# frozen_string_literal: true

require 'pg'
require 'pgvector'

module Boxcars
  module VectorStore
    module Pgvector
      class SaveToDatabase
        include VectorStore

        # @param pg_vectors [Array] array of Boxcars::VectorStore::Document
        # @param database_url [String] database url
        # @param table_name [String] table name
        # @param embedding_column_name [String] embedding column name
        # @param content_column_name [String] content column name
        # @param metadata_column_name [String] metadata column name
        # @return [Array] array of Boxcars::VectorStore::Document
        def initialize(params)
          validate_param_types(params)
          @db_connection = test_db_params(params)

          @table_name = params[:table_name]
          @content_column_name = params[:content_column_name]
          @embedding_column_name = params[:embedding_column_name]
          @metadata_column_name = params[:metadata_column_name]

          @pg_vectors = params[:pg_vectors]
        end

        # @return [Array] array of Boxcars::VectorStore::Document
        def call
          add_vectors_to_database
        end

        private

        attr_reader :database_url, :pg_vectors, :db_connection, :table_name,
                    :embedding_column_name, :content_column_name,
                    :metadata_column_name

        def validate_param_types(params)
          pg_vectors = params[:pg_vectors]

          raise_argument_error('pg_vectors must be an array') unless pg_vectors.is_a?(Array)
          raise_argument_error('missing data') if pg_vectors.empty?
          raise_argument_error('invalid vector_store') unless valid_vector_store?(pg_vectors)
          @database_url = params[:database_url]
          raise_argument_error('missing database_url argument') if @database_url.to_s.empty?
        end

        def valid_vector_store?(pg_vectors)
          pg_vectors.all? do |doc|
            doc.is_a?(Boxcars::VectorStore::Document)
          end
        rescue TypeError => e
          raise_argument_error(e.message)
        end

        def test_db_params(params)
          conn = ::PG::Connection.new(@database_url)

          check_db_connection(conn)
          check_vector_extension(conn)
          check_table_exists(conn, params[:table_name])
          check_column_exists(conn, params)

          registry = PG::BasicTypeRegistry.new.define_default_types
          ::Pgvector::PG.register_vector(registry)
          conn.type_map_for_queries = PG::BasicTypeMapForQueries.new(conn, registry: registry)
          conn.type_map_for_results = PG::BasicTypeMapForResults.new(conn, registry: registry)
          conn
        rescue PG::Error, NameError => e
          raise_argument_error(e.message)
        end

        def check_db_connection(conn)
          return if conn.status == PG::CONNECTION_OK

          raise_argument_error("PostgreSQL connection is not ok")
        end

        def check_vector_extension(conn)
          return if conn.exec("SELECT 1 FROM pg_extension WHERE extname = 'vector'").any?

          raise_argument_error("PostgreSQL 'vector' extension is not installed")
        end

        def check_table_exists(conn, table_name)
          table_exists = conn.exec_params(
            "SELECT EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = $1)", [table_name]
          ).getvalue(0, 0) == "t"
          return if table_exists

          raise_argument_error("Table '#{table_name}' does not exist")
        end

        def check_column_exists(conn, params)
          column_names = %i[embedding_column_name content_column_name metadata_column_name]
          table_name = params[:table_name]

          column_names.each do |target|
            column_name = params[target]
            column_exists = conn.exec_params(
              "SELECT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name = $1 AND column_name = $2)",
              [table_name, column_name]
            ).getvalue(0, 0) == "t"
            next if column_exists

            raise_argument_error("Column '#{column_name}' does not exist in table '#{table_name}'")
          end
        end

        def add_vectors_to_database
          pg_vectors.each do |document|
            embedding = document.embedding.map(&:to_f)
            content = document.content
            metadata = document.metadata.to_json

            if document.metadata[:id]
              id = document.metadata[:id]
              # directly inserting table_name, embedding_column_name, and content_column_name
              # into the SQL command. If these values are coming from an untrusted source,
              # there is a risk of SQL injection
              sql = <<-SQL
                INSERT INTO #{table_name} (id, #{embedding_column_name}, #{content_column_name}, #{metadata_column_name})
                VALUES ($1, $2, $3, $4)
                ON CONFLICT (id) DO UPDATE
                SET #{embedding_column_name} = EXCLUDED.#{embedding_column_name},
                    #{content_column_name} = EXCLUDED.#{content_column_name},
                    #{metadata_column_name} = EXCLUDED.#{metadata_column_name}
              SQL
              # parameters are given separately from the SQL command,
              # there's no risk of them being interpreted as part of the command.
              db_connection.exec_params(sql, [id, embedding, content, metadata])
            else
              sql = <<-SQL
                INSERT INTO #{table_name} (#{embedding_column_name}, #{content_column_name}, #{metadata_column_name})
                VALUES ($1, $2, $3)
              SQL
              db_connection.exec_params(sql, [embedding, content, metadata])
            end
          end
        rescue PG::Error => e
          raise_argument_error(e.message)
        end
      end
    end
  end
end