"""Orchestrator: one-shot sync of a Provider's activities into Wealthfolio."""
from __future__ import annotations

import logging
from collections.abc import AsyncIterator
from dataclasses import dataclass
from datetime import datetime
from decimal import Decimal

from broker_sync.dedup import SyncRecordStore
from broker_sync.models import Account, Activity, ActivityType
from broker_sync.providers.base import Provider
from broker_sync.sinks.wealthfolio import WealthfolioSink

log = logging.getLogger(__name__)

# Wealthfolio's CSV import accepts arbitrary sizes but we batch to keep
# any single-row validation error from failing the whole run.
_BATCH_SIZE = 200


@dataclass
class SyncResult:
    provider: str
    fetched: int
    new_after_dedup: int
    imported: int
    failed: int  # rows that import_activities returned errors for


async def sync_provider_to_wealthfolio(
    *,
    provider: Provider,
    sink: WealthfolioSink,
    dedup: SyncRecordStore,
    since: datetime | None = None,
    before: datetime | None = None,
) -> SyncResult:
    """Run the fetch → dedup → import → record pipeline for one provider.

    Caller owns sink lifecycle (including `login()` and `close()`).
    """
    wf_account_ids = await _ensure_accounts(sink, provider.accounts())

    fetched = 0
    new_after_dedup = 0
    imported = 0
    failed = 0
    # Batches are (original_account_id, remapped_for_import Activity) pairs.
    # Dedup keys on our stable account_id; the import row uses Wealthfolio's UUID.
    batch: list[tuple[str, Activity]] = []

    async for activity in provider.fetch(since=since, before=before):
        fetched += 1
        # Expand each BUY/SELL into (original, matching DEPOSIT/WITHDRAWAL).
        # See `_matched_cash_flow` — without the match, WF's historical Net
        # Worth chart shows phantom spikes because BUYs consume cash that
        # was never "deposited" according to the activity log.
        for act in _with_cash_flow_match(activity):
            if dedup.has_seen(provider.name, act.account_id, act.external_id):
                continue
            new_after_dedup += 1
            _tag_notes(act, provider.name)
            original_account_id = act.account_id
            # Submit under Wealthfolio's UUID; keep dedup keyed on our id.
            wf_id = wf_account_ids.get(original_account_id)
            if wf_id:
                act.account_id = wf_id
            batch.append((original_account_id, act))
            if len(batch) >= _BATCH_SIZE:
                ok, bad = await _flush_batch(sink, dedup, provider.name, batch)
                imported += ok
                failed += bad
                batch = []

    if batch:
        ok, bad = await _flush_batch(sink, dedup, provider.name, batch)
        imported += ok
        failed += bad

    log.info(
        "sync complete provider=%s fetched=%d new=%d imported=%d failed=%d",
        provider.name,
        fetched,
        new_after_dedup,
        imported,
        failed,
    )
    return SyncResult(
        provider=provider.name,
        fetched=fetched,
        new_after_dedup=new_after_dedup,
        imported=imported,
        failed=failed,
    )


async def _ensure_accounts(sink: WealthfolioSink, accounts: list[Account]) -> dict[str, str]:
    """Return {our_account_id: wealthfolio_uuid}."""
    out: dict[str, str] = {}
    for account in accounts:
        out[account.id] = await sink.ensure_account(account)
    return out


def _tag_notes(activity: Activity, provider_name: str) -> None:
    """Stamp the notes field with a dedup-friendly tag (belt-and-braces)."""
    tag = f"sync:{provider_name}:{activity.external_id}"
    if activity.notes:
        if tag not in activity.notes:
            activity.notes = f"{activity.notes} | {tag}"
    else:
        activity.notes = tag


async def _flush_batch(
    sink: WealthfolioSink,
    dedup: SyncRecordStore,
    provider_name: str,
    batch: list[tuple[str, Activity]],
) -> tuple[int, int]:
    activities_only = [a for _, a in batch]
    try:
        created = await sink.import_activities(activities_only)
    except Exception:
        log.exception("Wealthfolio import failed for batch of %d", len(batch))
        return 0, len(batch)

    # Map returned Wealthfolio activity ids back to our external_ids.
    by_external: dict[str, str | None] = {}
    for row in created:
        ext = row.get("external_id") if isinstance(row, dict) else None
        wf_id = row.get("id") if isinstance(row, dict) else None
        if ext:
            by_external[str(ext)] = str(wf_id) if wf_id is not None else None

    ok = 0
    for original_account_id, a in batch:
        wf_id = by_external.get(a.external_id)
        dedup.record(
            provider_name,
            original_account_id,
            a.external_id,
            wealthfolio_activity_id=wf_id,
        )
        ok += 1
    return ok, 0


async def collect(iterator: AsyncIterator[Activity]) -> list[Activity]:
    """Tiny helper — drain an async iterator to a list. Mainly for tests."""
    return [a async for a in iterator]


# -- Cash-flow matching --------------------------------------------------
# BUY and SELL activities touch shares, not cash. Without an explicit
# DEPOSIT/WITHDRAWAL on the same day, WF models the account as having
# "phantom" cash debt — and its Net Worth chart shows cliff-jumps
# whenever a lump offset is applied after the fact.
#
# The pipeline emits a matching DEPOSIT (for BUY) or WITHDRAWAL (for SELL)
# right alongside each trade so the account's cash balance reconciles to
# ~0 at every point in time. Providers that already emit real cash flows
# (e.g. a Trading212 "deposit" endpoint, if we ever wire it) should set
# `Provider.emits_matching_cash_flow = True` to opt out — no provider
# does today (Trading212 only exposes BUY/SELL via the /orders endpoint).


def _matched_cash_flow(a: Activity) -> Activity | None:
    """Return the DEPOSIT/WITHDRAWAL that funds/receives the BUY/SELL `a`.

    Returns None for every other activity type — those already touch cash
    directly (DEPOSIT, WITHDRAWAL, DIVIDEND, FEE, TAX, TRANSFER_*,
    CONVERSION_*).
    """
    if a.activity_type is ActivityType.BUY:
        if a.quantity is None or a.unit_price is None:
            return None
        amount = a.quantity * a.unit_price + (a.fee or Decimal(0))
        kind, tag = ActivityType.DEPOSIT, "buy"
    elif a.activity_type is ActivityType.SELL:
        if a.quantity is None or a.unit_price is None:
            return None
        amount = a.quantity * a.unit_price - (a.fee or Decimal(0))
        kind, tag = ActivityType.WITHDRAWAL, "sell"
    else:
        return None
    if amount <= 0:
        return None
    return Activity(
        external_id=f"cash-flow-match:{tag}:{a.external_id}",
        account_id=a.account_id,
        account_type=a.account_type,
        date=a.date,
        activity_type=kind,
        currency=a.currency,
        amount=amount,
        notes=f"cash-flow-match:{tag}:{a.external_id}",
    )


def _with_cash_flow_match(a: Activity) -> list[Activity]:
    """Expand one activity into [original] or [original, matching cash flow]."""
    match = _matched_cash_flow(a)
    return [a] if match is None else [a, match]