//! `Textable` is a property to display text on an item

use super::writeable::ModifyText;
use crate::prelude::*;
use anyhow::Result;

use super::texturedvertex::TexturedVertex;

use std::{
    convert::TryFrom,
    sync::{
        atomic::{AtomicI32, AtomicU32, Ordering::SeqCst},
        Arc, RwLock,
    },
};

/// `TextAlignment` is used to describe where the text of `Textable` is aligned to
#[derive(Clone, Copy, Debug)]
pub enum TextAlignment {
    Left,
    Right,
    Top,
    Bottom,
    Center,
}

impl Default for TextAlignment {
    fn default() -> Self {
        Self::Center
    }
}

impl TryFrom<String> for TextAlignment {
    type Error = anyhow::Error;

    fn try_from(text: String) -> Result<TextAlignment> {
        Ok(match text.as_str() {
            "left" => Self::Left,
            "right" => Self::Right,
            "top" => Self::Top,
            "bottom" => Self::Bottom,
            "center" => Self::Center,

            _ => {
                return Err(anyhow::Error::msg(format!(
                    "Failed parsing TextAlignment from: {}",
                    text
                )))
            }
        })
    }
}

/// `Textable` gives the ability to display text inside an item
pub struct Textable {
    framable: Arc<Framable>,

    text_alignment: RwLock<TextAlignment>,
    text: RwLock<String>,
    vertex_count: AtomicU32,
    height_ratio: RwLock<f32>,
    character_size: AtomicU32,

    descriptor_set: RwLock<Arc<DescriptorSet>>,

    buffer: Arc<RwLock<Option<Arc<Buffer<TexturedVertex>>>>>,

    ui_layer: AtomicI32,
}

impl Textable {
    /// Factory method for `Textable`, returns `Arc<Textable>`.
    ///
    /// # Arguments
    ///
    /// * `framable` is a `Arc<Framable>` instance
    /// * `text` the text to be displayed
    /// * `height_ratio` the ratio of the height in respect to the framable height
    /// * `text_alignment` where the text is aligned to
    pub fn new(
        framable: Arc<Framable>,
        text: String,
        height_ratio: f32,
        text_alignment: TextAlignment,
        text_color: Color,
    ) -> Result<Arc<Self>> {
        let set = framable.gui_handler().color_descriptor(text_color)?;

        let buffer = if text.is_empty() {
            None
        } else {
            Some(Self::create_text_buffer(
                framable.gui_handler().device(),
                text.len() as u32 * 6,
            )?)
        };

        let textable = Arc::new(Textable {
            vertex_count: AtomicU32::new(text.len() as u32 * 6),
            text_alignment: RwLock::new(text_alignment),
            text: RwLock::new(text),
            height_ratio: RwLock::new(height_ratio),
            character_size: AtomicU32::new(
                ((framable.bottom() as i32 - framable.top()) as f32 * height_ratio) as u32,
            ),

            framable,

            descriptor_set: RwLock::new(set),

            buffer: Arc::new(RwLock::new(buffer)),

            ui_layer: AtomicI32::new(0),
        });

        let textable_clone = textable.clone();
        let weak_textable = Arc::downgrade(&textable);

        textable.framable.add_callback(
            weak_textable,
            Box::new(move || textable_clone.update_text()),
        );

        Ok(textable)
    }

    fn create_text_buffer(
        device: &Arc<Device>,
        letter_count: u32,
    ) -> Result<Arc<Buffer<TexturedVertex>>> {
        Buffer::builder()
            .set_usage(VK_BUFFER_USAGE_VERTEX_BUFFER_BIT)
            .set_memory_usage(MemoryUsage::CpuOnly)
            .set_size(letter_count as VkDeviceSize)
            .build(device.clone())
    }

    /// Add method
    ///
    /// # Arguments
    ///
    /// * `textable` is a `&Arc<Textable>` instance that is going to be added
    pub fn add(self: &Arc<Self>) -> Result<()> {
        self.framable
            .gui_handler()
            .add_textable(self.ui_layer.load(SeqCst), self.clone())
    }

    /// Delete method, has to be explicitly called, otherwise it will remain in memory.
    ///
    /// # Arguments
    ///
    /// * `textable` is a `&Arc<Textable>` instance that is going to be deleted
    pub fn delete(self: &Arc<Self>) -> Result<()> {
        self.framable
            .gui_handler()
            .delete_textable(self.ui_layer.load(SeqCst), self)
    }

    pub fn set_ui_layer(&self, ui_layer: i32) {
        self.ui_layer.store(ui_layer, SeqCst);
    }

    pub fn clear_callback(self: &Arc<Self>) {
        let weak_textable = Arc::downgrade(self);
        self.framable.remove_callback(weak_textable);
    }

    /// Changes text color
    ///
    /// # Arguments
    ///
    /// * `text_color` defines the color of the text
    pub fn set_text_color(&self, text_color: Color) -> Result<()> {
        let set = self.framable.gui_handler().color_descriptor(text_color)?;

        *self.descriptor_set.write().unwrap() = set;

        Ok(())
    }

    /// Sets the text alignment
    ///
    /// # Arguments
    ///
    /// * `text_alignment` where the text is aligned to
    pub fn set_text_alignment(&self, text_alignment: TextAlignment) -> Result<()> {
        *self.text_alignment.write().unwrap() = text_alignment;
        self.update_text()?;

        Ok(())
    }

    /// Returns the count of vertices described by the buffer
    pub fn vertex_count(&self) -> u32 {
        self.vertex_count.load(SeqCst)
    }

    /// Returns the internal vulkan buffer
    pub fn buffer(&self) -> Option<Arc<Buffer<TexturedVertex>>> {
        self.buffer.read().unwrap().clone()
    }

    /// Returns the internal vulkan descriptor set
    pub fn descriptor_set(&self) -> Arc<DescriptorSet> {
        self.descriptor_set.read().unwrap().clone()
    }

    /// Sets the text with height ratio
    ///
    /// # Arguments
    ///
    /// * `text` the text to be displayed
    /// * `height_ratio` the ratio of the height in respect to the framable height
    pub fn set_text(&self, text: impl ToString) -> Result<()> {
        let text = text.to_string();

        if text.is_empty() {
            self.vertex_count.store(0, SeqCst);
            *self.text.write().unwrap() = String::new();

            self.framable.gui_handler().enqueue_text_update({
                let weak_buffer = Arc::downgrade(&self.buffer);

                Box::new(move || {
                    if let Some(buffer) = weak_buffer.upgrade() {
                        *buffer.write().unwrap() = None;
                    }
                    Ok(())
                })
            });
        } else {
            self.vertex_count.store(text.len() as u32 * 6, SeqCst);
            *self.text.write().unwrap() = text;
            self.update_text()?;
        }

        Ok(())
    }

    /// Sets the text size with the given height ratio
    ///
    /// # Arguments
    ///
    /// * `height_ratio` the ratio of the height in respect to the framable height
    pub fn set_size(&self, height_ratio: f32) -> Result<()> {
        *self.height_ratio.write().unwrap() = height_ratio;
        self.update_text()?;

        Ok(())
    }

    /// Returns the text
    pub fn text(&self) -> String {
        self.text.read().unwrap().clone()
    }

    fn calculate_text_size(&self) {
        self.character_size.store(
            ((self.framable.bottom() as i32 - self.framable.top()) as f32
                * *self.height_ratio.read().unwrap()) as u32,
            SeqCst,
        );

        let width = self.framable.right() as i32 - self.framable.left();
        let text_len = self.text.read().unwrap().len();

        let text_width = (self.character_size.load(SeqCst) as f32 * 0.5 * text_len as f32) as u32;

        if text_width > width as u32 {
            self.character_size.store(
                ((self.framable.right() as i32 - self.framable.left()) / text_len as i32) as u32
                    * 2,
                SeqCst,
            );
        }
    }

    /// Updates the texts buffer
    pub fn update_text(&self) -> Result<()> {
        self.calculate_text_size();

        let (x, y) = self.calc_pos_from_alignment();

        self.create_buffer(x, y)?;

        Ok(())
    }

    fn center_y(&self) -> f32 {
        (self.framable.top() + self.framable.bottom()) as f32 * 0.5
            - self.character_size.load(SeqCst) as f32 * 0.5
    }

    fn center_x(&self) -> f32 {
        (self.framable.left() + self.framable.right()) as f32 * 0.5
            - (self.character_size.load(SeqCst) as f32
                * 0.25
                * self.text.read().unwrap().len() as f32)
    }

    fn calc_pos_from_alignment(&self) -> (f32, f32) {
        match *self.text_alignment.read().unwrap() {
            TextAlignment::Left => (self.framable.left() as f32, self.center_y()),
            TextAlignment::Right => (
                self.framable.right() as f32
                    - (self.character_size.load(SeqCst) as f32
                        * 0.5
                        * self.text.read().unwrap().len() as f32),
                self.center_y(),
            ),
            TextAlignment::Top => (self.center_x(), self.framable.top() as f32),
            TextAlignment::Bottom => (
                self.center_x(),
                (self.framable.bottom() - self.character_size.load(SeqCst) as i32) as f32,
            ),
            TextAlignment::Center => (self.center_x(), self.center_y()),
        }
    }

    fn create_buffer(&self, win_x: f32, win_y: f32) -> Result<()> {
        let weak_buffer = Arc::downgrade(&self.buffer);
        let text = self.text.read().unwrap().clone();
        let character_size = self.character_size.load(SeqCst);
        let ortho = self.framable.ortho();

        let device = self.framable.gui_handler().device().clone();

        let async_buffer_creation = Box::new(move || {
            if let Some(buffer) = weak_buffer.upgrade() {
                let mut offset = 0.0;

                // variable to calculate letter position in bitmap font
                let letters_in_row = 16;
                let inverse_row = 0.0625;
                let inverse_col = 0.125;

                let letter_height = character_size as f32;
                let letter_width = letter_height * 0.5;

                let priority = 0.0;

                let mut buffer = buffer.write().unwrap();

                let text_buffer_len = text.len() as u32 * 6;

                match buffer.as_mut() {
                    Some(buf) => {
                        if buf.size() != text_buffer_len as VkDeviceSize {
                            *buffer = if text.is_empty() {
                                None
                            } else {
                                Some(Self::create_text_buffer(&device, text_buffer_len)?)
                            }
                        }
                    }
                    None => {
                        if !text.is_empty() {
                            *buffer = Some(Self::create_text_buffer(&device, text_buffer_len)?)
                        }
                    }
                }

                if let Some(buffer) = buffer.as_ref() {
                    let mut buffer_mapping = buffer.map_complete()?;

                    let mut i = 0;

                    for letter in text.chars() {
                        let mod_number = if letter as u32 >= 32 {
                            letter as u32 - 32
                        } else {
                            0
                        };

                        // coordinates to describe letter position in bitmap font
                        let y = ((mod_number as f32) * inverse_row).floor();
                        let x = (mod_number - (y as u32 * letters_in_row)) as f32;

                        buffer_mapping[i] = TexturedVertex {
                            position: ortho
                                * cgmath::Vector4::new(
                                    win_x + offset,
                                    win_y + letter_height,
                                    priority,
                                    1.0,
                                ),
                            texture_coordinates: cgmath::Vector2::new(
                                inverse_row * x,
                                inverse_col + inverse_col * y,
                            ),
                        };

                        i += 1;

                        buffer_mapping[i] = TexturedVertex {
                            position: ortho
                                * cgmath::Vector4::new(
                                    win_x + offset + letter_width,
                                    win_y + letter_height,
                                    priority,
                                    1.0,
                                ),
                            texture_coordinates: cgmath::Vector2::new(
                                inverse_row + inverse_row * x,
                                inverse_col + inverse_col * y,
                            ),
                        };

                        i += 1;

                        buffer_mapping[i] = TexturedVertex {
                            position: ortho
                                * cgmath::Vector4::new(
                                    win_x + offset + letter_width,
                                    win_y,
                                    priority,
                                    1.0,
                                ),
                            texture_coordinates: cgmath::Vector2::new(
                                inverse_row + inverse_row * x,
                                inverse_col * y,
                            ),
                        };

                        i += 1;

                        buffer_mapping[i] = TexturedVertex {
                            position: ortho
                                * cgmath::Vector4::new(
                                    win_x + offset + letter_width,
                                    win_y,
                                    priority,
                                    1.0,
                                ),
                            texture_coordinates: cgmath::Vector2::new(
                                inverse_row + inverse_row * x,
                                inverse_col * y,
                            ),
                        };

                        i += 1;

                        buffer_mapping[i] = TexturedVertex {
                            position: ortho
                                * cgmath::Vector4::new(win_x + offset, win_y, priority, 1.0),
                            texture_coordinates: cgmath::Vector2::new(
                                inverse_row * x,
                                inverse_col * y,
                            ),
                        };

                        i += 1;

                        buffer_mapping[i] = TexturedVertex {
                            position: ortho
                                * cgmath::Vector4::new(
                                    win_x + offset,
                                    win_y + letter_height,
                                    priority,
                                    1.0,
                                ),
                            texture_coordinates: cgmath::Vector2::new(
                                inverse_row * x,
                                inverse_col + inverse_col * y,
                            ),
                        };

                        i += 1;

                        offset += letter_width;
                    }
                }
            }

            Ok(())
        });

        self.framable
            .gui_handler()
            .enqueue_text_update(async_buffer_creation);

        Ok(())
    }

    fn text_changed_through_write(&self) -> Result<()> {
        self.vertex_count
            .store(self.text.read().unwrap().len() as u32 * 6, SeqCst);
        self.character_size.store(
            ((self.framable.bottom() as i32 - self.framable.top()) as f32
                * *self.height_ratio.read().unwrap()) as u32,
            SeqCst,
        );

        self.update_text()?;

        Ok(())
    }
}

impl ModifyText for Textable {
    fn set_text(&self, text: String) -> Result<()> {
        *self.text.write().unwrap() = text;
        self.text_changed_through_write()
    }

    fn add_letter(&self, letter: char) -> Result<String> {
        self.text.write().unwrap().push(letter);
        self.text_changed_through_write()?;

        Ok(self.text.read().unwrap().clone())
    }

    fn remove_last(&self) -> Result<Option<String>> {
        self.text.write().unwrap().pop();
        self.text_changed_through_write()?;

        let text = self.text.read().unwrap().clone();

        if text.is_empty() {
            Ok(None)
        } else {
            Ok(Some(text))
        }
    }
}