"""Fidelity UK PlanViewer provider — workplace pension backfill + monthly sync.

PlanViewer has no public individual-member API. The SPA (at
``pv.planviewer.fidelity.co.uk``) and the legacy HTML app (at
``www.planviewer.fidelity.co.uk``) share session cookies via PingFederate
OAuth at ``id.fidelity.co.uk``.

We keep a Playwright-maintained session via ``storage_state.json``:

1. **One-off seed** (``broker-sync fidelity-seed``): Viktor runs a headed
   Chromium, logs in (password + memorable word + SMS MFA), clicks
   "Remember device". The storage_state is persisted to Vault.
2. **Monthly cron**: loads storage_state, boots headless Chromium, navigates
   to the transaction-history page with a wide date range, parses the HTML
   table, and intercepts the ``DisplayValuation`` XHR for the current
   fund holdings. On 401/idle-timeout we raise
   :class:`FidelitySessionError` so Prometheus alerts Viktor to re-seed.

## Emitted Activity shape

- One ``DEPOSIT`` per cash-impacting transaction (Regular Premium, Single
  Premium, rebate, etc.). ``external_id = fidelity:tx:<sha256[:16]>``.
- One synthetic ``DEPOSIT`` for unrealised gains so WF's Net Worth matches
  the Fidelity dashboard. ``external_id =
  fidelity:gains:<YYYY-MM-DD>``.
- Bulk Switches / Fund Switches are skipped (no cash movement).
"""
from __future__ import annotations

import contextlib
import logging
from collections.abc import AsyncIterator
from datetime import UTC, datetime
from decimal import Decimal
from pathlib import Path
from typing import Any, NamedTuple

from broker_sync.models import Account, AccountType, Activity, ActivityType
from broker_sync.providers.parsers.fidelity import (
    FidelityCashTx,
    FidelityHolding,
    parse_transactions_html,
    parse_valuation_json,
)

log = logging.getLogger(__name__)

ACCOUNT_ID = "fidelity-workplace-pension"
_CCY = "GBP"

_PV_BASE = "https://www.planviewer.fidelity.co.uk"
_PV_TX_PATH = "/planviewer/DisplayMyPlanMemberTransHist.action"
_PV_VALUATION_PATH = "/planviewer/DisplayValuation.action"
_PV_LANDING = "https://www.planviewer.fidelity.co.uk/"

# A wide backfill cap; scheme can't predate 1990.
_BACKFILL_START = "01 Jan 1990"


class FidelityCreds(NamedTuple):
    """Paths needed to run the provider."""
    storage_state_path: str
    plan_id: str
    headless: bool = True


class FidelitySessionError(Exception):
    """Raised when PlanViewer rejects the saved session — re-seed required."""


class FidelityProviderConfigError(Exception):
    """Raised when provider config is missing or obviously wrong."""


def _tx_to_activity(tx: FidelityCashTx) -> Activity:
    """Map a Fidelity cash transaction to a canonical DEPOSIT."""
    return Activity(
        external_id=tx.external_id,
        account_id=ACCOUNT_ID,
        account_type=AccountType.WORKPLACE_PENSION,
        date=tx.date,
        activity_type=ActivityType.DEPOSIT,
        currency=_CCY,
        amount=tx.amount,
        notes=f"fidelity-planviewer:{tx.tx_type}",
    )


def _gains_offset_activity(
    holdings: list[FidelityHolding],
    transactions: list[FidelityCashTx],
    as_of: datetime,
) -> Activity | None:
    """Create a synthetic DEPOSIT/WITHDRAWAL so WF Net Worth matches the
    Fidelity dashboard's reported pot value.

    The offset carries a date-derived external_id so monthly runs refresh
    the same synthetic entry rather than stacking duplicates.
    """
    if not holdings:
        return None
    total_value = sum((h.total_value for h in holdings), Decimal(0))
    total_contrib = sum((t.amount for t in transactions), Decimal(0))
    gains = total_value - total_contrib
    if gains == 0:
        return None
    return Activity(
        external_id=f"fidelity:gains:{as_of.date().isoformat()}",
        account_id=ACCOUNT_ID,
        account_type=AccountType.WORKPLACE_PENSION,
        date=as_of,
        activity_type=ActivityType.DEPOSIT if gains > 0 else ActivityType.WITHDRAWAL,
        currency=_CCY,
        amount=abs(gains),
        notes=(f"fidelity-planviewer:unrealised-gains-offset "
               f"(pot=£{total_value}, contrib=£{total_contrib})"),
    )


class FidelityPlanViewerProvider:
    """Read-only provider against Fidelity UK PlanViewer.

    Lifecycle:
    - ``accounts()`` advertises the single WF workplace-pension account.
    - ``fetch(since, before)`` opens a Playwright session with the saved
      storage_state, navigates to the transaction-history page with a wide
      date range, scrapes the table, and intercepts the valuation XHR.
    """
    name = "fidelity-planviewer"

    def __init__(self, creds: FidelityCreds) -> None:
        self._creds = creds

    def accounts(self) -> list[Account]:
        return [
            Account(
                id=ACCOUNT_ID,
                name="Fidelity UK Pension",
                account_type=AccountType.WORKPLACE_PENSION,
                currency=_CCY,
                provider=self.name,
            ),
        ]

    async def fetch(
        self,
        *,
        since: datetime | None = None,
        before: datetime | None = None,
    ) -> AsyncIterator[Activity]:
        state_path = self._creds.storage_state_path
        if not Path(state_path).exists():
            raise FidelityProviderConfigError(
                f"storage_state not found at {state_path} — "
                "run `broker-sync fidelity-seed` first")

        tx_html, valuation_json = await _scrape_live_session(
            state_path=state_path, headless=self._creds.headless,
        )
        transactions = parse_transactions_html(tx_html)
        holdings = parse_valuation_json(valuation_json)
        log.info("fidelity: parsed %d transactions, %d holdings",
                 len(transactions), len(holdings))

        for tx in transactions:
            if since is not None and tx.date < since:
                continue
            if before is not None and tx.date >= before:
                continue
            yield _tx_to_activity(tx)

        # The gains offset is always "as of now" so it reflects today's pot.
        # Only emit when the caller isn't windowing (full state).
        if since is None and before is None:
            offset = _gains_offset_activity(holdings, transactions, datetime.now(UTC))
            if offset is not None:
                yield offset


async def _scrape_live_session(
    *,
    state_path: str,
    headless: bool,
) -> tuple[str, dict[str, Any]]:
    """Load storage_state, navigate the transaction + valuation pages,
    return (transactions HTML, valuation JSON payload).

    Raises :class:`FidelitySessionError` if the session is dead (15-min idle,
    cookie expiry, etc.) — Viktor must re-seed.
    """
    from playwright.async_api import async_playwright

    captured_valuation: dict[str, dict[str, Any]] = {}
    async with async_playwright() as pw:
        browser = await pw.chromium.launch(headless=headless)
        try:
            ctx = await browser.new_context(
                storage_state=state_path,
                user_agent=("Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) "
                            "AppleWebKit/537.36 (KHTML, like Gecko) "
                            "Chrome/147.0.0.0 Safari/537.36"),
                viewport={"width": 1280, "height": 900},
            )
            page = await ctx.new_page()

            async def on_response(resp: Any) -> None:
                if _PV_VALUATION_PATH in resp.url and resp.status < 400:
                    with contextlib.suppress(Exception):
                        captured_valuation["payload"] = await resp.json()
            page.on("response", on_response)

            # Trigger session + capture valuation by navigating through landing
            # → main page. The SPA fires DisplayValuation on the main page.
            await page.goto(_PV_LANDING, wait_until="networkidle", timeout=30000)
            await page.wait_for_timeout(2000)
            main_url = f"{_PV_BASE}/planviewer/DisplayMainPage.action"
            await page.goto(main_url, wait_until="networkidle", timeout=30000)
            await page.wait_for_timeout(3000)
            if "idle for more than 15 minutes" in (await page.content()) \
                    or "id.fidelity.co.uk" in page.url:
                raise FidelitySessionError(
                    "PlanViewer session stale — run `broker-sync fidelity-seed`")

            # Now pull the transactions page with a wide date range.
            await page.goto(f"{_PV_BASE}{_PV_TX_PATH}",
                            wait_until="networkidle", timeout=30000)
            await page.wait_for_timeout(1500)
            await page.fill('input[name="startDate"]', _BACKFILL_START)
            today = await page.evaluate(
                "new Date().toLocaleDateString('en-GB',"
                "{day:'2-digit',month:'short',year:'numeric'}).replace(/,/g,'')")
            await page.fill('input[name="endDate"]', today)
            await page.focus('input[name="endDate"]')
            await page.keyboard.press("Enter")
            with contextlib.suppress(Exception):
                await page.wait_for_load_state("networkidle", timeout=15000)
            await page.wait_for_timeout(2000)
            tx_html = await page.content()

            # If valuation wasn't picked up on the main page, request directly.
            if "payload" not in captured_valuation:
                r = await page.request.get(f"{_PV_BASE}{_PV_VALUATION_PATH}")
                if r.ok:
                    with contextlib.suppress(Exception):
                        captured_valuation["payload"] = await r.json()

            # Roll the storage_state so the next run benefits from any refresh.
            await ctx.storage_state(path=state_path)
        finally:
            await browser.close()

    valuation: dict[str, Any] = captured_valuation.get("payload") or {}
    return tx_html, valuation