# plugins/host_agent/routes.py
from __future__ import annotations

import hashlib
from datetime import datetime, timezone
from typing import Any

from pathlib import Path

import secrets
from quart import Blueprint, current_app, jsonify, request, Response, render_template, redirect, url_for
from roundtable.auth.middleware import require_role
from roundtable.models.users import UserRole
from sqlalchemy import select, func
from datetime import timedelta

from roundtable.core.settings import public_base_url
from roundtable.models.hosts import Host
from roundtable.models.metrics import PluginMetric
from .models import HostAgentRegistration

host_agent_bp = Blueprint("host_agent", __name__, template_folder="templates")

SOURCE_MODULE = "host_agent"


def _hash_token(raw: str) -> str:
    return hashlib.sha256(raw.encode("utf-8")).hexdigest()


def _parse_ts(ts: str) -> datetime:
    if ts.endswith("Z"):
        ts = ts[:-1] + "+00:00"
    return datetime.fromisoformat(ts)


def _expand_sample_to_metrics(
    sample: dict, host_name: str, recorded_at: datetime
) -> list[PluginMetric]:
    rows: list[PluginMetric] = []

    def row(metric: str, resource: str, value: float) -> None:
        rows.append(PluginMetric(
            source_module=SOURCE_MODULE,
            resource_name=resource,
            metric_name=metric,
            value=float(value),
            recorded_at=recorded_at,
        ))

    if sample.get("cpu_pct") is not None:
        row("cpu_pct", host_name, sample["cpu_pct"])

    mem = sample.get("mem") or {}
    if mem.get("total_bytes"):
        total = mem["total_bytes"]
        available = mem.get("available_bytes", 0)
        used_pct = 100.0 * (total - available) / total if total else 0.0
        row("mem_used_pct", host_name, used_pct)
        row("mem_available_bytes", host_name, available)
        row("swap_used_bytes", host_name, mem.get("swap_used_bytes", 0))

    load = sample.get("load") or {}
    for key in ("1m", "5m", "15m"):
        if key in load:
            row(f"load_{key}", host_name, load[key])

    if sample.get("uptime_secs") is not None:
        row("uptime_secs", host_name, sample["uptime_secs"])

    worst_pct = 0.0
    for disk in sample.get("storage") or []:
        total = disk.get("total_bytes", 0)
        used = disk.get("used_bytes", 0)
        pct = 100.0 * used / total if total else 0.0
        mount_res = f"{host_name}:{disk['mount']}"
        row("disk_used_pct", mount_res, pct)
        row("disk_used_bytes", mount_res, used)
        row("disk_total_bytes", mount_res, total)
        if pct > worst_pct:
            worst_pct = pct
    if sample.get("storage"):
        row("disk_used_pct_worst", host_name, worst_pct)

    return rows


def _error(status: int, code: str, detail: str | None = None) -> tuple[Any, int]:
    body: dict = {"ok": False, "error": code}
    if detail:
        body["detail"] = detail
    return jsonify(body), status


@host_agent_bp.post("/ingest")
async def ingest():
    auth = request.headers.get("Authorization", "")
    if not auth.startswith("Bearer "):
        return _error(401, "invalid_token")
    raw = auth[len("Bearer "):].strip()
    if not raw:
        return _error(401, "invalid_token")

    try:
        payload = await request.get_json(force=True)
    except Exception:
        return _error(400, "malformed_payload", "invalid JSON")
    if not isinstance(payload, dict) or "samples" not in payload:
        return _error(400, "malformed_payload", "missing 'samples'")

    samples = payload.get("samples") or []
    if not isinstance(samples, list) or not samples:
        return _error(400, "malformed_payload", "'samples' must be a non-empty list")

    token_hash = _hash_token(raw)
    async with current_app.db_sessionmaker() as session:
        reg = (await session.execute(
            select(HostAgentRegistration).where(
                HostAgentRegistration.token_hash == token_hash)
        )).scalar_one_or_none()
        if reg is None:
            return _error(401, "invalid_token")
        host = (await session.execute(
            select(Host).where(Host.id == reg.host_id)
        )).scalar_one_or_none()
        if host is None:
            return _error(401, "invalid_token")

        accepted = 0
        latest_ts: datetime | None = None
        for sample in samples:
            try:
                recorded_at = _parse_ts(sample["ts"])
            except (KeyError, ValueError):
                continue
            metrics = _expand_sample_to_metrics(sample, host.name, recorded_at)
            for m in metrics:
                session.add(m)
            accepted += 1
            if latest_ts is None or recorded_at > latest_ts:
                latest_ts = recorded_at

        if accepted == 0:
            await session.rollback()
            return _error(400, "malformed_payload", "no valid samples")

        md = payload.get("metadata") or {}
        changed = False
        if latest_ts and (reg.last_seen_at is None or latest_ts > reg.last_seen_at):
            reg.last_seen_at = latest_ts
            changed = True
        version = payload.get("agent_version")
        if version and reg.agent_version != version:
            reg.agent_version = version
            changed = True
        for field in ("kernel", "distro", "arch"):
            if field in md and getattr(reg, field) != md[field]:
                setattr(reg, field, md[field])
                changed = True
        if changed:
            reg.updated_at = datetime.now(timezone.utc)

        if latest_ts:
            skew = abs((datetime.now(timezone.utc) - latest_ts).total_seconds())
            if skew > 300:
                current_app.logger.warning(
                    "host_agent ingest: clock skew %.0fs for host=%s", skew, host.name)

        await session.commit()

    return jsonify({"ok": True, "samples_accepted": accepted}), 200


AGENT_SOURCE_PATH = Path(__file__).parent / "agent.py"


def _agent_version() -> str:
    try:
        for line in AGENT_SOURCE_PATH.read_text().splitlines():
            if line.startswith("AGENT_VERSION"):
                return line.split("=", 1)[1].strip().strip('"').strip("'")
    except OSError:
        pass
    return "unknown"


@host_agent_bp.get("/install.sh")
async def install_script():
    token = request.args.get("token", "")
    if not token:
        return _error(401, "invalid_token")
    async with current_app.db_sessionmaker() as session:
        reg = (await session.execute(
            select(HostAgentRegistration).where(
                HostAgentRegistration.token_hash == _hash_token(token))
        )).scalar_one_or_none()
        if reg is None:
            return _error(401, "invalid_token")
        host = (await session.execute(
            select(Host).where(Host.id == reg.host_id)
        )).scalar_one_or_none()
        if host is None:
            return _error(401, "invalid_token")

    url = public_base_url(request)

    rendered = await render_template(
        "install.sh.j2",
        url=url,
        token=token,
        agent_version=_agent_version(),
        host_name=host.name,
        host_address=host.address,
    )
    return Response(rendered, mimetype="text/plain")


@host_agent_bp.get("/agent.py")
async def agent_source():
    try:
        body = AGENT_SOURCE_PATH.read_text(encoding="utf-8")
    except OSError:
        return _error(500, "agent_missing")
    return Response(body, mimetype="text/x-python")


@host_agent_bp.get("/widget")
async def widget_table():
    """Fleet-glance table: one row per monitored host, latest metrics."""
    async with current_app.db_sessionmaker() as session:
        regs = (await session.execute(select(HostAgentRegistration))).scalars().all()
        host_ids = [r.host_id for r in regs]
        hosts = {
            h.id: h for h in (await session.execute(
                select(Host).where(Host.id.in_(host_ids))
            )).scalars().all()
        } if host_ids else {}

        subq = (
            select(
                PluginMetric.resource_name,
                PluginMetric.metric_name,
                func.max(PluginMetric.recorded_at).label("max_ts"),
            )
            .where(PluginMetric.source_module == SOURCE_MODULE)
            .group_by(PluginMetric.resource_name, PluginMetric.metric_name)
        ).subquery()
        latest_rows = (await session.execute(
            select(PluginMetric).join(
                subq,
                (PluginMetric.resource_name == subq.c.resource_name) &
                (PluginMetric.metric_name == subq.c.metric_name) &
                (PluginMetric.recorded_at == subq.c.max_ts),
            ).where(PluginMetric.source_module == SOURCE_MODULE)
        )).scalars().all()

    latest: dict[str, dict[str, float]] = {}
    for row in latest_rows:
        if ":" in row.resource_name:
            continue
        latest.setdefault(row.resource_name, {})[row.metric_name] = row.value

    rows = []
    for reg in regs:
        host = hosts.get(reg.host_id)
        if host is None:
            continue
        m = latest.get(host.name, {})
        rows.append({
            "host": host,
            "reg": reg,
            "cpu_pct": m.get("cpu_pct"),
            "mem_used_pct": m.get("mem_used_pct"),
            "disk_worst": m.get("disk_used_pct_worst"),
            "load_1m": m.get("load_1m"),
        })

    return await render_template("widget_table.html", rows=rows)


@host_agent_bp.get("/widget/history")
async def widget_history():
    host_id = request.args.get("host_id", "")
    hours = int(request.args.get("hours", "6"))
    cutoff = datetime.now(timezone.utc) - timedelta(hours=hours)

    async with current_app.db_sessionmaker() as session:
        host = (await session.execute(
            select(Host).where(Host.id == host_id))).scalar_one_or_none()
        if host is None:
            return _error(404, "not_found")
        points = (await session.execute(
            select(PluginMetric).where(
                PluginMetric.source_module == SOURCE_MODULE,
                PluginMetric.resource_name == host.name,
                PluginMetric.metric_name.in_(
                    ("cpu_pct", "mem_used_pct", "disk_used_pct_worst")),
                PluginMetric.recorded_at >= cutoff,
            ).order_by(PluginMetric.recorded_at)
        )).scalars().all()

    series: dict[str, list[dict]] = {"cpu_pct": [], "mem_used_pct": [], "disk_used_pct_worst": []}
    for p in points:
        series[p.metric_name].append({"t": p.recorded_at.isoformat(), "v": p.value})

    return await render_template("widget_history.html", host=host, series=series, hours=hours)


def _new_token_pair() -> tuple[str, str]:
    raw = secrets.token_urlsafe(32)
    return raw, _hash_token(raw)


@host_agent_bp.get("/settings/")
@require_role(UserRole.admin)
async def settings_list():
    async with current_app.db_sessionmaker() as session:
        regs = (await session.execute(select(HostAgentRegistration))).scalars().all()
        hosts_by_id = {
            h.id: h for h in (await session.execute(
                select(Host).where(Host.id.in_([r.host_id for r in regs])))).scalars().all()
        } if regs else {}

    new_token = request.args.get("new_token")
    new_host_id = request.args.get("host_id")
    install_url = None
    if new_token and new_host_id:
        install_url = f"{public_base_url(request)}/plugins/host_agent/install.sh?token={new_token}"

    return await render_template(
        "settings_list.html",
        registrations=[
            {"reg": r, "host": hosts_by_id.get(r.host_id)} for r in regs
        ],
        new_token=new_token,
        install_url=install_url,
    )


@host_agent_bp.post("/settings/add-host")
@require_role(UserRole.admin)
async def add_host():
    form = await request.form
    name = (form.get("name") or "").strip()
    address = (form.get("address") or "").strip()
    if not name:
        return _error(400, "missing_name")

    async with current_app.db_sessionmaker() as session:
        host = (await session.execute(
            select(Host).where(Host.name == name))).scalar_one_or_none()
        if host is None:
            host = Host(name=name, address=address)
            session.add(host)
            await session.flush()
        existing = (await session.execute(
            select(HostAgentRegistration).where(
                HostAgentRegistration.host_id == host.id))).scalar_one_or_none()
        if existing is not None:
            await session.rollback()
            return _error(400, "already_registered")

        raw, hashed = _new_token_pair()
        reg = HostAgentRegistration(host_id=host.id, token_hash=hashed)
        session.add(reg)
        await session.commit()
        host_id = host.id

    return redirect(url_for("host_agent.settings_list") + f"?new_token={raw}&host_id={host_id}")


@host_agent_bp.post("/settings/<host_id>/rotate-token")
@require_role(UserRole.admin)
async def rotate_token(host_id: str):
    async with current_app.db_sessionmaker() as session:
        reg = (await session.execute(
            select(HostAgentRegistration).where(
                HostAgentRegistration.host_id == host_id))).scalar_one_or_none()
        if reg is None:
            return _error(404, "not_found")
        raw, hashed = _new_token_pair()
        reg.token_hash = hashed
        reg.token_created_at = datetime.now(timezone.utc)
        await session.commit()
    return redirect(url_for("host_agent.settings_list") + f"?new_token={raw}&host_id={host_id}")


@host_agent_bp.post("/settings/<host_id>/delete")
@require_role(UserRole.admin)
async def delete_registration(host_id: str):
    async with current_app.db_sessionmaker() as session:
        reg = (await session.execute(
            select(HostAgentRegistration).where(
                HostAgentRegistration.host_id == host_id))).scalar_one_or_none()
        if reg is not None:
            await session.delete(reg)
            await session.commit()
    return redirect(url_for("host_agent.settings_list"))