"""Surface-agnostic core for the ``/subscription`` TUI screen.

Companion to :mod:`agent.billing_view` — same fail-open philosophy (``logged_in=False``
when not logged in / portal unreachable; never crash) and decimal money end-to-end.

The TUI ``SubscriptionOverlay`` drives the plan change in-terminal: preview, then
schedule a downgrade / cancellation / resume (chargeless) or apply an upgrade
(charges the subscription card). The portal deep-link (``portal_url`` + ``org_id``)
remains the fallback for an upgrade that needs 3DS / was declined. Until the NAS
``GET /api/billing/subscription`` endpoint ships, 404s take the fail-open path.
"""

from __future__ import annotations

import logging
import os
from dataclasses import dataclass
from decimal import Decimal
from typing import Any, Optional

from agent.billing_view import OrgRoleCapability, fetch_portal_state, format_money, parse_money, parse_org_fields

logger = logging.getLogger(__name__)


# ── Parsed sub-structures ────────────────────────────────────────────────────


@dataclass(frozen=True)
class CurrentSubscription:
    """The user's active subscription. ``None`` (not this object) = no plan.

    NAS guarantees a present ``current`` is fully populated: ``tier_id`` /
    ``tier_name`` / ``monthly_credits`` / ``cycle_ends_at`` are always set; only
    ``credits_remaining`` and the cancel/downgrade fields are optional.
    """

    tier_id: Optional[str] = None
    tier_name: Optional[str] = None
    monthly_credits: Optional[Decimal] = None
    credits_remaining: Optional[Decimal] = None
    cycle_ends_at: Optional[str] = None  # ISO
    pending_downgrade_tier_name: Optional[str] = None
    pending_downgrade_at: Optional[str] = None  # ISO
    cancel_at_period_end: bool = False
    cancellation_effective_at: Optional[str] = None  # ISO


@dataclass(frozen=True)
class SubscriptionTier:
    """One row of the tier picker (mirrors NAS ``SubscriptionTierOption``).

    ``is_current`` = active plan (shown, not selectable); ``is_enabled=False`` = a
    grandfathered tier the user is on but can no longer select. ``tier_order`` sorts
    the picker and drives the upgrade-vs-downgrade hint.
    """

    tier_id: str
    name: str
    tier_order: int = 0
    dollars_per_month: Optional[Decimal] = None
    monthly_credits: Optional[Decimal] = None
    is_current: bool = False
    is_enabled: bool = True


@dataclass(frozen=True)
class SubscriptionChangePreview:
    """Parsed ``POST /api/billing/subscription/preview``.

    ``effect``: ``charge_now`` (upgrade; ``amount_due_now_cents`` is the prorated
    charge) · ``scheduled`` (downgrade / same-price change at ``effective_at``) ·
    ``no_op`` (already on target) · ``blocked`` (commit refused; ``reason`` says why).
    """

    effect: str
    reason: Optional[str] = None
    current_tier_id: Optional[str] = None
    current_tier_name: Optional[str] = None
    target_tier_id: Optional[str] = None
    target_tier_name: Optional[str] = None
    monthly_credits_delta: Optional[Decimal] = None
    amount_due_now_cents: Optional[int] = None
    effective_at: Optional[str] = None  # ISO


@dataclass(frozen=True)
class SubscriptionState(OrgRoleCapability):
    """Parsed ``GET /api/billing/subscription``. Fail-open: ``logged_in=False``
    (empty fields) when not logged in or the portal is unreachable."""

    logged_in: bool
    org_name: Optional[str] = None
    org_id: Optional[str] = None  # org.id from the NAS response
    role: Optional[str] = None  # "OWNER" | "ADMIN" | "FINANCE_ADMIN" | "SECURITY_ADMIN" | "MEMBER"
    can_change_plan_raw: Optional[bool] = None
    context: str = "personal"  # "personal" | "team"
    current: Optional[CurrentSubscription] = None
    tiers: tuple[SubscriptionTier, ...] = ()  # selectable catalog (picker)
    portal_url: Optional[str] = None
    error: Optional[str] = None  # set when the fetch failed (vs cleanly not-logged-in)


# ── Payload parsing ──────────────────────────────────────────────────────────


def _parse_current(raw: Any) -> Optional[CurrentSubscription]:
    # "No plan" is wire-represented as current:null; a present current is a real
    # plan, so guard on a real tier id and return None otherwise.
    if not isinstance(raw, dict):
        return None
    tier_id = raw.get("tierId") or raw.get("id")
    if not tier_id:
        return None
    return CurrentSubscription(
        tier_id=tier_id,
        tier_name=raw.get("tierName") or raw.get("name"),
        monthly_credits=parse_money(raw.get("monthlyCredits")),
        credits_remaining=parse_money(raw.get("creditsRemaining")),
        cycle_ends_at=raw.get("cycleEndsAt"),
        pending_downgrade_tier_name=raw.get("pendingDowngradeTierName"),
        pending_downgrade_at=raw.get("pendingDowngradeAt"),
        cancel_at_period_end=bool(raw.get("cancelAtPeriodEnd")),
        cancellation_effective_at=raw.get("cancellationEffectiveAt") or None,
    )


def _coalesce(*vals: Any) -> Any:
    """First non-``None`` value. NAS sends ``0`` for the free tier's ``tierOrder`` /
    ``dollarsPerMonth``, which a plain ``x or default`` would drop."""
    for v in vals:
        if v is not None:
            return v
    return None


def _parse_tier(raw: Any) -> Optional[SubscriptionTier]:
    """Map one NAS ``SubscriptionTierOption`` dict into a :class:`SubscriptionTier`."""
    if not isinstance(raw, dict):
        return None
    tier_id = raw.get("tierId") or raw.get("id")
    if not tier_id:
        return None
    return SubscriptionTier(
        tier_id=tier_id,
        name=raw.get("name") or "",
        tier_order=int(_coalesce(raw.get("tierOrder"), 0)),
        dollars_per_month=parse_money(raw.get("dollarsPerMonthDisplay")),
        monthly_credits=parse_money(raw.get("monthlyCredits")),
        is_current=bool(raw.get("isCurrent")),
        is_enabled=bool(_coalesce(raw.get("isEnabled"), True)),
    )


def subscription_change_preview_from_payload(
    payload: dict[str, Any],
) -> SubscriptionChangePreview:
    """Map a raw ``/subscription/preview`` JSON dict into :class:`SubscriptionChangePreview`."""
    effect = payload.get("effect")
    cents = payload.get("amountDueNowCents")
    return SubscriptionChangePreview(
        # Unrecognized/missing effect → ``blocked``: fail safe, never charge on a malformed quote.
        effect=effect if isinstance(effect, str) else "blocked",
        reason=payload.get("reason") or None,
        current_tier_id=payload.get("currentTierId"),
        current_tier_name=payload.get("currentTierName"),
        target_tier_id=payload.get("targetTierId"),
        target_tier_name=payload.get("targetTierName"),
        monthly_credits_delta=parse_money(payload.get("monthlyCreditsDelta")),
        amount_due_now_cents=int(cents) if isinstance(cents, (int, float)) else None,
        effective_at=payload.get("effectiveAt") or None,
    )


def subscription_state_from_payload(
    payload: dict[str, Any], *, portal_url: Optional[str] = None
) -> SubscriptionState:
    """Map a raw ``/api/billing/subscription`` JSON dict into :class:`SubscriptionState`."""
    org, can_change_plan_raw = parse_org_fields(payload)
    raw_context = payload.get("context")
    raw_tiers = payload.get("tiers")
    tiers = (
        tuple(t for t in (_parse_tier(x) for x in raw_tiers) if t is not None)
        if isinstance(raw_tiers, list)
        else ()
    )
    return SubscriptionState(
        logged_in=True,
        org_name=org.get("name"),
        org_id=org.get("id") or None,
        role=org.get("role"),
        can_change_plan_raw=can_change_plan_raw,
        context=raw_context if raw_context in ("personal", "team") else "personal",
        current=_parse_current(payload.get("current")),
        tiers=tiers,
        portal_url=portal_url,
    )


# ── Fail-open builders (the surface front doors) ─────────────────────────────


def build_subscription_state(*, timeout: float = 15.0) -> SubscriptionState:
    """Fetch + parse ``GET /api/billing/subscription``. Fail-open (see
    :func:`agent.billing_view.fetch_portal_state`).

    ``HERMES_DEV_SUBSCRIPTION_FIXTURE`` short-circuits to a fixture so every
    plan/cancel/downgrade/team/not-admin state is testable on CLI and TUI offline.
    """
    fixture = dev_fixture_subscription_state()
    if fixture is not None:
        return fixture
    return fetch_portal_state(
        "get_subscription_state",
        "subscription",
        failed=lambda **kw: SubscriptionState(logged_in=False, **kw),
        parse=lambda payload, portal_url: subscription_state_from_payload(payload, portal_url=portal_url),
        portal_fallback=lambda base: base,
        timeout=timeout,
        log=logger,
    )


def subscription_manage_url(
    state: SubscriptionState, tier_id: Optional[str] = None
) -> Optional[str]:
    """Build ``{portal_origin}/manage-subscription?org_id=<id>[&plan=<tier_id>]``.

    Mirrors the TUI's ``buildManageUrl``: the target is NAS's OWN ``/manage-subscription``
    page (NOT the Stripe Billing Portal), which routes upgrade→Checkout /
    downgrade→scheduled internally. ``org_id`` pins the right account in multi-org
    situations. ``tier_id`` (the stable ``tiers[]`` id, never a name/slug) preselects
    the picked plan; the portal ignores an unknown tier, so it's appended
    unconditionally when picked. None when no portal URL is resolvable.
    """
    from urllib.parse import parse_qsl, urlencode, urlsplit, urlunsplit

    if not state.portal_url:
        return None
    try:
        parts = urlsplit(state.portal_url)
    except Exception:
        return None
    if parts.scheme not in ("http", "https") or not parts.netloc:
        return None

    # Preserve unrelated portal query params; org_id / plan are contract-owned
    # (org_id before plan — insertion order is the emitted query order).
    params = dict(parse_qsl(parts.query, keep_blank_values=True))
    params.pop("org_id", None)
    params.pop("plan", None)
    if state.org_id:
        params["org_id"] = state.org_id
    if tier_id:
        params["plan"] = tier_id
    return urlunsplit((parts.scheme, parts.netloc, "/manage-subscription", urlencode(params), ""))


# ── Shared plan-catalog helpers (CLI Free catalog + paid picker) ─────────────


def selectable_tiers(state: SubscriptionState) -> list[SubscriptionTier]:
    """Enabled paid tiers other than the current plan, cheapest first (``tier_order > 0``
    — dropping to free is a cancellation, not a plan pick)."""
    return sorted(
        (t for t in (state.tiers or ()) if t.is_enabled and not t.is_current and (t.tier_order or 0) > 0),
        key=lambda t: t.tier_order or 0,
    )


def format_tier_row(tier: SubscriptionTier) -> str:
    """``name · $X/mo[ · $Y credits/mo]`` — thousands-grouped money (mirrors the TUI
    Free rows); the credits suffix appears ONLY when monthly credits are present and > 0."""
    row = f"{tier.name} · {format_money(tier.dollars_per_month, grouped=True)}/mo"
    mc = tier.monthly_credits
    if mc is not None and mc > 0:
        row += f" · {format_money(mc, grouped=True)} credits/mo"
    return row


def is_upgrade(state: SubscriptionState, tier_id: str) -> bool:
    """True when ``tier_id`` ranks above the current plan by ``tier_order``. Prefers the
    active subscription's tier; falls back to the ``tiers[]`` ``is_current`` marker, else 0."""
    orders = {t.tier_id: (t.tier_order or 0) for t in (state.tiers or ())}
    cur_id = state.current.tier_id if state.current else None
    if cur_id is not None and cur_id in orders:
        cur_order = orders[cur_id]
    else:
        cur_order = next((t.tier_order or 0 for t in (state.tiers or ()) if t.is_current), 0)
    return orders.get(tier_id, 0) > cur_order


# ── Dev fixtures (throwaway scaffolding — env-var driven, no live portal) ────

_DEV_FIXTURE_PORTAL = "https://portal.nousresearch.com/billing"


def _dev_current(**over: Any) -> CurrentSubscription:
    base: dict[str, Any] = dict(
        tier_id="plus", tier_name="Plus", monthly_credits=Decimal("1000"),
        credits_remaining=Decimal("420"), cycle_ends_at="2026-07-01",
    )
    return CurrentSubscription(**{**base, **over})


def _dev_tiers(current_id: Optional[str]) -> tuple[SubscriptionTier, ...]:
    """A sample plan catalog for fixtures (marks ``current_id`` as the active tier)."""
    specs = (("free", "Free", 0, "0", "0"), ("plus", "Plus", 1, "20", "1000"),
             ("super", "Super", 2, "40", "3000"), ("ultra", "Ultra", 3, "80", "7000"))
    return tuple(
        SubscriptionTier(
            tier_id=tid, name=name, tier_order=order, dollars_per_month=parse_money(dpm),
            monthly_credits=parse_money(mc), is_current=(tid == current_id), is_enabled=True,
        )
        for tid, name, order, dpm, mc in specs
    )


def dev_fixture_subscription_state() -> Optional[SubscriptionState]:
    """``HERMES_DEV_SUBSCRIPTION_FIXTURE`` -> fixture :class:`SubscriptionState`; None when unset.

    ``free | mid | top | not-admin | downgrade | cancel | team | logged-out``. Unknown
    name → logged-out with ``error`` so the misconfiguration is visible.
    """
    name = (os.getenv("HERMES_DEV_SUBSCRIPTION_FIXTURE") or "").strip().lower()
    if not name:
        return None
    name = {"logged_out": "logged-out", "loggedout": "logged-out", "mid-tier": "mid",
            "top-tier": "top", "member": "not-admin"}.get(name, name)
    if name == "logged-out":
        return SubscriptionState(logged_in=False)

    common = dict(logged_in=True, org_name="Acme Inc", org_id="org_acme", role="OWNER", portal_url=_DEV_FIXTURE_PORTAL)
    plus = dict(current=_dev_current(), tiers=_dev_tiers("plus"))
    states: dict[str, dict[str, Any]] = {
        "free": dict(current=None, tiers=_dev_tiers(None)),
        "mid": plus,
        "top": dict(
            current=_dev_current(tier_id="ultra", tier_name="Ultra", monthly_credits=Decimal("7000"), credits_remaining=Decimal("5000")),
            tiers=_dev_tiers("ultra"),
        ),
        "not-admin": {**plus, "role": "MEMBER"},
        "downgrade": dict(
            current=_dev_current(tier_id="super", tier_name="Super", monthly_credits=Decimal("3000"), credits_remaining=Decimal("1500"), pending_downgrade_tier_name="Plus", pending_downgrade_at="2026-07-15"),
            tiers=_dev_tiers("super"),
        ),
        "cancel": dict(current=_dev_current(cancel_at_period_end=True, cancellation_effective_at="2026-07-01"), tiers=_dev_tiers("plus")),
        "team": dict(context="team", current=None, org_name="Acme Engineering", org_id="org_eng"),
    }
    if name not in states:
        return SubscriptionState(logged_in=False, error=f"unknown HERMES_DEV_SUBSCRIPTION_FIXTURE: {name}")
    return SubscriptionState(**{**common, **states[name]})