btrc-hub/backend/app/controllers/materials_controller.rb

class MaterialsController < ApplicationController
  def index
    page = (params[:page].presence || 1).to_i
    limit = (params[:limit].presence || 20).to_i

    page = 1 if page < 1
    limit = 1 if limit < 1

    offset = (page - 1) * limit

    tag_id = params[:tag_id].presence
    parent_id = params[:parent_id].presence

    q = Material.includes(:tag, :created_by_user).with_attached_file
    q = q.where(tag_id:) if tag_id
    q = q.where(parent_id:) if parent_id

    count = q.count
    materials = q.order(created_at: :desc, id: :desc).limit(limit).offset(offset)

    render json: { materials: materials.map { |m| material_json(m) }, count: count }
  end

  def show
    material = Material.includes(:tag, :created_by_user).with_attached_file.find_by(id: params[:id])
    return head :not_found unless material

    render json: material_json(material)
  end

  def create
    return head :unauthorized unless current_user
    return head :forbidden unless current_user.gte_member?

    file = params[:file]
    return head :bad_request if file.blank?

    material = Material.new(
        url: params[:url].presence,
        parent_id: params[:parent_id].presence,
        tag_id: params[:tag_id].presence,
        created_by_user: current_user)
    material.file.attach(file)

    if material.save
      render json: material_json(material), status: :created
    else
      render json: { errors: material.errors.full_messages }, status: :unprocessable_entity
    end
  end

  def update
    return head :unauthorized unless current_user
    return head :forbidden unless current_user.gte_member?

    material = Material.with_attached_file.find_by(id: params[:id])
    return head :not_found unless material

    material.assign_attributes(
      url: params[:url].presence,
      parent_id: params[:parent_id].presence,
      tag_id: params[:tag_id].presence
    )
    material.file.attach(params[:file]) if params[:file].present?

    if material.save
      render json: material_json(material)
    else
      render json: { errors: material.errors.full_messages }, status: :unprocessable_entity
    end
  end

  def destroy
    return head :unauthorized unless current_user
    return head :forbidden unless current_user.gte_member?

    material = Material.find_by(id: params[:id])
    return head :not_found unless material

    material.discard
    head :no_content
  end

  private

  def material_json(material)
    MaterialRepr.base(material).merge(
      'filename' => material.file.attached? ? material.file.filename.to_s : nil,
      'byte_size' => material.file.attached? ? material.file.byte_size : nil,
      'content_type' => material.file.attached? ? material.file.content_type : nil,
      'url' => material.file.attached? ? url_for(material.file) : nil
    )
  end
end