#![warn(clippy::all, clippy::pedantic, clippy::nursery)]

use std::{
    collections::BTreeMap,
    error::Error,
    fmt::{self, Debug, Display},
    fs::{File, OpenOptions},
    io::{Read, Seek, SeekFrom, Write},
    path::Path,
};

use eframe::{
    egui::{self, FontData, FontDefinitions, Key, TextEdit, ViewportBuilder},
    epaint::{FontFamily, FontId},
    CreationContext,
};

enum RunError {
    HomeDir(homedir::GetHomeError),
    NoHome,
    OpenFile(std::io::Error),
    EFrame(eframe::Error),
}

impl Debug for RunError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        Display::fmt(self, f)
    }
}
impl Display for RunError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::HomeDir(e) => f.write_fmt(format_args!("homedir error: {e}")),
            Self::NoHome => f.write_fmt(format_args!("failed to find home directory")),
            Self::OpenFile(e) => f.write_fmt(format_args!("error while opening todo.txt: {e}")),
            Self::EFrame(e) => f.write_fmt(format_args!("eframe error: {e}")),
        }
    }
}
impl Error for RunError {}

fn main() -> Result<(), RunError> {
    for argument in std::env::args() {
        if argument == "-v" || argument == "--version" {
            println!(env!("CARGO_PKG_VERSION"));
            return Ok(());
        }
    }
    std::env::set_var("WINIT_UNIX_BACKEND", "wayland");
    let home_dir = homedir::get_my_home()
        .map_err(RunError::HomeDir)?
        .ok_or(RunError::NoHome)?;
    let todo_file = OpenOptions::new()
        .create(true)
        .read(true)
        .write(true)
        .append(false)
        .open(Path::join(&home_dir, "todo.txt"))
        .map_err(RunError::OpenFile)?;

    let native_options = eframe::NativeOptions {
        viewport: ViewportBuilder::default().with_app_id("todoodoo"),
        ..Default::default()
    };
    eframe::run_native(
        "To-DooDoo",
        native_options,
        Box::new(|creation_context| Box::new(ToDooDooApp::new(creation_context, todo_file))),
    )
    .map_err(RunError::EFrame)?;
    Ok(())
}

struct ToDooDooApp {
    notes: String,
    file: File,
}

impl ToDooDooApp {
    fn new(creation_context: &CreationContext, mut file: File) -> Self {
        const FONT_NAME: &str = "Monocraft";
        let mut families = BTreeMap::new();
        families.insert(FontFamily::Proportional, vec![FONT_NAME.to_string()]);
        families.insert(FontFamily::Monospace, vec![FONT_NAME.to_string()]);
        let mut font_data = BTreeMap::new();
        font_data.insert(
            "Monocraft".into(),
            FontData::from_static(include_bytes!(concat!(
                env!("CARGO_MANIFEST_DIR"),
                "/fonts/Monocraft-NF.ttf"
            ))),
        );
        creation_context.egui_ctx.set_fonts(FontDefinitions {
            font_data,
            families,
        });
        creation_context.egui_ctx.style_mut(|style| {
            style.override_font_id = Some(FontId::new(12.0, FontFamily::Monospace));
        });
        let mut notes = String::with_capacity(
            file.metadata()
                .expect("file metadata")
                .len()
                .try_into()
                .expect("file too big"),
        );
        file.read_to_string(&mut notes)
            .expect("failed to read file");
        Self { notes, file }
    }

    fn save(&mut self) {
        self.file.set_len(0).expect("failed to truncate file");
        self.file.seek(SeekFrom::Start(0)).expect("failed to seek");
        self.file
            .write_all(self.notes.as_bytes())
            .expect("failed to write file");
        self.file.flush().expect("failed to flush");
    }
}

impl eframe::App for ToDooDooApp {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        egui::TopBottomPanel::top("button_bar")
            .frame(egui::Frame::none())
            .show(ctx, |ui| {
                ui.horizontal(|ui| {
                    ui.with_layout(egui::Layout::left_to_right(egui::Align::Center), |ui| {
                        if ui.button("save").on_hover_text("or use <C-s>").clicked() {
                            self.save();
                        }
                    });
                    ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
                        ui.label("hover for licenses")
                            .on_hover_text("Monocraft font - SIL OPEN FONT LICENSE Version 1.1");
                    });
                });
            });
        egui::CentralPanel::default()
            .frame(egui::Frame::none())
            .show(ctx, |ui| {
                if ctx.input(|i| i.key_pressed(Key::S) && i.modifiers.command) {
                    self.save();
                }
                ui.add_sized(ui.available_size(), TextEdit::multiline(&mut self.notes));
            });
    }

    fn save(&mut self, _storage: &mut dyn eframe::Storage) {
        self.save();
    }
}