require 'pp'

module Reckon
  class App
    VERSION = "Reckon 0.1"
    attr_accessor :options, :csv_data, :accounts, :tokens, :money_column_indices, :date_column_index, :description_column_indices, :seen

    def initialize(options = {})
      self.options = options
      self.tokens = {}
      self.accounts = {}
      self.seen = {}
      learn!
      parse
      filter_csv
      detect_columns
    end

    def filter_csv
      if options[:ignore_columns]
        new_columns = []
        columns.each_with_index do |column, index|
          new_columns << column unless options[:ignore_columns].include?(index + 1)
        end
        @columns = new_columns
      end
    end

    def learn_from(ledger)
      LedgerParser.new(ledger).entries.each do |entry|
        entry[:accounts].each do |account|
          learn_about_account( account[:name],
                               [entry[:desc], account[:amount]].join(" ") ) unless account[:name] == options[:bank_account]
          seen[entry[:date]] ||= {}
          seen[entry[:date]][pretty_money(account[:amount])] = true
        end
      end
    end

    def already_seen?(row)
      seen[row[:pretty_date]] && seen[row[:pretty_date]][row[:pretty_money]]
    end

    def learn!
      if options[:existing_ledger_file]
        fail "#{options[:existing_ledger_file]} doesn't exist!" unless File.exists?(options[:existing_ledger_file])
        ledger_data = File.read(options[:existing_ledger_file])
        learn_from(ledger_data)
      end
    end

    def learn_about_account(account, data)
      accounts[account] ||= 0
      tokenize(data).each do |token|
        tokens[token] ||= {}
        tokens[token][account] ||= 0
        tokens[token][account] += 1
        accounts[account] += 1
      end
    end

    def tokenize(str)
      str.downcase.split(/[\s\-]/)
    end

    def walk_backwards
      seen_anything_new = false
      each_row_backwards do |row|
        puts Terminal::Table.new(:rows => [ [ row[:pretty_date], row[:pretty_money], row[:description] ] ])

        if already_seen?(row)
          puts "NOTE: This row is very similar to a previous one!"
          if !seen_anything_new
            puts "Skipping..."
            next
          end
        else
          seen_anything_new = true
        end

        ledger = if row[:money] > 0
          out_of_account = ask("Which account provided this income? ([account]/[q]uit/[s]kip) ") { |q| q.default = guess_account(row) }
          finish if out_of_account == "quit" || out_of_account == "q"
          if out_of_account == "skip" || out_of_account == "s"
            puts "Skipping"
            next
          end

          ledger_format( row,
                         [options[:bank_account], row[:pretty_money]],
                         [out_of_account, row[:pretty_money_negated]] )
        else
          into_account = ask("To which account did this money go? ([account]/[q]uit/[s]kip) ") { |q| q.default = guess_account(row) }
          finish if into_account == "quit" || into_account == 'q'
          if into_account == "skip" || into_account == 's'
            puts "Skipping"
            next
          end

          ledger_format( row,
                         [into_account, row[:pretty_money_negated]],
                         [options[:bank_account], row[:pretty_money]] )
        end

        learn_from(ledger)
        output(ledger)
      end
    end

    def finish
      options[:output_file].close unless options[:output_file] == STDOUT
      puts "Exiting."
      exit
    end

    def output(ledger_line)
      options[:output_file].puts ledger_line
      options[:output_file].flush
    end

    def guess_account(row)
      query_tokens = tokenize(row[:description])

      search_vector = []
      account_vectors = {}

      query_tokens.each do |token|
        idf = Math.log((accounts.keys.length + 1) / ((tokens[token] || {}).keys.length.to_f + 1))
        tf = 1.0 / query_tokens.length.to_f
        search_vector << tf*idf

        accounts.each do |account, total_terms|
          tf = (tokens[token] && tokens[token][account]) ? tokens[token][account] / total_terms.to_f : 0
          account_vectors[account] ||= []
          account_vectors[account] << tf*idf
        end
      end

      # Should I normalize the vectors?  Probably unnecessary due to tf-idf and short documents.

      account_vectors = account_vectors.to_a.map do |account, account_vector|
        { :cosine => (0...account_vector.length).to_a.inject(0) { |m, i| m + search_vector[i] * account_vector[i] },
          :account => account }
      end

      account_vectors.sort! {|a, b| b[:cosine] <=> a[:cosine] }
      account_vectors.first && account_vectors.first[:account]
    end

    def ledger_format(row, line1, line2)
      out = "#{row[:pretty_date]}\t#{row[:description]}\n"
      out += "\t#{line1.first}\t\t\t\t\t#{line1.last}\n"
      out += "\t#{line2.first}\t\t\t\t\t#{line2.last}\n\n"
      out
    end

    def money_for(index)
      value = money_column_indices.inject("") { |m, i| m + columns[i][index] }
      value = value.gsub(/\./, '').gsub(/,/, '.') if options[:comma_separates_cents]
      cleaned_value = value.gsub(/[^\d\.]/, '').to_f
      cleaned_value *= -1 if value =~ /[\(\-]/
      cleaned_value = -(cleaned_value) if options[:inverse]
      cleaned_value
    end

    def pretty_money_for(index, negate = false)
      pretty_money(money_for(index), negate)
    end

    def pretty_money(amount, negate = false)
      (amount >= 0 ? " " : "") + sprintf("%0.2f", amount * (negate ? -1 : 1)).gsub(/^((\-)|)(?=\d)/, '\1$')
    end

    def date_for(index)
      value = columns[date_column_index][index]
      value = [$1, $2, $3].join("/") if value =~ /^(\d{4})(\d{2})(\d{2})\d+\[\d+\:GMT\]$/ # chase format
      value = [$3, $2, $1].join("/") if value =~ /^(\d{2})\.(\d{2})\.(\d{4})$/            # german format
      value = [$3, $2, $1].join("/") if value =~ /^(\d{2})\-(\d{2})\-(\d{4})$/            # nordea format
      begin
        guess = Chronic.parse(value, :context => :past)
        if guess.to_i < 953236800 && value =~ /\//
          guess = Chronic.parse((value.split("/")[0...-1] + [(2000 + value.split("/").last.to_i).to_s]).join("/"), :context => :past)
        end
        guess
      rescue
        puts "I'm having trouble parsing #{value}, which I thought was a date.  Please report this so that we"
        puts "can make this parser better!"
      end
    end

    def pretty_date_for(index)
      date_for(index).strftime("%Y/%m/%d")
    end

    def description_for(index)
      description_column_indices.map { |i| columns[i][index] }.join("; ").squeeze(" ").gsub(/(;\s+){2,}/, '').strip
    end

    def output_table
      output = Terminal::Table.new do |t|
        t.headings = 'Date', 'Amount', 'Description'
        each_row_backwards do |row|
          t << [ row[:pretty_date], row[:pretty_money], row[:description] ]
        end
      end
      puts output
    end

    def evaluate_columns(cols)
      results = []
      found_likely_money_column = false
      cols.each_with_index do |column, index|
        money_score = date_score = possible_neg_money_count = possible_pos_money_count = 0
        last = nil
        column.reverse.each_with_index do |entry, row_from_bottom|
          row = csv_data[csv_data.length - 1 - row_from_bottom]
          entry = entry.strip
          money_score += 20 if entry[/^[\-\+\(]{0,2}\$/]
          money_score += 20 if entry[/^\$?\-?\$?\d+[\.,\d]*?[\.,]\d\d$/]
          money_score += entry.gsub(/[^\d\.\-\+,\(\)]/, '').length if entry.length < 7
          money_score -= entry.length if entry.length > 8
          money_score -= 20 if entry !~ /^[\$\+\.\-,\d\(\)]+$/
          possible_neg_money_count += 1 if entry =~ /^\$?[\-\(]\$?\d+/
          possible_pos_money_count += 1 if entry =~ /^\+?\$?\+?\d+/
          date_score += 10 if entry =~ /\b(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)/i
          date_score += 5 if entry =~ /^[\-\/\.\d:\[\]]+$/
          date_score += entry.gsub(/[^\-\/\.\d:\[\]]/, '').length if entry.gsub(/[^\-\/\.\d:\[\]]/, '').length > 3
          date_score -= entry.gsub(/[\-\/\.\d:\[\]]/, '').length
          date_score += 30 if entry =~ /^\d+[:\/\.]\d+[:\/\.]\d+([ :]\d+[:\/\.]\d+)?$/
          date_score += 10 if entry =~ /^\d+\[\d+:GMT\]$/i

          # Try to determine if this is a balance column
          entry_as_num = entry.gsub(/[^\-\d\.]/, '').to_f
          if last && entry_as_num != 0 && last != 0
            row.each do |row_entry|
              row_entry = row_entry.to_s.gsub(/[^\-\d\.]/, '').to_f
              if row_entry != 0 && last + row_entry == entry_as_num
                 money_score -= 10
                 break
              end
            end
          end
          last = entry_as_num
        end

        if possible_neg_money_count > (column.length / 5.0) && possible_pos_money_count > (column.length / 5.0)
          money_score += 10 * column.length
          found_likely_money_column = true
        end

        results << { :index => index, :money_score => money_score, :date_score => date_score }
      end

      return [results, found_likely_money_column]
    end

    def merge_columns(a, b)
      output_columns = []
      columns.each_with_index do |column, index|
        if index == a
          new_column = []
          column.each_with_index do |row, row_index|
            new_column << row + " " + (columns[b][row_index] || '')
          end
          output_columns << new_column
        elsif index == b
          # skip
        else
          output_columns << column
        end
      end
      output_columns
    end

    def detect_columns
      results, found_likely_money_column = evaluate_columns(columns)
      self.money_column_indices = [ results.sort { |a, b| b[:money_score] <=> a[:money_score] }.first[:index] ]

      if !found_likely_money_column
        found_likely_double_money_columns = false
        0.upto(columns.length - 2) do |i|
          _, found_likely_double_money_columns = evaluate_columns(merge_columns(i, i+1))

          if found_likely_double_money_columns
            self.money_column_indices = [ i, i+1 ]
            unless settings[:testing]
              puts "It looks like this CSV has two seperate columns for money, one of which shows positive"
              puts "changes and one of which shows negative changes.  If this is true, great.  Otherwise,"
              puts "please report this issue to us so we can take a look!\n"
            end
            break
          end
        end

        if !found_likely_double_money_columns && !settings[:testing]
          puts "I didn't find a high-likelyhood money column, but I'm taking my best guess with column #{money_column_indices.first + 1}."
        end
      end

      results.reject! {|i| money_column_indices.include?(i[:index]) }
      self.date_column_index = results.sort { |a, b| b[:date_score] <=> a[:date_score] }.first[:index]
      results.reject! {|i| i[:index] == date_column_index }

      self.description_column_indices = results.map { |i| i[:index] }
    end

    def each_row_backwards
      rows = []
      (0...columns.first.length).to_a.each do |index|
        rows << { :date => date_for(index), :pretty_date => pretty_date_for(index),
                  :pretty_money => pretty_money_for(index), :pretty_money_negated => pretty_money_for(index, :negate),
                  :money => money_for(index), :description => description_for(index) }
      end
      rows.sort { |a, b| a[:date] <=> b[:date] }.each do |row|
        yield row
      end
    end

    def columns
      @columns ||= begin
        last_row_length = nil
        csv_data.inject([]) do |memo, row|
          # fail "Input CSV must have consistent row lengths." if last_row_length && row.length != last_row_length
          unless row.all? { |i| i.nil? || i.length == 0 }
            row.each_with_index do |entry, index|
              memo[index] ||= []
              memo[index] << (entry || '').strip
            end
            last_row_length = row.length
          end
          memo
        end
      end
    end

    def parse
      data = options[:string] || File.read(options[:file])

      if RUBY_VERSION =~ /^1\.9/ || RUBY_VERSION =~ /^2/
        data = data.force_encoding(options[:encoding] || 'BINARY').encode('UTF-8', :invalid => :replace, :undef => :replace, :replace => '?')
        csv_engine = CSV
      else
        csv_engine = FasterCSV
      end

      @csv_data = csv_engine.parse data.strip, :col_sep => options[:csv_separator] || ','
      csv_data.shift if options[:contains_header]
      csv_data
    end

    def self.parse_opts(args = ARGV)
      options = { :output_file => STDOUT }
      parser = OptionParser.new do |opts|
        opts.banner = "Usage: Reckon.rb [options]"
        opts.separator ""

        opts.on("-f", "--file FILE", "The CSV file to parse") do |file|
          options[:file] = file
        end

        opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
          options[:verbose] = v
        end

        opts.on("-i", "--inverse", "Use the negative of each amount") do |v|
          options[:inverse] = v
        end

        opts.on("-p", "--print-table", "Print out the parsed CSV in table form") do |p|
          options[:print_table] = p
        end

        opts.on("-o", "--output-file FILE", "The ledger file to append to") do |o|
          options[:output_file] = File.open(o, 'a')
        end

        opts.on("-l", "--learn-from FILE", "An existing ledger file to learn accounts from") do |l|
          options[:existing_ledger_file] = l
        end

        opts.on("", "--ignore-columns 1,2,5", "Columns to ignore in the CSV file - the first column is column 1") do |ignore|
          options[:ignore_columns] = ignore.split(",").map { |i| i.to_i }
        end

        opts.on("", "--contains-header", "The first row of the CSV is a header and should be skipped") do |contains_header|
          options[:contains_header] = contains_header
        end

        opts.on("", "--csv-separator ','", "Separator for parsing the CSV - default is comma.") do |csv_separator|
          options[:csv_separator] = csv_separator
        end

        opts.on("", "--comma-separates-cents", "Use comma instead of period to deliminate dollars from cents when parsing ($100,50 instead of $100.50)") do |c|
          options[:comma_separates_cents] = c
        end

        opts.on("", "--encoding", "Specify an encoding for the CSV file") do |e|
          options[:encoding] = e
        end

        opts.on_tail("-h", "--help", "Show this message") do
          puts opts
          exit
        end

        opts.on_tail("--version", "Show version") do
          puts VERSION
          exit
        end

        opts.parse!(args)
      end

      unless options[:file]
        options[:file] = ask("What CSV file should I parse? ")
        unless options[:file].length > 0
          puts "\nYou must provide a CSV file to parse.\n"
          puts parser
          exit
        end
      end

      unless options[:bank_account]
        options[:bank_account] = ask("What is the account name of this bank account in Ledger? ") do |q|
          q.validate = /^.{2,}$/
          q.default = "Assets:Bank:Checking"
        end
      end

      options
    end

    @settings = { :testing => false }

    def self.settings
      @settings
    end

    def settings
      self.class.settings
    end
  end
end