#![allow(missing_docs)]
use crate::runtime::futures;
use iced_program as program;
use iced_widget::core;
use iced_widget::runtime;

use crate::core::Element;
use crate::core::theme;
use crate::core::window;
use crate::futures::Subscription;
use crate::program::Program;
use crate::runtime::Task;

use std::fmt;

pub fn attach(program: impl Program + 'static) -> impl Program {
    struct Attach<P> {
        program: P,
    }

    impl<P> Program for Attach<P>
    where
        P: Program + 'static,
    {
        type State = DevTools<P>;
        type Message = Message<P>;
        type Theme = P::Theme;
        type Renderer = P::Renderer;
        type Executor = P::Executor;

        fn name() -> &'static str {
            P::name()
        }

        fn boot(&self) -> (Self::State, Task<Self::Message>) {
            let (state, task) = self.program.boot();

            (DevTools { state }, task.map(Message::Program))
        }

        fn update(
            &self,
            state: &mut Self::State,
            message: Self::Message,
        ) -> Task<Self::Message> {
            state.update(&self.program, message)
        }

        fn view<'a>(
            &self,
            state: &'a Self::State,
            window: window::Id,
        ) -> Element<'a, Self::Message, Self::Theme, Self::Renderer> {
            state.view(&self.program, window)
        }

        fn title(&self, state: &Self::State, window: window::Id) -> String {
            state.title(&self.program, window)
        }

        fn subscription(
            &self,
            state: &Self::State,
        ) -> runtime::futures::Subscription<Self::Message> {
            state.subscription(&self.program)
        }

        fn theme(
            &self,
            state: &Self::State,
            window: window::Id,
        ) -> Self::Theme {
            state.theme(&self.program, window)
        }

        fn style(
            &self,
            state: &Self::State,
            theme: &Self::Theme,
        ) -> theme::Style {
            state.style(&self.program, theme)
        }

        fn scale_factor(&self, state: &Self::State, window: window::Id) -> f64 {
            state.scale_factor(&self.program, window)
        }
    }

    Attach { program }
}

struct DevTools<P>
where
    P: Program,
{
    state: P::State,
}

impl<P> DevTools<P>
where
    P: Program + 'static,
{
    pub fn title(&self, program: &P, window: window::Id) -> String {
        program.title(&self.state, window)
    }

    pub fn update(
        &mut self,
        program: &P,
        message: Message<P>,
    ) -> Task<Message<P>> {
        match message {
            Message::Program(message) => program
                .update(&mut self.state, message)
                .map(Message::Program),
        }
    }

    pub fn view(
        &self,
        program: &P,
        window: window::Id,
    ) -> Element<'_, Message<P>, P::Theme, P::Renderer> {
        program.view(&self.state, window).map(Message::Program)
    }

    pub fn subscription(&self, program: &P) -> Subscription<Message<P>> {
        program.subscription(&self.state).map(Message::Program)
    }

    pub fn theme(&self, program: &P, window: window::Id) -> P::Theme {
        program.theme(&self.state, window)
    }

    pub fn style(&self, program: &P, theme: &P::Theme) -> theme::Style {
        program.style(&self.state, theme)
    }

    pub fn scale_factor(&self, program: &P, window: window::Id) -> f64 {
        program.scale_factor(&self.state, window)
    }
}

#[derive(Clone)]
enum Message<P>
where
    P: Program,
{
    Program(P::Message),
}

impl<P> fmt::Debug for Message<P>
where
    P: Program,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Message::Program(message) => message.fmt(f),
        }
    }
}