mod build;
mod edit;

pub use build::*;
pub use edit::*;
use iris_core::util::MutDetect;

use crate::prelude::*;
use cosmic_text::{Attrs, BufferLine, Cursor, Metrics, Shaping};
use std::ops::{Deref, DerefMut};

pub const SHAPING: Shaping = Shaping::Advanced;

pub struct Text {
    pub content: MutDetect<String>,
    view: TextView,
}

pub struct TextView {
    pub attrs: MutDetect<TextAttrs>,
    pub buf: MutDetect<TextBuffer>,
    // cache
    tex: Option<RenderedText>,
    width: Option<f32>,
    pub hint: Option<WidgetHandle>,
}

impl TextView {
    pub fn new(buf: TextBuffer, attrs: TextAttrs, hint: Option<WidgetHandle>) -> Self {
        Self {
            attrs: attrs.into(),
            buf: buf.into(),
            tex: None,
            width: None,
            hint,
        }
    }

    /// region where the text should be draw
    /// does not include extra height or width from weird unicode
    pub fn region(&self) -> UiRegion {
        self.tex()
            .map(|t| t.size)
            .unwrap_or(Vec2::ZERO)
            .align(self.align)
    }

    fn tex_region(&self, tex: &RenderedText) -> UiRegion {
        let region = tex.size.align(self.align);
        let dims = tex.handle.size();
        let mut region = region.offset(tex.top_left_offset);
        region.x.end = region.x.start + UiScalar::abs(dims.x);
        region.y.end = region.y.start + UiScalar::abs(dims.y);
        region
    }

    fn render(&mut self, ctx: &mut SizeCtx) -> RenderedText {
        let width = if self.attrs.wrap {
            Some(ctx.px_size().x)
        } else {
            None
        };
        if width == self.width
            && let Some(tex) = &self.tex
            && !self.attrs.changed
            && !self.buf.changed
        {
            return tex.clone();
        }
        self.width = width;
        let font_system = &mut ctx.text.font_system;
        self.attrs.apply(font_system, &mut self.buf, width);
        self.buf.shape_until_scroll(font_system, false);
        let tex = ctx.draw_text(&mut self.buf, &self.attrs);
        self.tex = Some(tex.clone());
        self.attrs.changed = false;
        self.buf.changed = false;
        tex
    }
    pub fn tex(&self) -> Option<&RenderedText> {
        self.tex.as_ref()
    }
    pub fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len {
        if let Some(hint) = &self.hint
            && let [line] = &self.buf.lines[..]
            && line.text().is_empty()
        {
            ctx.width(hint)
        } else {
            Len::abs(self.render(ctx).size.x)
        }
    }
    pub fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len {
        if let Some(hint) = &self.hint
            && let [line] = &self.buf.lines[..]
            && line.text().is_empty()
        {
            ctx.height(hint)
        } else {
            Len::abs(self.render(ctx).size.y)
        }
    }
    pub fn draw(&mut self, painter: &mut Painter) -> UiRegion {
        let tex = self.render(&mut painter.size_ctx());
        let region = self.tex_region(&tex);
        if let Some(hint) = &self.hint
            && let [line] = &self.buf.lines[..]
            && line.text().is_empty()
        {
            painter.widget(hint);
        } else {
            painter.texture_within(&tex.handle, region);
        }
        region
    }

    pub fn content(&self) -> String {
        self.buf
            .lines
            .iter()
            .map(|l| l.text())
            .collect::<Vec<_>>()
            .join("\n")
    }
}

impl Text {
    pub fn new(content: impl Into<String>) -> Self {
        let attrs = TextAttrs::default();
        let buf = TextBuffer::new_empty(Metrics::new(attrs.font_size, attrs.line_height));
        Self {
            content: content.into().into(),
            view: TextView::new(buf, attrs, None),
        }
    }
    fn update_buf(&mut self, ctx: &mut SizeCtx) {
        if self.content.changed {
            self.content.changed = false;
            self.view.buf.set_text(
                &mut ctx.text.font_system,
                &self.content,
                &Attrs::new().family(self.view.attrs.family),
                SHAPING,
                None,
            );
        }
    }
}

impl Widget for Text {
    fn draw(&mut self, painter: &mut Painter) {
        self.update_buf(&mut painter.size_ctx());
        self.view.draw(painter);
    }

    fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len {
        self.update_buf(ctx);
        self.view.desired_width(ctx)
    }

    fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len {
        self.update_buf(ctx);
        self.view.desired_height(ctx)
    }
}

pub fn sort_cursors(a: Cursor, b: Cursor) -> (Cursor, Cursor) {
    let start = a.min(b);
    let end = a.max(b);
    (start, end)
}

pub fn edit_line(line: &mut BufferLine, text: String) {
    line.set_text(text, line.ending(), line.attrs_list().clone());
}

impl Deref for Text {
    type Target = TextAttrs;

    fn deref(&self) -> &Self::Target {
        &self.view
    }
}

impl DerefMut for Text {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.view
    }
}

impl Deref for TextView {
    type Target = TextAttrs;

    fn deref(&self) -> &Self::Target {
        &self.attrs
    }
}

impl DerefMut for TextView {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.attrs
    }
}