[r/boards] post freezing

[salmad3]

Context:

Freezing posts (i.e., individual replies or comments within a thread) is aimed at ensuring that once a post is frozen, it becomes completely immutable. This prevents any further editing, deletion, or flagging actions, even if the post’s author or a moderator would normally be allowed to modify it.

Follows: #3755
Related to:

Acceptance Criteria:

• Updates the Post (or reply/comment) struct to include a Frozen boolean field.

  Example

  type Post struct {
      PostID    string
      ParentID  string    // if empty, this is a thread; if set, it's a reply/comment
      Author    Address
      Content   string
      Timestamp time.Time
      Flags     []Flag
      Frozen    bool // indicates whether the post is frozen
      // ... other fields
  }

• Implements a FreezePost(boardID BoardID, threadID PostID, postID PostID) function that:

  • Checks that the specified post is not already frozen.
  • Validates the caller's permission to freeze posts (e.g., PermissionPostFreeze).
  • Sets the post’s Frozen flag to true to block any further modifications.
  Example

  func FreezePost(boardID BoardID, threadID PostID, postID PostID) {
      board := mustGetBoard(boardID)
      thread := mustGetThread(board, threadID)
      post := mustGetReply(thread, postID) // assuming posts are accessed via replies in a thread
      if post.Frozen {
          panic("post is already frozen")
      }
  
      caller := std.GetOrigCaller()
      args := Args{boardID, threadID, postID}
      board.perms.WithPermission(caller, PermissionPostFreeze, args, func(Args) {
          // Re-check the post to ensure it hasn't been frozen in the meantime
          post := mustGetReply(thread, postID)
          if post.Frozen {
              panic("post is already frozen")
          }
          post.Frozen = true
      })
  }

• Provides an UnfreezePost(boardID BoardID, threadID PostID, postID PostID) function that:

  • Validates that the post is currently frozen.
  • Checks that the caller is authorized to perform the unfreeze operation.
  • Resets the Frozen flag to false.

• Overrides Existing Permissions

  • Once a post is frozen, any actions that would normally modify it (editing, deleting, adding flags, etc.) are blocked.
  • Relevant post-modification functions check for the Frozen state and respond with an error or panic if true.

• Tests

  • Confirms that a frozen post cannot be edited, deleted, or flagged.
  • Ensures that only users with the freeze permission can freeze or unfreeze a post.
  • Attempting to freeze an already frozen post results in an appropriate error.
  • Validate that once a post is unfrozen, normal modifications are allowed again.

[x1unix]

#3829