from __future__ import annotations

import json
from collections.abc import Iterable
from dataclasses import dataclass
from datetime import UTC, date
from decimal import Decimal
from pathlib import Path
from typing import Any

import httpx

from broker_sync.models import Account, Activity

_LOGIN_PATH = "/api/v1/auth/login"
_ACCOUNTS_PATH = "/api/v1/accounts"
_IMPORT_CHECK = "/api/v1/activities/import/check"
_IMPORT_REAL = "/api/v1/activities/import"
_SNAPSHOTS_IMPORT = "/api/v1/snapshots/import"
_ACTIVITIES_SEARCH = "/api/v1/activities/search"


class WealthfolioError(Exception):
    pass


class WealthfolioUnauthorizedError(WealthfolioError):
    """Raised when login itself fails (bad creds or Wealthfolio down).

    Distinct from a 401 on a random endpoint — those trigger an
    automatic re-login attempt.
    """


class ImportValidationError(WealthfolioError):
    """`/activities/import/check` returned a non-2xx. We never reach the real import."""


class WealthfolioSink:
    """Push canonical Activities to Wealthfolio via its CSV import endpoint.

    Auth is JWT-cookie via POST /api/v1/auth/login. Cookies are persisted
    to disk so CronJob pods can reuse them across runs (Wealthfolio's
    /auth/login is 5-req/min rate-limited).

    Not multi-process safe — file locking is added in Phase 1 when we
    fan out to multiple CronJobs.
    """

    def __init__(
        self,
        *,
        base_url: str,
        username: str,
        password: str,
        session_path: Path | str,
        transport: httpx.AsyncBaseTransport | None = None,
    ) -> None:
        self._username = username
        self._password = password
        self._session_path = Path(session_path)
        self._client = httpx.AsyncClient(
            base_url=base_url.rstrip("/"),
            timeout=30.0,
            transport=transport,
        )

    async def close(self) -> None:
        await self._client.aclose()

    # -- session --

    def _load_cookies(self) -> dict[str, str]:
        if not self._session_path.exists():
            return {}
        raw = json.loads(self._session_path.read_text())
        got = raw.get("cookies", {})
        assert isinstance(got, dict)
        return got

    def _save_cookies(self, cookies: dict[str, str]) -> None:
        self._session_path.parent.mkdir(parents=True, exist_ok=True)
        self._session_path.write_text(json.dumps({"cookies": cookies}))

    async def login(self) -> None:
        # Wealthfolio 3.2's LoginRequest is `{ password: String }` only — a
        # username key is rejected as an unknown field (HTTP 400). The
        # `username` constructor arg is kept for a future Wealthfolio
        # release that may add multi-user support.
        resp = await self._client.post(
            _LOGIN_PATH,
            json={"password": self._password},
        )
        if resp.status_code == 401:
            raise WealthfolioUnauthorizedError("Wealthfolio /auth/login returned 401")
        resp.raise_for_status()
        cookies = dict(resp.cookies.items())
        if not cookies:
            raise WealthfolioError("/auth/login returned 2xx but no Set-Cookie")
        self._save_cookies(cookies)

    @staticmethod
    def _cookie_header(cookies: dict[str, str]) -> str:
        return "; ".join(f"{k}={v}" for k, v in cookies.items())

    async def _request(self, method: str, path: str, **kw: Any) -> httpx.Response:
        cookies = self._load_cookies()
        headers = dict(kw.pop("headers", {}) or {})
        if cookies:
            headers["Cookie"] = self._cookie_header(cookies)
        resp = await self._client.request(method, path, headers=headers, **kw)
        if resp.status_code == 401 and path != _LOGIN_PATH:
            await self.login()
            cookies = self._load_cookies()
            headers["Cookie"] = self._cookie_header(cookies)
            resp = await self._client.request(method, path, headers=headers, **kw)
        return resp

    # -- accounts --

    async def list_accounts(self) -> list[dict[str, Any]]:
        resp = await self._request("GET", _ACCOUNTS_PATH)
        resp.raise_for_status()
        raw = resp.json()
        assert isinstance(raw, list)
        return raw

    async def ensure_account(self, account: Account) -> str:
        """Idempotently create the account and return Wealthfolio's UUID for it.

        Wealthfolio generates its own UUIDs on POST /accounts, ignoring any
        `id` we supply. We identify accounts by (provider, providerAccountId)
        which Wealthfolio DOES preserve verbatim. Our own Account.id is
        used as the providerAccountId.
        """
        existing = await self.list_accounts()
        for a in existing:
            if (a.get("provider") == account.provider and a.get("providerAccountId") == account.id):
                wf_id = a.get("id")
                assert isinstance(wf_id, str)
                return wf_id

        # NewAccount is camelCase with required booleans.
        # See apps/server/src/models.rs#NewAccount.
        resp = await self._request(
            "POST",
            _ACCOUNTS_PATH,
            json={
                "name": account.name,
                "accountType": str(account.account_type),
                "currency": account.currency,
                "isDefault": False,
                "isActive": True,
                "isArchived": False,
                "trackingMode": "TRANSACTIONS",
                "provider": account.provider,
                "providerAccountId": account.id,
            },
        )
        resp.raise_for_status()
        created = resp.json()
        wf_id = created.get("id")
        if not isinstance(wf_id, str):
            raise WealthfolioError(f"POST /accounts returned no id: {created}")
        return wf_id

    # -- activity import --

    @staticmethod
    def _activity_to_import_row(a: Activity) -> dict[str, Any]:
        """Match Wealthfolio's ActivityImport struct (camelCase JSON)."""
        # WF /import rejects naive datetimes with "Invalid date" (even though
        # /import/check accepts them) — coerce to UTC if tzinfo is missing.
        date = a.date if a.date.tzinfo is not None else a.date.replace(tzinfo=UTC)
        row: dict[str, Any] = {
            "date": date.isoformat(),
            "symbol": a.symbol or "$CASH",
            "activityType": str(a.activity_type),
            "currency": a.currency,
            "accountId": a.account_id,
            # Required booleans on ActivityImport (no defaults in Rust struct).
            "isDraft": False,
            "isValid": True,
        }
        if a.quantity is not None:
            row["quantity"] = format(a.quantity, "f")
        if a.unit_price is not None:
            row["unitPrice"] = format(a.unit_price, "f")
        if a.amount is not None:
            row["amount"] = format(a.amount, "f")
        if a.fee:
            row["fee"] = format(a.fee, "f")
        if a.notes:
            row["comment"] = a.notes
        return row

    async def import_activities(self, activities: Iterable[Activity]) -> list[dict[str, Any]]:
        rows = [self._activity_to_import_row(a) for a in activities]
        if not rows:
            return []

        # Step 1 — /import/check hydrates each row with resolved asset_id,
        # exchange_mic, quote_ccy, instrument_type, quote_mode (and flags
        # errors). The /import endpoint on Wealthfolio 3.2+ DOES NOT
        # re-resolve — if we send the un-enriched row the activity is
        # silently dropped (import returns 200 OK with activities=[] in
        # the payload). We must feed check's output into import.
        check = await self._request("POST", _IMPORT_CHECK, json={"activities": rows})
        if check.status_code >= 400:
            try:
                payload = check.json()
            except Exception:
                payload = {"raw": check.text}
            raise ImportValidationError(f"Wealthfolio /import/check rejected: {payload}")

        checked = check.json()
        if not isinstance(checked, list):
            raise ImportValidationError(
                f"Wealthfolio /import/check returned non-list: {type(checked).__name__}")

        invalid = [r for r in checked if isinstance(r, dict) and r.get("errors")]
        if invalid:
            raise ImportValidationError(f"Wealthfolio /import/check flagged {len(invalid)} row(s); "
                                        f"first: {invalid[0]}")
        # Drop any row the server marked is_valid=false (shouldn't happen
        # without errors, but defensive).
        valid_rows = [r for r in checked if isinstance(r, dict) and r.get("isValid")]

        real = await self._request("POST", _IMPORT_REAL, json={"activities": valid_rows})
        real.raise_for_status()
        raw = real.json()
        # Two observed response shapes:
        #   - {activities:[...], importRunId:"...", summary:{total,imported,skipped,...}}
        #   - bare list (older builds)
        if isinstance(raw, dict) and "activities" in raw:
            got = raw["activities"]
            summary = raw.get("summary") if isinstance(raw.get("summary"), dict) else None
        elif isinstance(raw, list):
            got = raw
            summary = None
        else:
            got = []
            summary = None
        # Summary.imported is THE truth. The `activities` field echoes input
        # with errors annotated — its length equals input even when zero
        # actually persisted.
        if summary is not None:
            imported_n = int(summary.get("imported", 0))
            total_n = int(summary.get("total", len(valid_rows)))
            dupes = int(summary.get("duplicates", 0))
            skipped = int(summary.get("skipped", 0))
            # Duplicates are expected on every re-run (the cron re-processes the
            # full IMAP window each night) — treat (imported + duplicates) as
            # accounted-for. Only fail if something was genuinely lost.
            accounted = imported_n + dupes
            if accounted < total_n:
                err_msg = summary.get("errorMessage") or "no errorMessage"
                raise ImportValidationError(f"Wealthfolio /import persisted {imported_n}/{total_n} "
                                            f"(skipped={skipped} duplicates={dupes}). "
                                            f"errorMessage: {err_msg}")
        # Legacy silent-drop guard for no-summary responses.
        elif valid_rows and not got:
            first_warn = next(
                (r.get("warnings") for r in checked if isinstance(r, dict) and r.get("warnings")),
                None,
            )
            raise ImportValidationError(
                f"Wealthfolio /import silently dropped all {len(valid_rows)} rows. "
                f"First checked row: {checked[0] if checked else 'none'}. "
                f"First warning: {first_warn}")
        assert isinstance(got, list)
        return [r for r in got if isinstance(r, dict)]

    # -- activity lookups --

    async def cumulative_amount_with_notes_prefix(
        self,
        account_id: str,
        notes_prefix: str,
    ) -> Decimal:
        """Sum the amount of DEPOSIT/WITHDRAWAL activities whose notes start
        with ``notes_prefix``, signed (deposits positive, withdrawals negative).

        Used by the Fidelity provider to compute the delta gains-offset:
        ``current_gain - cumulative_existing_offset`` becomes the new
        DEPOSIT to emit on each monthly run.
        """
        try:
            resp = await self._request(
                "POST", _ACTIVITIES_SEARCH,
                json={"accountIds": [account_id], "page": 1, "pageSize": 500},
            )
        except Exception:
            return Decimal(0)
        if resp.status_code >= 400:
            return Decimal(0)
        payload = resp.json()
        rows = payload.get("data", payload) if isinstance(payload, dict) else payload
        if not isinstance(rows, list):
            return Decimal(0)
        total = Decimal(0)
        for r in rows:
            if not isinstance(r, dict):
                continue
            notes = r.get("comment") or r.get("notes") or ""
            if not isinstance(notes, str) or not notes.startswith(notes_prefix):
                continue
            amt_raw = r.get("amount")
            if amt_raw is None:
                continue
            try:
                amt = Decimal(str(amt_raw))
            except Exception:
                continue
            atype = (r.get("activityType") or r.get("activity_type") or "").upper()
            if atype == "WITHDRAWAL":
                total -= amt
            else:
                total += amt
        return total

    async def compute_position_qty(self, account_id: str) -> dict[str, Decimal]:
        """Return per-symbol net position quantity (BUY/IN minus SELL/OUT) for
        one account. Skips cash activities and unknown activity types.

        Used by the IBKR reconciliation step to compare against broker-reported
        OpenPositions.
        """
        qty_by_symbol: dict[str, Decimal] = {}
        page = 1
        while True:
            resp = await self._request(
                "POST", _ACTIVITIES_SEARCH,
                json={"accountIds": [account_id], "page": page, "pageSize": 500},
            )
            resp.raise_for_status()
            payload = resp.json()
            activities = payload.get("activities", []) if isinstance(payload, dict) else []
            if not activities:
                break
            for act in activities:
                if not isinstance(act, dict):
                    continue
                symbol = act.get("symbol") or ""
                if not symbol or symbol.startswith("$CASH"):
                    continue
                act_type = act.get("activityType") or ""
                sign: int
                if act_type in {"BUY", "ADD_HOLDING", "TRANSFER_IN"}:
                    sign = 1
                elif act_type in {"SELL", "REMOVE_HOLDING", "TRANSFER_OUT"}:
                    sign = -1
                else:
                    continue
                try:
                    qty = Decimal(str(act.get("quantity") or 0))
                except Exception:
                    continue
                qty_by_symbol[symbol] = qty_by_symbol.get(symbol, Decimal(0)) + sign * qty
            total_pages = int(payload.get("totalPages") or 1) if isinstance(payload, dict) else 1
            if page >= total_pages:
                break
            page += 1
        return qty_by_symbol

    # -- manual holdings snapshots --

    async def push_manual_snapshots(
        self,
        account_id: str,
        snapshots: list[ManualSnapshotPayload],
    ) -> dict[str, Any]:
        """Push manual holdings snapshots to /api/v1/snapshots/import.

        Each snapshot carries a date + per-fund positions + cash balances.
        Wealthfolio auto-creates any unknown asset symbol with
        ``kind=INVESTMENT, quoteMode=MANUAL, quoteCcy=<currency>`` and uses
        the snapshot to derive holdings + valuation for that date — bypassing
        the activity-ledger derivation entirely for the targeted day.

        Used by the Fidelity provider since PlanViewer exposes current
        fund units + price but no per-trade history. Re-imports for the
        same (account, date) overwrite in place.
        """
        if not snapshots:
            return {"snapshotsImported": 0, "snapshotsFailed": 0, "errors": []}
        body = {
            "accountId": account_id,
            "snapshots": [_snapshot_to_payload(s) for s in snapshots],
        }
        resp = await self._request("POST", _SNAPSHOTS_IMPORT, json=body)
        if resp.status_code >= 400:
            try:
                payload = resp.json()
            except Exception:
                payload = {"raw": resp.text}
            raise WealthfolioError(
                f"Wealthfolio /snapshots/import rejected: {payload}")
        result = resp.json()
        assert isinstance(result, dict)
        failed = int(result.get("snapshotsFailed", 0))
        if failed > 0:
            raise WealthfolioError(
                f"Wealthfolio /snapshots/import: {failed} snapshot(s) failed; "
                f"errors={result.get('errors')}")
        return result


@dataclass(frozen=True)
class SnapshotPosition:
    """A per-fund position row in a Wealthfolio manual snapshot."""
    symbol: str
    quantity: Decimal
    average_cost: Decimal
    total_cost_basis: Decimal
    currency: str


@dataclass(frozen=True)
class ManualSnapshotPayload:
    """Sink-facing snapshot row. Mirrors the JSON shape WF expects."""
    date: date
    currency: str
    positions: list[SnapshotPosition]
    cash_balances: dict[str, Decimal]


def _snapshot_to_payload(s: ManualSnapshotPayload) -> dict[str, Any]:
    """Serialise a ManualSnapshotPayload into WF's import wire format."""
    return {
        "date": s.date.isoformat(),
        "currency": s.currency,
        "positions": [
            {
                "symbol": p.symbol,
                "quantity": format(p.quantity, "f"),
                "averageCost": format(p.average_cost, "f"),
                "totalCostBasis": format(p.total_cost_basis, "f"),
                "currency": p.currency,
            }
            for p in s.positions
        ],
        "cashBalances": {k: format(v, "f") for k, v in s.cash_balances.items()},
    }