From 074af007d560b51c0ed03657e3c24a850e2b4b62 Mon Sep 17 00:00:00 2001
From: Cyberarm <matthewlikesrobots@gmail.com>
Date: Thu, 25 Nov 2021 18:27:23 -0600
Subject: [PATCH] Added digest-crc gem, added Mixer class to read and write
 Renegade MIX1 files

---
 Gemfile      |   1 +
 lib/mixer.rb | 170 +++++++++++++++++++++++++++++++++++++++++++++++++++
 w3dhub.rb    |   1 +
 3 files changed, 172 insertions(+)
 create mode 100644 lib/mixer.rb

diff --git a/Gemfile b/Gemfile
index d60d4a0..484913f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,4 +4,5 @@ gem "cyberarm_engine"
 gem "launchy"
 gem "i18n"
 gem "rexml"
+gem "digest-crc"
 # gem "async-websocket"
diff --git a/lib/mixer.rb b/lib/mixer.rb
new file mode 100644
index 0000000..e8c14ef
--- /dev/null
+++ b/lib/mixer.rb
@@ -0,0 +1,170 @@
+require "digest"
+
+class W3DHub
+
+  # https://github.com/TheUnstoppable/MixLibrary used for reference
+  class Mixer
+    class MixParserException < RuntimeError; end
+    class MixFormatException < RuntimeError; end
+
+    class Reader
+      attr_reader :package
+
+      def initialize(file_path:, ignore_crc_mismatches: false)
+        @package = Package.new
+        @file = File.open(file_path)
+
+        @file.pos = 0
+
+        # Valid header
+        if read_i32 == 0x3158494D
+          file_data_offset = read_i32
+          file_names_offset = read_i32
+
+          @file.pos = file_names_offset
+          file_count = read_i32
+
+          file_count.times do
+            @package.files << Package::File.new(name: read_string)
+          end
+
+          @file.pos = file_data_offset
+          _file_count = read_i32
+
+          file_count.times do |i|
+            file = @package.files[i]
+
+            file.mix_crc = read_u32.to_s(16)
+            file.content_offset = read_u32
+            file.content_length = read_u32
+
+            if file.mix_crc != file.file_crc && !ignore_crc_mismatches
+              raise MixParserException, "CRC mismatch for #{file.name}. #{file.mix_crc.inspect} != #{file.file_crc.inspect}"
+            end
+
+            pos = @file.pos
+            @file.pos = file.content_offset
+            file.data = @file.read(file.content_length)
+            @file.pos = pos
+          end
+        else
+          raise MixParserException, "Invalid MIX file"
+        end
+
+      ensure
+        @file&.close
+      end
+
+      def read_i32
+        @file.read(4).unpack1("l")
+      end
+
+      def read_u32
+        @file.read(4).unpack1("L")
+      end
+
+      def read_string
+        buffer = ""
+
+        length = @file.readbyte
+
+        length.times do
+          buffer << @file.readbyte
+        end
+
+        buffer.strip
+      end
+    end
+
+    class Writer
+      attr_reader :package
+
+      def initialize(file_path:, package:)
+        @package = package
+
+        @file = File.open(file_path, "wb")
+        @file.pos = 0
+
+        @file.write("MIX1")
+
+        files = @package.files.sort { |a, b| a.file_crc <=> b.file_crc }
+
+        @file.pos = 16
+
+        files.each do |file|
+          file.content_offset = @file.pos
+          file.content_length = file.data.length
+          @file.write(file.data)
+
+          @file.pos += -@file.pos & 7
+        end
+
+        file_data_offset = @file.pos
+        write_i32(files.count)
+
+        files.each do |file|
+          write_u32(file.file_crc.to_i(16))
+          write_u32(file.content_offset)
+          write_u32(file.content_length)
+        end
+
+        file_name_offset = @file.pos
+        write_i32(files.count)
+
+        files.each do |file|
+          write_byte(file.name.length + 1)
+          @file.write("#{file.name}\0")
+        end
+
+        @file.pos = 4
+        write_i32(file_data_offset)
+        write_i32(file_name_offset)
+
+        @file.pos = 0
+        @file.flush
+      ensure
+        @file&.close
+      end
+
+      def write_i32(int)
+        @file.write([int].pack("l"))
+      end
+
+      def write_u32(uint)
+        @file.write([uint].pack("L"))
+      end
+
+      def write_byte(byte)
+        @file.write([byte].pack("c"))
+      end
+    end
+
+    class Package
+      attr_reader :files
+
+      def initialize(files: [])
+        @files = files
+      end
+
+      class File
+        attr_accessor :name, :mix_crc, :content_offset, :content_length, :data
+
+        def initialize(name:, mix_crc: nil, content_offset: nil, content_length: nil, data: nil)
+          @name = name
+          @mix_crc = mix_crc
+          @content_offset = content_offset
+          @content_length = content_length
+          @data = data
+        end
+
+        def file_crc
+          Digest::CRC32.hexdigest(@name.upcase)
+        end
+
+        def data_crc
+          Digest::CRC32.hexdigest(@data)
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/w3dhub.rb b/w3dhub.rb
index 3b72948..d2260ed 100644
--- a/w3dhub.rb
+++ b/w3dhub.rb
@@ -32,6 +32,7 @@ require_relative "lib/store"
 require_relative "lib/window"
 require_relative "lib/cache"
 require_relative "lib/settings"
+require_relative "lib/mixer"
 require_relative "lib/application_manager"
 require_relative "lib/application_manager/manifest"
 require_relative "lib/application_manager/task"