from __future__ import annotations
import hashlib
import json
import secrets
from datetime import datetime, timezone, timedelta
from urllib.parse import urlencode
from quart import Blueprint, render_template, current_app, abort, redirect, request, session
from sqlalchemy import select, func, update
from steward.auth.middleware import require_role, current_user_id
from steward.models.users import UserRole
from steward.models.hosts import Host
from steward.models.dashboard import Dashboard, DashboardWidget, DashboardShareToken
from steward.core.settings import public_base_url
from steward.core.widgets import get_available_widgets, WIDGET_REGISTRY

dashboard_bp = Blueprint("dashboard", __name__)


# ── Access helpers ────────────────────────────────────────────────────────────

def _can_view(dash: Dashboard, user_id: str, user_role: str) -> bool:
    if user_role == UserRole.admin:
        return True
    if dash.owner_id is None:       # system dashboard
        return True
    if dash.owner_id == user_id:    # own dashboard
        return True
    return dash.is_shared           # shared by another user


def _can_edit(dash: Dashboard, user_id: str, user_role: str) -> bool:
    if user_role == UserRole.admin:
        return True
    return dash.owner_id == user_id


# ── DB helpers ────────────────────────────────────────────────────────────────

async def _get_widgets(db, dashboard_id: int) -> list[DashboardWidget]:
    # Reading order = grid order (top-to-bottom, then left-to-right). This drives
    # DOM order, which is what the responsive single-column fallback collapses to.
    result = await db.execute(
        select(DashboardWidget)
        .where(DashboardWidget.dashboard_id == dashboard_id)
        .order_by(DashboardWidget.grid_y, DashboardWidget.grid_x, DashboardWidget.id)
    )
    return list(result.scalars())


async def _accessible_dashboards(db, user_id: str, user_role: str) -> list[Dashboard]:
    """All dashboards visible to this user, ordered by id."""
    result = await db.execute(select(Dashboard).order_by(Dashboard.id))
    all_dashes = list(result.scalars())
    return [d for d in all_dashes if _can_view(d, user_id, user_role)]


async def _resolve_default(db, user_id: str, user_role: str) -> Dashboard | None:
    """
    1. User's own dashboard with is_default=True
    2. System dashboard (owner_id=None) with is_default=True
    3. First accessible dashboard
    """
    result = await db.execute(
        select(Dashboard)
        .where(Dashboard.owner_id == user_id, Dashboard.is_default.is_(True))
        .limit(1)
    )
    dash = result.scalar_one_or_none()
    if dash:
        return dash

    result = await db.execute(
        select(Dashboard)
        .where(Dashboard.owner_id.is_(None), Dashboard.is_default.is_(True))
        .limit(1)
    )
    dash = result.scalar_one_or_none()
    if dash:
        return dash

    accessible = await _accessible_dashboards(db, user_id, user_role)
    return accessible[0] if accessible else None


async def _get_or_create_system_default(db) -> Dashboard:
    """Ensure a system (owner_id=None) default dashboard exists."""
    result = await db.execute(
        select(Dashboard).where(Dashboard.owner_id.is_(None)).limit(1)
    )
    dash = result.scalar_one_or_none()
    if dash is None:
        dash = Dashboard(name="Default", owner_id=None, is_default=True, is_shared=True)
        db.add(dash)
        await db.flush()
        plugins_cfg = current_app.config.get("PLUGINS", {})
        # Seed a 3-up grid (each widget 4 cols wide x 4 cells tall on the 12-col grid).
        for pos, w in enumerate(get_available_widgets(plugins_cfg)):
            db.add(DashboardWidget(
                dashboard_id=dash.id, widget_key=w["key"],
                grid_x=(pos % 3) * 4, grid_y=(pos // 3) * 4, grid_w=4, grid_h=4,
            ))
    return dash


def _resolve_widgets(widgets: list[DashboardWidget]) -> list[dict]:
    plugins_cfg = current_app.config.get("PLUGINS", {})
    out = []
    for w in widgets:
        defn = WIDGET_REGISTRY.get(w.widget_key)
        if defn is None:
            continue
        if defn["plugin"] and not plugins_cfg.get(defn["plugin"], {}).get("enabled", False):
            continue
        # Build stored config (falls back to empty; defaults live in the registry)
        config: dict = {}
        if w.config_json:
            try:
                config = json.loads(w.config_json)
            except (ValueError, TypeError):
                pass
        # Always append wid so widget templates can create unique canvas IDs
        url_params = {**config, "wid": w.id}
        hx_url = defn["hx_url"] + "?" + urlencode(url_params)
        out.append({
            "db": w,
            "defn": defn,
            "hx_url": hx_url,
            "title": w.title or defn["label"],
        })
    return out


# ── Edit panel helpers ────────────────────────────────────────────────────────

# ── Root redirect ─────────────────────────────────────────────────────────────

@dashboard_bp.get("/")
@require_role(UserRole.viewer)
async def index():
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            await _get_or_create_system_default(db)
        dash = await _resolve_default(db, user_id, user_role)
    if dash is None:
        abort(404)
    return redirect(f"/d/{dash.id}")


# ── Dashboard view ────────────────────────────────────────────────────────────

@dashboard_bp.get("/d/<int:dash_id>")
@require_role(UserRole.viewer)
async def view(dash_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")

    async with current_app.db_sessionmaker() as db:
        result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
        dash   = result.scalar_one_or_none()
        if dash is None or not _can_view(dash, user_id, user_role):
            abort(404)

        widgets    = await _get_widgets(db, dash_id)
        accessible = await _accessible_dashboards(db, user_id, user_role)
        can_edit   = _can_edit(dash, user_id, user_role)
        # Editors get the bottom-drawer picker (available widgets + host list);
        # viewers/shared-readers don't, so skip the extra queries for them.
        if can_edit:
            plugins_cfg = current_app.config.get("PLUGINS", {})
            addable = get_available_widgets(plugins_cfg)
            hosts   = list((await db.execute(select(Host).order_by(Host.name))).scalars())
        else:
            addable, hosts = [], []

    resolved      = _resolve_widgets(widgets)
    poll_interval = current_app.config.get("MONITORS_POLL_INTERVAL", 60)

    return await render_template(
        "dashboard/index.html",
        dashboard=dash,
        all_dashboards=accessible,
        widgets=resolved,
        poll_interval=poll_interval,
        can_edit=can_edit,
        addable=addable,
        hosts=hosts,
    )


# ── Dashboard management ──────────────────────────────────────────────────────

@dashboard_bp.get("/dashboards/")
@require_role(UserRole.viewer)
async def list_dashboards():
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")

    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            await _get_or_create_system_default(db)
        accessible = await _accessible_dashboards(db, user_id, user_role)

    my_dashes     = [d for d in accessible if d.owner_id == user_id]
    shared_dashes = [d for d in accessible if d.owner_id != user_id]

    return await render_template(
        "dashboard/list.html",
        my_dashboards=my_dashes,
        shared_dashboards=shared_dashes,
        user_id=user_id,
        user_role=user_role,
    )


@dashboard_bp.post("/dashboards/create")
@require_role(UserRole.viewer)
async def create_dashboard():
    user_id = current_user_id()
    form    = await request.form
    name    = (form.get("name") or "New Dashboard").strip()[:128]
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            dash = Dashboard(name=name, owner_id=user_id, is_default=False, is_shared=False)
            db.add(dash)
            await db.flush()
            dash_id = dash.id
    # Open the new (empty) dashboard straight into edit mode to add widgets.
    return redirect(f"/d/{dash_id}?edit=1")


@dashboard_bp.post("/dashboards/<int:dash_id>/rename")
@require_role(UserRole.viewer)
async def rename_dashboard(dash_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    form      = await request.form
    name      = (form.get("name") or "").strip()[:128]
    if name:
        async with current_app.db_sessionmaker() as db:
            async with db.begin():
                result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
                dash   = result.scalar_one_or_none()
                if dash and _can_edit(dash, user_id, user_role):
                    dash.name = name
    return redirect("/dashboards/")


@dashboard_bp.post("/dashboards/<int:dash_id>/toggle-share")
@require_role(UserRole.viewer)
async def toggle_share(dash_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
            dash   = result.scalar_one_or_none()
            if dash and _can_edit(dash, user_id, user_role):
                dash.is_shared = not dash.is_shared
    return redirect("/dashboards/")


@dashboard_bp.post("/dashboards/<int:dash_id>/set-default")
@require_role(UserRole.viewer)
async def set_default_dashboard(dash_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
            dash   = result.scalar_one_or_none()
            if dash is None or not _can_view(dash, user_id, user_role):
                abort(404)
            # Clear is_default on all dashboards this user owns
            await db.execute(
                update(Dashboard)
                .where(Dashboard.owner_id == user_id)
                .values(is_default=False)
            )
            # If setting a system/shared dashboard as default, we instead create
            # a personal preference record by marking the system one (safe since
            # system dashboards are shared — the flag just signals this user's preference)
            dash.is_default = True
    return redirect("/dashboards/")


@dashboard_bp.post("/dashboards/<int:dash_id>/delete")
@require_role(UserRole.viewer)
async def delete_dashboard(dash_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
            dash   = result.scalar_one_or_none()
            if dash is None or not _can_edit(dash, user_id, user_role):
                abort(403)
            # Count remaining owned by this user (don't delete their last one if any)
            owned_count = (await db.execute(
                select(func.count()).select_from(Dashboard)
                .where(Dashboard.owner_id == user_id)
            )).scalar()
            if dash.owner_id == user_id and owned_count <= 1:
                pass  # refuse to delete user's last owned dashboard
            else:
                await db.delete(dash)
    return redirect("/dashboards/")


# ── Dashboard edit (in-place over the live dashboard) ─────────────────────────

@dashboard_bp.post("/d/<int:dash_id>/edit/add/<widget_key>")
@require_role(UserRole.viewer)
async def add_widget(dash_id: int, widget_key: str):
    """Add a widget and return its single grid-item HTML for in-place insertion."""
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    defn = WIDGET_REGISTRY.get(widget_key)
    if defn is None:
        abort(400)
    form = await request.form
    title = form.get("title", "").strip() or None
    # Parse configured params
    config: dict = {}
    for p in defn.get("params", []):
        val = form.get(f"param_{p['key']}")
        if val is not None:
            if isinstance(p["default"], int):
                try:
                    config[p["key"]] = int(val)
                except ValueError:
                    config[p["key"]] = p["default"]
            else:
                config[p["key"]] = val
    config_json = json.dumps(config) if config else None
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
            dash   = result.scalar_one_or_none()
            if dash is None or not _can_edit(dash, user_id, user_role):
                abort(403)
            widgets = await _get_widgets(db, dash_id)
            # Append below everything at full-left; the user then drags/resizes.
            next_y = max((w.grid_y + w.grid_h for w in widgets), default=0)
            new = DashboardWidget(
                dashboard_id=dash_id, widget_key=widget_key,
                grid_x=0, grid_y=next_y, grid_w=4, grid_h=4,
                title=title, config_json=config_json,
            )
            db.add(new)
            await db.flush()
            new_id = new.id
        new = (await db.execute(
            select(DashboardWidget).where(DashboardWidget.id == new_id))).scalar_one()
        resolved = _resolve_widgets([new])
    if not resolved:
        return ("", 204)
    poll_interval = current_app.config.get("MONITORS_POLL_INTERVAL", 60)
    return await render_template(
        "dashboard/_grid_item.html",
        item=resolved[0], poll_interval=poll_interval, can_edit=True,
    )


@dashboard_bp.post("/d/<int:dash_id>/edit/remove/<int:widget_id>")
@require_role(UserRole.viewer)
async def remove_widget(dash_id: int, widget_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
            dash   = result.scalar_one_or_none()
            if dash is None or not _can_edit(dash, user_id, user_role):
                abort(403)
            result = await db.execute(
                select(DashboardWidget).where(DashboardWidget.id == widget_id)
            )
            widget = result.scalar_one_or_none()
            if widget and widget.dashboard_id == dash_id:
                await db.delete(widget)
    # Client removes the DOM/grid item itself; nothing to render back.
    return ("", 204)


@dashboard_bp.post("/d/<int:dash_id>/edit/layout")
@require_role(UserRole.viewer)
async def save_layout(dash_id: int):
    """Persist the drag-resize grid (Gridstack) — one {id,x,y,w,h} per widget."""
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    data = await request.get_json(silent=True)
    if not data or not isinstance(data.get("items"), list):
        abort(400)
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
            dash   = result.scalar_one_or_none()
            if dash is None or not _can_edit(dash, user_id, user_role):
                abort(403)
            widget_map = {w.id: w for w in await _get_widgets(db, dash_id)}
            for it in data["items"]:
                if not isinstance(it, dict):
                    continue
                w = widget_map.get(it.get("id"))
                if w is None:
                    continue
                try:
                    # Clamp to the 12-col grid; widths can't exceed it.
                    w.grid_x = max(0, min(11, int(it["x"])))
                    w.grid_w = max(1, min(12, int(it["w"])))
                    w.grid_y = max(0, int(it["y"]))
                    w.grid_h = max(1, int(it["h"]))
                except (KeyError, TypeError, ValueError):
                    continue
    return ("", 204)


# ── Share tokens ──────────────────────────────────────────────────────────────

@dashboard_bp.get("/d/<int:dash_id>/share")
@require_role(UserRole.viewer)
async def manage_share_tokens(dash_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
        dash   = result.scalar_one_or_none()
        if dash is None or not _can_edit(dash, user_id, user_role):
            abort(403)
        result = await db.execute(
            select(DashboardShareToken)
            .where(DashboardShareToken.dashboard_id == dash_id)
            .order_by(DashboardShareToken.created_at.desc())
        )
        tokens = list(result.scalars())
    now = datetime.now(timezone.utc)
    return await render_template(
        "dashboard/share.html",
        dashboard=dash, tokens=tokens, now=now,
    )


@dashboard_bp.post("/d/<int:dash_id>/share/create")
@require_role(UserRole.viewer)
async def create_share_token(dash_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
        dash   = result.scalar_one_or_none()
        if dash is None or not _can_edit(dash, user_id, user_role):
            abort(403)

    form       = await request.form
    label      = (form.get("label") or "").strip()[:128]
    expires_in = form.get("expires_in", "")

    expires_at = None
    if expires_in.isdigit() and int(expires_in) > 0:
        expires_at = datetime.now(timezone.utc) + timedelta(days=int(expires_in))

    raw_token  = secrets.token_urlsafe(32)
    token_hash = hashlib.sha256(raw_token.encode()).hexdigest()

    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            db.add(DashboardShareToken(
                dashboard_id=dash_id,
                token_hash=token_hash,
                label=label,
                expires_at=expires_at,
                created_by=user_id,
                created_at=datetime.now(timezone.utc),
            ))

    async with current_app.db_sessionmaker() as db:
        result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
        dash   = result.scalar_one_or_none()

    share_url = f"{public_base_url(request)}/share/{raw_token}"
    return await render_template(
        "dashboard/share_created.html",
        dashboard=dash,
        raw_token=raw_token,
        label=label,
        expires_at=expires_at,
        share_url=share_url,
    )


@dashboard_bp.post("/d/<int:dash_id>/share/revoke/<int:token_id>")
@require_role(UserRole.viewer)
async def revoke_share_token(dash_id: int, token_id: int):
    user_id   = current_user_id()
    user_role = session.get("user_role", "viewer")
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(Dashboard).where(Dashboard.id == dash_id))
            dash   = result.scalar_one_or_none()
            if dash is None or not _can_edit(dash, user_id, user_role):
                abort(403)
            result = await db.execute(
                select(DashboardShareToken).where(DashboardShareToken.id == token_id)
            )
            token = result.scalar_one_or_none()
            if token and token.dashboard_id == dash_id:
                await db.delete(token)
    return redirect(f"/d/{dash_id}/share")


# ── Public share view (no login required) ────────────────────────────────────

@dashboard_bp.get("/share/<raw_token>")
async def public_share(raw_token: str):
    token_hash = hashlib.sha256(raw_token.encode()).hexdigest()
    now        = datetime.now(timezone.utc)

    async with current_app.db_sessionmaker() as db:
        result = await db.execute(
            select(DashboardShareToken)
            .where(DashboardShareToken.token_hash == token_hash)
        )
        share = result.scalar_one_or_none()
        if share is None:
            abort(404)
        if share.expires_at is not None and share.expires_at <= now:
            abort(410)
        result = await db.execute(
            select(Dashboard).where(Dashboard.id == share.dashboard_id)
        )
        dash = result.scalar_one_or_none()
        if dash is None:
            abort(404)
        widgets = await _get_widgets(db, dash.id)

    resolved      = _resolve_widgets(widgets)
    poll_interval = current_app.config.get("MONITORS_POLL_INTERVAL", 60)

    return await render_template(
        "dashboard/share_view.html",
        dashboard=dash,
        widgets=resolved,
        poll_interval=poll_interval,
        raw_token=raw_token,
    )