mod build;
mod edit;
mod selection;

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

use crate::prelude::*;
use std::ops::{Deref, DerefMut};

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

pub struct TextView {
    pub attrs: MutDetect<TextAttrs>,
    pub buf: MutDetect<TextBuffer>,
    tex: Option<RenderedText>,
    width: Option<f32>,
    pub hint: Option<StrongWidget>,
    selection: TextSelection,
}

impl TextView {
    fn is_blank(&self) -> bool {
        self.buf.is_empty()
    }

    pub fn wrap_width(&self) -> Option<f32> {
        self.width
    }

    pub fn new(buf: TextBuffer, attrs: TextAttrs, hint: Option<StrongWidget>) -> Self {
        Self {
            attrs: attrs.into(),
            buf: buf.into(),
            tex: None,
            width: None,
            hint,
            selection: TextSelection::default(),
        }
    }

    pub fn region(&self) -> UiRegion {
        self.tex()
            .map(|t| t.size)
            .unwrap_or(Vec2::ZERO)
            .align(self.align)
    }

    fn render(&mut self, painter: &mut Painter) -> RenderedText {
        let width = if self.attrs.wrap {
            Some(painter.px_size().x)
        } else {
            None
        };
        let generation = painter.atlas_generation();
        if width == self.width
            && let Some(tex) = &self.tex
            && tex.generation == generation
            && !self.attrs.changed
            && !self.buf.changed
        {
            return tex.clone();
        }
        self.width = width;
        let tex = painter.render_text(&mut self.buf, &self.attrs, width);
        if crate::diagnostics::trace_enabled() {
            log::debug!(
                target: "iris::frame",
                "iris text render: chars={} width={width:?} glyphs={} size={:?}",
                self.buf.text().chars().count(),
                tex.glyphs.len(),
                tex.size,
            );
        }
        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 draw(&mut self, painter: &mut Painter) -> Size {
        let tex = self.render(painter);
        if self.is_blank()
            && let Some(hint) = &self.hint
        {
            return painter.widget(hint).size();
        }
        let region = tex.size.align(self.align);
        let within = region.within(&painter.region());
        painter.glyphs(&tex, within);
        Size::abs(tex.size)
    }

    pub(super) fn draw_selectable(&mut self, painter: &mut Painter, caret: bool) -> Size {
        let base = painter.layer;
        painter.child_layer();
        let used = self.draw(painter);
        painter.layer = base;
        let region = self.region();

        let Some(selection) = self.selection.range else {
            return used;
        };
        let layout = self.buf.layout();
        for (rect, _) in selection.geometry(layout) {
            let size = vec2(rect.width() as f32, rect.height() as f32);
            let top_left = vec2(rect.x0 as f32, rect.y0 as f32);
            let paint = painter.paint(&PaintId::SKY);
            painter.primitive_within(
                RectPrimitive::color(paint),
                size.align(Align::TOP_LEFT).offset(top_left).within(&region),
            );
        }
        if caret {
            let caret = selection.focus().geometry(layout, CARET_WIDTH);
            let size = vec2(caret.width() as f32, caret.height() as f32);
            let top_left = vec2(caret.x0 as f32, caret.y0 as f32);
            let paint = painter.paint(&PaintId::WHITE);
            painter.primitive_within(
                RectPrimitive::color(paint),
                size.align(Align::TOP_LEFT).offset(top_left).within(&region),
            );
        }
        used
    }

    pub fn content(&self) -> String {
        self.buf.text().to_string()
    }
}

impl Text {
    pub fn new(content: impl Into<String>) -> Self {
        let content: String = content.into();
        Self {
            view: TextView::new(TextBuffer::new(&content), TextAttrs::default(), None),
            content: content.into(),
        }
    }
    fn update_buf(&mut self) {
        if self.content.changed {
            self.content.changed = false;
            self.view.buf.set_text(self.content.as_str());
            self.view.selection.deselect();
        }
    }

    pub fn selected_text(&self) -> Option<String> {
        self.view.selection.selected_text(self.view.buf.text())
    }

    pub fn selection_range(&self) -> Option<std::ops::Range<usize>> {
        self.view.selection.range()
    }

    pub fn set_with_spans(&mut self, content: impl Into<String>, spans: Vec<SpanStyle>) {
        let content = content.into();
        *self.content = content.clone();
        self.content.changed = false;
        self.view.buf.set_text(content);
        self.view.buf.set_spans(spans);
        self.view.selection.deselect();
    }
}

impl Widget for Text {
    fn draw(&mut self, painter: &mut Painter) {
        self.update_buf();
        let size = if self.view.selection.range.is_some() {
            self.view.draw_selectable(painter, false)
        } else {
            self.view.draw(painter)
        };
        painter.set_size(size);
    }

    fn requires_exact_region(&self) -> bool {
        true
    }
}

pub(super) const CARET_WIDTH: f32 = 1.0;

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
    }
}

#[cfg(test)]
mod tests {
    use crate::layout_tests::TestRsc;
    use crate::prelude::*;

    fn rendered_text(content: &str) -> (TestRsc, UiRenderState, WeakWidget<Text>, StrongWidget) {
        let mut rsc = TestRsc {
            ui: UiData::default(),
        };
        let text = wtext(content).add_strong(&mut rsc);
        let id = text.weak();
        let root = text.any();
        let mut render = UiRenderState::new();
        render.resize((800.0, 600.0));
        render.update(&root, &mut rsc);
        (rsc, render, id, root)
    }

    #[test]
    fn display_text_and_edit_text_use_the_same_selection_engine() {
        let (mut rsc, _render, text, _root) = rendered_text("hello there");
        text.selection(&mut rsc).select_all();

        let view = TextView::new(TextBuffer::new("hello there"), TextAttrs::default(), None);
        let mut edit = TextEdit::new(view, EditMode::MultiLine);
        let mut data = TextData::default();
        TextEditCtx {
            text: &mut edit,
            data: &mut data,
        }
        .select_all();

        assert_eq!(
            rsc.ui.widgets[text].selection_range(),
            edit.selection_range()
        );
        assert_eq!(rsc.ui.widgets[text].selected_text(), edit.selected_text());
    }

    #[test]
    fn changing_display_text_clears_its_now_stale_selection() {
        let (mut rsc, mut render, text, root) = rendered_text("before");
        text.selection(&mut rsc).select_all();
        assert_eq!(
            rsc.ui.widgets[text].selected_text().as_deref(),
            Some("before")
        );

        *rsc.ui.widgets[text].content = "after".to_string();
        render.update(&root, &mut rsc);

        assert_eq!(rsc.ui.widgets[text].selected_text(), None);
        assert_eq!(rsc.ui.widgets[text].selection_range(), None);
    }

    #[test]
    fn display_text_draws_the_shared_highlight_without_an_editing_caret() {
        let (mut rsc, mut render, text, root) = rendered_text("selected");
        let plain = render.active[&text.id()].primitives.len();
        text.selection(&mut rsc).select_all();
        render.update(&root, &mut rsc);
        let selected = render.active[&text.id()].primitives.len();

        let view = TextView::new(TextBuffer::new("selected"), TextAttrs::default(), None);
        let edit = rsc
            .ui
            .widgets
            .add_strong(TextEdit::new(view, EditMode::MultiLine));
        let edit_id = edit.weak();
        let edit_root = edit.any();
        let mut edit_render = UiRenderState::new();
        edit_render.resize((800.0, 600.0));
        edit_render.update(&edit_root, &mut rsc);
        edit_id.edit(&mut rsc).select_all();
        edit_render.update(&edit_root, &mut rsc);
        let editable = edit_render.active[&edit_id.id()].primitives.len();

        assert!(
            selected > plain,
            "the selection added no highlight primitive"
        );
        assert_eq!(
            editable,
            selected + 1,
            "editable text should add exactly its caret to the shared highlight"
        );
    }

    #[test]
    fn clearing_the_atlas_re_renders_cached_text_instead_of_reusing_it() {
        let mut rsc = TestRsc {
            ui: UiData::default(),
        };
        let root = wtext("hello there")
            .size(18)
            .color(PaintId::WHITE)
            .add_strong(&mut rsc)
            .any();
        let mut render = UiRenderState::new();
        render.resize((800.0, 600.0));
        render.update(&root, &mut rsc);

        let rasterised = rsc.ui.text.atlas.glyph_count();
        assert!(rasterised > 0, "the first frame rasterised no glyphs");

        rsc.ui.text.atlas.clear();
        assert_eq!(rsc.ui.text.atlas.glyph_count(), 0);
        render.resize((800.0, 600.0));
        render.update(&root, &mut rsc);

        assert_eq!(
            rsc.ui.text.atlas.glyph_count(),
            rasterised,
            "the second frame re-emitted its cached glyphs instead of \
             re-rendering them against the fresh atlas"
        );
    }
}