use crate::vm::{Value, VirtualMachine};
use crate::Machine;

pub trait NativeInterface {
    fn syscall(&mut self, id: u32, vm: &mut VirtualMachine) -> Result<u64, String>;
}

impl NativeInterface for Machine {
    fn syscall(&mut self, id: u32, vm: &mut VirtualMachine) -> Result<u64, String> {
        match id {
            // system.has_cart() -> bool
            0x0001 => {
                vm.push(Value::Boolean(self.cartridge.is_some()));
                Ok(10)
            }
            // system.run_cart()
            0x0002 => {
                if let Some(cart) = self.cartridge.as_ref() {
                    vm.program = cart.program.clone();
                    vm.pc = 0;
                    vm.operand_stack.clear();
                    vm.call_stack.clear();
                    vm.globals.clear();
                    vm.heap.clear();
                    vm.halted = false;
                } else {
                    return Err("No cartridge inserted".into());
                }
                Ok(100)
            }
            // gfx.clear(color_index)
            0x1001 => {
                let color_idx = vm.pop_integer()? as usize;
                let color = self.get_color(color_idx);
                self.gfx.clear(color);
                Ok(100)
            }
            // gfx.draw_rect(x, y, w, h, color_index)
            0x1002 => {
                let color_idx = vm.pop_integer()? as usize;
                let h = vm.pop_integer()? as i32;
                let w = vm.pop_integer()? as i32;
                let y = vm.pop_integer()? as i32;
                let x = vm.pop_integer()? as i32;
                let color = self.get_color(color_idx);
                self.gfx.fill_rect(x, y, w, h, color);
                Ok(200)
            }
            // input.get_pad(button_id) -> bool
            0x2001 => {
                let button_id = vm.pop_integer()? as u32;
                let is_down = self.is_button_down(button_id);
                vm.push(Value::Boolean(is_down));
                Ok(50)
            }
            // audio.play_sample(sample_id, voice_id, volume, pan, pitch)
            // sample_id: 0=square, 1=kick, 2=snare
            0x3001 => {
                let pitch = vm.pop_number()?;
                let pan = vm.pop_integer()? as u8;
                let volume = vm.pop_integer()? as u8;
                let voice_id = vm.pop_integer()? as usize;
                let sample_id = vm.pop_integer()? as u32;

                let sample = match sample_id {
                    0 => self.sample_square.clone(),
                    1 => self.sample_kick.clone(),
                    2 => self.sample_snare.clone(),
                    _ => None,
                };

                if let Some(s) = sample {
                    self.audio.play(s, voice_id, volume, pan, pitch, 0, crate::peripherals::LoopMode::Off);
                }
                Ok(300)
            }
            _ => Err(format!("Unknown syscall: 0x{:08X}", id)),
        }
    }
}