module PgHero
  class HomeController < ActionController::Base
    layout "pg_hero/application"

    protect_from_forgery

    http_basic_authenticate_with name: ENV["PGHERO_USERNAME"], password: ENV["PGHERO_PASSWORD"] if ENV["PGHERO_PASSWORD"]

    if respond_to?(:before_action)
      before_action :set_database
      before_action :set_query_stats_enabled
      before_action :set_show_details, only: [:index, :queries, :show_query]
    else
      before_filter :set_database
      before_filter :set_query_stats_enabled
      before_filter :set_show_details, only: [:index, :queries, :show_query]
    end

    def index
      @title = "Overview"
      @extended = params[:extended]

      if @replica
        @replication_lag = @database.replication_lag
        @good_replication_lag = @replication_lag < 5
      else
        @inactive_replication_slots = @database.replication_slots.select { |r| !r[:active] }
      end

      @autovacuum_queries, @long_running_queries = @database.long_running_queries.partition { |q| q[:query].starts_with?("autovacuum:") }

      @total_connections = @database.total_connections
      @good_total_connections = @total_connections < @database.total_connections_threshold

      @transaction_id_danger = @database.transaction_id_danger(threshold: 1500000000)
      @sequence_danger = @database.sequence_danger(threshold: (params[:sequence_threshold] || 0.9).to_f)

      @indexes = @database.indexes
      @invalid_indexes = @indexes.select { |i| !i[:valid] }
      @duplicate_indexes = @database.duplicate_indexes(indexes: @indexes)

      if @query_stats_enabled
        @query_stats = @database.query_stats(historical: true, start_at: 3.hours.ago)
        @slow_queries = @database.slow_queries(query_stats: @query_stats)
        set_suggested_indexes((params[:min_average_time] || 20).to_f, (params[:min_calls] || 50).to_i)
      else
        @query_stats_available = @database.query_stats_available?
        @query_stats_extension_enabled = @database.query_stats_extension_enabled? if @query_stats_available
        @suggested_indexes = []
      end

      if @extended
        @index_hit_rate = @database.index_hit_rate || 0
        @table_hit_rate = @database.table_hit_rate || 0
        @good_cache_rate = @table_hit_rate >= @database.cache_hit_rate_threshold / 100.0 && @index_hit_rate >= @database.cache_hit_rate_threshold / 100.0
        @unused_indexes = @database.unused_indexes(max_scans: 0)
      end

      @show_migrations = PgHero.show_migrations
    end

    def space
      @title = "Space"
      @days = (params[:days] || 7).to_i
      @database_size = @database.database_size
      @relation_sizes = params[:tables] ? @database.table_sizes : @database.relation_sizes
      @space_stats_enabled = @database.space_stats_enabled? && !params[:tables]
      if @space_stats_enabled
        space_growth = @database.space_growth(days: @days, relation_sizes: @relation_sizes)
        @growth_bytes_by_relation = Hash[ space_growth.map { |r| [[r[:schema], r[:relation]], r[:growth_bytes]] } ]
        case params[:sort]
        when "growth"
          @relation_sizes.sort_by! { |r| s = @growth_bytes_by_relation[[r[:schema], r[:relation]]]; [s ? 0 : 1, -s.to_i, r[:schema], r[:relation]] }
        when "name"
          @relation_sizes.sort_by! { |r| r[:relation] || r[:table] }
        end
      end

      @unused_indexes = @database.unused_indexes(max_scans: 0)
      @unused_index_names = Set.new(@unused_indexes.map { |r| r[:index] })
      @show_migrations = PgHero.show_migrations
      @system_stats_enabled = @database.system_stats_enabled?
      @index_bloat = @database.index_bloat
    end

    def relation_space
      @schema = params[:schema] || "public"
      @relation = params[:relation]
      @title = @relation
      relation_space_stats = @database.relation_space_stats(@relation, schema: @schema)
      @chart_data = [{name: "Value", data: relation_space_stats.map { |r| [r[:captured_at], (r[:size_bytes].to_f / 1.megabyte).round(1)] }, library: chart_library_options}]
    end

    def index_bloat
      @title = "Index Bloat"
      @index_bloat = @database.index_bloat
      @show_sql = params[:sql]
    end

    def live_queries
      @title = "Live Queries"
      @running_queries = @database.running_queries
    end

    def queries
      @title = "Queries"
      @sort = %w(average_time calls).include?(params[:sort]) ? params[:sort] : nil
      @min_average_time = params[:min_average_time] ? params[:min_average_time].to_i : nil
      @min_calls = params[:min_calls] ? params[:min_calls].to_i : nil

      if @historical_query_stats_enabled
        begin
          @start_at = params[:start_at] ? Time.zone.parse(params[:start_at]) : 24.hours.ago
          @end_at = Time.zone.parse(params[:end_at]) if params[:end_at]
        rescue
          @error = true
        end
      end

      @query_stats =
        if @historical_query_stats_enabled && !request.xhr?
          []
        else
          @database.query_stats(
            historical: true,
            start_at: @start_at,
            end_at: @end_at,
            sort: @sort,
            min_average_time: @min_average_time,
            min_calls: @min_calls
          )
        end

      @indexes = @database.indexes
      set_suggested_indexes

      # fix back button issue with caching
      response.headers["Cache-Control"] = "must-revalidate, no-store, no-cache, private"
      if request.xhr?
        render layout: false, partial: "queries_table", locals: {queries: @query_stats, xhr: true}
      end
    end

    def show_query
      @query_hash = params[:query_hash].to_i
      @title = @query_hash

      stats = @database.query_stats(historical: true, query_hash: @query_hash, start_at: 24.hours.ago).first
      if stats
        @query = stats[:query]
        @explainable_query = stats[:explainable_query]

        if @show_details
          query_hash_stats = @database.query_hash_stats(@query_hash)

          @chart_data = [{name: "Value", data: query_hash_stats.map { |r| [r[:captured_at], (r[:total_minutes] * 60 * 1000).round] }, library: chart_library_options}]
          @chart2_data = [{name: "Value", data: query_hash_stats.map { |r| [r[:captured_at], r[:average_time].round(1)] }, library: chart_library_options}]
          @chart3_data = [{name: "Value", data: query_hash_stats.map { |r| [r[:captured_at], r[:calls]] }, library: chart_library_options}]

          @origins = Hash[query_hash_stats.group_by { |r| r[:origin].to_s }.map { |k, v| [k, v.size] }]
          @total_count = query_hash_stats.size
        end

        @tables = PgQuery.parse(@query).tables rescue []
        @tables.sort!

        if @tables.any?
          @row_counts = Hash[@database.table_stats(table: @tables).map { |i| [i[:table], i[:estimated_rows]] }]
          @indexes_by_table = @database.indexes.group_by { |i| i[:table] }
        end
      else
        render text: "Unknown query"
      end
    end

    def system
      @title = "System"
      @periods = {
        "1 hour" => {duration: 1.hour, period: 60.seconds},
        "1 day" => {duration: 1.day, period: 10.minutes},
        "1 week" => {duration: 1.week, period: 30.minutes},
        "2 weeks" => {duration: 2.weeks, period: 1.hours}
      }
    end

    def cpu_usage
      render json: [{name: "CPU", data: @database.cpu_usage(system_params).map { |k, v| [k, v.round] }, library: chart_library_options}]
    end

    def connection_stats
      render json: [{name: "Connections", data: @database.connection_stats(system_params), library: chart_library_options}]
    end

    def replication_lag_stats
      render json: [{name: "Lag", data: @database.replication_lag_stats(system_params), library: chart_library_options}]
    end

    def load_stats
      render json: [
        {name: "Read IOPS", data: @database.read_iops_stats(system_params).map { |k, v| [k, v.round] }, library: chart_library_options},
        {name: "Write IOPS", data: @database.write_iops_stats(system_params).map { |k, v| [k, v.round] }, library: chart_library_options}
      ]
    end

    def free_space_stats
      render json: [
        {name: "Free Space", data: @database.free_space_stats(duration: 14.days, period: 1.hour).map { |k, v| [k, (v / 1.gigabyte).round] }, library: chart_library_options},
      ]
    end

    def explain
      @title = "Explain"
      @query = params[:query]
      # TODO use get + token instead of post so users can share links
      # need to prevent CSRF and DoS
      if request.post? && @query
        begin
          prefix =
            case params[:commit]
            when "Analyze"
              "ANALYZE "
            when "Visualize"
              "(ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON) "
            else
              ""
            end
          @explanation = @database.explain("#{prefix}#{@query}")
          @suggested_index = @database.suggested_indexes(queries: [@query]).first
          @visualize = params[:commit] == "Visualize"
        rescue ActiveRecord::StatementInvalid => e
          @error = e.message
        end
      end
    end

    def tune
      @title = "Tune"
      @settings = @database.settings
    end

    def connections
      @title = "Connections"
      @connection_sources = @database.connection_sources
      @total_connections = @connection_sources.sum { |cs| cs[:total_connections] }

      @connections_by_database = group_connections(@connection_sources, :database)
      @connections_by_user = group_connections(@connection_sources, :user)
    end

    def maintenance
      @title = "Maintenance"
      @maintenance_info = @database.maintenance_info
      @time_zone = PgHero.time_zone
    end

    def kill
      if @database.kill(params[:pid])
        redirect_to root_path, notice: "Query killed"
      else
        redirect_backward notice: "Query no longer running"
      end
    end

    def kill_long_running_queries
      @database.kill_long_running_queries
      redirect_backward notice: "Queries killed"
    end

    def kill_all
      @database.kill_all
      redirect_backward notice: "Connections killed"
    end

    def enable_query_stats
      @database.enable_query_stats
      redirect_backward notice: "Query stats enabled"
    rescue ActiveRecord::StatementInvalid
      redirect_backward alert: "The database user does not have permission to enable query stats"
    end

    def reset_query_stats
      @database.reset_query_stats
      redirect_backward notice: "Query stats reset"
    rescue ActiveRecord::StatementInvalid
      redirect_backward alert: "The database user does not have permission to reset query stats"
    end

    protected

    def redirect_backward(options = {})
      if Rails.version >= "5.1"
        redirect_back options.merge(fallback_location: root_path)
      else
        redirect_to :back, options
      end
    end

    def set_database
      @databases = PgHero.databases.values
      if params[:database]
        # don't do direct lookup, since you don't want to call to_sym on user input
        @database = @databases.find { |d| d.id == params[:database] }
      elsif @databases.size > 1
        redirect_to url_for(controller: controller_name, action: action_name, database: @databases.first.id)
      else
        @database = @databases.first
      end
    end

    def default_url_options
      {database: params[:database]}
    end

    def set_query_stats_enabled
      @query_stats_enabled = @database.query_stats_enabled?
      @system_stats_enabled = @database.system_stats_enabled?
      @replica = @database.replica?
    end

    def set_suggested_indexes(min_average_time = 0, min_calls = 0)
      @suggested_indexes_by_query = @database.suggested_indexes_by_query(query_stats: @query_stats.select { |qs| qs[:average_time] >= min_average_time && qs[:calls] >= min_calls })
      @suggested_indexes = @database.suggested_indexes(suggested_indexes_by_query: @suggested_indexes_by_query, indexes: @indexes)
      @query_stats_by_query = @query_stats.index_by { |q| q[:query] }
      @debug = params[:debug].present?
    end

    def system_params
      {
        duration: params[:duration],
        period: params[:period]
      }.delete_if { |_, v| v.nil? }
    end

    def chart_library_options
      {pointRadius: 0, pointHitRadius: 5, borderWidth: 4}
    end

    def set_show_details
      @historical_query_stats_enabled = @query_stats_enabled && @database.historical_query_stats_enabled?
      @show_details = @historical_query_stats_enabled && @database.supports_query_hash?
    end

    def group_connections(connection_sources, key)
      top_connections = Hash.new(0)
      connection_sources.each do |source|
        top_connections[source[key]] += source[:total_connections]
      end
      top_connections.sort_by { |k, v| [-v, k] }
    end
  end
end