use crate::prelude::*;
use cosmic_text::{Attrs, Family, Metrics};
use std::marker::Sized;

pub struct TextBuilder<O = TextOutput, H: WidgetOption = ()> {
    pub content: String,
    pub attrs: TextAttrs,
    pub hint: H,
    pub output: O,
}

impl<O, H: WidgetOption> TextBuilder<O, H> {
    pub fn size(mut self, size: impl UiNum) -> Self {
        self.attrs.font_size = size.to_f32();
        self.attrs.line_height = self.attrs.font_size * LINE_HEIGHT_MULT;
        self
    }
    pub fn color(mut self, color: UiColor) -> Self {
        self.attrs.color = color;
        self
    }
    pub fn family(mut self, family: Family<'static>) -> Self {
        self.attrs.family = family;
        self
    }
    pub fn line_height(mut self, height: f32) -> Self {
        self.attrs.line_height = height;
        self
    }
    pub fn text_align(mut self, align: impl Into<RegionAlign>) -> Self {
        self.attrs.align = align.into();
        self
    }
    pub fn center_text(mut self) -> Self {
        self.attrs.align = Align::CENTER;
        self
    }
    pub fn wrap(mut self, wrap: bool) -> Self {
        self.attrs.wrap = wrap;
        self
    }
    pub fn editable(self, single_line: bool) -> TextBuilder<TextEditOutput, H> {
        TextBuilder {
            content: self.content,
            attrs: self.attrs,
            hint: self.hint,
            output: TextEditOutput { single_line },
        }
    }
}

impl<O> TextBuilder<O> {
    pub fn hint<W: WidgetLike<Tag>, Tag>(self, hint: W) -> TextBuilder<O, impl WidgetOption> {
        TextBuilder {
            content: self.content,
            attrs: self.attrs,
            hint: move |ui: &mut Ui| Some(hint.add(ui).any()),
            output: self.output,
        }
    }
}

pub trait TextBuilderOutput: Sized {
    type Output;
    fn run<H: WidgetOption>(ui: &mut Ui, builder: TextBuilder<Self, H>) -> Self::Output;
}

pub struct TextOutput;
impl TextBuilderOutput for TextOutput {
    type Output = Text;

    fn run<H: WidgetOption>(ui: &mut Ui, builder: TextBuilder<Self, H>) -> Self::Output {
        let mut buf = TextBuffer::new_empty(Metrics::new(
            builder.attrs.font_size,
            builder.attrs.line_height,
        ));
        let hint = builder.hint.get(ui);
        let font_system = &mut ui.data.text.font_system;
        buf.set_text(font_system, &builder.content, &Attrs::new(), SHAPING, None);
        let mut text = Text {
            content: builder.content.into(),
            view: TextView::new(buf, builder.attrs, hint),
        };
        text.content.changed = false;
        builder.attrs.apply(font_system, &mut text.view.buf, None);
        text
    }
}

pub struct TextEditOutput {
    single_line: bool,
}
impl TextBuilderOutput for TextEditOutput {
    type Output = TextEdit;

    fn run<H: WidgetOption>(ui: &mut Ui, builder: TextBuilder<Self, H>) -> Self::Output {
        let buf = TextBuffer::new_empty(Metrics::new(
            builder.attrs.font_size,
            builder.attrs.line_height,
        ));
        let mut text = TextEdit::new(
            TextView::new(buf, builder.attrs, builder.hint.get(ui)),
            builder.output.single_line,
        );
        let font_system = &mut ui.data.text.font_system;
        text.buf
            .set_text(font_system, &builder.content, &Attrs::new(), SHAPING, None);
        builder.attrs.apply(font_system, &mut text.buf, None);
        text
    }
}

impl<O: TextBuilderOutput, H: WidgetOption> FnOnce<(&mut Ui,)> for TextBuilder<O, H> {
    type Output = O::Output;

    extern "rust-call" fn call_once(self, args: (&mut Ui,)) -> Self::Output {
        O::run(args.0, self)
    }
}

pub fn wtext(content: impl Into<String>) -> TextBuilder {
    TextBuilder {
        content: content.into(),
        attrs: TextAttrs::default(),
        hint: (),
        output: TextOutput,
    }
}