require 'csv'

class Post < Prism::Orm::Model
  # Result of .import_csv below - `imported` are posts that actually made
  # it to disk, `skipped` are { title:, errors: } pairs for rows that
  # never did (blank title, or a slug collision that outlived
  # MAX_SLUG_ATTEMPTS).
  ImportResult = Struct.new(:imported, :skipped)

  MAX_SLUG_ATTEMPTS = 20

  belongs_to :user
  has_many :comments, dependent: :destroy
  has_many :likes, as: :likeable, dependent: :destroy
  # dependent: :destroy, not :nullify - same reasoning as comments/likes
  # above: Claim is paranoid too (see the model), so trashing this post
  # soft-deletes its claims along with it and #restore(recursive: true)
  # brings them back, rather than a plain trash permanently erasing the
  # record of who already won a giveaway slot.
  has_many :claims, dependent: :destroy

  # A deleted post lands in the trash (see PostsController#destroy/#trash/
  # #restore) instead of vanishing outright - Post.all/#find already hide
  # it everywhere else in the app for free. Comment and Like are paranoid
  # too, so the `dependent: :destroy` cascades above soft-delete them the
  # moment a post is trashed instead of removing them for real, and
  # PostsController#restore(recursive: true) brings them all back together
  # with the post (see Associable#cascade_restore_dependent_associations).
  acts_as_paranoid

  # Every post starts life as a draft (column default 0, see the
  # add_status_to_posts migration) - only #publish! on posts#show makes it
  # show up on the public index (see PostsController#index below).
  enum :status, { draft: 0, published: 1, archived: 2 }

  # Prism::Orm::Attributes: casts the "featured" checkbox's form value
  # ("1"/"0", always a String off an HTTP request - see the hidden-field
  # trick in _form.erb) into a real TrueClass/FalseClass on write, instead
  # of leaving the literal string "1" sitting in the featured column. That
  # distinction is not cosmetic: `where(featured: true)` (see the
  # .featured scope below and PostsController#index's `?featured=1`
  # filter) does a plain Ruby `==` against whatever is actually stored,
  # so a stored String would never match a query for the Boolean `true`.
  attribute :featured, :boolean, default: false

  # Same reasoning as TypeCasting.cast_integer's own comment: blank input
  # from the (optional) giveaway_slots form field casts to nil, not 0 - nil
  # means "not a giveaway post" (see #giveaway? below), 0 means "was a
  # giveaway, every slot already claimed", and those are not the same
  # state for #giveaway_sold_out? to report.
  attribute :giveaway_slots, :integer

  scope :featured, -> { where(featured: true) }

  # acts_as_list scoped by the featured flag itself: every post gets a
  # position within its own featured/non-featured group (the non-featured
  # group's numbers are never shown or reordered - see posts#index and
  # PostsController#move_up/#move_down, both gated on featured_only), so
  # toggling a post's own featured flag on/off cheaply hops it between two
  # already-maintained lists (append to the bottom of whichever group it
  # lands in) instead of needing a bespoke third state to track "not in
  # any list yet". Editors use #move_up/#move_down to curate which
  # featured posts lead the homepage instead of always showing the most
  # recently featured one first.
  acts_as_list column: :position, scope: :featured

  # Backed by the range-capable secondary index on created_at
  # (db/migrate/20260907000004_add_index_on_posts_created_at.rb) - the
  # gte/lte hash this builds is exactly what
  # Query::ConditionNode#indexable_ranges recognizes, so PostsController#index
  # chaining this onto .published (see below) hits
  # Store#lookup_by_index_range with an O(log n) binary search over
  # sorted_values instead of a full table scan. See Store#lookup_by_index_range.
  scope :created_within, ->(days) { where(created_at: { gte: Time.now.utc - (days.to_i * 86_400) }) }

  # Lets the author moderate comments (edit or remove) from the same form
  # used to edit the post itself - reject_if: :all_blank so a moderation
  # form that only ever submits EXISTING comment rows (no "add a comment"
  # field on this screen) never has to worry about accidentally building
  # a blank new one.
  accepts_nested_attributes_for :comments, allow_destroy: true, reject_if: :all_blank

  validates :title, presence: true, length: { minimum: 3 }
end