import type { SupabaseClient } from '@supabase/supabase-js'
import type { CashAccount, CashAccountSource } from '@/types'
import { createLogger } from '@/lib/logger'
import { syncMappedAccounts } from '@/lib/import/account-sync'

const log = createLogger('cash-accounts')

/**
 * Suggested BAS account per currency. Single source — the enable-banking
 * callback and the AccountPickerDialog both key off these.
 */
export const CURRENCY_LEDGER_DEFAULTS: Record<string, string> = {
  SEK: '1930',
  EUR: '1932',
  USD: '1933',
  GBP: '1934',
}

export function defaultLedgerForCurrency(currency: string): string {
  return CURRENCY_LEDGER_DEFAULTS[currency.toUpperCase()] ?? '1930'
}

/**
 * Canonical read/write surface for cash_accounts.
 *
 * Replaces ad-hoc reads of bank_connections.accounts_data for routing decisions.
 * UI panels that just display balances may still read accounts_data until the
 * follow-up migration drops that column.
 *
 * All methods accept an authenticated SupabaseClient and rely on RLS for tenancy
 * isolation. Defense-in-depth filter by company_id is applied regardless.
 */

export interface ListCashAccountsOptions {
  enabledOnly?: boolean
}

export interface UpsertFromPsd2Input {
  bank_connection_id: string
  external_uid: string
  currency: string
  ledger_account: string
  iban?: string | null
  name?: string | null
  balance?: number | null
  balance_updated_at?: string | null
  enabled?: boolean
}

export async function listForCompany(
  supabase: SupabaseClient,
  companyId: string,
  opts: ListCashAccountsOptions = {},
): Promise<CashAccount[]> {
  let q = supabase
    .from('cash_accounts')
    .select('*')
    .eq('company_id', companyId)
    .order('is_primary', { ascending: false })
    .order('ledger_account', { ascending: true })

  if (opts.enabledOnly) q = q.eq('enabled', true)

  const { data, error } = await q
  if (error) {
    log.error('listForCompany failed', { companyId, error: error.message })
    return []
  }
  return (data ?? []) as CashAccount[]
}

/**
 * Primary cash account for a company. Filters by currency when provided. Falls
 * back to the global primary (`is_primary = true`) when no currency-specific
 * match exists.
 *
 * Used by skattekonto-booking's __PRIMARY_SEK__ sentinel and by transfer-pairing
 * to identify the company's default settlement account.
 */
export async function getPrimary(
  supabase: SupabaseClient,
  companyId: string,
  currency?: string,
): Promise<CashAccount | null> {
  let q = supabase
    .from('cash_accounts')
    .select('*')
    .eq('company_id', companyId)
    .eq('is_primary', true)
    .limit(1)

  if (currency) q = q.eq('currency', currency.toUpperCase())

  const { data, error } = await q.maybeSingle()
  if (error) {
    log.warn('getPrimary failed', { companyId, currency, error: error.message })
  }
  if (data) return data as CashAccount

  if (currency) {
    // Fall back to any-currency primary so a company without a SEK account still
    // resolves the sentinel: rare but possible (manual cash-on-hand only).
    const { data: anyPrimary } = await supabase
      .from('cash_accounts')
      .select('*')
      .eq('company_id', companyId)
      .eq('is_primary', true)
      .maybeSingle()
    if (anyPrimary) return anyPrimary as CashAccount
  }

  return null
}

export async function findByIban(
  supabase: SupabaseClient,
  companyId: string,
  iban: string,
): Promise<CashAccount | null> {
  if (!iban) return null
  const { data, error } = await supabase
    .from('cash_accounts')
    .select('*')
    .eq('company_id', companyId)
    .eq('iban', iban)
    .maybeSingle()
  if (error) {
    log.warn('findByIban failed', { companyId, iban, error: error.message })
    return null
  }
  return (data as CashAccount | null) ?? null
}

/**
 * Of the given bank_connection ids, return the subset whose connection row has
 * status 'revoked'. A revoked connection no longer holds a live claim on its
 * cash_accounts rows: the allocator, the picker-save collision guard, and
 * upsertFromPsd2's promote-in-place path all treat those rows like manual
 * holders so a reconnect can land back on its original ledger account.
 *
 * On lookup failure this returns an empty set (treat every connection as
 * active): the conservative pre-fix behavior.
 */
export async function getRevokedConnectionIds(
  supabase: SupabaseClient,
  companyId: string,
  connectionIds: readonly string[],
): Promise<Set<string>> {
  if (connectionIds.length === 0) return new Set()

  const { data, error } = await supabase
    .from('bank_connections')
    .select('id, status')
    .eq('company_id', companyId)
    .in('id', [...connectionIds])

  if (error) {
    log.warn('getRevokedConnectionIds lookup failed', { companyId, error: error.message })
    return new Set()
  }

  return new Set(
    ((data ?? []) as Array<{ id: string; status: string }>)
      .filter(c => c.status === 'revoked')
      .map(c => c.id),
  )
}

/**
 * Find a free BAS class-19 slot for a new PSD2 cash account, respecting the
 * UNIQUE (company_id, ledger_account) constraint. A bank returning N
 * same-currency accounts must not map them all to the currency default —
 * that's exactly the collision this prevents.
 *
 * Rules:
 *   - The currency default (1930/1932/1933/1934) is available when no
 *     PSD2-backed row holds it. A manual holder (the seeded 1930 row) does
 *     not block it — upsertFromPsd2 promotes that row in place.
 *     Rows held by a REVOKED connection count as manual too: disconnecting a
 *     bank releases its ledger claims, so reconnecting the same bank gets its
 *     original slot back instead of overflowing to 1939.
 *   - Overflow walks the free-use 1931–1959 sub-account slots, skipping the
 *     four currency defaults (reserved as suggestions for their currencies)
 *     and any slot held by ANY existing row — promoting an unrelated manual
 *     account (SIE-imported, kassa) would silently steal it.
 *   - `exclude` carries slots already assigned earlier in the caller's loop
 *     but not yet visible in the table.
 *
 * Returns null when no slot is free (or the lookup fails) — callers fall back
 * to their previous behavior and surface the error.
 */
export async function findFreeLedgerAccount(
  supabase: SupabaseClient,
  companyId: string,
  currency: string,
  exclude: ReadonlySet<string> = new Set(),
): Promise<string | null> {
  const preferred = defaultLedgerForCurrency(currency)

  const { data: rows, error } = await supabase
    .from('cash_accounts')
    .select('ledger_account, bank_connection_id')
    .eq('company_id', companyId)

  if (error) {
    log.error('findFreeLedgerAccount lookup failed', { companyId, error: error.message })
    return null
  }

  const typedRows = (rows ?? []) as Array<{ ledger_account: string; bank_connection_id: string | null }>
  const revokedConnectionIds = await getRevokedConnectionIds(
    supabase,
    companyId,
    [...new Set(typedRows.map(r => r.bank_connection_id).filter((id): id is string => id !== null))],
  )

  const anyTaken = new Set<string>()
  const connectedTaken = new Set<string>()
  for (const row of typedRows) {
    anyTaken.add(row.ledger_account)
    if (row.bank_connection_id !== null && !revokedConnectionIds.has(row.bank_connection_id)) {
      connectedTaken.add(row.ledger_account)
    }
  }

  if (!exclude.has(preferred) && !connectedTaken.has(preferred)) return preferred

  const reserved = new Set(Object.values(CURRENCY_LEDGER_DEFAULTS))
  for (let n = 1931; n <= 1959; n++) {
    const candidate = String(n)
    if (reserved.has(candidate)) continue
    if (exclude.has(candidate) || anyTaken.has(candidate)) continue
    return candidate
  }

  log.warn('findFreeLedgerAccount exhausted 1931–1959', { companyId, currency })
  return null
}

/**
 * Allocate a ledger slot for a new PSD2 account AND make sure that account
 * number exists in the company's chart of accounts — cash_accounts has no FK
 * to the chart, but booking (and the AccountPicker, which only lists chart
 * accounts) breaks on numbers the chart doesn't know. Sub-accounts outside
 * the BAS reference (1931, …) are created with metadata derived from the
 * account number; standard numbers get their BAS name.
 */
export async function allocatePsd2LedgerAccount(
  supabase: SupabaseClient,
  companyId: string,
  userId: string,
  input: { currency: string; accountName?: string | null; exclude?: ReadonlySet<string> },
): Promise<string | null> {
  const ledger = await findFreeLedgerAccount(supabase, companyId, input.currency, input.exclude ?? new Set())
  if (!ledger) return null

  const name = input.accountName?.trim() || `Bankkonto ${input.currency.toUpperCase()}`
  const sync = await syncMappedAccounts(
    supabase,
    companyId,
    userId,
    [
      {
        sourceAccount: ledger,
        sourceName: name,
        targetAccount: ledger,
        targetName: name,
        confidence: 1,
        matchType: 'exact',
        isOverride: false,
      },
    ],
    false,
  )
  if (sync.error) {
    log.error('allocatePsd2LedgerAccount chart sync failed', {
      companyId,
      ledger,
      error: sync.error,
    })
    return null
  }
  return ledger
}

/**
 * Upsert a PSD2-sourced cash account during connection callback / sync. Keyed on
 * (company_id, bank_connection_id, external_uid). When the row exists, balance
 * and ledger_account are refreshed; the rest of the metadata stays put.
 *
 * Never sets is_primary: that's owned by the user via the AccountPicker or by
 * the initial-backfill migration.
 */
export async function upsertFromPsd2(
  supabase: SupabaseClient,
  companyId: string,
  input: UpsertFromPsd2Input,
): Promise<void> {
  const payload = {
    company_id: companyId,
    bank_connection_id: input.bank_connection_id,
    external_uid: input.external_uid,
    iban: input.iban ?? null,
    name: input.name ?? null,
    currency: input.currency.toUpperCase(),
    ledger_account: input.ledger_account,
    balance: input.balance ?? null,
    balance_updated_at: input.balance_updated_at ?? null,
    enabled: input.enabled ?? true,
    source: 'enable_banking' as CashAccountSource,
  }

  // create_company_with_owner and the seed_default_cash_account migration plant
  // a manual (bank_connection_id IS NULL) row on the same ledger_account so
  // reconciliation routes work before any PSD2 connection exists, and the
  // disconnect handler demotes a revoked connection's rows to manual the same
  // way. Rows still pointing at a REVOKED connection (orphans from before the
  // disconnect handler released claims) no longer hold a live claim either.
  // In all three cases the PSD2 sync claiming that BAS slot has to promote the
  // holder row in place: a plain upsert on (company_id, bank_connection_id,
  // external_uid) wouldn't match it and the INSERT path then trips the
  // (company_id, ledger_account) UNIQUE constraint. Promoting (instead of
  // inserting) keeps the row id stable so transactions.cash_account_id links
  // and the ledger's history stay attached.
  const { data: holderRow, error: holderLookupError } = await supabase
    .from('cash_accounts')
    .select('id, bank_connection_id')
    .eq('company_id', companyId)
    .eq('ledger_account', input.ledger_account)
    .maybeSingle()

  if (holderLookupError) {
    log.error('upsertFromPsd2 holder lookup failed', {
      companyId,
      bankConnectionId: input.bank_connection_id,
      externalUid: input.external_uid,
      error: holderLookupError.message,
    })
    throw new Error(`cash_accounts upsert failed: ${holderLookupError.message}`)
  }

  const typedHolder = holderRow as { id: string; bank_connection_id: string | null } | null
  let promotableRowId: string | null = null
  if (typedHolder) {
    if (typedHolder.bank_connection_id === null) {
      promotableRowId = typedHolder.id
    } else if (typedHolder.bank_connection_id !== input.bank_connection_id) {
      const revoked = await getRevokedConnectionIds(supabase, companyId, [
        typedHolder.bank_connection_id,
      ])
      if (revoked.has(typedHolder.bank_connection_id)) {
        promotableRowId = typedHolder.id
      }
    }
    // Holder owned by the input connection itself (or by another ACTIVE
    // connection): fall through to the plain upsert. For the former the upsert
    // matches on (company_id, bank_connection_id, external_uid) and updates in
    // place; for the latter the UNIQUE constraint rejects the write and the
    // error surfaces to the caller (the picker-save collision guard should
    // have caught it earlier).
  }

  if (promotableRowId) {
    // Promoting the holder makes it THE row for this (bank_connection_id,
    // external_uid). If this connection + uid already has a row on another
    // ledger (the reconnect callback mirrored it onto an overflow slot while
    // the target slot was still wrongly blocked by a revoked connection), that
    // duplicate must be resolved first or the promote trips the UNIQUE
    // (company_id, bank_connection_id, external_uid) constraint.
    const { data: ownRow, error: ownLookupError } = await supabase
      .from('cash_accounts')
      .select('id, is_primary')
      .eq('company_id', companyId)
      .eq('bank_connection_id', input.bank_connection_id)
      .eq('external_uid', input.external_uid)
      .neq('id', promotableRowId)
      .maybeSingle()

    if (ownLookupError) {
      log.error('upsertFromPsd2 duplicate lookup failed', {
        companyId,
        bankConnectionId: input.bank_connection_id,
        externalUid: input.external_uid,
        error: ownLookupError.message,
      })
      throw new Error(`cash_accounts upsert failed: ${ownLookupError.message}`)
    }

    const typedOwn = ownRow as { id: string; is_primary: boolean } | null
    let transferPrimary = false
    if (typedOwn) {
      // With linked transactions the duplicate is demoted to a plain manual
      // row (deleting it would SET NULL those transactions' cash_account_id
      // links). Without any, it is a leftover mirror from the broken reconnect
      // and is deleted outright so its overflow slot frees up.
      const { data: linkedTx, error: linkedTxError } = await supabase
        .from('transactions')
        .select('id')
        .eq('company_id', companyId)
        .eq('cash_account_id', typedOwn.id)
        .limit(1)

      if (linkedTxError) {
        log.error('upsertFromPsd2 duplicate transaction check failed', {
          companyId,
          bankConnectionId: input.bank_connection_id,
          externalUid: input.external_uid,
          error: linkedTxError.message,
        })
        throw new Error(`cash_accounts upsert failed: ${linkedTxError.message}`)
      }

      if ((linkedTx ?? []).length > 0) {
        const { error: demoteError } = await supabase
          .from('cash_accounts')
          .update({ bank_connection_id: null, external_uid: null })
          .eq('id', typedOwn.id)
        if (demoteError) {
          throw new Error(`cash_accounts upsert failed: ${demoteError.message}`)
        }
      } else {
        const { error: deleteError } = await supabase
          .from('cash_accounts')
          .delete()
          .eq('id', typedOwn.id)
        if (deleteError) {
          throw new Error(`cash_accounts upsert failed: ${deleteError.message}`)
        }
      }
      // A primary duplicate must hand the flag to the promoted row either way:
      // deleted, it would leave the __PRIMARY_SEK__ sentinel unresolvable;
      // demoted, the sentinel would keep resolving to the stale manual row.
      transferPrimary = typedOwn.is_primary
    }

    // .select() so we can detect a 0-row UPDATE: Supabase's update().eq() returns
    // { error: null, data: [] } if the row was deleted between the SELECT above
    // and this UPDATE (rare but theoretically possible under concurrent ops).
    // If that happens, fall through to the normal upsert path instead of
    // silently returning success without persisting anything.
    const { data: promoted, error: promoteError } = await supabase
      .from('cash_accounts')
      .update(payload)
      .eq('id', promotableRowId)
      .select('id')
    if (promoteError) {
      log.error('upsertFromPsd2 promote-holder failed', {
        companyId,
        bankConnectionId: input.bank_connection_id,
        externalUid: input.external_uid,
        error: promoteError.message,
      })
      throw new Error(`cash_accounts upsert failed: ${promoteError.message}`)
    }
    if (promoted && promoted.length > 0) {
      if (transferPrimary) {
        try {
          await setPrimary(supabase, companyId, promotableRowId)
        } catch (primaryError) {
          // The promote itself succeeded; losing the primary flag is
          // recoverable via the AccountPicker, so log instead of unwinding.
          log.error('upsertFromPsd2 primary transfer failed', {
            companyId,
            cashAccountId: promotableRowId,
            error: primaryError instanceof Error ? primaryError.message : String(primaryError),
          })
        }
      }
      return
    }
    // Holder row vanished between SELECT and UPDATE: fall through to upsert.
  }

  const { error } = await supabase
    .from('cash_accounts')
    .upsert(payload, { onConflict: 'company_id,bank_connection_id,external_uid' })

  if (error) {
    log.error('upsertFromPsd2 failed', {
      companyId,
      bankConnectionId: input.bank_connection_id,
      externalUid: input.external_uid,
      error: error.message,
    })
    throw new Error(`cash_accounts upsert failed: ${error.message}`)
  }
}

/**
 * Toggle a cash account's enabled flag. Used by the AccountPicker when a user
 * opts in or out of syncing a particular PSD2 account.
 */
export async function setEnabled(
  supabase: SupabaseClient,
  companyId: string,
  cashAccountId: string,
  enabled: boolean,
): Promise<void> {
  const { error } = await supabase
    .from('cash_accounts')
    .update({ enabled })
    .eq('company_id', companyId)
    .eq('id', cashAccountId)
  if (error) throw new Error(`cash_accounts setEnabled failed: ${error.message}`)
}

/**
 * Remap a cash account to a different BAS ledger account. Triggers RLS + the
 * (company_id, ledger_account) UNIQUE constraint: surface conflict errors so
 * the UI can prompt the user to resolve.
 */
export async function setLedgerAccount(
  supabase: SupabaseClient,
  companyId: string,
  cashAccountId: string,
  ledgerAccount: string,
): Promise<void> {
  const { error } = await supabase
    .from('cash_accounts')
    .update({ ledger_account: ledgerAccount })
    .eq('company_id', companyId)
    .eq('id', cashAccountId)
  if (error) throw new Error(`cash_accounts setLedgerAccount failed: ${error.message}`)
}

/**
 * Mark a cash account as the primary for its company. Delegates to the
 * `set_cash_account_primary` RPC so the clear-old-primary and set-new-primary
 * updates happen inside a single transaction. The intermediate "no primary"
 * state is never visible to concurrent readers: important because
 * skattekonto-booking's __PRIMARY_SEK__ resolver runs through getPrimary() and
 * would otherwise see null in the gap and mis-route the counter account.
 */
export async function setPrimary(
  supabase: SupabaseClient,
  companyId: string,
  cashAccountId: string,
): Promise<void> {
  const { error } = await supabase.rpc('set_cash_account_primary', {
    p_company_id: companyId,
    p_cash_account_id: cashAccountId,
  })
  if (error) {
    throw new Error(`cash_accounts setPrimary failed: ${error.message}`)
  }
}