1 files changed, 104 insertions, 0 deletions
diff --git a/src/components/metadata.rs b/src/components/metadata.rs
new file mode 100644
index 0000000..5c2361b
--- /dev/null
+++ b/src/components/metadata.rs
@@ -0,0 +1,104 @@
+pub struct Metadata<'a> {
+    program: &'a [u8],
+}
+
+impl<'a> Metadata<'a> {
+    pub fn from(program: &'a [u8]) -> Option<Self> {
+        if program.len() < 10 {
+            return None;
+        }
+        let identifier = [0xE8,0x00,0x18,0x42,0x45,0x44,0x52,0x4F,0x43,0x4B];
+        match program[0..10] == identifier {
+            true => Some(Self { program }),
+            false => None,
+        }
+    }
+
+    pub fn name(&self) -> Option<String> {
+        let pointer = self.get_pointer(0x000A)?;
+        self.get_string(pointer)
+    }
+
+    pub fn authors(&self) -> Option<Vec<String>> {
+        let pointer = self.get_pointer(0x000C)?;
+        let string = self.get_string(pointer)?;
+        Some(string.lines().map(String::from).collect())
+    }
+
+    pub fn description(&self) -> Option<String> {
+        let pointer = self.get_pointer(0x000E)?;
+        self.get_string(pointer)
+    }
+
+    pub fn bg_colour(&self) -> Option<MetadataColour> {
+        let pointer = self.get_pointer(0x0010)?;
+        let colour = self.get_pointer(pointer)?;
+        Some(MetadataColour::from_double(colour))
+    }
+
+    pub fn fg_colour(&self) -> Option<MetadataColour> {
+        let pointer = self.get_pointer(0x0012)?;
+        let colour = self.get_pointer(pointer)?;
+        Some(MetadataColour::from_double(colour))
+    }
+
+    pub fn small_icon(&self) -> Option<Vec<u8>> {
+        let pointer = self.get_pointer(0x0014)?;
+        self.get_icon(pointer, 72)
+    }
+
+    pub fn large_icon(&self) -> Option<Vec<u8>> {
+        let pointer = self.get_pointer(0x0016)?;
+        self.get_icon(pointer, 512)
+    }
+
+    fn get_byte(&self, address: u16) -> Option<u8> {
+        self.program.get(address as usize).copied()
+    }
+
+    fn get_pointer(&self, address: u16) -> Option<u16> {
+        let high = self.get_byte(address)?;
+        let low = self.get_byte(address.checked_add(1)?)?;
+        let pointer = u16::from_be_bytes([high, low]);
+        if pointer != 0 { Some(pointer) } else { None }
+    }
+
+    fn get_string(&self, address: u16) -> Option<String> {
+        let start = address as usize;
+        let mut end = address as usize;
+        loop {
+            match self.program.get(end) {
+                Some(0) => break,
+                Some(_) => end += 1,
+                None    => return None,
+            }
+        }
+        let vec = self.program[start..end].to_vec();
+        String::from_utf8(vec).ok()
+    }
+
+    fn get_icon(&self, address: u16, length: usize) -> Option<Vec<u8>> {
+        let address = address as usize;
+        let data = &self.program[address..address+length];
+        match data.len() == length {
+            true => Some(data.to_vec()),
+            false => None,
+        }
+    }
+}
+
+
+pub struct MetadataColour {
+    pub red: u8,
+    pub green: u8,
+    pub blue: u8,
+}
+
+impl MetadataColour {
+    pub fn from_double(colour: u16) -> Self {
+        let red   = (colour & 0x0F00 >> 8) as u8 * 17;
+        let green = (colour & 0x00F0 >> 4) as u8 * 17;
+        let blue  = (colour & 0x000F >> 0) as u8 * 17;
+        Self { red, green, blue }
+    }
+}