ArJdbc.load_java_part :SQLite3

require "arjdbc/common_jdbc_methods"
require "active_record/connection_adapters/statement_pool"
require "active_record/connection_adapters/abstract/database_statements"
require "active_record/connection_adapters/sqlite3/explain_pretty_printer"
require "active_record/connection_adapters/sqlite3/quoting"
require "active_record/connection_adapters/sqlite3/schema_creation"

module ArJdbc
  # All the code in this module is a copy of ConnectionAdapters::SQLite3Adapter from active_record 5.
  # The constants at the front of this file are to allow the rest of the file to remain with no modifications
  # from its original source.
  module SQLite3
    # DIFFERENCE: Some common constant names to reduce differences in rest of this module from AR5 version
    ConnectionAdapters = ::ActiveRecord::ConnectionAdapters
    IndexDefinition = ::ActiveRecord::ConnectionAdapters::IndexDefinition
    Quoting = ::ActiveRecord::ConnectionAdapters::SQLite3::Quoting
    RecordNotUnique = ::ActiveRecord::RecordNotUnique
    SchemaCreation = ConnectionAdapters::SQLite3::SchemaCreation
    SQLite3Adapter = ConnectionAdapters::AbstractAdapter

    ADAPTER_NAME = 'SQLite'.freeze

    include Quoting

    NATIVE_DATABASE_TYPES = {
        primary_key:  "INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL",
        string:       { name: "varchar" },
        text:         { name: "text" },
        integer:      { name: "integer" },
        float:        { name: "float" },
        decimal:      { name: "decimal" },
        datetime:     { name: "datetime" },
        time:         { name: "time" },
        date:         { name: "date" },
        binary:       { name: "blob" },
        boolean:      { name: "boolean" }
    }

    class StatementPool < ConnectionAdapters::StatementPool
      private

      def dealloc(stmt)
        stmt[:stmt].close unless stmt[:stmt].closed?
      end
    end

    def schema_creation # :nodoc:
      SQLite3::SchemaCreation.new self
    end

    def arel_visitor # :nodoc:
      Arel::Visitors::SQLite.new(self)
    end

    def initialize(connection, logger, connection_options, config)
      super(connection, logger, config)

      @active     = nil
      @statements = StatementPool.new(self.class.type_cast_config_to_integer(config[:statement_limit]))
    end

    def supports_ddl_transactions?
      true
    end

    def supports_savepoints?
      true
    end

    def supports_partial_index?
      sqlite_version >= "3.8.0"
    end

    # Returns true, since this connection adapter supports prepared statement
    # caching.
    def supports_statement_cache?
      true
    end

    # Returns true, since this connection adapter supports migrations.
    def supports_migrations? #:nodoc:
      true
    end

    def supports_primary_key? #:nodoc:
      true
    end

    def requires_reloading?
      true
    end

    def supports_views?
      true
    end

    def supports_datetime_with_precision?
      true
    end

    def supports_multi_insert?
      sqlite_version >= "3.7.11"
    end

    def active?
      @active != false
    end

    # Disconnects from the database if already connected. Otherwise, this
    # method does nothing.
    def disconnect!
      super
      @active = false
      @connection.close rescue nil
    end

    # Clears the prepared statements cache.
    def clear_cache!
      @statements.clear
    end

    def supports_index_sort_order?
      true
    end

    def valid_type?(type)
      true
    end

    # Returns 62. SQLite supports index names up to 64
    # characters. The rest is used by Rails internally to perform
    # temporary rename operations
    def allowed_index_name_length
      index_name_length - 2
    end

    def native_database_types #:nodoc:
      NATIVE_DATABASE_TYPES
    end

    # Returns the current database encoding format as a string, eg: 'UTF-8'
    def encoding
      @connection.encoding.to_s
    end

    def supports_explain?
      true
    end

    #--
    # DATABASE STATEMENTS ======================================
    #++

    def explain(arel, binds = [])
      sql = "EXPLAIN QUERY PLAN #{to_sql(arel, binds)}"
      ::ActiveRecord::ConnectionAdapters::SQLite3::ExplainPrettyPrinter.new.pp(exec_query(sql, "EXPLAIN", []))
    end

    def exec_query(sql, name = nil, binds = [], prepare: false)
      type_casted_binds = binds.map { |attr| type_cast(attr.value_for_database) }

      log(sql, name, binds) do
        # Don't cache statements if they are not prepared
        unless prepare
          stmt    = @connection.prepare(sql)
          begin
            cols    = stmt.columns
            unless without_prepared_statement?(binds)
              stmt.bind_params(type_casted_binds)
            end
            records = stmt.to_a
          ensure
            stmt.close
          end
          stmt = records
        else
          cache = @statements[sql] ||= {
              :stmt => @connection.prepare(sql)
          }
          stmt = cache[:stmt]
          cols = cache[:cols] ||= stmt.columns
          stmt.reset!
          stmt.bind_params(type_casted_binds)
        end

        ActiveRecord::Result.new(cols, stmt.to_a)
      end
    end

    def exec_delete(sql, name = 'SQL', binds = [])
      exec_query(sql, name, binds)
      @connection.changes
    end
    alias :exec_update :exec_delete

    def last_inserted_id(result)
      @connection.last_insert_row_id
    end

    def execute(sql, name = nil) #:nodoc:
      log(sql, name) { @connection.execute(sql) }
    end

    def begin_db_transaction #:nodoc:
      log("begin transaction",nil) { @connection.transaction }
    end

    def commit_db_transaction #:nodoc:
      log("commit transaction",nil) { @connection.commit }
    end

    def exec_rollback_db_transaction #:nodoc:
      log("rollback transaction",nil) { @connection.rollback }
    end

    # SCHEMA STATEMENTS ========================================

    def tables(name = nil) # :nodoc:
      ActiveSupport::Deprecation.warn(<<-MSG.squish)
          #tables currently returns both tables and views.
          This behavior is deprecated and will be changed with Rails 5.1 to only return tables.
          Use #data_sources instead.
      MSG

      if name
        ActiveSupport::Deprecation.warn(<<-MSG.squish)
            Passing arguments to #tables is deprecated without replacement.
        MSG
      end

      data_sources
    end

    def data_sources
      select_values("SELECT name FROM sqlite_master WHERE type IN ('table','view') AND name <> 'sqlite_sequence'", "SCHEMA")
    end

    def table_exists?(table_name)
      ActiveSupport::Deprecation.warn(<<-MSG.squish)
          #table_exists? currently checks both tables and views.
          This behavior is deprecated and will be changed with Rails 5.1 to only check tables.
          Use #data_source_exists? instead.
      MSG

      data_source_exists?(table_name)
    end

    def data_source_exists?(table_name)
      return false unless table_name.present?

      sql = "SELECT name FROM sqlite_master WHERE type IN ('table','view') AND name <> 'sqlite_sequence'"
      sql << " AND name = #{quote(table_name)}"

      select_values(sql, "SCHEMA").any?
    end

    def views # :nodoc:
      select_values("SELECT name FROM sqlite_master WHERE type = 'view' AND name <> 'sqlite_sequence'", "SCHEMA")
    end

    def view_exists?(view_name) # :nodoc:
      return false unless view_name.present?

      sql = "SELECT name FROM sqlite_master WHERE type = 'view' AND name <> 'sqlite_sequence'"
      sql << " AND name = #{quote(view_name)}"

      select_values(sql, "SCHEMA").any?
    end

    # Returns an array of +Column+ objects for the table specified by +table_name+.
    def columns(table_name) # :nodoc:
      table_name = table_name.to_s
      table_structure(table_name).map do |field|
        case field["dflt_value"]
          when /^null$/i
            field["dflt_value"] = nil
          when /^'(.*)'$/m
            field["dflt_value"] = $1.gsub("''", "'")
          when /^"(.*)"$/m
            field["dflt_value"] = $1.gsub('""', '"')
        end

        collation = field["collation"]
        sql_type = field["type"]
        type_metadata = fetch_type_metadata(sql_type)
        new_column(field["name"], field["dflt_value"], type_metadata, field["notnull"].to_i == 0, table_name, nil, collation)
      end
    end

    # Returns an array of indexes for the given table.
    def indexes(table_name, name = nil) #:nodoc:
      exec_query("PRAGMA index_list(#{quote_table_name(table_name)})", "SCHEMA").map do |row|
        sql = <<-SQL
            SELECT sql
            FROM sqlite_master
            WHERE name=#{quote(row['name'])} AND type='index'
            UNION ALL
            SELECT sql
            FROM sqlite_temp_master
            WHERE name=#{quote(row['name'])} AND type='index'
        SQL
        index_sql = exec_query(sql).first["sql"]
        match = /\sWHERE\s+(.+)$/i.match(index_sql)
        where = match[1] if match
        IndexDefinition.new(
            table_name,
            row["name"],
            row["unique"] != 0,
            exec_query("PRAGMA index_info('#{row['name']}')", "SCHEMA").map { |col|
              col["name"]
            }, nil, nil, where)
      end
    end

    def primary_keys(table_name) # :nodoc:
      pks = table_structure(table_name).select { |f| f["pk"] > 0 }
      pks.sort_by { |f| f["pk"] }.map { |f| f["name"] }
    end

    def remove_index(table_name, options = {}) #:nodoc:
      index_name = index_name_for_remove(table_name, options)
      exec_query "DROP INDEX #{quote_column_name(index_name)}"
    end

    # Renames a table.
    #
    # Example:
    #   rename_table('octopuses', 'octopi')
    def rename_table(table_name, new_name)
      exec_query "ALTER TABLE #{quote_table_name(table_name)} RENAME TO #{quote_table_name(new_name)}"
      rename_table_indexes(table_name, new_name)
    end

    # See: http://www.sqlite.org/lang_altertable.html
    # SQLite has an additional restriction on the ALTER TABLE statement
    def valid_alter_table_type?(type)
      type.to_sym != :primary_key
    end

    def add_column(table_name, column_name, type, options = {}) #:nodoc:
      if valid_alter_table_type?(type)
        super(table_name, column_name, type, options)
      else
        alter_table(table_name) do |definition|
          definition.column(column_name, type, options)
        end
      end
    end

    def remove_column(table_name, column_name, type = nil, options = {}) #:nodoc:
      alter_table(table_name) do |definition|
        definition.remove_column column_name
      end
    end

    def change_column_default(table_name, column_name, default_or_changes) #:nodoc:
      default = extract_new_default_value(default_or_changes)

      alter_table(table_name) do |definition|
        definition[column_name].default = default
      end
    end

    def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
      unless null || default.nil?
        exec_query("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
      end
      alter_table(table_name) do |definition|
        definition[column_name].null = null
      end
    end

    def change_column(table_name, column_name, type, options = {}) #:nodoc:
      alter_table(table_name) do |definition|
        include_default = options_include_default?(options)
        definition[column_name].instance_eval do
          self.type    = type
          self.limit   = options[:limit] if options.include?(:limit)
          self.default = options[:default] if include_default
          self.null    = options[:null] if options.include?(:null)
          self.precision = options[:precision] if options.include?(:precision)
          self.scale   = options[:scale] if options.include?(:scale)
          self.collation = options[:collation] if options.include?(:collation)
        end
      end
    end

    def rename_column(table_name, column_name, new_column_name) #:nodoc:
      column = column_for(table_name, column_name)
      alter_table(table_name, rename: { column.name => new_column_name.to_s })
      rename_column_indexes(table_name, column.name, new_column_name)
    end

    protected

    def table_structure(table_name)
      structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", "SCHEMA")
      raise(ActiveRecord::StatementInvalid, "Could not find table '#{table_name}'") if structure.empty?
      table_structure_with_collation(table_name, structure)
    end

    def alter_table(table_name, options = {}) #:nodoc:
      altered_table_name = "a#{table_name}"
      caller = lambda { |definition| yield definition if block_given? }

      transaction do
        move_table(table_name, altered_table_name,
                   options.merge(temporary: true))
        move_table(altered_table_name, table_name, &caller)
      end
    end

    def move_table(from, to, options = {}, &block) #:nodoc:
      copy_table(from, to, options, &block)
      drop_table(from)
    end

    def copy_table(from, to, options = {}) #:nodoc:
      from_primary_key = primary_key(from)
      options[:id] = false
      create_table(to, options) do |definition|
        @definition = definition
        @definition.primary_key(from_primary_key) if from_primary_key.present?
        columns(from).each do |column|
          column_name = options[:rename] ?
              (options[:rename][column.name] ||
                  options[:rename][column.name.to_sym] ||
                  column.name) : column.name
          next if column_name == from_primary_key

          @definition.column(column_name, column.type,
                             limit: column.limit, default: column.default,
                             precision: column.precision, scale: column.scale,
                             null: column.null, collation: column.collation)
        end
        yield @definition if block_given?
      end
      copy_table_indexes(from, to, options[:rename] || {})
      copy_table_contents(from, to,
                          @definition.columns.map(&:name),
                          options[:rename] || {})
    end

    def copy_table_indexes(from, to, rename = {}) #:nodoc:
      indexes(from).each do |index|
        name = index.name
        if to == "a#{from}"
          name = "t#{name}"
        elsif from == "a#{to}"
          name = name[1..-1]
        end

        to_column_names = columns(to).map(&:name)
        columns = index.columns.map { |c| rename[c] || c }.select do |column|
          to_column_names.include?(column)
        end

        unless columns.empty?
          # index name can't be the same
          opts = { name: name.gsub(/(^|_)(#{from})_/, "\\1#{to}_"), internal: true }
          opts[:unique] = true if index.unique
          add_index(to, columns, opts)
        end
      end
    end

    def copy_table_contents(from, to, columns, rename = {}) #:nodoc:
      column_mappings = Hash[columns.map { |name| [name, name] }]
      rename.each { |a| column_mappings[a.last] = a.first }
      from_columns = columns(from).collect(&:name)
      columns = columns.find_all { |col| from_columns.include?(column_mappings[col]) }
      from_columns_to_copy = columns.map { |col| column_mappings[col] }
      quoted_columns = columns.map { |col| quote_column_name(col) } * ","
      quoted_from_columns = from_columns_to_copy.map { |col| quote_column_name(col) } * ","

      exec_query("INSERT INTO #{quote_table_name(to)} (#{quoted_columns})
                     SELECT #{quoted_from_columns} FROM #{quote_table_name(from)}")
    end

    def sqlite_version
      @sqlite_version ||= SQLite3Adapter::Version.new(select_value("select sqlite_version(*)"))
    end

    def translate_exception(exception, message)
      case exception.message
        # SQLite 3.8.2 returns a newly formatted error message:
        #   UNIQUE constraint failed: *table_name*.*column_name*
        # Older versions of SQLite return:
        #   column *column_name* is not unique
        when /column(s)? .* (is|are) not unique/, /UNIQUE constraint failed: .*/
          RecordNotUnique.new(message)
        else
          super
      end
    end

    private
    COLLATE_REGEX = /.*\"(\w+)\".*collate\s+\"(\w+)\".*/i.freeze

    def table_structure_with_collation(table_name, basic_structure)
      collation_hash = {}
      sql            = "SELECT sql FROM
                              (SELECT * FROM sqlite_master UNION ALL
                               SELECT * FROM sqlite_temp_master)
                            WHERE type='table' and name='#{ table_name }' \;"

      # Result will have following sample string
      # CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
      #                       "password_digest" varchar COLLATE "NOCASE");
      result = exec_query(sql, 'SCHEMA').first

      if result
        # Splitting with left parentheses and picking up last will return all
        # columns separated with comma(,).
        columns_string = result["sql"].split('(').last

        columns_string.split(',').each do |column_string|
          # This regex will match the column name and collation type and will save
          # the value in $1 and $2 respectively.
          collation_hash[$1] = $2 if (COLLATE_REGEX =~ column_string)
        end

        basic_structure.map! do |column|
          column_name = column['name']

          if collation_hash.has_key? column_name
            column['collation'] = collation_hash[column_name]
          end

          column
        end
      else
        basic_structure.to_hash
      end
    end
  end
end

module ActiveRecord::ConnectionAdapters
  class SQLite3Column < JdbcColumn
    def initialize(name, *args)
      if Hash === name
        super
      else
        super(nil, name, *args)
      end
    end

    def self.string_to_binary(value)
      value
    end

    def self.binary_to_string(value)
      if value.respond_to?(:encoding) && value.encoding != Encoding::ASCII_8BIT
        value = value.force_encoding(Encoding::ASCII_8BIT)
      end
      value
    end

    # @override {ActiveRecord::ConnectionAdapters::JdbcColumn#init_column}
    def init_column(name, default, *args)
      if default =~ /NULL/
        @default = nil
      else
        super
      end
    end

    # @override {ActiveRecord::ConnectionAdapters::JdbcColumn#default_value}
    def default_value(value)
      # JDBC returns column default strings with actual single quotes :
      return $1 if value =~ /^'(.*)'$/

      value
    end

    # @override {ActiveRecord::ConnectionAdapters::Column#type_cast}
    def type_cast(value)
      return nil if value.nil?
      case type
        when :string then value
        when :primary_key
          value.respond_to?(:to_i) ? value.to_i : ( value ? 1 : 0 )
        when :float    then value.to_f
        when :decimal  then self.class.value_to_decimal(value)
        when :boolean  then self.class.value_to_boolean(value)
        else super
      end
    end

    private

    # @override {ActiveRecord::ConnectionAdapters::Column#simplified_type}
    def simplified_type(field_type)
      case field_type
        when /boolean/i       then :boolean
        when /text/i          then :text
        when /varchar/i       then :string
        when /int/i           then :integer
        when /float/i         then :float
        when /real|decimal/i  then
          extract_scale(field_type) == 0 ? :integer : :decimal
        when /datetime/i      then :datetime
        when /date/i          then :date
        when /time/i          then :time
        when /blob/i          then :binary
        else super
      end
    end

    # @override {ActiveRecord::ConnectionAdapters::Column#extract_limit}
    def extract_limit(sql_type)
      return nil if sql_type =~ /^(real)\(\d+/i
      super
    end

    def extract_precision(sql_type)
      case sql_type
        when /^(real)\((\d+)(,\d+)?\)/i then $2.to_i
        else super
      end
    end

    def extract_scale(sql_type)
      case sql_type
        when /^(real)\((\d+)\)/i then 0
        when /^(real)\((\d+)(,(\d+))\)/i then $4.to_i
        else super
      end
    end
  end

  remove_const(:SQLite3Adapter) if const_defined?(:SQLite3Adapter)

  # Currently our adapter is named the same as what AR5 names its adapter.  We will need to get
  # this changed at some point so this can be a unique name and we can extend activerecord
  # ActiveRecord::ConnectionAdapters::SQLite3Adapter.  Once we can do that we can remove the
  # module SQLite3 above and remove a majority of this file.
  class SQLite3Adapter < AbstractAdapter
    include ArJdbc::CommonJdbcMethods
    include ArJdbc::SQLite3

    # FIXME: Add @connection.encoding then remove this method
    def encoding
      select_value 'PRAGMA encoding'
    end

    def exec_query(sql, name = nil, binds = [], prepare: false)
      use_prepared = prepare || !without_prepared_statement?(binds)

      if use_prepared
        type_casted_binds = prepare_binds_for_jdbc(binds)
        log(sql, name, binds) { @connection.execute_prepared(sql, type_casted_binds) }
      else
        log(sql, name) { @connection.execute(sql) }
      end
    end

    def exec_update(sql, name = nil, binds = [])
      use_prepared = !without_prepared_statement?(binds)

      if use_prepared
        type_casted_binds = prepare_binds_for_jdbc(binds)
        log(sql, name, binds) { @connection.execute_prepared_update(sql, type_casted_binds) }
      else
        log(sql, name) { @connection.execute_update(sql, nil) }
      end
    end
    alias :exec_delete :exec_update

    # Sqlite3 JDBC types in prepared statements seem to report blob as varchar (12).
    # So to work around this we will pass attribute type in with the value so we can
    # then remap to appropriate type in JDBC without needing to ask JDBC what type
    # it should be using.  No one likes a stinking liar...
    def prepare_binds_for_jdbc(binds)
      binds.map do |attribute|
        [attribute.type.type, type_cast(attribute.value_for_database)]
      end
    end

    # last two values passed but not used so I cannot alias to exec_query
    def exec_insert(sql, name, binds, pk = nil, sequence_name = nil)
      exec_update(sql, name, binds)
    end

    def indexes(table_name, name = nil) #:nodoc:
      # on JDBC 3.7 we'll simply do super since it can not handle "PRAGMA index_info"
      return @connection.indexes(table_name, name) if sqlite_version < '3.8' # super
      super
    end

    def jdbc_column_class
      ::ActiveRecord::ConnectionAdapters::SQLite3Column
    end

    def jdbc_connection_class(spec)
      self.class.jdbc_connection_class
    end

    # @see ActiveRecord::ConnectionAdapters::JdbcAdapter#jdbc_connection_class
    def self.jdbc_connection_class
      ::ActiveRecord::ConnectionAdapters::SQLite3JdbcConnection
    end
  end
end