"""Accounts API (SPEC §9.1): discover, test, create, list, update, delete."""

from __future__ import annotations

import uuid
from typing import Annotated

from fastapi import APIRouter, Depends
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.accounts.discovery import discover
from app.accounts.schemas import (
    AccountDetailOut,
    CandidateOut,
    CreateAccountRequest,
    DiscoverRequest,
    DiscoverResponse,
    DiscoveryStepOut,
    HelpBlockOut,
    ServerConfigIn,
    TestRequest,
    TestResponse,
    UpdateAccountRequest,
)
from app.accounts.service import AccountExistsError, create_account, delete_account
from app.accounts.testing import AccountTestError, test_account
from app.accounts.types import CandidateConfig, ServerConfig
from app.api.errors import raise_api_error
from app.api.schemas import AccountOut
from app.config import get_settings
from app.db import get_session
from app.identity.deps import CurrentUser, require_csrf
from app.models import Account
from app.queue import enqueue_job
from app.redis_client import get_redis
from app.security.crypto import encrypt_secret

router = APIRouter(prefix="/accounts", tags=["accounts"])

DbSession = Annotated[AsyncSession, Depends(get_session)]

_DISCOVER_LIMIT = 10  # per minute per user (SPEC §10.5)
_DISCOVER_WINDOW = 60


async def _rate_limit_discover(user_id: uuid.UUID) -> None:
    redis = get_redis()
    key = f"rl:discover:{user_id}"
    count = await redis.incr(key)
    if count == 1:
        await redis.expire(key, _DISCOVER_WINDOW)
    if count > _DISCOVER_LIMIT:
        raise_api_error(429, "rate_limited", "too many discovery requests; slow down")


def _server_in(cfg: ServerConfig) -> ServerConfigIn:
    return ServerConfigIn(host=cfg.host, port=cfg.port, tls=cfg.tls, auth=cfg.auth)


def _candidate_out(c: CandidateConfig) -> CandidateOut:
    return CandidateOut(
        imap=_server_in(c.imap),
        smtp=_server_in(c.smtp),
        source=c.source,
        oauth_provider=c.oauth_provider,
        auth_strategy=list(c.auth_strategy),
        help=(
            HelpBlockOut(
                help_id=c.help.help_id,
                deep_link=c.help.deep_link,
                app_name_hint=c.help.app_name_hint,
                steps=list(c.help.steps),
                docs_url=c.help.docs_url,
                setup_link=c.help.setup_link,
                button_after_step=c.help.button_after_step,
            )
            if c.help
            else None
        ),
    )


def _to_server_config(cfg: ServerConfigIn) -> ServerConfig:
    return ServerConfig(cfg.host, cfg.port, cfg.tls, cfg.auth)


@router.get("", response_model=list[AccountOut])
async def list_accounts(user: CurrentUser, db: DbSession) -> list[AccountOut]:
    accounts = await db.scalars(
        select(Account).where(Account.user_id == user.id).order_by(Account.created_at)
    )
    return [
        AccountOut(
            id=a.id,
            email=a.email,
            display_name=a.display_name,
            color=a.color,
            state=a.state,
            signature=a.signature,
            sync_window=a.sync_window,
            backfill_total=a.backfill_total,
            backfill_done=a.backfill_done,
        )
        for a in accounts
    ]


@router.post("/sync", dependencies=[Depends(require_csrf)])
async def sync_all_accounts(user: CurrentUser, db: DbSession) -> dict[str, str]:
    """Poll every folder of each of the user's accounts (manual Refresh)."""
    account_ids = list(await db.scalars(select(Account.id).where(Account.user_id == user.id)))
    for account_id in account_ids:
        await enqueue_job("refresh_account_job", str(account_id))
    return {"status": "queued"}


@router.post("/discover", response_model=DiscoverResponse, dependencies=[Depends(require_csrf)])
async def discover_account(body: DiscoverRequest, user: CurrentUser) -> DiscoverResponse:
    await _rate_limit_discover(user.id)
    result = await discover(str(body.email))
    return DiscoverResponse(
        candidates=[_candidate_out(c) for c in result.candidates],
        steps=[
            DiscoveryStepOut(method=s.method, status=s.status, detail=s.detail)
            for s in result.steps
        ],
        google_oauth_enabled=get_settings().google_oauth_enabled,
    )


@router.post("/test", response_model=TestResponse, dependencies=[Depends(require_csrf)])
async def test_account_credentials(body: TestRequest, _user: CurrentUser) -> TestResponse:
    try:
        await test_account(
            imap=_to_server_config(body.imap),
            smtp=_to_server_config(body.smtp),
            username=body.username or str(body.email),
            password=body.password,
        )
    except AccountTestError as exc:
        raise_api_error(400, exc.code, exc.detail)
    return TestResponse(ok=True)


@router.post("", response_model=AccountDetailOut, dependencies=[Depends(require_csrf)])
async def create_new_account(
    body: CreateAccountRequest, user: CurrentUser, db: DbSession
) -> AccountDetailOut:
    # Validate credentials before persisting (also the §10.2 decryption sibling).
    try:
        await test_account(
            imap=_to_server_config(body.imap),
            smtp=_to_server_config(body.smtp),
            username=body.username or str(body.email),
            password=body.password,
        )
    except AccountTestError as exc:
        raise_api_error(400, exc.code, exc.detail)

    try:
        account = await create_account(db, user_id=user.id, req=body)
    except AccountExistsError:
        raise_api_error(409, "account_exists", "an account for this email already exists")
    await db.commit()

    await enqueue_job("sync_bootstrap_account", str(account.id))

    return _detail(account)


@router.get("/{account_id}", response_model=AccountDetailOut)
async def get_account(account_id: uuid.UUID, user: CurrentUser, db: DbSession) -> AccountDetailOut:
    account = await db.scalar(
        select(Account).where(Account.id == account_id, Account.user_id == user.id)
    )
    if account is None:
        raise_api_error(404, "not_found", "account not found")
    return _detail(account)


def _server_from_config(cfg: dict[str, object]) -> ServerConfig:
    return ServerConfig(
        str(cfg["host"]),
        int(str(cfg["port"])),
        str(cfg.get("tls", "ssl")),
        str(cfg.get("auth", "password")),
    )


@router.patch(
    "/{account_id}", response_model=AccountDetailOut, dependencies=[Depends(require_csrf)]
)
async def update_account(
    account_id: uuid.UUID, body: UpdateAccountRequest, user: CurrentUser, db: DbSession
) -> AccountDetailOut:
    account = await db.scalar(
        select(Account).where(Account.id == account_id, Account.user_id == user.id)
    )
    if account is None:
        raise_api_error(404, "not_found", "account not found")
    if body.display_name is not None:
        account.display_name = body.display_name
    if body.color is not None:
        account.color = body.color
    if body.signature is not None:
        account.signature = body.signature

    # Broadening the sync window (e.g. "new" -> "all", "Download all mail") means
    # importing history not fetched before, so re-run the backfill (SPEC §12 M2).
    # persist_message is idempotent on (mailbox_id, uid), so already-synced mail
    # is skipped. Narrowing keeps existing mail — nothing to fetch.
    _COVERAGE = {"new": 0, "3months": 1, "all": 2}
    broaden = False
    if body.sync_window is not None and body.sync_window != account.sync_window:
        broaden = _COVERAGE[body.sync_window] > _COVERAGE.get(account.sync_window, 0)
        account.sync_window = body.sync_window
        if broaden:
            account.state = "backfilling"

    # Connection settings and/or password: re-validate against the servers, then
    # re-encrypt the secret and re-sync. The password must be supplied (§10.2: the
    # stored secret is only decrypted in the worker, never here).
    conn_change = body.imap is not None or body.smtp is not None or body.password is not None
    if conn_change:
        if not body.password:
            raise_api_error(
                400,
                "password_required",
                "the mailbox password is required to change server settings",
            )
        imap = (
            _to_server_config(body.imap) if body.imap else _server_from_config(account.imap_config)
        )
        smtp = (
            _to_server_config(body.smtp) if body.smtp else _server_from_config(account.smtp_config)
        )
        try:
            await test_account(imap=imap, smtp=smtp, username=account.email, password=body.password)
        except AccountTestError as exc:
            raise_api_error(400, exc.code, exc.detail)
        account.imap_config = {
            "host": imap.host,
            "port": imap.port,
            "tls": imap.tls,
            "auth": imap.auth,
        }
        account.smtp_config = {
            "host": smtp.host,
            "port": smtp.port,
            "tls": smtp.tls,
            "auth": smtp.auth,
        }
        account.secret_ct = encrypt_secret(body.password.encode("utf-8"))
        account.state = "backfilling"

    await db.commit()

    if conn_change or broaden:
        await enqueue_job("sync_bootstrap_account", str(account.id))

    return _detail(account)


@router.delete("/{account_id}", dependencies=[Depends(require_csrf)])
async def remove_account(account_id: uuid.UUID, user: CurrentUser, db: DbSession) -> dict[str, str]:
    ok = await delete_account(db, user_id=user.id, account_id=account_id)
    if not ok:
        raise_api_error(404, "not_found", "account not found")
    await db.commit()
    return {"status": "deleted"}


def _detail(account: Account) -> AccountDetailOut:
    return AccountDetailOut(
        id=account.id,
        email=account.email,
        display_name=account.display_name,
        color=account.color,
        state=account.state,
        state_detail=account.state_detail,
        signature=account.signature,
        sync_window=account.sync_window,
        backfill_total=account.backfill_total,
        backfill_done=account.backfill_done,
        imap_config=account.imap_config,
        smtp_config=account.smtp_config,
    )