require 'set'
require 'redis/connection/registry'
require 'redis/connection/command_helper'
require "fakeredis/expiring_hash"
require "fakeredis/sorted_set_argument_handler"
require "fakeredis/sorted_set_store"
require "fakeredis/zset"

class Redis
  module Connection
    class Memory
      include Redis::Connection::CommandHelper
      include FakeRedis

      attr_accessor :buffer, :options

      # Tracks all databases for all instances across the current process.
      # We have to be able to handle two clients with the same host/port accessing
      # different databases at once without overwriting each other. So we store our
      # "data" outside the client instances, in this class level instance method.
      # Client instances access it with a key made up of their host/port, and then select
      # which DB out of the array of them they want. Allows the access we need.
      def self.databases
        @databases ||= Hash.new {|h,k| h[k] = [] }
      end

      # Used for resetting everything in specs
      def self.reset_all_databases
        @databases = nil
      end

      def self.connect(options = {})
        new(options)
      end

      def initialize(options = {})
        self.options = options
      end

      def database_id
        @database_id ||= 0
      end
      attr_writer :database_id

      def database_instance_key
        [options[:host], options[:port]].hash
      end

      def databases
        self.class.databases[database_instance_key]
      end

      def find_database id=database_id
        databases[id] ||= ExpiringHash.new
      end

      def data
        find_database
      end

      def replies
        @replies ||= []
      end
      attr_writer :replies

      def connected?
        true
      end

      def connect_unix(path, timeout)
      end

      def disconnect
      end

      def timeout=(usecs)
      end

      def write(command)
        meffod = command.shift
        if respond_to?(meffod)
          reply = send(meffod, *command)
        else
          raise Redis::CommandError, "ERR unknown command '#{meffod}'"
        end

        if reply == true
          reply = 1
        elsif reply == false
          reply = 0
        end

        replies << reply
        buffer << reply if buffer && meffod != :multi
        nil
      end

      def read
        replies.shift
      end

      # NOT IMPLEMENTED:
      # * blpop
      # * brpop
      # * brpoplpush
      # * discard
      # * sort
      # * subscribe
      # * psubscribe
      # * publish

      def flushdb
        databases.delete_at(database_id)
        "OK"
      end

      def flushall
        self.class.databases[database_instance_key] = []
        "OK"
      end

      def auth(password)
        "OK"
      end

      def select(index)
        data_type_check(index, Integer)
        self.database_id = index
        "OK"
      end

      def info
        {
          "redis_version" => "0.07",
          "connected_clients" => "1",
          "connected_slaves" => "0",
          "used_memory" => "3187",
          "changes_since_last_save" => "0",
          "last_save_time" => "1237655729",
          "total_connections_received" => "1",
          "total_commands_processed" => "1",
          "uptime_in_seconds" => "36000",
          "uptime_in_days" => 0
        }
      end

      def monitor; end

      def save; end

      def bgsave ; end

      def bgreriteaof ; end

      def move key, destination_id
        raise Redis::CommandError, "ERR source and destination objects are the same" if destination_id == database_id
        destination = find_database(destination_id)
        return false unless data.has_key?(key)
        return false if destination.has_key?(key)
        destination[key] = data.delete(key)
        true
      end

      def get(key)
        data_type_check(key, String)
        data[key]
      end

      def getbit(key, offset)
        return unless data[key]
        data[key].unpack('B*')[0].split("")[offset].to_i
      end

      def getrange(key, start, ending)
        return unless data[key]
        data[key][start..ending]
      end
      alias :substr :getrange

      def getset(key, value)
        data_type_check(key, String)
        data[key].tap do
          set(key, value)
        end
      end

      def mget(*keys)
        raise Redis::CommandError, "wrong number of arguments for 'mget' command" if keys.empty?
        # We work with either an array, or list of arguments
        keys = keys.first if keys.size == 1
        data.values_at(*keys)
      end

      def append(key, value)
        data[key] = (data[key] || "")
        data[key] = data[key] + value.to_s
      end

      def strlen(key)
        return unless data[key]
        data[key].size
      end

      def hgetall(key)
        data_type_check(key, Hash)
        data[key].to_a.flatten || {}
      end

      def hget(key, field)
        data_type_check(key, Hash)
        data[key] && data[key][field.to_s]
      end

      def hdel(key, field)
        data_type_check(key, Hash)
        data[key] && data[key].delete(field)
        remove_key_for_empty_collection(key)
      end

      def hkeys(key)
        data_type_check(key, Hash)
        return [] if data[key].nil?
        data[key].keys
      end

      def keys(pattern = "*")
        regexp = Regexp.new(pattern.split("*").map { |r| Regexp.escape(r) }.join(".*"))
        data.keys.select { |key| key =~ regexp }
      end

      def randomkey
        data.keys[rand(dbsize)]
      end

      def echo(string)
        string
      end

      def ping
        "PONG"
      end

      def lastsave
        Time.now.to_i
      end

      def dbsize
        data.keys.count
      end

      def exists(key)
        data.key?(key)
      end

      def llen(key)
        data_type_check(key, Array)
        return 0 unless data[key]
        data[key].size
      end

      def lrange(key, startidx, endidx)
        data_type_check(key, Array)
        (data[key] && data[key][startidx..endidx]) || []
      end

      def ltrim(key, start, stop)
        data_type_check(key, Array)
        return unless data[key]
        data[key] = data[key][start..stop]
      end

      def lindex(key, index)
        data_type_check(key, Array)
        data[key] && data[key][index]
      end

      def linsert(key, where, pivot, value)
        data_type_check(key, Array)
        return unless data[key]
        index = data[key].index(pivot)
        case where
          when :before then data[key].insert(index, value)
          when :after  then data[key].insert(index + 1, value)
          else raise Redis::CommandError, "ERR syntax error"
        end
      end

      def lset(key, index, value)
        data_type_check(key, Array)
        return unless data[key]
        raise(Redis::CommandError, "ERR index out of range") if index >= data[key].size
        data[key][index] = value
      end

      def lrem(key, count, value)
        data_type_check(key, Array)
        return unless data[key]
        old_size = data[key].size
        diff =
          if count == 0
            data[key].delete(value)
            old_size - data[key].size
          else
            array = count > 0 ? data[key].dup : data[key].reverse
            count.abs.times{ array.delete_at(array.index(value) || array.length) }
            data[key] = count > 0 ? array.dup : array.reverse
            old_size - data[key].size
          end
        remove_key_for_empty_collection(key)
        diff
      end

      def rpush(key, value)
        data_type_check(key, Array)
        data[key] ||= []
        [value].flatten.each do |val|
          data[key].push(val.to_s)
        end
        data[key].size
      end

      def rpushx(key, value)
        data_type_check(key, Array)
        return unless data[key]
        rpush(key, value)
      end

      def lpush(key, value)
        data_type_check(key, Array)
        data[key] ||= []
        [value].flatten.each do |val|
          data[key].unshift(val.to_s)
        end
        data[key].size
      end

      def lpushx(key, value)
        data_type_check(key, Array)
        return unless data[key]
        lpush(key, value)
      end

      def rpop(key)
        data_type_check(key, Array)
        return unless data[key]
        data[key].pop
      end

      def rpoplpush(key1, key2)
        data_type_check(key1, Array)
        rpop(key1).tap do |elem|
          lpush(key2, elem)
        end
      end

      def lpop(key)
        data_type_check(key, Array)
        return unless data[key]
        data[key].shift
      end

      def smembers(key)
        data_type_check(key, ::Set)
        return [] unless data[key]
        data[key].to_a.reverse
      end

      def sismember(key, value)
        data_type_check(key, ::Set)
        return false unless data[key]
        data[key].include?(value.to_s)
      end

      def sadd(key, value)
        data_type_check(key, ::Set)
        value = Array(value)

        result = if data[key]
          old_set = data[key].dup
          data[key].merge(value.map(&:to_s))
          (data[key] - old_set).size
        else
          data[key] = ::Set.new(value.map(&:to_s))
          data[key].size
        end

        # 0 = false, 1 = true, 2+ untouched
        return result == 1 if result < 2
        result
      end

      def srem(key, value)
        data_type_check(key, ::Set)
        deleted = !!(data[key] && data[key].delete?(value.to_s))
        remove_key_for_empty_collection(key)
        deleted
      end

      def smove(source, destination, value)
        data_type_check(destination, ::Set)
        result = self.srem(source, value)
        self.sadd(destination, value) if result
        result
      end

      def spop(key)
        data_type_check(key, ::Set)
        elem = srandmember(key)
        srem(key, elem)
        elem
      end

      def scard(key)
        data_type_check(key, ::Set)
        return 0 unless data[key]
        data[key].size
      end

      def sinter(*keys)
        keys.each { |k| data_type_check(k, ::Set) }
        return ::Set.new if keys.any? { |k| data[k].nil? }
        keys = keys.map { |k| data[k] || ::Set.new }
        keys.inject do |set, key|
          set & key
        end.to_a
      end

      def sinterstore(destination, *keys)
        data_type_check(destination, ::Set)
        result = sinter(*keys)
        data[destination] = ::Set.new(result)
      end

      def sunion(*keys)
        keys.each { |k| data_type_check(k, ::Set) }
        keys = keys.map { |k| data[k] || ::Set.new }
        keys.inject(::Set.new) do |set, key|
          set | key
        end.to_a
      end

      def sunionstore(destination, *keys)
        data_type_check(destination, ::Set)
        result = sunion(*keys)
        data[destination] = ::Set.new(result)
      end

      def sdiff(key1, *keys)
        [key1, *keys].each { |k| data_type_check(k, ::Set) }
        keys = keys.map { |k| data[k] || ::Set.new }
        keys.inject(data[key1]) do |memo, set|
          memo - set
        end.to_a
      end

      def sdiffstore(destination, key1, *keys)
        data_type_check(destination, ::Set)
        result = sdiff(key1, *keys)
        data[destination] = ::Set.new(result)
      end

      def srandmember(key)
        data_type_check(key, ::Set)
        return nil unless data[key]
        data[key].to_a[rand(data[key].size)]
      end

      def del(*keys)
        keys = keys.flatten(1)
        raise Redis::CommandError, "ERR wrong number of arguments for 'del' command" if keys.empty?
        old_count = data.keys.size
        keys.each do |key|
          data.delete(key)
        end
        old_count - data.keys.size
      end

      def setnx(key, value)
        if exists(key)
          false
        else
          set(key, value)
          true
        end
      end

      def rename(key, new_key)
        return unless data[key]
        data[new_key] = data[key]
        data.expires[new_key] = data.expires[key] if data.expires.include?(key)
        data.delete(key)
      end

      def renamenx(key, new_key)
        if exists(new_key)
          false
        else
          rename(key, new_key)
          true
        end
      end

      def expire(key, ttl)
        return unless data[key]
        data.expires[key] = Time.now + ttl
        true
      end

      def ttl(key)
        if data.expires.include?(key) && (ttl = data.expires[key].to_i - Time.now.to_i) > 0
          ttl
        else
          -1
        end
      end

      def expireat(key, timestamp)
        data.expires[key] = Time.at(timestamp)
        true
      end

      def persist(key)
        !!data.expires.delete(key)
      end

      def hset(key, field, value)
        data_type_check(key, Hash)
        field = field.to_s
        if data[key]
          result = !data[key].include?(field)
          data[key][field] = value.to_s
          result
        else
          data[key] = { field => value.to_s }
          true
        end
      end

      def hsetnx(key, field, value)
        data_type_check(key, Hash)
        field = field.to_s
        return false if data[key] && data[key][field]
        hset(key, field, value)
      end

      def hmset(key, *fields)
        # mapped_hmset gives us [[:k1, "v1", :k2, "v2"]] for `fields`. Fix that.
        fields = fields[0] if mapped_param?(fields)
        raise Redis::CommandError, "ERR wrong number of arguments for HMSET" if fields.empty? || fields.size.odd?
        data_type_check(key, Hash)
        data[key] ||= {}
        fields.each_slice(2) do |field|
          data[key][field[0].to_s] = field[1].to_s
        end
      end

      def hmget(key, *fields)
        raise Redis::CommandError, "wrong number of arguments for 'hmget' command" if fields.empty?
        data_type_check(key, Hash)
        fields.map do |field|
          field = field.to_s
          if data[key]
            data[key][field]
          else
            nil
          end
        end
      end

      def hlen(key)
        data_type_check(key, Hash)
        return 0 unless data[key]
        data[key].size
      end

      def hvals(key)
        data_type_check(key, Hash)
        return [] unless data[key]
        data[key].values
      end

      def hincrby(key, field, increment)
        data_type_check(key, Hash)
        if data[key]
          data[key][field] = (data[key][field.to_s].to_i + increment.to_i).to_s
        else
          data[key] = { field => increment.to_s }
        end
        data[key][field].to_i
      end

      def hexists(key, field)
        data_type_check(key, Hash)
        return false unless data[key]
        data[key].key?(field)
      end

      def sync ; end

      def [](key)
        get(key)
      end

      def []=(key, value)
        set(key, value)
      end

      def set(key, value)
        data[key] = value.to_s
        "OK"
      end

      def setbit(key, offset, bit)
        old_val = data[key] ? data[key].unpack('B*')[0].split("") : []
        size_increment = [((offset/8)+1)*8-old_val.length, 0].max
        old_val += Array.new(size_increment).map{"0"}
        original_val = old_val[offset]
        old_val[offset] = bit.to_s
        new_val = ""
        old_val.each_slice(8){|b| new_val = new_val + b.join("").to_i(2).chr }
        data[key] = new_val
        original_val
      end

      def setex(key, seconds, value)
        data[key] = value.to_s
        expire(key, seconds)
      end

      def setrange(key, offset, value)
        return unless data[key]
        s = data[key][offset,value.size]
        data[key][s] = value
      end

      def mset(*pairs)
        # Handle pairs for mapped_mset command
        pairs = pairs[0] if mapped_param?(pairs)
        pairs.each_slice(2) do |pair|
          data[pair[0].to_s] = pair[1].to_s
        end
        "OK"
      end

      def msetnx(*pairs)
        # Handle pairs for mapped_msetnx command
        pairs = pairs[0] if mapped_param?(pairs)
        keys = []
        pairs.each_with_index{|item, index| keys << item.to_s if index % 2 == 0}
        return false if keys.any?{|key| data.key?(key) }
        mset(*pairs)
        true
      end

      def sort(key)
        # TODO: Implement
      end

      def incr(key)
        data.merge!({ key => (data[key].to_i + 1).to_s || "1"})
        data[key].to_i
      end

      def incrby(key, by)
        data.merge!({ key => (data[key].to_i + by.to_i).to_s || by })
        data[key].to_i
      end

      def decr(key)
        data.merge!({ key => (data[key].to_i - 1).to_s || "-1"})
        data[key].to_i
      end

      def decrby(key, by)
        data.merge!({ key => ((data[key].to_i - by.to_i) || (by.to_i * -1)).to_s })
        data[key].to_i
      end

      def type(key)
        case data[key]
          when nil then "none"
          when String then "string"
          when Hash then "hash"
          when Array then "list"
          when ::Set then "set"
        end
      end

      def quit ; end

      def shutdown; end

      def slaveof(host, port) ; end

      def exec
        buffer.tap {|x| self.buffer = nil }
      end

      def multi
        self.buffer = []
        yield if block_given?
        "OK"
      end

      def watch(_)
        "OK"
      end

      def unwatch
        "OK"
      end

      def zadd(key, *args)
        if !args.first.is_a?(Array)
          if args.size < 2
            raise Redis::CommandError, "ERR wrong number of arguments for 'zadd' command"
          elsif args.size.odd?
            raise Redis::CommandError, "ERR syntax error"
          end
        else
          unless args.all? {|pair| pair.size == 2 }
            raise(Redis::CommandError, "ERR syntax error")
          end
        end

        data_type_check(key, ZSet)
        data[key] ||= ZSet.new

        if args.size == 2
          score, value = args
          exists = !data[key].key?(value.to_s)
          data[key][value.to_s] = score
        else
          # Turn [1, 2, 3, 4] into [[1, 2], [3, 4]] unless it is already
          args = args.each_slice(2).to_a unless args.first.is_a?(Array)
          exists = args.map(&:last).map { |el| data[key].key?(el.to_s) }.count(false)
          args.each { |s, v| data[key][v.to_s] = s }
        end

        exists
      end

      def zrem(key, value)
        data_type_check(key, ZSet)
        values = Array(value)
        return 0 unless data[key]

        response = values.map do |v|
          data[key].delete(v) if data[key].has_key?(v)
        end.compact.size

        remove_key_for_empty_collection(key)
        response
      end

      def zcard(key)
        data_type_check(key, ZSet)
        data[key] ? data[key].size : 0
      end

      def zscore(key, value)
        data_type_check(key, ZSet)
        value = data[key] && data[key][value.to_s]
        value && value.to_s
      end

      def zcount(key, min, max)
        data_type_check(key, ZSet)
        return 0 unless data[key]
        data[key].select_by_score(min, max).size
      end

      def zincrby(key, num, value)
        data_type_check(key, ZSet)
        data[key] ||= ZSet.new
        data[key][value.to_s] ||= 0
        data[key].increment(value.to_s, num)
        data[key][value.to_s].to_s
      end

      def zrank(key, value)
        data_type_check(key, ZSet)
        data[key].keys.sort_by {|k| data[key][k] }.index(value.to_s)
      end

      def zrevrank(key, value)
        data_type_check(key, ZSet)
        data[key].keys.sort_by {|k| -data[key][k] }.index(value.to_s)
      end

      def zrange(key, start, stop, with_scores = nil)
        data_type_check(key, ZSet)
        return [] unless data[key]

        # Sort by score, or if scores are equal, key alphanum
        results = data[key].sort do |(k1, v1), (k2, v2)|
          if v1 == v2
            k1 <=> k2
          else
            v1 <=> v2
          end
        end
        # Select just the keys unless we want scores
        results = results.map(&:first) unless with_scores
        results[start..stop].flatten.map(&:to_s)
      end

      def zrevrange(key, start, stop, with_scores = nil)
        data_type_check(key, ZSet)
        return [] unless data[key]

        if with_scores
          data[key].sort_by {|_,v| -v }
        else
          data[key].keys.sort_by {|k| -data[key][k] }
        end[start..stop].flatten.map(&:to_s)
      end

      def zrangebyscore(key, min, max, *opts)
        data_type_check(key, ZSet)
        return [] unless data[key]

        range = data[key].select_by_score(min, max)
        vals = if opts.include?('WITHSCORES')
          range.sort_by {|_,v| v }
        else
          range.keys.sort_by {|k| range[k] }
        end

        limit = get_limit(opts, vals)
        vals = vals[*limit] if limit

        vals.flatten.map(&:to_s)
      end

      def zrevrangebyscore(key, max, min, *opts)
        data_type_check(key, ZSet)
        return [] unless data[key]

        range = data[key].select_by_score(min, max)
        vals = if opts.include?('WITHSCORES')
          range.sort_by {|_,v| -v }
        else
          range.keys.sort_by {|k| -range[k] }
        end

        limit = get_limit(opts, vals)
        vals = vals[*limit] if limit

        vals.flatten.map(&:to_s)
      end

      def zremrangebyscore(key, min, max)
        data_type_check(key, ZSet)
        return 0 unless data[key]

        range = data[key].select_by_score(min, max)
        range.each {|k,_| data[key].delete(k) }
        range.size
      end

      def zinterstore(out, *args)
        data_type_check(out, ZSet)
        args_handler = SortedSetArgumentHandler.new(args)
        data[out] = SortedSetIntersectStore.new(args_handler, data).call
        data[out].size
      end

      def zunionstore(out, *args)
        data_type_check(out, ZSet)
        args_handler = SortedSetArgumentHandler.new(args)
        data[out] = SortedSetUnionStore.new(args_handler, data).call
        data[out].size
      end

      def zremrangebyrank(key, start, stop)
        sorted_elements = data[key].sort_by { |k, v| v }
        start = sorted_elements.length if start > sorted_elements.length
        elements_to_delete = sorted_elements[start..stop]
        elements_to_delete.each { |elem, rank| data[key].delete(elem) }
        elements_to_delete.size
      end

      private

        def remove_key_for_empty_collection(key)
          del(key) if data[key] && data[key].empty?
        end

        def data_type_check(key, klass)
          if data[key] && !data[key].is_a?(klass)
            warn "Operation against a key holding the wrong kind of value: Expected #{klass} at #{key}."
            raise Redis::CommandError.new("ERR Operation against a key holding the wrong kind of value")
          end
        end

        def get_limit(opts, vals)
          index = opts.index('LIMIT')

          if index
            offset = opts[index + 1]

            count = opts[index + 2]
            count = vals.size if count < 0

            [offset, count]
          end
        end

        def mapped_param? param
          param.size == 1 && param[0].is_a?(Array)
        end
    end
  end
end

Redis::Connection.drivers << Redis::Connection::Memory