require "digest/md5"

class EnableBankingEntry::Processor
  include CurrencyNormalizable

  # Small-merchant card terminal providers that prefix the payee with "KEYWORD *"
  PAYMENT_PROCESSOR_PREFIX = /\A(SUMUP|SQ|IZETTLE|ZETTLE|PAYPAL)\s*\*\s*/i

  # Guard against spurious matches from very short known merchant names (e.g. a
  # 2-letter FamilyMerchant name matching inside unrelated text, like "IT" would
  # inside "NAME IT" -- a real chain name observed in this issue's own data).
  MIN_KNOWN_MERCHANT_MATCH_LENGTH = 3

  # enable_banking_transaction is the raw hash fetched from Enable Banking API
  # Transaction structure from Enable Banking:
  # {
  #   transaction_id, entry_reference, booking_date, value_date, transaction_date,
  #   transaction_amount: { amount, currency },
  #   creditor_name, debtor_name, remittance_information, ...
  # }
  def self.compute_external_id(raw_transaction_data)
    data = raw_transaction_data.with_indifferent_access
    id = data[:transaction_id].presence || data[:entry_reference].presence
    return "enable_banking_#{id}" if id

    # Some ASPSPs omit both transaction_id and entry_reference (both are optional
    # in PSD2). Generate a deterministic content-based ID so these transactions
    # can still be imported idempotently. Uses the same fields as the importer's
    # dedup key so the two strategies stay in sync.
    date = data[:booking_date].presence || data[:value_date].presence || data[:transaction_date]
    amount = data.dig(:transaction_amount, :amount).presence || data[:amount]
    currency = data.dig(:transaction_amount, :currency).presence || data[:currency]
    direction = data[:credit_debit_indicator]
    creditor = data.dig(:creditor, :name).presence || data[:creditor_name]
    debtor = data.dig(:debtor, :name).presence || data[:debtor_name]
    remittance = data[:remittance_information]
    remittance_key = remittance.is_a?(Array) ? remittance.compact.map(&:to_s).sort.join("|") : remittance.to_s

    content = [ date, amount, currency, direction, creditor, debtor, remittance_key ].map(&:to_s).join("\x1F")
    return nil if content.gsub("\x1F", "").blank?

    "enable_banking_content_#{Digest::MD5.hexdigest(content)}"
  end

  # known_merchant_names: optional pre-fetched Family#known_merchant_names, so a
  # caller processing many transactions in one batch (see
  # EnableBankingAccount::Transactions::Processor) can compute it once instead of
  # once per row -- same pattern as the shared import_adapter. Falls back to
  # fetching it lazily per-instance when not provided (e.g. in isolation/tests).
  def initialize(enable_banking_transaction, enable_banking_account:, import_adapter: nil, known_merchant_names: nil)
    @enable_banking_transaction = enable_banking_transaction
    @enable_banking_account = enable_banking_account
    @import_adapter = import_adapter
    @known_merchant_names = known_merchant_names
  end

  def process
    # Cache a safe diagnostic id upfront — used in all logging paths so rescue
    # blocks never call the potentially-raising private external_id method.
    safe_id = self.class.compute_external_id(@enable_banking_transaction) || "unknown"

    unless account.present?
      Rails.logger.warn "EnableBankingEntry::Processor - No linked account for enable_banking_account #{enable_banking_account.id}, skipping transaction #{safe_id}"
      return nil
    end

    begin
      import_adapter.import_transaction(
        external_id: external_id,
        amount: amount,
        currency: currency,
        date: date,
        name: name,
        source: "enable_banking",
        merchant: merchant,
        notes: notes,
        extra: extra
      )
    rescue ArgumentError => e
      Rails.logger.error "EnableBankingEntry::Processor - Validation error for transaction #{safe_id}: #{e.message}"
      raise
    rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotSaved => e
      Rails.logger.error "EnableBankingEntry::Processor - Failed to save transaction #{safe_id}: #{e.message}"
      raise StandardError.new("Failed to import transaction: #{e.message}")
    rescue => e
      Rails.logger.error "EnableBankingEntry::Processor - Unexpected error processing transaction #{safe_id}: #{e.class} - #{e.message}"
      Rails.logger.error e.backtrace.join("\n")
      raise StandardError.new("Unexpected error importing transaction: #{e.message}")
    end
  end

  private

    attr_reader :enable_banking_transaction, :enable_banking_account

    def import_adapter
      @import_adapter ||= Account::ProviderImportAdapter.new(account)
    end

    def account
      @account ||= enable_banking_account.current_account
    end

    def data
      @data ||= enable_banking_transaction.with_indifferent_access
    end

    def external_id
      id = self.class.compute_external_id(data)
      raise ArgumentError, "Enable Banking transaction missing required identifier (transaction_id, entry_reference, or identifiable content)" unless id
      id
    end

    def name
      # Build name from available Enable Banking transaction fields
      # Priority: counterparty name > bank_transaction_code description > remittance_information

      counterparty = counterparty_name
      return counterparty if counterparty.present? && !technical_card_counterparty?(counterparty)

      # Some institutions (e.g. Wise) use technical CARD-* identifiers as counterparties
      # Prefer remittance_information first in that case since it contains the real merchant label for Wise
      if technical_card_counterparty?(counterparty)
        remittance = primary_remittance_information
        return remittance.truncate(100) if remittance.present?
      end

      # Fall back to bank_transaction_code description
      bank_tx_description = data.dig(:bank_transaction_code, :description)
      return bank_tx_description if bank_tx_description.present?

      # Fall back to remittance_information
      remittance = primary_remittance_information
      return remittance.truncate(100) if remittance.present?

      # Final fallback: use transaction type indicator
      credit_debit_indicator == "CRDT" ? "Incoming Transfer" : "Outgoing Transfer"
    end

    def merchant
      # Use the counterparty when it is human readable; otherwise fall back to remittance
      # for CARD-* transactions where the remittance often contains the actual merchant
      merchant_name = merchant_name_candidate
      return nil if merchant_name.blank?

      merchant_id = Digest::MD5.hexdigest(merchant_name.downcase)

      @merchant ||= begin
        import_adapter.find_or_create_merchant(
          provider_merchant_id: "enable_banking_merchant_#{merchant_id}",
          name: merchant_name,
          source: "enable_banking"
        )
      rescue ActiveRecord::RecordInvalid => e
        Rails.logger.error "EnableBankingEntry::Processor - Failed to create merchant '#{merchant_name}': #{e.message}"
        nil
      end
    end

    def notes
      parts = []

      remittance = data[:remittance_information]
      if remittance.is_a?(Array) && remittance.any?
        parts << remittance.join("\n")
      elsif remittance.is_a?(String) && remittance.present?
        parts << remittance
      end

      parts << data[:note] if data[:note].present?

      parts.join("\n\n").presence
    end

    def extra
      eb = {}

      if data[:exchange_rate].present?
        eb[:fx_rate]              = data.dig(:exchange_rate, :exchange_rate)
        eb[:fx_unit_currency]     = data.dig(:exchange_rate, :unit_currency)
        eb[:fx_instructed_amount] = data.dig(:exchange_rate, :instructed_amount, :amount)
      end

      eb[:merchant_category_code] = data[:merchant_category_code] if data[:merchant_category_code].present?
      eb[:pending] = true if data[:_pending] == true

      eb.compact!
      eb.empty? ? nil : { enable_banking: eb }
    end

    def amount_value
      @amount_value ||= begin
        tx_amount = data[:transaction_amount] || {}
        raw_amount = tx_amount[:amount] || data[:amount] || "0"

        absolute_amount = case raw_amount
        when String
          BigDecimal(raw_amount).abs
        when Numeric
          BigDecimal(raw_amount.to_s).abs
        else
          BigDecimal("0")
        end

        # Sure convention: positive = outflow (expense/debit from account), negative = inflow (income/credit)
        # Enable Banking: DBIT = debit from account (outflow), CRDT = credit to account (inflow)
        # Therefore: DBIT → +absolute_amount, CRDT → -absolute_amount
        credit_debit_indicator == "CRDT" ? -absolute_amount : absolute_amount
      rescue ArgumentError => e
        Rails.logger.error "Failed to parse Enable Banking transaction amount: #{raw_amount.inspect} - #{e.message}"
        raise
      end
    end

    def credit_debit_indicator
      data[:credit_debit_indicator]
    end

    def counterparty_name
      # Determine counterparty based on transaction direction
      # For outgoing payments (DBIT), counterparty is the creditor (who we paid)
      # For incoming payments (CRDT), counterparty is the debtor (who paid us)
      if credit_debit_indicator == "CRDT"
        data.dig(:debtor, :name).presence || data[:debtor_name].presence
      else
        data.dig(:creditor, :name).presence || data[:creditor_name].presence
      end
    end

    def technical_card_counterparty?(value)
      # Some providers expose card transactions with CARD-<digits> placeholders instead of a real counterparty name
      value.to_s.strip.match?(/\ACARD-\d+\z/i)
    end

    def primary_remittance_information
      lines = remittance_information_lines
      descriptive = lines.find { |line| !technical_remittance_line?(line) } || lines.first
      return descriptive if descriptive.blank?

      matched_known_merchant_name(descriptive) || strip_payment_processor_prefix(descriptive)
    end

    def remittance_information_lines
      remittance = data[:remittance_information]
      Array.wrap(remittance)
        .map { |value| value.to_s.strip.presence }
        .compact
    end

    def technical_remittance_line?(value)
      line = value.to_s.strip
      # Terminal booking line, e.g. "POS   45,13 AT  D6   31.07. 10:27": require the
      # keyword+amount prefix AND the trailing date+time stamp TOGETHER, not either
      # alone. Either signal in isolation false-positives on legitimate descriptors:
      # a line like "POS 45,13 BILLA DANKT ..." (merchant appended after the amount,
      # no separate technical-only element) would wrongly match on the prefix alone,
      # and a line like "Invoice paid 31.07. 10:27" would wrongly match on the date
      # suffix alone. Requiring both matches every real technical line observed in
      # production while leaving both of those legitimate shapes untouched. Day/month
      # accept 1-2 digits (not just 2) so an un-padded ASPSP date ("1.07." instead of
      # "01.07.") is still recognized as technical.
      line.match?(/\A(POS|ATM)\s+\d+[.,]\d{2}\b.*\d{1,2}[.\/]\d{1,2}\.?\s+\d{2}:\d{2}\z/i)
    end

    def strip_payment_processor_prefix(value)
      return value if value.blank?
      value.sub(PAYMENT_PROCESSOR_PREFIX, "").strip.presence || value
    end

    # Prefer a merchant name the family already knows over any text heuristic: it's
    # already clean/trusted, and sidesteps guessing which parts of a POS line are
    # noise (store numbers, city, loyalty markers, ...) vs. part of the name.
    # Case-insensitive, whole-word match; the *stored* name (and its casing) wins,
    # so e.g. "BILLA DANKT 0007114" resolves to "Billa", not "BILLA". Longest match
    # wins when multiple known names match (prefer the more specific one).
    def matched_known_merchant_name(line)
      candidates = known_merchant_names.select { |name| name.length >= MIN_KNOWN_MERCHANT_MATCH_LENGTH }
      # Lookaround instead of \b at both ends: \b only fires on a word/non-word
      # transition, so it silently fails to match right after a name that itself
      # ends in punctuation (e.g. "A+B (Café)" ends in ")" -- a non-word char next
      # to another non-word char has no \b between them). Asserting "the boundary
      # character, if any, isn't alphanumeric" works regardless of how the known
      # name itself starts/ends.
      matches = candidates.select do |name|
        line.match?(/(?<![[:alnum:]_])#{Regexp.escape(name)}(?![[:alnum:]_])/i)
      end
      matches.max_by(&:length)
    end

    def known_merchant_names
      @known_merchant_names ||= account&.family&.known_merchant_names || []
    end

    def merchant_name_candidate
      counterparty = counterparty_name.to_s.strip
      return counterparty if counterparty.present? && !technical_card_counterparty?(counterparty)

      remittance = primary_remittance_information
      return nil if remittance.blank?

      # Trust remittance-derived text as a merchant candidate when either the
      # counterparty was a technical CARD-* placeholder (existing Wise case), or
      # the text matched an ALREADY-KNOWN merchant for this family. Inventing a
      # brand-new merchant from raw noisy POS text (blank counterparty, no CARD-*
      # signal, no known-merchant match) stays out of scope, unchanged from #2935.
      return remittance.truncate(100, omission: "") if technical_card_counterparty?(counterparty)
      return remittance if known_merchant_names.include?(remittance)

      nil
    end

    def amount
      # Sure convention: positive = outflow (debit/expense), negative = inflow (credit/income)
      # amount_value already applies this: DBIT → +absolute, CRDT → -absolute
      amount_value
    end

    def currency
      tx_amount = data[:transaction_amount] || {}
      parse_currency(tx_amount[:currency]) || parse_currency(data[:currency]) || account&.currency || "EUR"
    end

    def log_invalid_currency(currency_value)
      safe_id = self.class.compute_external_id(data) || "unknown"
      Rails.logger.warn("Invalid currency code '#{currency_value}' in Enable Banking transaction #{safe_id}, falling back to account currency")
    end

    def date
      # Prefer booking_date, fall back to value_date, then transaction_date
      date_value = data[:booking_date] || data[:value_date] || data[:transaction_date]

      case date_value
      when String
        if date_value.include?("T") || date_value.include?(":")
          Time.parse(date_value).in_time_zone(account&.family&.timezone).to_date
        else
          Date.parse(date_value)
        end
      when Integer, Float
        Time.at(date_value).in_time_zone(account&.family&.timezone).to_date
      when Time, DateTime
        date_value.in_time_zone(account&.family&.timezone).to_date
      when Date
        date_value
      else
        Rails.logger.error("Enable Banking transaction has invalid date value: #{date_value.inspect}")
        raise ArgumentError, "Invalid date format: #{date_value.inspect}"
      end
    rescue ArgumentError, TypeError => e
      Rails.logger.error("Failed to parse Enable Banking transaction date '#{date_value}': #{e.message}")
      raise ArgumentError, "Unable to parse transaction date: #{date_value.inspect}"
    end
end