////////////
/// math ///
////////////

struct Vec2 { x: f32, y: f32 }

impl Vec2 {
    pub fn zero() -> Vec2 { Vec2 { x: 0.0, y: 0.0 } }
    pub fn at(x: f32, y: f32) -> Vec2 { Vec2 { x: x, y: y } }
}

//impl binop ()


///////////////////
/// SDL externs ///
///////////////////

struct SDL_FPoint { x: f32, y: f32 }
struct SDL_FColor { r: f32, g: f32, b: f32, a: f32 }
struct SDL_Vertex { position: SDL_FPoint, color: SDL_FColor, tex_coord: SDL_FPoint }
impl SDL_Vertex {
    pub fn new() -> SDL_Vertex {
        SDL_Vertex {
            position: SDL_FPoint { x: 0.0, y: 0.0 },
            color: SDL_FColor { r: 1.0, g: 0.0, b: 1.0, a: 1.0 },
            tex_coord: SDL_FPoint { x: 0.0, y: 0.0 },
        }
    }

    pub fn pos(self, pos: Vec2) -> SDL_Vertex {
        return SDL_Vertex {
            position: SDL_FPoint { x: pos.x, y: pos.y },
            color: self.color,
            tex_coord: self.tex_coord,
        };
    }

    pub fn col(self, color: [f32; 3]) -> SDL_Vertex {
        return SDL_Vertex {
            position: self.position,
            color: [color[0], color[1], color[2], self.color.a],
            tex_coord: self.tex_coord,
        };
    }
}

struct SDL_Window {}
struct SDL_Renderer {}
struct SDL_Texture {}
struct SDL_Event { type: u32, reserved: [u8; 124] }
struct SDL_FRect { x: f32, y: f32, w: f32, h: f32 }
struct SDL_Rect { x: i32, y: i32, w: i32, h: i32 }
extern fn SDL_malloc(size: u64) -> *u8;
extern fn SDL_Init(flags: u32) -> bool;
extern fn SDL_Quit();
extern fn SDL_CreateWindowAndRenderer(title: *char, width: i32, height: i32, flags: i32,
    window_out: &mut *SDL_Window, renderer_out: &mut *SDL_Renderer) -> bool;
extern fn SDL_Delay(ms: u32);
extern fn SDL_SetRenderDrawColor(renderer: *SDL_Renderer, r: u8, g: u8, b: u8, a: u8);
extern fn SDL_RenderClear(renderer: *SDL_Renderer);
extern fn SDL_RenderPresent(renderer: *SDL_Renderer);
extern fn SDL_HasEvent(event_type: u32) -> bool;
extern fn SDL_PollEvent(event: &mut SDL_Event) -> bool;
extern fn SDL_PumpEvents();
extern fn SDL_FlushEvents(min_type: u32, max_type: u32);
extern fn SDL_GetTicks() -> u64;
extern fn SDL_SetWindowTitle(window: *SDL_Window, title: *char) -> bool;
extern fn SDL_CreateTexture(renderer: *SDL_Renderer,
    pixel_format: u32, texture_access: u32, width: u32, height: u32) -> *SDL_Texture;
extern fn SDL_RenderTexture(renderer: *SDL_Renderer,
    texture: *SDL_Texture, srcfrect: &SDL_FRect, dstfrect: &SDL_FRect) -> bool;
extern fn SDL_UpdateTexture(texture: *SDL_Texture, rect: &SDL_Rect, pixels: *u8, pitch: u32) -> bool;
extern fn SDL_GetError() -> *char;
extern fn SDL_GetWindowSize(window: *SDL_Window, w: &mut i32, h: &mut i32) -> bool;
extern fn SDL_rand(max_exclusive: u32) -> u32;
extern fn SDL_SetTextureScaleMode(texture: *SDL_Texture, scale_mode: i32) -> bool;
extern fn SDL_sqrtf(value: f32) -> f32;
extern fn SDL_randf() -> f32;
extern fn SDL_powf(value: f32, power: f32) -> f32;
extern fn exit(exit_code: i32);
extern fn SDL_RenderGeometry(renderer: *SDL_Renderer, texture: *SDL_Texture,
    vertices: *SDL_Vertex, num_vertices: i32, indices: *i32, num_indices: i32) -> bool;

// SDL error reporting helper
import std::print;
import std::String;
fn print_sdl_error(context: *char) {
    let mut message = String::new();
    message = message + context + ": " + SDL_GetError();
    print(message);
    message.free();
}


////////////////
/// the game ///
////////////////

struct Ship {
    position: Vec2,
}

struct Game {
    ship: Ship,
}

impl Game {
    pub fn new() -> Game {
        Game {
            ship: Ship {
                position: Vec2::zero(),
            },
        }
    }

    pub fn run_frame(&mut self, dt: f32, renderer: *SDL_Renderer, aspect_ratio: f32) {
        let ship = *self.ship;
        let vertices = [
            SDL_Vertex::new().pos(ship.position).col([1.0, 1.0, 1.0]),
            SDL_Vertex::new().pos(ship.position).col([1.0, 1.0, 1.0]),
            SDL_Vertex::new().pos(ship.position).col([1.0, 1.0, 1.0])
        ];
        let borrow: &[SDL_Vertex; 3] = &vertices;
        SDL_RenderGeometry(renderer, SDL_Texture::null(),
            borrow as *SDL_Vertex, 3, i32::null(), 0);
        // TODO: add a ship
        // TODO: wind sim
        // TODO: wave sim
    }
}


////////////////
/// the game ///
////////////////

struct Platform {
    window: *SDL_Window,
    renderer: *SDL_Renderer,
    game: Game,
    last_frame_ticks: u64,
}

impl Platform {
    pub fn new() -> Platform {
        let SDL_INIT_VIDEO = 32;
        let SDL_WINDOW_RESIZABLE = 32;

        let init_success = SDL_Init(SDL_INIT_VIDEO);
        if init_success == false {
            print_sdl_error("SDL init failed");
            return exit(1);
        }

        let mut window = SDL_Window::null();
        let mut renderer = SDL_Renderer::null();
        let mut window_title = "Yacht Reid";
        let gfx_init_success = SDL_CreateWindowAndRenderer(
            window_title, 640, 480, SDL_WINDOW_RESIZABLE,
            &mut window, &mut renderer
        );
        if gfx_init_success == false {
            print_sdl_error("SDL renderer and window creation failed");
            return exit(1);
        }

        return Platform { 
            window: window, 
            renderer: renderer,
            game: Game::new(),
            last_frame_ticks: SDL_GetTicks(),
        };
    }

    pub fn run_frame(&mut self) -> bool {
        let mut event = SDL_Event { type: 0, reserved: [0; 124] };
        while (SDL_PollEvent(&mut event)) {
            if event.type == 256 { // SDL_EVENT_QUIT
                return false;
            }
        }

        let now = SDL_GetTicks();
        let dt = (now - *self.last_frame_ticks) as f32 / 1000.0;
        *self.last_frame_ticks = now;

        let mut screen_width = 0;
        let mut screen_height = 0;
        SDL_GetWindowSize(*self.window, &mut screen_width, &mut screen_height);
        let aspect_ratio = screen_width as f32 / screen_height as f32;

        SDL_SetRenderDrawColor(*self.renderer, 0, 50, 90, 255);
        SDL_RenderClear(*self.renderer);

        *self.game.run_frame(dt, *self.renderer, aspect_ratio);

        SDL_RenderPresent(*self.renderer);
        return true;
    }

    pub fn cleanup(&mut self) {
        SDL_Quit();
    }
}

////////////
/// main ///
////////////

fn main() -> i32 {
    let mut platform = Platform::new();
    while platform.run_frame() {}
    return 0;
}