#399

backend/app/services/post_import_source_parser.rb

@@ -4,6 +4,7 @@ class PostImportSourceParser
   MAX_ROWS = 100
   MAX_BYTES = 1.megabyte
   MAX_CELL_BYTES = 20.kilobytes
+  MAX_COLUMNS = 50
 
   def initialize source:, format:, has_header: false, json_path: nil
     @source = source.to_s
@@ -28,8 +29,9 @@ class PostImportSourceParser
     headers = @has_header ? table.shift : nil
     ensure_limits!(table)
     width = table.map(&:length).max.to_i
+    raise ArgumentError, "列数は #{ MAX_COLUMNS } 列までです．" if width > MAX_COLUMNS
     { columns: (0...width).map { |index| { key: index.to_s,
-                                          label: "#{ ('A'.ord + index).chr }：#{ headers&.[](index).presence || '列' }" } },
+                                          label: "#{ column_name(index) }：#{ headers&.[](index).presence || '列' }" } },
       rows: table.each_with_index.map { |values, index| { source_row: index + (@has_header ? 2 : 1), values: } } }
   rescue CSV::MalformedCSVError => e
     raise ArgumentError, "CSV・TSV の形式が不正です: #{ e.message }"
@@ -42,7 +44,8 @@ class PostImportSourceParser
 
     ensure_limits!(value)
     keys = value.grep(Hash).flat_map(&:keys).map(&:to_s).uniq
-    { columns: keys.each_with_index.map { |key, index| { key:, label: "#{ ('A'.ord + index).chr }：#{ key }" } },
+    raise ArgumentError, "列数は #{ MAX_COLUMNS } 列までです．" if keys.length > MAX_COLUMNS
+    { columns: keys.each_with_index.map { |key, index| { key:, label: "#{ column_name(index) }：#{ key }" } },
       rows: value.each_with_index.map { |item, index| { source_row: index + 1,
                                                          values: keys.map { json_cell(item.is_a?(Hash) ? item[_1] || item[_1.to_sym] : nil) } } } }
   rescue JSON::ParserError, KeyError, ArgumentError => e
@@ -62,4 +65,14 @@ class PostImportSourceParser
     else raise ArgumentError, 'JSON のセル値が不正です．'
     end
   end
+
+  def column_name index
+    name = +''
+    loop do
+      name.prepend((65 + (index % 26)).chr)
+      index = (index / 26) - 1
+      break if index < 0
+    end
+    name
+  end
 end