Switch over to use use blocks from nostrdb

This is still kind of broken until queries are switched over to nostrdb.
Will do this next

Signed-off-by: William Casarin <jb55@jb55.com>

nostrdb/NdbBlock.swift

@@ -0,0 +1,124 @@
+//
+//  NdbBlock.swift
+//  damus
+//
+//  Created by William Casarin on 2024-01-25.
+//
+
+import Foundation
+
+enum NdbBlockType: UInt32 {
+    case hashtag = 1
+    case text = 2
+    case mention_index = 3
+    case mention_bech32 = 4
+    case url = 5
+    case invoice = 6
+}
+
+extension ndb_mention_bech32_block {
+    var bech32_type: NdbBech32Type? {
+        NdbBech32Type(rawValue: self.bech32.type.rawValue)
+    }
+}
+
+enum NdbBech32Type: UInt32 {
+    case note = 1
+    case npub = 2
+    case nprofile = 3
+    case nevent = 4
+    case nrelay = 5
+    case naddr = 6
+    case nsec = 7
+
+    var is_notelike: Bool {
+        return self == .note || self == .nevent
+    }
+}
+
+extension ndb_invoice_block {
+    func as_invoice() -> Invoice? {
+        let b11 = self.invoice
+        let invstr = self.invstr.as_str()
+
+        guard let description = convert_invoice_description(b11: b11) else {
+            return nil
+        }
+        
+        let amount: Amount = b11.amount == 0 ? .any : .specific(Int64(b11.amount))
+
+        return Invoice(description: description, amount: amount, string: invstr, expiry: b11.expiry, created_at: b11.timestamp)
+    }
+}
+
+enum NdbBlock {
+    case text(ndb_str_block)
+    case mention(ndb_mention_bech32_block)
+    case hashtag(ndb_str_block)
+    case url(ndb_str_block)
+    case invoice(ndb_invoice_block)
+    case mention_index(UInt32)
+
+    init?(_ ptr: ndb_block_ptr) {
+        guard let type = NdbBlockType(rawValue: ndb_get_block_type(ptr.ptr).rawValue) else {
+            return nil
+        }
+        switch type {
+        case .hashtag: self = .hashtag(ptr.block.str)
+        case .text:    self = .text(ptr.block.str)
+        case .invoice: self = .invoice(ptr.block.invoice)
+        case .url:     self = .url(ptr.block.str)
+        case .mention_bech32: self = .mention(ptr.block.mention_bech32)
+        case .mention_index:  self = .mention_index(ptr.block.mention_index)
+        }
+    }
+    
+    var is_previewable: Bool {
+        switch self {
+        case .mention(let m):
+            switch m.bech32_type {
+            case .note, .nevent: return true
+            default: return false
+            }
+        case .invoice:
+            return true
+        case .url:
+            return true
+        default:
+            return false
+        }
+    }
+    
+    static func convertToStringCopy(from block: str_block_t) -> String? {
+        guard let cString = block.str else {
+            return nil
+        }
+        let byteBuffer = UnsafeBufferPointer(start: cString, count: Int(block.len)).map { UInt8(bitPattern: $0) }
+
+        // Create a Swift String from the byte array
+        return String(bytes: byteBuffer, encoding: .utf8)
+    }
+}
+
+
+struct NdbBlocks {
+    private let blocks_ptr: ndb_blocks_ptr
+
+    init(ptr: OpaquePointer?) {
+        self.blocks_ptr = ndb_blocks_ptr(ptr: ptr)
+    }
+
+    var words: Int {
+        Int(ndb_blocks_word_count(blocks_ptr.ptr))
+    }
+
+    func iter(note: NdbNote) -> BlocksSequence {
+        BlocksSequence(note: note, blocks: self)
+    }
+
+    func as_ptr() -> OpaquePointer? {
+        return self.blocks_ptr.ptr
+    }
+}
+
+