require 'date'
require 'time'
require_relative './converter'

module DuckDB
  # The DuckDB::Appender encapsulates DuckDB Appender.
  #
  #   require 'duckdb'
  #   db = DuckDB::Database.open
  #   con = db.connect
  #   con.query('CREATE TABLE users (id INTEGER, name VARCHAR)')
  #   appender = con.appender('users')
  #   appender.append_row(1, 'Alice')
  #
  class Appender
    include DuckDB::Converter

    RANGE_INT16 = -32_768..32_767
    RANGE_INT32 = -2_147_483_648..2_147_483_647
    RANGE_INT64 = -9_223_372_036_854_775_808..9_223_372_036_854_775_807

    #
    # appends huge int value.
    #
    #   require 'duckdb'
    #   db = DuckDB::Database.open
    #   con = db.connect
    #   con.query('CREATE TABLE numbers (num HUGEINT)')
    #   appender = con.appender('numbers')
    #   appender
    #     .begin_row
    #     .append_hugeint(-170_141_183_460_469_231_731_687_303_715_884_105_727)
    #     .end_row
    #
    def append_hugeint(value)
      case value
      when Integer
        half = 1 << 64
        upper = value / half
        lower = value - upper * half
        _append_hugeint(lower, upper)
      else
        raise(ArgumentError, "2nd argument `#{value}` must be Integer.")
      end
    end

    #
    # appends date value.
    #
    #   require 'duckdb'
    #   db = DuckDB::Database.open
    #   con = db.connect
    #   con.query('CREATE TABLE dates (date_value DATE)')
    #   appender = con.appender('dates')
    #   appender.begin_row
    #   appender.append_date(Date.today)
    #   # or
    #   # appender.append_date(Time.now)
    #   # appender.append_date('2021-10-10')
    #   appender.end_row
    #   appender.flush
    #
    def append_date(value)
      date = case value
             when Date, Time
               value
             else
               begin
                 Date.parse(value)
               rescue
                 raise(ArgumentError, "Cannot parse argument `#{value}` to Date.")
               end
             end

      _append_date(date.year, date.month, date.day)
    end

    #
    # appends time value.
    #
    #   require 'duckdb'
    #   db = DuckDB::Database.open
    #   con = db.connect
    #   con.query('CREATE TABLE times (time_value TIME)')
    #   appender = con.appender('times')
    #   appender.begin_row
    #   appender.append_time(Time.now)
    #   # or
    #   # appender.append_time('01:01:01')
    #   appender.end_row
    #   appender.flush
    #
    def append_time(value)
      time = case value
             when Time
               value
             else
               begin
                 Time.parse(value)
               rescue
                 raise(ArgumentError, "Cannot parse argument `#{value}` to Time.")
               end
             end

      _append_time(time.hour, time.min, time.sec, time.usec)
    end

    #
    # appends timestamp value.
    #
    #   require 'duckdb'
    #   db = DuckDB::Database.open
    #   con = db.connect
    #   con.query('CREATE TABLE timestamps (timestamp_value TIMESTAMP)')
    #   appender = con.appender('timestamps')
    #   appender.begin_row
    #   appender.append_time(Time.now)
    #   # or
    #   # appender.append_time(Date.today)
    #   # appender.append_time('2021-08-01 01:01:01')
    #   appender.end_row
    #   appender.flush
    #
    def append_timestamp(value)
      time = case value
             when Time
               value
             when Date
               value.to_time
             else
               begin
                 Time.parse(value)
               rescue
                 raise(ArgumentError, "Cannot parse argument `#{value}` to Time or Date.")
               end
             end

      _append_timestamp(time.year, time.month, time.day, time.hour, time.min, time.sec, time.nsec / 1000)
    end

    #
    # appends interval.
    # The argument must be ISO8601 duration format.
    # WARNING: This method is expremental.
    #
    #   require 'duckdb'
    #   db = DuckDB::Database.open
    #   con = db.connect
    #   con.query('CREATE TABLE intervals (interval_value INTERVAL)')
    #   appender = con.appender('intervals')
    #   appender
    #     .begin_row
    #     .append_interval('P1Y2D') # => append 1 year 2 days interval.
    #     .end_row
    #     .flush
    #
    def append_interval(value)
      raise ArgumentError, "Argument `#{value}` must be a string." unless value.is_a?(String)

      hash = iso8601_interval_to_hash(value)

      months, days, micros = hash_to__append_interval_args(hash)

      _append_interval(months, days, micros)
    end

    #
    # appends value.
    #
    #   require 'duckdb'
    #   db = DuckDB::Database.open
    #   con = db.connect
    #   con.query('CREATE TABLE users (id INTEGER, name VARCHAR)')
    #   appender = con.appender('users')
    #   appender.begin_row
    #   appender.append(1)
    #   appender.append('Alice')
    #   appender.end_row
    #
    def append(value)
      case value
      when NilClass
        append_null
      when Float
        append_double(value)
      when Integer
        case value
        when RANGE_INT16
          append_int16(value)
        when RANGE_INT32
          append_int32(value)
        when RANGE_INT64
          append_int64(value)
        else
          append_hugeint(value)
        end
      when String
        blob?(value) ? append_blob(value) : append_varchar(value)
      when TrueClass, FalseClass
        append_bool(value)
      when Time
        if respond_to?(:append_timestamp)
          append_timestamp(value)
        else
          append_varchar(value.strftime('%Y-%m-%d %H:%M:%S.%N'))
        end
      when Date
        if respond_to?(:append_date)
          append_date(value)
        else
          append_varchar(value.strftime('%Y-%m-%d'))
        end
      else
        raise(DuckDB::Error, "not supported type #{value} (#{value.class})")
      end
    end

    #
    # append a row.
    #
    #   appender.append_row(1, 'Alice')
    #
    # is same as:
    #
    #   appender.begin_row
    #   appender.append(1)
    #   appender.append('Alice')
    #   appender.end_row
    #
    def append_row(*args)
      begin_row
      args.each do |arg|
        append(arg)
      end
      end_row
    end

    private

    def blob?(value)
      value.instance_of?(DuckDB::Blob) || value.encoding == Encoding::BINARY
    end
  end
end