# Copyright (c) 2018 Yegor Bugayenko
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the 'Software'), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

require 'time'
require 'openssl'
require_relative 'version'
require_relative 'key'
require_relative 'id'
require_relative 'txn'
require_relative 'tax'
require_relative 'amount'
require_relative 'signature'
require_relative 'atomic_file'

# The wallet.
#
# It is a text file with a name equal to the wallet ID, which is
# a hexadecimal number of 16 digits, for example: "0123456789abcdef".
# More details about its format is in README.md.
#
# Author:: Yegor Bugayenko (yegor256@gmail.com)
# Copyright:: Copyright (c) 2018 Yegor Bugayenko
# License:: MIT
module Zold
  # A single wallet
  class Wallet
    # The name of the main production network. All other networks
    # must have different names.
    MAIN_NETWORK = 'zold'.freeze

    # The extension of the wallet files
    EXTENSION = '.z'.freeze

    def initialize(file)
      @file = file
      @file = "#{file}#{EXTENSION}" if File.extname(file).empty?
    end

    def ==(other)
      to_s == other.to_s
    end

    def to_s
      id.to_s
    end

    def network
      n = lines[0].strip
      raise "Invalid network name '#{n}'" unless n =~ /^[a-z]{4,16}$/
      n
    end

    def protocol
      v = lines[1].strip
      raise "Invalid protocol version name '#{v}'" unless v =~ /^[0-9]+$/
      v.to_i
    end

    def exists?
      File.exist?(@file)
    end

    def path
      @file
    end

    def init(id, pubkey, overwrite: false, network: 'test')
      raise "File '#{@file}' already exists" if File.exist?(@file) && !overwrite
      raise "Invalid network name '#{network}'" unless network =~ /^[a-z]{4,16}$/
      AtomicFile.new(@file).write("#{network}\n#{PROTOCOL}\n#{id}\n#{pubkey.to_pub}\n\n")
    end

    def root?
      id == Id::ROOT
    end

    def id
      Id.new(lines[2].strip)
    end

    def balance
      txns.inject(Amount::ZERO) { |sum, t| sum + t.amount }
    end

    def sub(amount, invoice, pvt, details = '-', time: Time.now)
      raise 'The amount has to be of type Amount' unless amount.is_a?(Amount)
      raise "The amount can't be negative: #{amount}" if amount.negative?
      raise 'The pvt has to be of type Key' unless pvt.is_a?(Key)
      prefix, target = invoice.split('@')
      tid = max + 1
      raise 'Too many transactions already, can\'t add more' if max > 0xffff
      txn = Txn.new(
        tid,
        time,
        amount * -1,
        prefix,
        Id.new(target),
        details
      )
      txn = txn.signed(pvt, id)
      raise 'This is not the private right key for this wallet' unless Signature.new.valid?(key, id, txn)
      add(txn)
      txn
    end

    def add(txn)
      raise 'The txn has to be of type Txn' unless txn.is_a?(Txn)
      dup = txns.find { |t| t.bnf == txn.bnf && t.id == txn.id }
      raise "The transaction with the same ID and BNF already exists: #{dup}" unless dup.nil?
      raise "The tax payment already exists: #{txn}" if Tax.new(self).exists?(txn)
      File.open(@file, 'a') { |f| f.print "#{txn}\n" }
    end

    def has?(id, bnf)
      raise 'The txn ID has to be of type Integer' unless id.is_a?(Integer)
      raise 'The bnf has to be of type Id' unless bnf.is_a?(Id)
      !txns.find { |t| t.id == id && t.bnf == bnf }.nil?
    end

    def key
      Key.new(text: lines[3].strip)
    end

    def income
      txns.each do |t|
        yield t unless t.amount.negative?
      end
    end

    def mtime
      File.mtime(@file)
    end

    def digest
      OpenSSL::Digest::SHA256.new(File.read(@file)).hexdigest
    end

    # Age of wallet in hours
    def age
      list = txns
      list.empty? ? 0 : (Time.now - list.min_by(&:date).date) / 60
    end

    def txns
      lines.drop(5)
        .each_with_index
        .map { |line, i| Txn.parse(line, i + 6) }
        .sort_by { |t| [t.date, t.amount * -1] }
    end

    private

    def max
      negative = txns.select { |t| t.amount.negative? }
      negative.empty? ? 0 : negative.max_by(&:id).id
    end

    def lines
      raise "Wallet file '#{@file}' is absent" unless File.exist?(@file)
      lines = AtomicFile.new(@file).read.split(/\n/)
      raise "Not enough lines in #{@file}, just #{lines.count}" if lines.count < 4
      lines
    end
  end
end