; lifecycle events are light, keep a month.
    "docker.retention.metrics_raw_days": 7,
    "docker.retention.metrics_rollup_days": 90,
    "docker.retention.events_days": 30,
    # Host/plugin metrics retention (plugin_metrics): keep a short raw window at
    # the agent's ~30s cadence, then roll up to hourly averages kept much longer.
    "metrics.retention.raw_days": 7,
    "metrics.retention.rollup_days": 90,
    "plugins.index_url": "https://git.fabledsword.com/bvandeusen/Steward-plugins/raw/branch/main/index.yaml",
    # Default-enabled plugins. These are the generic, non-vendor-specific
    # bundled plugins (protocols/standards, not a single product) — useful on
    # almost any install, so a fresh deployment comes up monitoring rather than
    # blank. Vendor-specific plugins (traefik, unifi) stay opt-in. An operator
    # who disables one writes plugin.<name>={"enabled": False}, which overrides
    # these defaults (stored value wins in get_all_settings/load_settings_sync).
    # Per-plugin yaml config defaults are merged on top at load time.
    "plugin.docker": {"enabled": True},
    "plugin.host_agent": {"enabled": True},
    "plugin.http": {"enabled": True},
    "plugin.snmp": {"enabled": True},
    # OIDC single-sign-on
    "oidc.enabled": False,
    "oidc.discovery_url": "",
    "oidc.client_id": "",
    "oidc.client_secret": "",
    "oidc.scopes": "openid profile email",
    "oidc.username_claim": "preferred_username",
    "oidc.email_claim": "email",
    "oidc.groups_claim": "groups",
    "oidc.admin_group": "",
    "oidc.operator_group": "",
    # LDAP authentication
    "ldap.enabled": False,
    "ldap.host": "",
    "ldap.port": 389,
    "ldap.tls": False,
    "ldap.bind_dn": "",
    "ldap.bind_password": "",
    "ldap.base_dn": "",
    "ldap.user_filter": "(uid={username})",
    "ldap.admin_group_dn": "",
    "ldap.operator_group_dn": "",
    "ldap.attr_username": "uid",
    "ldap.attr_email": "mail",
    # Scheduled reports
    "reports.enabled": False,
    "reports.schedule_day": 6,   # 0=Monday … 6=Sunday
    "reports.schedule_hour": 8,  # UTC hour
    "reports.last_sent_at": "",
}

# Settings encrypted at rest (transparent encrypt-on-write / decrypt-on-read).
# Adding a key here makes new writes ciphertext; run migrate_plaintext_secrets
# to convert any existing plaintext rows.
SECRET_KEYS: set[str] = {
    "smtp.password",
    "oidc.client_secret",
    "ldap.bind_password",
    "ansible.ssh_private_key",
    "ansible.become_password",
    "ansible.vault_password",
}


def _decode(value: Any, key: str = "") -> Any:
    """Decrypt a stored value if it's an encrypted token; else pass through.

    key is passed through to the decrypt log so a wrong-key failure names the
    exact setting that needs re-entering.
    """
    from steward.core.crypto import decrypt_secret, is_encrypted
    return decrypt_secret(value, context=key) if is_encrypted(value) else value


# Secret settings that are stored as ciphertext but won't decrypt with the
# current app key (key rotated or lost). Surfaced as an admin banner so the
# operator knows precisely which secrets to re-enter — instead of finding out
# only when something that uses one fails. Refreshed at startup
# (scan_undecryptable_secrets) and kept live: re-entering a secret clears it
# without a restart (set_setting discards it on a fresh write).
_undecryptable_secrets: set[str] = set()


def get_undecryptable_secrets() -> list[str]:
    """Sorted keys whose stored ciphertext won't decrypt (for the UI banner)."""
    return sorted(_undecryptable_secrets)


def _is_undecryptable(stored: Any, key: str = "") -> bool:
    """True iff `stored` is an encrypted token that fails to decrypt.

    A failed decrypt returns the ciphertext unchanged (still enc-prefixed), so a
    value that is still encrypted after a decrypt attempt is undecryptable.
    """
    from steward.core.crypto import decrypt_secret, is_encrypted
    return (
        isinstance(stored, str)
        and is_encrypted(stored)
        and is_encrypted(decrypt_secret(stored, context=key))
    )


# ─────────────────────────────────────────────────────────────────────────────
# Async helpers (use inside request handlers / scheduled tasks)
# ─────────────────────────────────────────────────────────────────────────────

async def get_setting(session: AsyncSession, key: str) -> Any:
    """Return the value for key, or the default if not set."""
    result = await session.execute(
        select(AppSetting).where(AppSetting.key == key)
    )
    row = result.scalar_one_or_none()
    if row is None:
        return DEFAULTS.get(key)
    return _decode(json.loads(row.value_json), key)


async def set_setting(session: AsyncSession, key: str, value: Any) -> None:
    """Upsert a setting (encrypting secret keys at rest). Call in a transaction."""
    to_store = value
    if key in SECRET_KEYS and isinstance(value, str) and value:
        from steward.core.crypto import encrypt_secret
        to_store = encrypt_secret(value)
    result = await session.execute(
        select(AppSetting).where(AppSetting.key == key)
    )
    row = result.scalar_one_or_none()
    now = datetime.now(timezone.utc)
    if row is None:
        session.add(AppSetting(key=key, value_json=json.dumps(to_store), updated_at=now))
    else:
        row.value_json = json.dumps(to_store)
        row.updated_at = now

    # A fresh write of a secret is encrypted with the current key (or cleared to
    # plaintext), so it's decryptable now — drop any stale "undecryptable" flag
    # so the banner clears without a restart.
    if key in SECRET_KEYS:
        _undecryptable_secrets.discard(key)


async def get_all_settings(session: AsyncSession) -> dict[str, Any]:
    """Return flat key→value dict with defaults filled in for missing keys."""
    result = await session.execute(select(AppSetting))
    stored = {row.key: _decode(json.loads(row.value_json), row.key) for row in result.scalars()}
    out: dict[str, Any] = {}
    for key, default in DEFAULTS.items():
        out[key] = stored.get(key, default)
    # Include any plugin.* keys stored in DB
    for key, value in stored.items():
        if key.startswith("plugin.") and key not in out:
            out[key] = value
    return out


# ─────────────────────────────────────────────────────────────────────────────
# Structured config extractors (dict shapes expected by existing consumers)
# ─────────────────────────────────────────────────────────────────────────────

def to_smtp_cfg(settings: dict[str, Any]) -> dict:
    return {
        "host": settings.get("smtp.host", ""),
        "port": settings.get("smtp.port", 587),
        "tls": settings.get("smtp.tls", True),
        "username": settings.get("smtp.username", ""),
        "password": settings.get("smtp.password", ""),
        "recipients": settings.get("smtp.recipients", []),
    }


def to_webhook_cfg(settings: dict[str, Any]) -> dict:
    return {
        "url": settings.get("webhook.url", ""),
        "template": settings.get("webhook.template", _DEFAULT_WEBHOOK_TEMPLATE),
    }


def to_ansible_cfg(settings: dict[str, Any]) -> dict:
    return {
        "sources": settings.get("ansible.sources", []),
        "ssh_private_key": settings.get("ansible.ssh_private_key", ""),
        "become_password": settings.get("ansible.become_password", ""),
        "vault_password": settings.get("ansible.vault_password", ""),
        "ssh_public_key": settings.get("ansible.ssh_public_key", ""),
        "ssh_user": settings.get("ansible.ssh_user", "steward"),
        "host_key_checking": settings.get("ansible.host_key_checking", False),
        "max_concurrent_runs": settings.get("ansible.max_concurrent_runs", 3),
    }


def to_oidc_cfg(settings: dict[str, Any]) -> dict:
    return {k[len("oidc."):]: settings.get(k, DEFAULTS[k]) for k in DEFAULTS if k.startswith("oidc.")}


def to_ldap_cfg(settings: dict[str, Any]) -> dict:
    return {k[len("ldap."):]: settings.get(k, DEFAULTS[k]) for k in DEFAULTS if k.startswith("ldap.")}


def to_thresholds_cfg(settings: dict[str, Any]) -> dict:
    """Per-metric (warn, crit, direction) policy for degraded-value coloring.

    Centralizes "what counts as degraded" so templates just name a metric kind
    via the threshold_style() jinja global. `dir` is "high" (higher is worse,
    e.g. CPU) or "low" (lower is worse, e.g. uptime %). Latency reuses the
    existing ping good/warn thresholds.
    """
    g = settings.get
    return {
        "cpu":     {"warn": g("thresholds.cpu_warn", 80),  "crit": g("thresholds.cpu_crit", 90),  "dir": "high"},
        "mem":     {"warn": g("thresholds.mem_warn", 80),  "crit": g("thresholds.mem_crit", 90),  "dir": "high"},
        "disk":    {"warn": g("thresholds.disk_warn", 80), "crit": g("thresholds.disk_crit", 90), "dir": "high"},
        "load":    {"warn": g("thresholds.load_warn", 80), "crit": g("thresholds.load_crit", 100), "dir": "high"},
        "temp":    {"warn": g("thresholds.temp_warn", 70), "crit": g("thresholds.temp_crit", 85), "dir": "high"},
        "latency": {"warn": g("ping.threshold.good_ms", 50), "crit": g("ping.threshold.warn_ms", 200), "dir": "high"},
        "uptime":  {"warn": g("thresholds.uptime_warn", 99.0), "crit": g("thresholds.uptime_crit", 95.0), "dir": "low"},
    }


def threshold_style_for(value: Any, kind: str, thresholds: dict) -> str:
    """Return an inline-style fragment (amber at warn, red at crit) for a metric.

    The Python twin of the old _macros.metric_style, but reading configurable
    cutoffs from `thresholds` (see to_thresholds_cfg) and handling both
    directions. Empty string when normal/unknown/None — drop straight into a
    span's style="".
    """
    if value is None:
        return ""
    th = thresholds.get(kind)
    if not th:
        return ""
    warn, crit, direction = th["warn"], th["crit"], th.get("dir", "high")
    if direction == "low":
        if value < crit:
            return "color:var(--red);font-weight:700;"
        if value < warn:
            return "color:var(--yellow);font-weight:600;"
    else:
        if value >= crit:
            return "color:var(--red);font-weight:700;"
        if value >= warn:
            return "color:var(--yellow);font-weight:600;"
    return ""


def to_plugins_cfg(settings: dict[str, Any]) -> dict:
    """Assemble {plugin_name: {...config}} from all plugin.* keys."""
    result = {}
    for key, value in settings.items():
        if key.startswith("plugin."):
            name = key[len("plugin."):]
            result[name] = value
    return result


# ─────────────────────────────────────────────────────────────────────────────
# Synchronous loader — safe to call before the event loop starts
# ─────────────────────────────────────────────────────────────────────────────

def load_settings_sync(db_url: str) -> dict[str, Any]:
    """Load all settings from DB synchronously via asyncio.run().

    Safe to call in create_app() before the Quart event loop starts.
    Returns flat key→value dict with defaults filled in.
    """
    async def _load() -> dict[str, Any]:
        from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker
        engine = create_async_engine(db_url, echo=False)
        factory = async_sessionmaker(engine, expire_on_commit=False)
        try:
            async with factory() as session:
                result = await session.execute(select(AppSetting))
                return {row.key: _decode(json.loads(row.value_json), row.key) for row in result.scalars()}
        finally:
            await engine.dispose()

    stored = asyncio.run(_load())
    out: dict[str, Any] = {}
    for key, default in DEFAULTS.items():
        out[key] = stored.get(key, default)
    for key, value in stored.items():
        if key.startswith("plugin.") and key not in out:
            out[key] = value
    return out


def migrate_plaintext_secrets(db_url: str) -> int:
    """Encrypt any existing plaintext secret rows in place. Idempotent.

    Returns the number of values converted. Run once at startup after the
    encryptor is initialised (already-encrypted rows are skipped).
    """
    from steward.core.crypto import encrypt_secret, is_encrypted

    async def _run() -> int:
        from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker
        engine = create_async_engine(db_url, echo=False)
        factory = async_sessionmaker(engine, expire_on_commit=False)
        converted = 0
        try:
            async with factory() as session:
                async with session.begin():
                    result = await session.execute(
                        select(AppSetting).where(AppSetting.key.in_(SECRET_KEYS))
                    )
                    for row in result.scalars():
                        val = json.loads(row.value_json)
                        if isinstance(val, str) and val and not is_encrypted(val):
                            row.value_json = json.dumps(encrypt_secret(val))
                            converted += 1
        finally:
            await engine.dispose()
        return converted

    return asyncio.run(_run())


def scan_undecryptable_secrets(db_url: str) -> list[str]:
    """Populate the undecryptable-secrets cache from the DB; return the keys found.

    Run once at startup, AFTER migrate_plaintext_secrets and init_crypto: any row
    that's encrypted but won't decrypt with the current key was sealed under a
    different (lost/rotated) key and must be re-entered. Surfaced via the admin
    banner (get_undecryptable_secrets).
    """
    async def _run() -> list[str]:
        from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker
        engine = create_async_engine(db_url, echo=False)
        factory = async_sessionmaker(engine, expire_on_commit=False)
        bad: list[str] = []
        try:
            async with factory() as session:
                result = await session.execute(
                    select(AppSetting).where(AppSetting.key.in_(SECRET_KEYS))
                )
                for row in result.scalars():
                    if _is_undecryptable(json.loads(row.value_json), row.key):
                        bad.append(row.key)
        finally:
            await engine.dispose()
        return bad

    global _undecryptable_secrets
    found = asyncio.run(_run())
    _undecryptable_secrets = set(found)
    return sorted(found)


# ─────────────────────────────────────────────────────────────────────────────
# External URL helper
# ─────────────────────────────────────────────────────────────────────────────

def public_base_url(request) -> str:
    """Return the externally-reachable base URL for this Steward instance.

    Prefers the admin-configured 'general.public_base_url' setting (cached in
    current_app.config['PUBLIC_BASE_URL']) when set. Falls back to
    request.host_url stripped of its trailing slash, so unconfigured
    single-hostname installs keep working with zero config.

    Use this — NOT request.host_url — anywhere you build a URL that will be
    consumed by something outside this Quart request: install scripts, share
    links, alert notifications, webhook callbacks. The Host header is not
    reliable behind proxies or on multi-hostname deployments.
    """
    from quart import current_app
    configured = (current_app.config.get("PUBLIC_BASE_URL") or "").strip()
    if configured:
        return configured.rstrip("/")
    return request.host_url.rstrip("/")