from __future__ import annotations

import logging
import math
from dataclasses import dataclass
from datetime import datetime, timezone
from typing import TYPE_CHECKING, Any, Optional

import httpx

from agent.anthropic_adapter import _is_oauth_token, resolve_anthropic_token
from hermes_cli.auth import _read_codex_tokens, resolve_codex_runtime_credentials
from hermes_cli.runtime_provider import resolve_runtime_provider

if TYPE_CHECKING:
    from typing import TypeGuard

logger = logging.getLogger(__name__)


def _utc_now() -> datetime:
    return datetime.now(timezone.utc)


@dataclass(frozen=True)
class AccountUsageWindow:
    label: str
    used_percent: Optional[float] = None
    reset_at: Optional[datetime] = None
    detail: Optional[str] = None


@dataclass(frozen=True)
class AccountUsageSnapshot:
    provider: str
    source: str
    fetched_at: datetime
    title: str = "Account limits"
    plan: Optional[str] = None
    windows: tuple[AccountUsageWindow, ...] = ()
    details: tuple[str, ...] = ()
    unavailable_reason: Optional[str] = None

    @property
    def available(self) -> bool:
        return bool(self.windows or self.details) and not self.unavailable_reason


def _title_case_slug(value: Optional[str]) -> Optional[str]:
    cleaned = str(value or "").strip()
    if not cleaned:
        return None
    return cleaned.replace("_", " ").replace("-", " ").title()


def _parse_dt(value: Any) -> Optional[datetime]:
    if value in {None, ""}:
        return None
    if isinstance(value, (int, float)):
        return datetime.fromtimestamp(float(value), tz=timezone.utc)
    if isinstance(value, str):
        text = value.strip()
        if not text:
            return None
        if text.endswith("Z"):
            text = text[:-1] + "+00:00"
        try:
            dt = datetime.fromisoformat(text)
            return dt if dt.tzinfo else dt.replace(tzinfo=timezone.utc)
        except ValueError:
            return None
    return None


def _format_reset(dt: Optional[datetime]) -> str:
    if not dt:
        return "unknown"
    local_dt = dt.astimezone()
    delta = dt - _utc_now()
    total_seconds = int(delta.total_seconds())
    if total_seconds <= 0:
        return f"now ({local_dt.strftime('%Y-%m-%d %H:%M %Z')})"
    hours, rem = divmod(total_seconds, 3600)
    minutes = rem // 60
    if hours >= 24:
        days, hours = divmod(hours, 24)
        rel = f"in {days}d {hours}h"
    elif hours > 0:
        rel = f"in {hours}h {minutes}m"
    else:
        rel = f"in {minutes}m"
    return f"{rel} ({local_dt.strftime('%Y-%m-%d %H:%M %Z')})"


def render_account_usage_lines(snapshot: Optional[AccountUsageSnapshot], *, markdown: bool = False) -> list[str]:
    if not snapshot:
        return []
    header = f"📈 {'**' if markdown else ''}{snapshot.title}{'**' if markdown else ''}"
    lines = [header]
    if snapshot.plan:
        lines.append(f"Provider: {snapshot.provider} ({snapshot.plan})")
    else:
        lines.append(f"Provider: {snapshot.provider}")
    for window in snapshot.windows:
        if window.used_percent is None:
            base = f"{window.label}: unavailable"
        else:
            remaining = max(0, round(100 - float(window.used_percent)))
            used = max(0, round(float(window.used_percent)))
            base = f"{window.label}: {remaining}% remaining ({used}% used)"
        if window.reset_at:
            base += f" • resets {_format_reset(window.reset_at)}"
        elif window.detail:
            base += f" • {window.detail}"
        lines.append(base)
    for detail in snapshot.details:
        lines.append(detail)
    if snapshot.unavailable_reason:
        lines.append(f"Unavailable: {snapshot.unavailable_reason}")
    return lines


def _fmt_usd(d: float) -> str:
    return f"${d:,.2f}"


def _is_finite_num(v: Any) -> TypeGuard[float]:
    """True iff v is a real numeric value (int or float, not bool, not NaN/Inf).

    Typed as a ``TypeGuard[float]`` so the type checker narrows ``v`` to a real
    number in the positive branch — callers can then do arithmetic / pass it to
    ``_fmt_usd`` without a None-operand warning.
    """
    return isinstance(v, (int, float)) and not isinstance(v, bool) and math.isfinite(v)


def build_nous_credits_snapshot(account_info) -> Optional[AccountUsageSnapshot]:
    """Map a NousPortalAccountInfo into an AccountUsageSnapshot for /usage.

    Shows dollar magnitudes (subscription / top-up / total) + renewal date + a
    portal CTA. When the portal supplies a subscription denominator
    (``monthly_credits``), also emits a subscription-usage window so the renderer
    shows a real ``% used`` gauge; when it's absent (older portals) the view
    gracefully degrades to magnitudes-only. Returns None when there's no usable
    account info to show (fail-open: caller just shows nothing).
    """
    try:
        from hermes_cli.nous_account import nous_portal_billing_url

        if account_info is None or not getattr(account_info, "logged_in", False):
            return None

        access = getattr(account_info, "paid_service_access_info", None)
        sub = getattr(account_info, "subscription", None)

        windows: list[AccountUsageWindow] = []
        details: list[str] = []

        # Subscription usage gauge — only when the portal supplies a positive
        # monthly_credits denominator AND a finite remaining balance that does
        # not exceed the cap. Money math is on float dollars (allowed: numeric
        # account fields, NOT a server-provided *_usd string). used = cap -
        # remaining; clamp [0,100] so a debt balance (remaining < 0) reads 100%.
        # Excluded on purpose:
        #   - non-finite values (NaN/Infinity slip past isinstance and json.loads
        #     parses bare NaN/Infinity by default) → would render "$nan"/"$inf"
        #     and a falsely-confident gauge;
        #   - remaining > cap (rollover balance spanning the period) → monthly_credits
        #     is no longer a meaningful denominator, and "$X of $Y left" with X>Y
        #     reads as a contradiction. Both fall back to the magnitudes lines.
        if sub is not None:
            monthly_credits = getattr(sub, "monthly_credits", None)
            sub_remaining = getattr(sub, "credits_remaining", None)
            if (
                _is_finite_num(monthly_credits)
                and monthly_credits > 0
                and _is_finite_num(sub_remaining)
                and sub_remaining <= monthly_credits
            ):
                used = monthly_credits - sub_remaining
                used_pct = max(0.0, min(100.0, used / monthly_credits * 100.0))
                windows.append(
                    AccountUsageWindow(
                        label="Subscription",
                        used_percent=used_pct,
                        detail=f"{_fmt_usd(sub_remaining)} of {_fmt_usd(monthly_credits)} left",
                    )
                )

        if access is not None:
            sub_credits = getattr(access, "subscription_credits_remaining", None)
            if _is_finite_num(sub_credits):
                details.append(f"Subscription credits: {_fmt_usd(sub_credits)}")
            purchased = getattr(access, "purchased_credits_remaining", None)
            if _is_finite_num(purchased):
                details.append(f"Top-up credits: {_fmt_usd(purchased)}")
            total_usable = getattr(access, "total_usable_credits", None)
            if _is_finite_num(total_usable):
                details.append(f"Total usable: {_fmt_usd(total_usable)}")

        if sub is not None:
            rollover = getattr(sub, "rollover_credits", None)
            if _is_finite_num(rollover) and rollover > 0:
                details.append(f"Rollover: {_fmt_usd(rollover)}")
            period_end = getattr(sub, "current_period_end", None)
            if period_end:
                details.append(f"Renews: {period_end}")

        paid = getattr(account_info, "paid_service_access", None)
        if paid is False:
            details.append("Status: access depleted — top up to restore")

        if not windows and not details:
            return None

        details.append(f"Manage / top up: {nous_portal_billing_url(account_info)}")

        plan = getattr(sub, "plan", None) if sub is not None else None
        return AccountUsageSnapshot(
            provider="nous",
            source="portal-account",
            fetched_at=_utc_now(),
            title="Nous credits",
            plan=plan,
            windows=tuple(windows),
            details=tuple(details),
        )
    except (AttributeError, TypeError):
        return None


def nous_credits_lines(*, markdown: bool = False, timeout: float = 10.0) -> list[str]:
    """Return rendered Nous-credits /usage lines, or [] when there's nothing to show.

    Account-independent of any live agent: gated on "a Nous account is logged in"
    (a cheap local auth-state check), then a wall-clock-bounded portal fetch. Shared
    by the CLI ``_show_usage`` and the TUI ``session.usage`` RPC so both surfaces show
    the same block regardless of session API-call count or resume state. Fail-open:
    any auth/portal hiccup or timeout returns [] (the caller shows nothing).

    Dev override: when HERMES_DEV_CREDITS_FIXTURE selects a fixture state, /usage
    renders from that fixture instead of the real portal (so the block + gauge are
    testable without a live account). Throwaway scaffolding.
    """
    # Dev fixture short-circuit — render /usage from the injected state, no portal.
    try:
        from agent.credits_tracker import dev_fixture_credits_state

        fixture = dev_fixture_credits_state()
    except Exception:
        fixture = None
    if fixture is not None:
        snapshot = _snapshot_from_credits_state(fixture)
        return render_account_usage_lines(snapshot, markdown=markdown)

    try:
        from hermes_cli.auth import get_provider_auth_state

        tok = (get_provider_auth_state("nous") or {}).get("access_token")
        if not (isinstance(tok, str) and tok.strip()):
            return []
    except Exception:
        return []
    try:
        import concurrent.futures

        from hermes_cli.nous_account import get_nous_portal_account_info

        with concurrent.futures.ThreadPoolExecutor(max_workers=1) as pool:
            account = pool.submit(
                get_nous_portal_account_info, force_fresh=True
            ).result(timeout=timeout)
        snapshot = build_nous_credits_snapshot(account)
        return render_account_usage_lines(snapshot, markdown=markdown)
    except Exception:
        # Fail-open (caller shows nothing), but leave a breadcrumb so a dead
        # /usage credits block is diagnosable in agent.log without a dev flag.
        logger.debug("credits ▸ /usage portal fetch/render failed (fail-open)", exc_info=True)
        return []


def _snapshot_from_credits_state(state) -> Optional[AccountUsageSnapshot]:
    """Map a header-shaped CreditsState (e.g. a dev fixture) to the /usage snapshot.

    Renders the same magnitudes + monthly-grant % window the portal path produces,
    so HERMES_DEV_CREDITS_FIXTURE can exercise /usage without a live account. The
    *_usd strings are mock display values here (not server balance to compute on);
    the % comes from CreditsState.used_fraction (micros math). Fail-open → None.
    """
    try:
        if state is None:
            return None

        windows: list[AccountUsageWindow] = []
        details: list[str] = []

        uf = getattr(state, "used_fraction", None)
        if isinstance(uf, (int, float)) and math.isfinite(uf):
            cap_usd = getattr(state, "subscription_limit_usd", None)
            sub_usd = getattr(state, "subscription_usd", None)
            detail = None
            if sub_usd and cap_usd:
                detail = f"${sub_usd} of ${cap_usd} left"
            windows.append(
                AccountUsageWindow(
                    label="Subscription",
                    used_percent=max(0.0, min(100.0, uf * 100.0)),
                    detail=detail,
                )
            )

        sub_usd = getattr(state, "subscription_usd", None)
        if sub_usd:
            details.append(f"Subscription credits: ${sub_usd}")
        purchased_usd = getattr(state, "purchased_usd", None)
        if purchased_usd:
            details.append(f"Top-up credits: ${purchased_usd}")
        remaining_usd = getattr(state, "remaining_usd", None)
        if remaining_usd:
            details.append(f"Total usable: ${remaining_usd}")
        if getattr(state, "paid_access", True) is False:
            details.append("Status: access depleted — top up to restore")

        if not windows and not details:
            return None

        details.append("(dev fixture — HERMES_DEV_CREDITS_FIXTURE)")
        return AccountUsageSnapshot(
            provider="nous",
            source="dev-fixture",
            fetched_at=_utc_now(),
            title="Nous credits",
            windows=tuple(windows),
            details=tuple(details),
        )
    except (AttributeError, TypeError):
        return None


def _resolve_codex_usage_url(base_url: str) -> str:
    normalized = (base_url or "").strip().rstrip("/")
    if not normalized:
        normalized = "https://chatgpt.com/backend-api/codex"
    if normalized.endswith("/codex"):
        normalized = normalized[: -len("/codex")]
    if "/backend-api" in normalized:
        return normalized + "/wham/usage"
    return normalized + "/api/codex/usage"


def _fetch_codex_account_usage() -> Optional[AccountUsageSnapshot]:
    creds = resolve_codex_runtime_credentials(refresh_if_expiring=True)
    token_data = _read_codex_tokens()
    tokens = token_data.get("tokens") or {}
    account_id = str(tokens.get("account_id", "") or "").strip() or None
    headers = {
        "Authorization": f"Bearer {creds['api_key']}",
        "Accept": "application/json",
        "User-Agent": "codex-cli",
    }
    if account_id:
        headers["ChatGPT-Account-Id"] = account_id
    with httpx.Client(timeout=15.0) as client:
        response = client.get(_resolve_codex_usage_url(creds.get("base_url", "")), headers=headers)
        response.raise_for_status()
    payload = response.json() or {}
    rate_limit = payload.get("rate_limit") or {}
    windows: list[AccountUsageWindow] = []
    for key, label in (("primary_window", "Session"), ("secondary_window", "Weekly")):
        window = rate_limit.get(key) or {}
        used = window.get("used_percent")
        if used is None:
            continue
        windows.append(
            AccountUsageWindow(
                label=label,
                used_percent=float(used),
                reset_at=_parse_dt(window.get("reset_at")),
            )
        )
    details: list[str] = []
    credits = payload.get("credits") or {}
    if credits.get("has_credits"):
        balance = credits.get("balance")
        if isinstance(balance, (int, float)):
            details.append(f"Credits balance: ${float(balance):.2f}")
        elif credits.get("unlimited"):
            details.append("Credits balance: unlimited")
    return AccountUsageSnapshot(
        provider="openai-codex",
        source="usage_api",
        fetched_at=_utc_now(),
        plan=_title_case_slug(payload.get("plan_type")),
        windows=tuple(windows),
        details=tuple(details),
    )


def _fetch_anthropic_account_usage() -> Optional[AccountUsageSnapshot]:
    token = (resolve_anthropic_token() or "").strip()
    if not token:
        return None
    if not _is_oauth_token(token):
        return AccountUsageSnapshot(
            provider="anthropic",
            source="oauth_usage_api",
            fetched_at=_utc_now(),
            unavailable_reason="Anthropic account limits are only available for OAuth-backed Claude accounts.",
        )
    headers = {
        "Authorization": f"Bearer {token}",
        "Accept": "application/json",
        "Content-Type": "application/json",
        "anthropic-beta": "oauth-2025-04-20",
        "User-Agent": "claude-code/2.1.0",
    }
    with httpx.Client(timeout=15.0) as client:
        response = client.get("https://api.anthropic.com/api/oauth/usage", headers=headers)
        response.raise_for_status()
    payload = response.json() or {}
    windows: list[AccountUsageWindow] = []
    mapping = (
        ("five_hour", "Current session"),
        ("seven_day", "Current week"),
        ("seven_day_opus", "Opus week"),
        ("seven_day_sonnet", "Sonnet week"),
    )
    for key, label in mapping:
        window = payload.get(key) or {}
        util = window.get("utilization")
        if util is None:
            continue
        used = float(util) * 100 if float(util) <= 1 else float(util)
        windows.append(
            AccountUsageWindow(
                label=label,
                used_percent=used,
                reset_at=_parse_dt(window.get("resets_at")),
            )
        )
    details: list[str] = []
    extra = payload.get("extra_usage") or {}
    if extra.get("is_enabled"):
        used_credits = extra.get("used_credits")
        monthly_limit = extra.get("monthly_limit")
        currency = extra.get("currency") or "USD"
        if isinstance(used_credits, (int, float)) and isinstance(monthly_limit, (int, float)):
            details.append(
                f"Extra usage: {used_credits:.2f} / {monthly_limit:.2f} {currency}"
            )
    return AccountUsageSnapshot(
        provider="anthropic",
        source="oauth_usage_api",
        fetched_at=_utc_now(),
        windows=tuple(windows),
        details=tuple(details),
    )


def _fetch_openrouter_account_usage(base_url: Optional[str], api_key: Optional[str]) -> Optional[AccountUsageSnapshot]:
    runtime = resolve_runtime_provider(
        requested="openrouter",
        explicit_base_url=base_url,
        explicit_api_key=api_key,
    )
    token = str(runtime.get("api_key", "") or "").strip()
    if not token:
        return None
    normalized = str(runtime.get("base_url", "") or "").rstrip("/")
    credits_url = f"{normalized}/credits"
    key_url = f"{normalized}/key"
    headers = {
        "Authorization": f"Bearer {token}",
        "Accept": "application/json",
    }
    with httpx.Client(timeout=10.0) as client:
        credits_resp = client.get(credits_url, headers=headers)
        credits_resp.raise_for_status()
        credits = (credits_resp.json() or {}).get("data") or {}
        try:
            key_resp = client.get(key_url, headers=headers)
            key_resp.raise_for_status()
            key_data = (key_resp.json() or {}).get("data") or {}
        except Exception:
            key_data = {}
    total_credits = float(credits.get("total_credits") or 0.0)
    total_usage = float(credits.get("total_usage") or 0.0)
    details = [f"Credits balance: ${max(0.0, total_credits - total_usage):.2f}"]
    windows: list[AccountUsageWindow] = []
    limit = key_data.get("limit")
    limit_remaining = key_data.get("limit_remaining")
    limit_reset = str(key_data.get("limit_reset") or "").strip()
    usage = key_data.get("usage")
    if (
        isinstance(limit, (int, float))
        and float(limit) > 0
        and isinstance(limit_remaining, (int, float))
        and 0 <= float(limit_remaining) <= float(limit)
    ):
        limit_value = float(limit)
        remaining_value = float(limit_remaining)
        used_percent = ((limit_value - remaining_value) / limit_value) * 100
        detail_parts = [f"${remaining_value:.2f} of ${limit_value:.2f} remaining"]
        if limit_reset:
            detail_parts.append(f"resets {limit_reset}")
        windows.append(
            AccountUsageWindow(
                label="API key quota",
                used_percent=used_percent,
                detail=" • ".join(detail_parts),
            )
        )
    if isinstance(usage, (int, float)):
        usage_parts = [f"API key usage: ${float(usage):.2f} total"]
        for value, label in (
            (key_data.get("usage_daily"), "today"),
            (key_data.get("usage_weekly"), "this week"),
            (key_data.get("usage_monthly"), "this month"),
        ):
            if isinstance(value, (int, float)) and float(value) > 0:
                usage_parts.append(f"${float(value):.2f} {label}")
        details.append(" • ".join(usage_parts))
    return AccountUsageSnapshot(
        provider="openrouter",
        source="credits_api",
        fetched_at=_utc_now(),
        windows=tuple(windows),
        details=tuple(details),
    )


def fetch_account_usage(
    provider: Optional[str],
    *,
    base_url: Optional[str] = None,
    api_key: Optional[str] = None,
) -> Optional[AccountUsageSnapshot]:
    normalized = str(provider or "").strip().lower()
    if normalized in {"", "auto", "custom"}:
        return None
    try:
        if normalized == "openai-codex":
            return _fetch_codex_account_usage()
        if normalized == "anthropic":
            return _fetch_anthropic_account_usage()
        if normalized == "openrouter":
            return _fetch_openrouter_account_usage(base_url, api_key)
    except Exception:
        return None
    return None