pub mod instance;

mod ipc;

mod world;

use gfx::{format::Formatted, Encoder};

use std::{

    ffi::CString,

    io::{Read, Write},

    mem::replace,

    os::raw::{c_char, c_void},

};

use gfx_device_gl as gfx_gl;

use self::instance::{EngineGlContext, EngineInstance};

#[repr(C)]

#[derive(Copy, Clone)]

pub struct PreviewInfo {

    width: u32,

    height: u32,

    hedgehogs_number: u8,

    land: *const u8,

}

#[no_mangle]

pub extern "C" fn protocol_version() -> u32 {

    56

}

#[no_mangle]

pub extern "C" fn start_engine() -> *mut EngineInstance {

    let engine_state = Box::new(EngineInstance::new());

    Box::leak(engine_state)

}

#[no_mangle]

pub extern "C" fn generate_preview(engine_state: &mut EngineInstance, preview: &mut PreviewInfo) {

    (*engine_state).process_ipc_queue();

    (*engine_state).world.generate_preview();

    let land_preview = (*engine_state).world.preview();

    *preview = PreviewInfo {

        width: land_preview.width() as u32,

        height: land_preview.height() as u32,

        hedgehogs_number: 0,

        land: land_preview.raw_pixels().as_ptr(),

    };

}

#[no_mangle]

pub extern "C" fn send_ipc(engine_state: &mut EngineInstance, buf: *const u8, size: usize) {

    unsafe {

        (*engine_state)

            .ipc

            .write(std::slice::from_raw_parts(buf, size))

            .unwrap();

    }

}

#[no_mangle]

pub extern "C" fn read_ipc(engine_state: &mut EngineInstance, buf: *mut u8, size: usize) -> usize {

    unsafe {

        (*engine_state)

            .ipc

            .read(std::slice::from_raw_parts_mut(buf, size))

            .unwrap_or(0)

    }

}

#[no_mangle]

pub extern "C" fn setup_current_gl_context(

    engine_state: &mut EngineInstance,

    width: u16,

    height: u16,

    gl_loader: extern "C" fn(*const c_char) -> *const c_void,

) {

    let (device, mut factory) = gfx_gl::create(|name| {

        let c_name = CString::new(name).unwrap();

        gl_loader(c_name.as_ptr())

    });

    let dimensions = (width, height, 1u16, gfx::texture::AaMode::Single);

    let (render_target, depth_buffer) = gfx_gl::create_main_targets_raw(

        dimensions,

        gfx::format::Rgba8::get_format().0,

        gfx::format::Depth::get_format().0,

    );

    let mut command_buffer: Encoder<_, _> = factory.create_command_buffer().into();

    engine_state.gl_context = Some(EngineGlContext {

        device,

        factory,

        render_target: gfx::memory::Typed::new(render_target),

        depth_buffer: gfx::memory::Typed::new(depth_buffer),

        command_buffer,

    })

}

#[no_mangle]

pub extern "C" fn render_frame(engine_state: &mut EngineInstance) {

    let mut context = replace(&mut engine_state.gl_context, None);

    if let Some(ref mut c) = context {

        engine_state.render(&mut c.command_buffer, &mut c.render_target)

    }

    replace(&mut engine_state.gl_context, context);

}

#[no_mangle]

pub extern "C" fn advance_simulation(engine_state: &mut EngineInstance, ticks: u32) -> bool {

    engine_state.world.step();

    true

}

#[no_mangle]

pub extern "C" fn cleanup(engine_state: *mut EngineInstance) {

    unsafe {

        Box::from_raw(engine_state);

    }

}