use crate::{
    AnyElement, BorrowWindow, Bounds, Component, Element, LayoutId, Line, Pixels, SharedString,
    Size, ViewContext,
};
use parking_lot::Mutex;
use smallvec::SmallVec;
use std::{marker::PhantomData, sync::Arc};
use util::ResultExt;

impl<V: 'static> Component<V> for SharedString {
    fn render(self) -> AnyElement<V> {
        Text {
            text: self,
            state_type: PhantomData,
        }
        .render()
    }
}

impl<V: 'static> Component<V> for &'static str {
    fn render(self) -> AnyElement<V> {
        Text {
            text: self.into(),
            state_type: PhantomData,
        }
        .render()
    }
}

// TODO: Figure out how to pass `String` to `child` without this.
// This impl doesn't exist in the `gpui2` crate.
impl<V: 'static> Component<V> for String {
    fn render(self) -> AnyElement<V> {
        Text {
            text: self.into(),
            state_type: PhantomData,
        }
        .render()
    }
}

pub struct Text<V> {
    text: SharedString,
    state_type: PhantomData<V>,
}

impl<V: 'static> Component<V> for Text<V> {
    fn render(self) -> AnyElement<V> {
        AnyElement::new(self)
    }
}

impl<V: 'static> Element<V> for Text<V> {
    type ElementState = Arc<Mutex<Option<TextElementState>>>;

    fn id(&self) -> Option<crate::ElementId> {
        None
    }

    fn initialize(
        &mut self,
        _view_state: &mut V,
        element_state: Option<Self::ElementState>,
        _cx: &mut ViewContext<V>,
    ) -> Self::ElementState {
        element_state.unwrap_or_default()
    }

    fn layout(
        &mut self,
        _view: &mut V,
        element_state: &mut Self::ElementState,
        cx: &mut ViewContext<V>,
    ) -> LayoutId {
        let text_system = cx.text_system().clone();
        let text_style = cx.text_style();
        let font_size = text_style.font_size * cx.rem_size();
        let line_height = text_style
            .line_height
            .to_pixels(font_size.into(), cx.rem_size());
        let text = self.text.clone();

        let rem_size = cx.rem_size();
        let layout_id = cx.request_measured_layout(Default::default(), rem_size, {
            let element_state = element_state.clone();
            move |known_dimensions, _| {
                let Some(lines) = text_system
                    .layout_text(
                        &text,
                        font_size,
                        &[text_style.to_run(text.len())],
                        known_dimensions.width, // Wrap if we know the width.
                    )
                    .log_err()
                else {
                    return Size::default();
                };

                let line_count = lines
                    .iter()
                    .map(|line| line.wrap_count() + 1)
                    .sum::<usize>();
                let size = Size {
                    width: lines.iter().map(|line| line.layout.width).max().unwrap(),
                    height: line_height * line_count,
                };

                element_state
                    .lock()
                    .replace(TextElementState { lines, line_height });

                size
            }
        });

        layout_id
    }

    fn paint(
        &mut self,
        bounds: Bounds<Pixels>,
        _: &mut V,
        element_state: &mut Self::ElementState,
        cx: &mut ViewContext<V>,
    ) {
        let element_state = element_state.lock();
        let element_state = element_state
            .as_ref()
            .expect("measurement has not been performed");

        let line_height = element_state.line_height;
        let mut line_origin = bounds.origin;
        for line in &element_state.lines {
            line.paint(line_origin, line_height, cx).log_err();
            line_origin.y += line.size(line_height).height;
        }
    }
}

pub struct TextElementState {
    lines: SmallVec<[Line; 1]>,
    line_height: Pixels,
}