Lunchflow integration (#259)

* First pass lunch flow

* Fixes

- Fix apikey not being saved properly due to provider no reload support
- Fix proper messages if we try to link existing accounts.

* Fix better error handling

* Filter existing transactions and skip duplicates

* FIX messaging

* Branding :)

* Fix XSS and linter

* FIX provider concern

- also fix code duplication

* FIX md5 digest

* Updated determine_sync_start_date to be account-aware

* Review fixes

* Broaden error catch to not crash UI

* Fix buttons styling

* FIX process account error handling

* FIX account cap and url parsing

* Lunch Flow brand

* Found orphan i18n strings

* Remove per conversation with @sokie

---------

Co-authored-by: Juan José Mata <juanjo.mata@gmail.com>

app/models/lunchflow_entry/processor.rb

@@ -0,0 +1,147 @@
+require "digest/md5"
+
+class LunchflowEntry::Processor
+  # lunchflow_transaction is the raw hash fetched from Lunchflow API and converted to JSONB
+  # Transaction structure: { id, accountId, amount, currency, date, merchant, description }
+  def initialize(lunchflow_transaction, lunchflow_account:)
+    @lunchflow_transaction = lunchflow_transaction
+    @lunchflow_account = lunchflow_account
+  end
+
+  def process
+    # Validate that we have a linked account before processing
+    unless account.present?
+      Rails.logger.warn "LunchflowEntry::Processor - No linked account for lunchflow_account #{lunchflow_account.id}, skipping transaction #{external_id}"
+      return nil
+    end
+
+    # Wrap import in error handling to catch validation and save errors
+    begin
+      import_adapter.import_transaction(
+        external_id: external_id,
+        amount: amount,
+        currency: currency,
+        date: date,
+        name: name,
+        source: "lunchflow",
+        merchant: merchant
+      )
+    rescue ArgumentError => e
+      # Re-raise validation errors (missing required fields, invalid data)
+      Rails.logger.error "LunchflowEntry::Processor - Validation error for transaction #{external_id}: #{e.message}"
+      raise
+    rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotSaved => e
+      # Handle database save errors
+      Rails.logger.error "LunchflowEntry::Processor - Failed to save transaction #{external_id}: #{e.message}"
+      raise StandardError.new("Failed to import transaction: #{e.message}")
+    rescue => e
+      # Catch unexpected errors with full context
+      Rails.logger.error "LunchflowEntry::Processor - Unexpected error processing transaction #{external_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 :lunchflow_transaction, :lunchflow_account
+
+    def import_adapter
+      @import_adapter ||= Account::ProviderImportAdapter.new(account)
+    end
+
+    def account
+      @account ||= lunchflow_account.current_account
+    end
+
+    def data
+      @data ||= lunchflow_transaction.with_indifferent_access
+    end
+
+    def external_id
+      id = data[:id].presence
+      raise ArgumentError, "Lunchflow transaction missing required field 'id'" unless id
+      "lunchflow_#{id}"
+    end
+
+    def name
+      # Use Lunchflow's merchant and description to create informative transaction names
+      merchant_name = data[:merchant]
+      description = data[:description]
+
+      # Combine merchant + description when both are present and different
+      if merchant_name.present? && description.present? && merchant_name != description
+        "#{merchant_name} - #{description}"
+      elsif merchant_name.present?
+        merchant_name
+      elsif description.present?
+        description
+      else
+        "Unknown transaction"
+      end
+    end
+
+    def merchant
+      return nil unless data[:merchant].present?
+
+      # Create a stable merchant ID from the merchant name
+      # Using digest to ensure uniqueness while keeping it deterministic
+      merchant_name = data[:merchant].to_s.strip
+      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: "lunchflow_merchant_#{merchant_id}",
+          name: merchant_name,
+          source: "lunchflow"
+        )
+      rescue ActiveRecord::RecordInvalid => e
+        Rails.logger.error "LunchflowEntry::Processor - Failed to create merchant '#{merchant_name}': #{e.message}"
+        nil
+      end
+    end
+
+    def amount
+      parsed_amount = case data[:amount]
+      when String
+        BigDecimal(data[:amount])
+      when Numeric
+        BigDecimal(data[:amount].to_s)
+      else
+        BigDecimal("0")
+      end
+
+      # Lunchflow likely uses standard convention where negative is expense, positive is income
+      # Maybe expects opposite convention (expenses positive, income negative)
+      # So we negate the amount to convert from Lunchflow to Maybe format
+      -parsed_amount
+    rescue ArgumentError => e
+      Rails.logger.error "Failed to parse Lunchflow transaction amount: #{data[:amount].inspect} - #{e.message}"
+      raise
+    end
+
+    def currency
+      data[:currency].presence || account&.currency || "USD"
+    end
+
+    def date
+      case data[:date]
+      when String
+        Date.parse(data[:date])
+      when Integer, Float
+        # Unix timestamp
+        Time.at(data[:date]).to_date
+      when Time, DateTime
+        data[:date].to_date
+      when Date
+        data[:date]
+      else
+        Rails.logger.error("Lunchflow transaction has invalid date value: #{data[:date].inspect}")
+        raise ArgumentError, "Invalid date format: #{data[:date].inspect}"
+      end
+    rescue ArgumentError, TypeError => e
+      Rails.logger.error("Failed to parse Lunchflow transaction date '#{data[:date]}': #{e.message}")
+      raise ArgumentError, "Unable to parse transaction date: #{data[:date].inspect}"
+    end
+end