#A wrapper of several possible database-types.
#
#===Examples
# db = Baza::Db.new(type: :mysql2, db: "mysql", user: "user", pass: "password")
# mysql_table = db.tables['mysql']
# name = mysql_table.name
# cols = mysql_table.columns
#
# db = Baza::Db.new(type: :sqlite3, path: "some_db.sqlite3")
#
# db.q("SELECT * FROM users") do |data|
#   print data[:name]
# end
class Baza::Db
  attr_reader :sep_col, :sep_table, :sep_val, :opts, :conn, :conns, :int_types

  #Returns an array containing hashes of information about each registered driver.
  def self.drivers
    path = "#{File.dirname(__FILE__)}/drivers"
    drivers = []

    Dir.foreach(path) do |file|
      next if file.to_s.slice(0, 1) == "."
      fp = "#{path}/#{file}"
      next unless File.directory?(fp)

      driver_file = "#{fp}/#{file}.rb"
      class_name = StringCases.snake_to_camel(file).to_sym

      drivers << {
        name: file,
        driver_path: driver_file,
        class_name: class_name
      }
    end

    return drivers
  end

  #Tries to create a database-object based on the given object which could be a SQLite3 object or a MySQL 2 object (or other supported).
  def self.from_object(args)
    args = {object: args} unless args.is_a?(Hash)
    raise "No :object was given." unless args[:object]

    Baza::Db.drivers.each do |driver|
      const = Baza::Driver.const_get(driver[:class_name])
      next unless const.respond_to?(:from_object)

      obj = const.from_object(args)
      if obj.is_a?(Hash) && obj[:type] == :success
        if obj[:args]
          new_args = obj[:args]
          new_args = new_args.merge(args[:new_args]) if args[:new_args]
          return Baza::Db.new(new_args)
        else
          raise "Didnt know what to do."
        end
      end
    end

    raise "Could not figure out what to do what object of type: '#{args[:object].class.name}'."
  end

  def initialize(opts)
    @conn = opts.delete(:driver) if opts[:driver]
    self.opts = opts if opts != nil
    @int_types = [:int, :bigint, :tinyint, :smallint, :mediumint]

    unless @opts[:threadsafe]
      require 'monitor'
      @mutex = Monitor.new
    end

    @debug = @opts[:debug]

    conn_exec do |driver|
      @sep_table = driver.sep_table
      @sep_col = driver.sep_col
      @sep_val = driver.sep_val
      @esc_driver = driver
    end

    if block_given?
      begin
        yield self
      ensure
        close
      end
    end
  end

  def args
    return @opts
  end

  def opts=(arr_opts)
    @opts = {}
    arr_opts.each do |key, val|
      @opts[key.to_sym] = val
    end

    if RUBY_PLATFORM == 'java'
      @opts[:type] = :sqlite3_java if @opts[:type] == :sqlite3
      @opts[:type] = :mysql_java if @opts[:type] == :mysql || @opts[:type] == :mysql2
    end

    @type_cc = StringCases.snake_to_camel(@opts[:type])
    self.connect
  end

  #Actually connects to the database. This is useually done automatically.
  def connect
    if @opts[:threadsafe]
      require "#{$knjpath}threadhandler"
      @conns = Knj::Threadhandler.new

      @conns.on_spawn_new do
        self.spawn
      end

      @conns.on_inactive do |data|
        data[:obj].close
      end

      @conns.on_activate do |data|
        data[:obj].reconnect
      end
    else
      @conn = self.spawn
    end
  end

  #Spawns a new driver (useally done automatically).
  #===Examples
  # driver_instance = db.spawn
  def spawn
    raise "No type given (#{@opts.keys.join(",")})." unless @opts[:type]
    rpath = "#{File.dirname(__FILE__)}/drivers/#{@opts[:type]}.rb"
    require rpath if File.exists?(rpath)
    return Baza::Driver.const_get(@type_cc).new(self)
  end

  #Registers a driver to the current thread.
  def get_and_register_thread
    raise "Baza-object is not in threadding mode" unless @conns

    thread_cur = Thread.current
    tid = self.__id__
    thread_cur[:baza] = {} if !thread_cur[:baza]

    if thread_cur[:baza][tid]
      #An object has already been spawned - free that first to avoid endless "used" objects.
      self.free_thread
    end

    thread_cur[:baza][tid] = @conns.get_and_lock unless thread_cur[:baza][tid]

    #If block given then be ensure to free thread after yielding.
    if block_given?
      begin
        yield
      ensure
        self.free_thread
      end
    end
  end

  #Frees the current driver from the current thread.
  def free_thread
    thread_cur = Thread.current
    tid = self.__id__

    if thread_cur[:baza] && thread_cur[:baza].key?(tid)
      db = thread_cur[:baza][tid]
      thread_cur[:baza].delete(tid)
      @conns.free(db) if @conns
    end
  end

  #Clean up various memory-stuff if possible.
  def clean
    if @conns
      @conns.objects.each do |data|
        data[:object].clean if data[:object].respond_to?("clean")
      end
    elsif @conn
      @conn.clean if @conn.respond_to?("clean")
    end
  end

  #The all driver-database-connections.
  def close
    @conn.close if @conn
    @conns.destroy if @conns

    @conn = nil
    @conns = nil

    @closed = true
  end

  def closed?
    @closed
  end

  #Clones the current database-connection with possible extra arguments.
  def clone_conn(args = {})
    conn = Baza::Db.new(opts = @opts.clone.merge(args))

    if block_given?
      begin
        yield(conn)
      ensure
        conn.close
      end

      return nil
    else
      return conn
    end
  end

  COPY_TO_ALLOWED_ARGS = [:tables, :debug]
  #Copies the content of the current database to another instance of Baza::Db.
  def copy_to(db, args = {})
    debug = args[:debug]
    raise "No tables given." if !data[:tables]

    data[:tables].each do |table|
      table_args = nil
      table_args = args[:tables][table[:name.to_sym]] if args && args[:tables] && args[:tables][table[:name].to_sym]
      next if table_args && table_args[:skip]
      table.delete(:indexes) if table.key?(:indexes) && args[:skip_indexes]

      table_name = table.delete(:name)
      puts "Creating table: '#{table_name}'." if debug
      db.tables.create(table_name, table)

      limit_from = 0
      limit_incr = 1000

      loop do
        puts "Copying rows (#{limit_from}, #{limit_incr})." if debug
        ins_arr = []
        q_rows = self.select(table_name, {}, {limit_from: limit_from, limit_to: limit_incr}) do |d_rows|
          col_args = nil

          if table_args && table_args[:columns]
            d_rows.each do |col_name, col_data|
              col_args = table_args[:columns][col_name.to_sym] if table_args && table_args[:columns]
              d_rows[col_name] = "" if col_args && col_args[:empty]
            end
          end

          ins_arr << d_rows
        end

        break if ins_arr.empty?

        puts "Insertering #{ins_arr.length} rows." if debug
        db.insert_multi(table_name, ins_arr)
        limit_from += limit_incr
      end
    end
  end

  #Returns the data of this database in a hash.
  #===Examples
  # data = db.data
  # tables_hash = data['tables']
  def data
    tables_ret = []
    tables.list.each do |name, table|
      tables_ret << table.data
    end

    return {
      tables: tables_ret
    }
  end

  #Simply inserts data into a table.
  #
  #===Examples
  # db.insert(:users, name: "John", lastname: "Doe")
  # id = db.insert(:users, {name: "John", lastname: "Doe"}, return_id: true)
  # sql = db.insert(:users, {name: "John", lastname: "Doe"}, return_sql: true) #=> "INSERT INTO `users` (`name`, `lastname`) VALUES ('John', 'Doe')"
  def insert(tablename, arr_insert, args = nil)
    sql = "INSERT INTO #{@sep_table}#{self.esc_table(tablename)}#{@sep_table}"

    if !arr_insert || arr_insert.empty?
      # This is the correct syntax for inserting a blank row in MySQL.
      if @opts[:type].to_s.include?("mysql")
        sql << " VALUES ()"
      elsif @opts[:type].to_s.include?("sqlite3")
        sql << " DEFAULT VALUES"
      else
        raise "Unknown database-type: '#{@opts[:type]}'."
      end
    else
      sql << " ("

      first = true
      arr_insert.each do |key, value|
        if first
          first = false
        else
          sql << ", "
        end

        sql << "#{@sep_col}#{self.esc_col(key)}#{@sep_col}"
      end

      sql << ") VALUES ("

      first = true
      arr_insert.each do |key, value|
        if first
          first = false
        else
          sql << ", "
        end

        sql << self.sqlval(value)
      end

      sql << ")"
    end

    return sql if args && args[:return_sql]

    conn_exec do |driver|
      begin
        driver.query(sql)
      rescue => e
        self.add_sql_to_error(e, sql) if @opts[:sql_to_error]
        raise e
      end

      return driver.last_id if args && args[:return_id]
      return nil
    end
  end

  def add_sql_to_error(error, sql)
    error.message << " (SQL: #{sql})"
  end

  #Returns the correct SQL-value for the given value. If it is a number, then just the raw number as a string will be returned. nil's will be NULL and strings will have quotes and will be escaped.
  def sqlval(val)
    return @conn.sqlval(val) if @conn.respond_to?(:sqlval)

    if val.is_a?(Fixnum) || val.is_a?(Integer)
      return val.to_s
    elsif val == nil
      return "NULL"
    elsif val.is_a?(Date)
      return "#{@sep_val}#{Datet.in(val).dbstr(time: false)}#{@sep_val}"
    elsif val.is_a?(Time) || val.is_a?(DateTime)
      return "#{@sep_val}#{Datet.in(val).dbstr}#{@sep_val}"
    else
      return "#{@sep_val}#{self.escape(val)}#{@sep_val}"
    end
  end

  #Simply and optimal insert multiple rows into a table in a single query. Uses the drivers functionality if supported or inserts each row manually.
  #
  #===Examples
  # db.insert_multi(:users, [
  #   {name: "John", lastname: "Doe"},
  #   {name: "Kasper", lastname: "Johansen"}
  # ])
  def insert_multi(tablename, arr_hashes, args = nil)
    return false if arr_hashes.empty?

    if @esc_driver.respond_to?(:insert_multi)
      if args && args[:return_sql]
        res =  @esc_driver.insert_multi(tablename, arr_hashes, args)
        if res.is_a?(String)
          return [res]
        elsif res.is_a?(Array)
          return res
        else
          raise "Unknown result: '#{res.class.name}'."
        end
      end

      conn_exec do |driver|
        return driver.insert_multi(tablename, arr_hashes, args)
      end
    else
      transaction do
        arr_hashes.each do |hash|
          self.insert(tablename, hash, args)
        end
      end

      return nil
    end
  end

  #Simple updates rows.
  #
  #===Examples
  # db.update(:users, {name: "John"}, {lastname: "Doe"})
  def update(tablename, hash_update, arr_terms = {}, args = nil)
    raise "'hash_update' was not a hash: '#{hash_update.class.name}'." if !hash_update.is_a?(Hash)
    return false if hash_update.empty?

    sql = ""
    sql << "UPDATE #{@sep_col}#{tablename}#{@sep_col} SET "

    first = true
    hash_update.each do |key, value|
      if first
        first = false
      else
        sql << ", "
      end

      #Convert dates to valid dbstr.
      value = self.date_out(value) if value.is_a?(Datet) || value.is_a?(Time)

      sql << "#{@sep_col}#{self.esc_col(key)}#{@sep_col} = "
      sql << self.sqlval(value)
    end

    if arr_terms && arr_terms.length > 0
      sql << " WHERE #{self.makeWhere(arr_terms)}"
    end

    return sql if args && args[:return_sql]

    conn_exec do |driver|
      driver.query(sql)
    end
  end

  #Checks if a given terms exists. If it does, updates it to match data. If not inserts the row.
  def upsert(table, data, terms, args = nil)
    row = self.single(table, terms)

    if args && args[:buffer]
      obj = args[:buffer]
    else
      obj = self
    end

    if row
      obj.update(table, data, terms)
    else
      obj.insert(table, terms.merge(data))
    end
  end

  SELECT_ARGS_ALLOWED_KEYS = [:limit, :limit_from, :limit_to]
  #Makes a select from the given arguments: table-name, where-terms and other arguments as limits and orders. Also takes a block to avoid raping of memory.
  def select(tablename, arr_terms = nil, args = nil, &block)
    #Set up vars.
    sql = ""
    args_q = nil
    select_sql = "*"

    #Give 'cloned_ubuf' argument to 'q'-method.
    if args && args[:cloned_ubuf]
      args_q = {cloned_ubuf: true}
    end

    #Set up IDQuery-stuff if that is given in arguments.
    if args && args[:idquery]
      if args[:idquery] == true
        select_sql = "`id`"
        col = :id
      else
        select_sql = "`#{self.esc_col(args[:idquery])}`"
        col = args[:idquery]
      end
    end

    sql = "SELECT #{select_sql} FROM #{@sep_table}#{tablename}#{@sep_table}"

    if arr_terms != nil && !arr_terms.empty?
      sql << " WHERE #{self.makeWhere(arr_terms)}"
    end

    if args != nil
      if args[:orderby]
        sql << " ORDER BY #{args[:orderby]}"
      end

      if args[:limit]
        sql << " LIMIT #{args[:limit]}"
      end

      if args[:limit_from] && args[:limit_to]
        raise "'limit_from' was not numeric: '#{args[:limit_from]}'." if !(Float(args[:limit_from]) rescue false)
        raise "'limit_to' was not numeric: '#{args[:limit_to]}'." if !(Float(args[:limit_to]) rescue false)
        sql << " LIMIT #{args[:limit_from]}, #{args[:limit_to]}"
      end
    end

    #Do IDQuery if given in arguments.
    if args && args[:idquery]
      res = Baza::Idquery.new(db: self, table: tablename, query: sql, col: col, &block)
    else
      res = q(sql, args_q, &block)
    end

    #Return result if a block wasnt given.
    if block
      return nil
    else
      return res
    end
  end

  def count(tablename, arr_terms = nil)
    #Set up vars.
    sql = ""
    args_q = nil

    sql = "SELECT COUNT(*) AS count FROM #{@sep_table}#{tablename}#{@sep_table}"

    if arr_terms != nil && !arr_terms.empty?
      sql << " WHERE #{self.makeWhere(arr_terms)}"
    end

    return q(sql).fetch.fetch(:count).to_i
  end

  #Returns a single row from a database.
  #
  #===Examples
  # row = db.single(:users, lastname: "Doe")
  def single(tablename, terms = nil, args = {})
    select(tablename, terms, args.merge(limit: 1)) { |data| return data } #Experienced very weird memory leak if this was not done by block. Maybe bug in Ruby 1.9.2? - knj
    return false
  end

  alias :selectsingle :single

  #Deletes rows from the database.
  #
  #===Examples
  # db.delete(:users, {lastname: "Doe"})
  def delete(tablename, arr_terms, args = nil)
    sql = "DELETE FROM #{@sep_table}#{tablename}#{@sep_table}"

    if arr_terms != nil && !arr_terms.empty?
      sql << " WHERE #{self.makeWhere(arr_terms)}"
    end

    return sql if args && args[:return_sql]

    conn_exec do |driver|
      driver.query(sql)
    end

    return nil
  end

  #Internally used to generate SQL.
  #
  #===Examples
  # sql = db.makeWhere({lastname: "Doe"}, driver_obj)
  def makeWhere(arr_terms, driver = nil)
    sql = ""

    first = true
    arr_terms.each do |key, value|
      if first
        first = false
      else
        sql << " AND "
      end

      if value.is_a?(Array)
        raise "Array for column '#{key}' was empty." if value.empty?
        values = value.map { |v| "'#{escape(v)}'" }.join(',')
        sql << "#{@sep_col}#{key}#{@sep_col} IN (#{values})"
      elsif value.is_a?(Hash)
        raise "Dont know how to handle hash."
      else
        sql << "#{@sep_col}#{key}#{@sep_col} = #{self.sqlval(value)}"
      end
    end

    return sql
  end

  #Returns a driver-object based on the current thread and free driver-objects.
  #
  #===Examples
  # db.conn_exec do |driver|
  #   str = driver.escape('something̈́')
  # end
  def conn_exec
    raise "Call to closed database" if @closed

    if tcur = Thread.current && Thread.current[:baza]
      tid = self.__id__

      if tcur[:baza].key?(tid)
        yield(tcur[:baza][tid])
        return nil
      end
    end

    if @conns
      conn = @conns.get_and_lock

      begin
        yield(conn)
        return nil
      ensure
        @conns.free(conn)
      end
    elsif @conn
      @mutex.synchronize do
        yield(@conn)
        return nil
      end
    end

    raise "Could not figure out which driver to use?"
  end

  #Executes a query and returns the result.
  #
  #===Examples
  # res = db.query('SELECT * FROM users')
  # while data = res.fetch
  #   print data[:name]
  # end
  def query(string)
    if @debug
      print "SQL: #{string}\n"

      if @debug.is_a?(Fixnum) && @debug >= 2
        print caller.join("\n")
        print "\n"
      end
    end

    begin
      conn_exec do |driver|
        return driver.query(string)
      end
    rescue => e
      e.message << " (SQL: #{string})" if @opts[:sql_to_error]
      raise e
    end
  end

  #Execute an ubuffered query and returns the result.
  #
  #===Examples
  # db.query_ubuf('SELECT * FROM users') do |data|
  #   print data[:name]
  # end
  def query_ubuf(string, &block)
    ret = nil

    conn_exec do |driver|
      ret = driver.query_ubuf(string, &block)
    end

    if block
      ret.each(&block)
      return nil
    end

    return ret
  end

  #Clones the connection, executes the given block and closes the connection again.
  #
  #===Examples
  # db.cloned_conn do |conn|
  #   conn.q('SELCET * FROM users') do |data|
  #     print data[:name]
  #   end
  # end
  def cloned_conn(args = nil, &block)
    clone_conn_args = {
      threadsafe: false
    }

    clone_conn_args.merge!(args[:clone_args]) if args && args[:clone_args]
    dbconn = self.clone_conn(clone_conn_args)

    begin
      yield(dbconn)
    ensure
      dbconn.close
    end
  end

  #Executes a query and returns the result. If a block is given the result is iterated over that block instead and it returns nil.
  #
  #===Examples
  # db.q('SELECT * FROM users') do |data|
  #   print data[:name]
  # end
  def q(sql, args = nil, &block)
    #If the query should be executed in a new connection unbuffered.
    if args && args[:cloned_ubuf]
      raise "No block given." unless block

      self.cloned_conn(clone_args: args[:clone_args]) do |cloned_conn|
        ret = cloned_conn.query_ubuf(sql)
        ret.each(&block)
      end

      return nil
    end

    if args && args[:type] == :unbuffered
      ret = self.query_ubuf(sql)
    else
      ret = self.query(sql)
    end

    if block
      ret.each(&block)
      return nil
    end

    return ret
  end

  #Yields a query-buffer and flushes at the end of the block given.
  def q_buffer(args = {}, &block)
    Baza::QueryBuffer.new(args.merge(db: self), &block)
    return nil
  end

  #Returns the last inserted ID.
  #
  #===Examples
  # id = db.last_id
  def last_id
    conn_exec do |driver|
      return driver.last_id
    end
  end

  #Escapes a string to be safe-to-use in a query-string.
  #
  #===Examples
  # db.q("INSERT INTO users (name) VALUES ('#{db.esc('John')}')")
  def escape(string)
    return @esc_driver.escape(string)
  end

  alias :esc :escape

  #Escapes the given string to be used as a column.
  def esc_col(str)
    return @esc_driver.esc_col(str)
  end

  #Escapes the given string to be used as a table.
  def esc_table(str)
    return @esc_driver.esc_table(str)
  end

  #Returns a string which can be used in SQL with the current driver.
  #===Examples
  # str = db.date_out(Time.now) #=> "2012-05-20 22:06:09"
  def date_out(date_obj = Datet.new, args = {})
    if @esc_driver.respond_to?(:date_out)
      return @esc_driver.date_out(date_obj, args)
    end

    return Datet.in(date_obj).dbstr(args)
  end

  #Takes a valid date-db-string and converts it into a Datet.
  #===Examples
  # db.date_in('2012-05-20 22:06:09') #=> 2012-05-20 22:06:09 +0200
  def date_in(date_obj)
    if @esc_driver.respond_to?(:date_in)
      return @esc_driver.date_in(date_obj)
    end

    return Datet.in(date_obj)
  end

  #Returns the table-module and spawns it if it isnt already spawned.
  def tables
    unless @tables
      @tables = Baza::Driver.const_get(@type_cc).const_get(:Tables).new(
        db: self
      )
    end

    return @tables
  end

  #Returns the columns-module and spawns it if it isnt already spawned.
  def cols
    unless @cols
      @cols = Baza::Driver.const_get(@type_cc).const_get(:Columns).new(
        db: self
      )
    end

    return @cols
  end

  #Returns the index-module and spawns it if it isnt already spawned.
  def indexes
    unless @indexes
      @indexes = Baza::Driver.const_get(@type_cc).const_get(:Indexes).new(
        db: self
      )
    end

    return @indexes
  end

  #Returns the SQLSpec-module and spawns it if it isnt already spawned.
  def sqlspecs
    unless @sqlspecs
      @sqlspecs = Baza::Driver.const_get(@type_cc).const_get(:Sqlspecs).new(
        db: self
      )
    end

    return @sqlspecs
  end

  #Beings a transaction and commits when the block ends.
  #
  #===Examples
  # db.transaction do |db|
  #   db.insert(:users, name: "John")
  #   db.insert(:users, name: "Kasper")
  # end
  def transaction(&block)
    conn_exec do |driver|
      driver.transaction(&block)
    end

    return nil
  end

  #Optimizes all tables in the database.
  def optimize(args = nil)
    STDOUT.puts "Beginning optimization of database." if @debug || (args && args[:debug])
    tables.list do |table|
      STDOUT.puts "Optimizing table: '#{table.name}'." if @debug || (args && args[:debug])
      table.optimize
    end

    return nil
  end

  #Proxies the method to the driver.
  #
  #===Examples
  # db.method_on_driver
  def method_missing(method_name, *args)
    conn_exec do |driver|
      if driver.respond_to?(method_name.to_sym)
        return driver.send(method_name, *args)
      end
    end

    raise "Method not found: '#{method_name}'."
  end

  def to_s
    "#<Baza::Db driver \"#{@opts[:type]}\">"
  end

  def inspect
    to_s
  end
end