mod cache;
mod event;
mod graphic;
mod scale;
mod util;
mod widgets;
#[macro_use]
pub mod img_ids;
#[macro_use]
mod font_ids;

pub use event::Event;
pub use graphic::Graphic;
pub use scale::ScaleMode;
pub use widgets::{image_slider::ImageSlider, toggle_button::ToggleButton};

use crate::{
    render::{
        create_ui_quad, create_ui_tri, DynamicModel, Mesh, RenderError, Renderer, UiMode,
        UiPipeline,
    },
    window::Window,
    Error,
};
use cache::Cache;
use common::assets;
use conrod_core::{
    event::Input,
    graph::Graph,
    image::{Id as ImgId, Map},
    input::{touch::Touch, Motion, Widget},
    render::Primitive,
    text::{self, font},
    widget::{id::Generator, Id as WidgId},
    Ui as CrUi, UiBuilder, UiCell,
};
use graphic::Id as GraphicId;
use scale::Scale;
use std::io::Read;
use std::ops::Range;
use std::sync::Arc;
use util::{linear_to_srgb, srgb_to_linear};
use vek::*;

#[derive(Debug)]
pub enum UiError {
    RenderError(RenderError),
}

enum DrawKind {
    Image,
    // Text and non-textured geometry
    Plain,
}
enum DrawCommand {
    Draw { kind: DrawKind, verts: Range<usize> },
    Scissor(Aabr<u16>),
}
impl DrawCommand {
    fn image(verts: Range<usize>) -> DrawCommand {
        DrawCommand::Draw {
            kind: DrawKind::Image,
            verts,
        }
    }
    fn plain(verts: Range<usize>) -> DrawCommand {
        DrawCommand::Draw {
            kind: DrawKind::Plain,
            verts,
        }
    }
}

pub struct Font(text::Font);
impl assets::Asset for Font {
    fn load(specifier: &str) -> Result<Self, assets::Error> {
        let mut buf = Vec::new();
        assets::load_from_path(specifier)?.read_to_end(&mut buf)?;
        Ok(Font(text::Font::from_bytes(buf.clone()).unwrap()))
    }
}

pub struct Ui {
    ui: CrUi,
    image_map: Map<GraphicId>,
    cache: Cache,
    // Draw commands for the next render
    draw_commands: Vec<DrawCommand>,
    // Model for drawing the ui
    model: DynamicModel<UiPipeline>,
    // Window size for updating scaling
    window_resized: Option<Vec2<f64>>,
    // Scaling of the ui
    scale: Scale,
}

impl Ui {
    pub fn new(window: &mut Window) -> Result<Self, Error> {
        let scale = Scale::new(window, ScaleMode::Absolute(1.0));
        let win_dims = scale.scaled_window_size().into_array();

        Ok(Self {
            ui: UiBuilder::new(win_dims).build(),
            image_map: Map::new(),
            cache: Cache::new(window.renderer_mut())?,
            draw_commands: vec![],
            model: window.renderer_mut().create_dynamic_model(100)?,
            window_resized: None,
            scale,
        })
    }

    // Set the scaling mode of the ui.
    pub fn scaling_mode(&mut self, mode: ScaleMode) {
        self.scale.scaling_mode(mode);
        // Give conrod the new size.
        let (w, h) = self.scale.scaled_window_size().into_tuple();
        self.ui.handle_event(Input::Resize(w, h));
    }

    pub fn add_graphic(&mut self, graphic: Graphic) -> ImgId {
        self.image_map.insert(self.cache.add_graphic(graphic))
    }

    pub fn new_font(&mut self, font: Arc<Font>) -> font::Id {
        self.ui.fonts.insert(font.as_ref().0.clone())
    }

    pub fn id_generator(&mut self) -> Generator {
        self.ui.widget_id_generator()
    }

    pub fn set_widgets(&mut self) -> UiCell {
        self.ui.set_widgets()
    }

    // Accepts Option so widget can be unfocused.
    pub fn focus_widget(&mut self, id: Option<WidgId>) {
        self.ui.keyboard_capture(match id {
            Some(id) => id,
            None => self.ui.window,
        });
    }

    // Get id of current widget capturing keyboard.
    pub fn widget_capturing_keyboard(&self) -> Option<WidgId> {
        self.ui.global_input().current.widget_capturing_keyboard
    }

    // Get whether a widget besides the window is capturing the mouse.
    pub fn no_widget_capturing_mouse(&self) -> bool {
        self.ui
            .global_input()
            .current
            .widget_capturing_mouse
            .filter(|id| id != &self.ui.window)
            .is_none()
    }

    // Get the widget graph.
    pub fn widget_graph(&self) -> &Graph {
        self.ui.widget_graph()
    }
    pub fn handle_event(&mut self, event: Event) {
        match event.0 {
            Input::Resize(w, h) if w > 1.0 && h > 1.0 => {
                self.window_resized = Some(Vec2::new(w, h))
            }
            Input::Touch(touch) => self.ui.handle_event(Input::Touch(Touch {
                xy: self.scale.scale_point(touch.xy.into()).into_array(),
                ..touch
            })),
            Input::Motion(motion) => self.ui.handle_event(Input::Motion(match motion {
                Motion::MouseCursor { x, y } => {
                    let (x, y) = self.scale.scale_point(Vec2::new(x, y)).into_tuple();
                    Motion::MouseCursor { x, y }
                }
                Motion::MouseRelative { x, y } => {
                    let (x, y) = self.scale.scale_point(Vec2::new(x, y)).into_tuple();
                    Motion::MouseRelative { x, y }
                }
                Motion::Scroll { x, y } => {
                    let (x, y) = self.scale.scale_point(Vec2::new(x, y)).into_tuple();
                    Motion::Scroll { x, y }
                }
                _ => motion,
            })),
            _ => self.ui.handle_event(event.0),
        }
    }

    pub fn widget_input(&self, id: WidgId) -> Widget {
        self.ui.widget_input(id)
    }

    pub fn maintain(&mut self, renderer: &mut Renderer) {
        // Regenerate draw commands and associated models only if the ui changed
        let mut primitives = match self.ui.draw_if_changed() {
            Some(primitives) => primitives,
            None => return,
        };

        self.draw_commands.clear();
        let mut mesh = Mesh::new();

        // TODO: this could be removed entirely if the draw call just used both textures,
        //  however this allows for flexibility if we want to interweave other draw calls later.
        enum State {
            Image,
            Plain,
        };

        let mut current_state = State::Plain;
        let mut start = 0;

        let window_scissor = default_scissor(renderer);
        let mut current_scissor = window_scissor;

        // Switches to the `Plain` state and completes the previous `Command` if not already in the
        // `Plain` state.
        macro_rules! switch_to_plain_state {
            () => {
                if let State::Image = current_state {
                    self.draw_commands
                        .push(DrawCommand::image(start..mesh.vertices().len()));
                    current_state = State::Plain;
                    start = mesh.vertices().len();
                }
            };
        }

        let p_scale_factor = self.scale.scale_factor_physical();

        while let Some(prim) = primitives.next() {
            let Primitive {
                kind,
                scizzor,
                rect,
                ..
            } = prim;

            // Check for a change in the scissor.
            let new_scissor = {
                let (l, b, w, h) = scizzor.l_b_w_h();
                // Calculate minimum x and y coordinates while
                // flipping y axis (from +up to +down) and
                // moving origin to top-left corner (from middle).
                let min_x = self.ui.win_w / 2.0 + l;
                let min_y = self.ui.win_h / 2.0 - b - h;
                Aabr {
                    min: Vec2 {
                        x: (min_x * p_scale_factor) as u16,
                        y: (min_y * p_scale_factor) as u16,
                    },
                    max: Vec2 {
                        x: ((min_x + w) * p_scale_factor) as u16,
                        y: ((min_y + h) * p_scale_factor) as u16,
                    },
                }
                .intersection(window_scissor)
            };
            if new_scissor != current_scissor {
                // Finish the current command.
                self.draw_commands.push(match current_state {
                    State::Plain => DrawCommand::plain(start..mesh.vertices().len()),
                    State::Image => DrawCommand::image(start..mesh.vertices().len()),
                });
                start = mesh.vertices().len();

                // Update the scissor and produce a command.
                current_scissor = new_scissor;
                self.draw_commands.push(DrawCommand::Scissor(new_scissor));
            }

            // Functions for converting for conrod scalar coords to GL vertex coords (-1.0 to 1.0).
            let ui_win_w = self.ui.win_w;
            let ui_win_h = self.ui.win_h;
            let vx = |x: f64| (x / ui_win_w * 2.0) as f32;
            let vy = |y: f64| (y / ui_win_h * 2.0) as f32;
            let gl_aabr = |rect: conrod_core::Rect| {
                let (l, r, b, t) = rect.l_r_b_t();
                Aabr {
                    min: Vec2::new(vx(l), vy(b)),
                    max: Vec2::new(vx(r), vy(t)),
                }
            };

            use conrod_core::render::PrimitiveKind;
            match kind {
                PrimitiveKind::Image {
                    image_id,
                    color,
                    source_rect,
                } => {
                    let graphic_id = self
                        .image_map
                        .get(&image_id)
                        .expect("Image does not exist in image map");
                    let (graphic_cache, cache_tex) = self.cache.graphic_cache_mut_and_tex();

                    match graphic_cache.get_graphic(*graphic_id) {
                        Some(Graphic::Blank) | None => continue,
                        _ => {}
                    }

                    // Switch to the image state if we are not in it already.
                    if let State::Plain = current_state {
                        self.draw_commands
                            .push(DrawCommand::plain(start..mesh.vertices().len()));
                        start = mesh.vertices().len();
                        current_state = State::Image;
                    }

                    let color =
                        srgb_to_linear(color.unwrap_or(conrod_core::color::WHITE).to_fsa().into());

                    let resolution = Vec2::new(
                        (rect.w() * p_scale_factor).round() as u16,
                        (rect.h() * p_scale_factor).round() as u16,
                    );
                    // Transform the source rectangle into uv coordinate.
                    // TODO: Make sure this is right.
                    let source_aabr = {
                        let (uv_l, uv_r, uv_b, uv_t) = (0.0, 1.0, 0.0, 1.0); /*match source_rect {
                                                                                 Some(src_rect) => {
                                                                                     let (l, r, b, t) = src_rect.l_r_b_t();
                                                                                     ((l / image_w) as f32,
                                                                                     (r / image_w) as f32,
                                                                                     (b / image_h) as f32,
                                                                                     (t / image_h) as f32)
                                                                                 }
                                                                                 None => (0.0, 1.0, 0.0, 1.0),
                                                                             };*/
                        Aabr {
                            min: Vec2::new(uv_l, uv_b),
                            max: Vec2::new(uv_r, uv_t),
                        }
                    };
                    let (cache_w, cache_h) =
                        cache_tex.get_dimensions().map(|e| e as f32).into_tuple();

                    // Cache graphic at particular resolution.
                    let uv_aabr = match graphic_cache.cache_res(
                        *graphic_id,
                        resolution,
                        source_aabr,
                        |aabr, data| {
                            let offset = aabr.min.into_array();
                            let size = aabr.size().into_array();
                            renderer.update_texture(cache_tex, offset, size, data);
                        },
                    ) {
                        Some(aabr) => Aabr {
                            min: Vec2::new(
                                aabr.min.x as f32 / cache_w,
                                aabr.max.y as f32 / cache_h,
                            ),
                            max: Vec2::new(
                                aabr.max.x as f32 / cache_w,
                                aabr.min.y as f32 / cache_h,
                            ),
                        },
                        None => continue,
                    };

                    mesh.push_quad(create_ui_quad(gl_aabr(rect), uv_aabr, color, UiMode::Image));
                }
                PrimitiveKind::Text {
                    color,
                    text,
                    font_id,
                } => {
                    switch_to_plain_state!();
                    // Get screen width and height.
                    let (screen_w, screen_h) =
                        renderer.get_resolution().map(|e| e as f32).into_tuple();
                    // Calculate dpi factor.
                    let dpi_factor = screen_w / ui_win_w as f32;

                    let positioned_glyphs = text.positioned_glyphs(dpi_factor);
                    let (glyph_cache, cache_tex) = self.cache.glyph_cache_mut_and_tex();
                    // Queue the glyphs to be cached.
                    for glyph in positioned_glyphs {
                        glyph_cache.queue_glyph(font_id.index(), glyph.clone());
                    }

                    glyph_cache
                        .cache_queued(|rect, data| {
                            let offset = [rect.min.x as u16, rect.min.y as u16];
                            let size = [rect.width() as u16, rect.height() as u16];

                            let new_data = data
                                .iter()
                                .map(|x| [255, 255, 255, *x])
                                .collect::<Vec<[u8; 4]>>();

                            renderer.update_texture(cache_tex, offset, size, &new_data);
                        })
                        .unwrap();

                    let color = srgb_to_linear(color.to_fsa().into());

                    for g in positioned_glyphs {
                        if let Ok(Some((uv_rect, screen_rect))) =
                            glyph_cache.rect_for(font_id.index(), g)
                        {
                            let uv = Aabr {
                                min: Vec2::new(uv_rect.min.x, uv_rect.max.y),
                                max: Vec2::new(uv_rect.max.x, uv_rect.min.y),
                            };
                            let rect = Aabr {
                                min: Vec2::new(
                                    (screen_rect.min.x as f32 / screen_w - 0.5) * 2.0,
                                    (screen_rect.max.y as f32 / screen_h - 0.5) * -2.0,
                                ),
                                max: Vec2::new(
                                    (screen_rect.max.x as f32 / screen_w - 0.5) * 2.0,
                                    (screen_rect.min.y as f32 / screen_h - 0.5) * -2.0,
                                ),
                            };
                            mesh.push_quad(create_ui_quad(rect, uv, color, UiMode::Text));
                        }
                    }
                }
                PrimitiveKind::Rectangle { color } => {
                    let color = srgb_to_linear(color.to_fsa().into());
                    // Don't draw a transparent rectangle.
                    if color[3] == 0.0 {
                        continue;
                    }

                    switch_to_plain_state!();

                    mesh.push_quad(create_ui_quad(
                        gl_aabr(rect),
                        Aabr {
                            min: Vec2::new(0.0, 0.0),
                            max: Vec2::new(0.0, 0.0),
                        },
                        color,
                        UiMode::Geometry,
                    ));
                }
                PrimitiveKind::TrianglesSingleColor { color, triangles } => {
                    // Don't draw transparent triangle or switch state if there are actually no triangles.
                    let color = srgb_to_linear(Rgba::from(Into::<[f32; 4]>::into(color)));
                    if triangles.is_empty() || color[3] == 0.0 {
                        continue;
                    }

                    switch_to_plain_state!();

                    for tri in triangles {
                        let p1 = Vec2::new(vx(tri[0][0]), vy(tri[0][1]));
                        let p2 = Vec2::new(vx(tri[1][0]), vy(tri[1][1]));
                        let p3 = Vec2::new(vx(tri[2][0]), vy(tri[2][1]));
                        // If triangle is clockwise, reverse it.
                        let (v1, v2): (Vec3<f32>, Vec3<f32>) = ((p2 - p1).into(), (p3 - p1).into());
                        let triangle = if v1.cross(v2).z > 0.0 {
                            [p1.into_array(), p2.into_array(), p3.into_array()]
                        } else {
                            [p2.into_array(), p1.into_array(), p3.into_array()]
                        };
                        mesh.push_tri(create_ui_tri(
                            triangle,
                            [[0.0; 2]; 3],
                            color,
                            UiMode::Geometry,
                        ));
                    }
                }
                _ => {} // TODO: Add this.
                        //PrimitiveKind::TrianglesMultiColor {..} => {println!("primitive kind multicolor with id {:?}", id);}
                        // Other unneeded for now.
                        //PrimitiveKind::Other {..} => {println!("primitive kind other with id {:?}", id);}
            }
        }
        // Enter the final command.
        self.draw_commands.push(match current_state {
            State::Plain => DrawCommand::plain(start..mesh.vertices().len()),
            State::Image => DrawCommand::image(start..mesh.vertices().len()),
        });

        // Create a larger dynamic model if the mesh is larger than the current model size.
        if self.model.vbuf.len() < mesh.vertices().len() {
            self.model = renderer
                .create_dynamic_model(mesh.vertices().len() * 4 / 3)
                .unwrap();
        }
        renderer.update_model(&self.model, &mesh, 0).unwrap();
        // Update model with new mesh.

        // Handle window resizing.
        if let Some(new_dims) = self.window_resized.take() {
            self.scale.window_resized(new_dims, renderer);
            let (w, h) = self.scale.scaled_window_size().into_tuple();
            self.ui.handle_event(Input::Resize(w, h));

            let res = renderer.get_resolution();
            // Avoid panic in graphic cache when minimizing.
            if res.x > 0 && res.y > 0 {
                self.cache
                    .clear_graphic_cache(renderer, renderer.get_resolution().map(|e| e * 4));
            }
            // TODO: Probably need to resize glyph cache, see conrod's gfx backend for reference.
        }
    }

    pub fn render(&self, renderer: &mut Renderer) {
        let mut scissor_to_render = default_scissor(renderer);
        for draw_command in self.draw_commands.iter() {
            match draw_command {
                DrawCommand::Scissor(scissor) => {
                    scissor_to_render = *scissor;
                }
                DrawCommand::Draw { kind, verts } => {
                    let tex = match kind {
                        DrawKind::Image => self.cache.graphic_cache_tex(),
                        DrawKind::Plain => self.cache.glyph_cache_tex(),
                    };
                    let model = self.model.submodel(verts.clone());
                    renderer.render_ui_element(&model, &tex, scissor_to_render);
                }
            }
        }
    }
}

fn default_scissor(renderer: &mut Renderer) -> Aabr<u16> {
    let (screen_w, screen_h) = renderer.get_resolution().map(|e| e as u16).into_tuple();
    Aabr {
        min: Vec2 { x: 0, y: 0 },
        max: Vec2 {
            x: screen_w,
            y: screen_h,
        },
    }
}