// This file is part of Deja-vu.
//
// Deja-vu is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Deja-vu is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Deja-vu. If not, see <https://www.gnu.org/licenses/>.
//
use ratatui::widgets::ListState;
use serde::Deserialize;
use std::{
    env, error, fs, io,
    path::PathBuf,
    process::{Command, Output},
    thread::{self, JoinHandle},
};

/// Application result type.
#[allow(clippy::module_name_repetitions)]
pub type AppResult<T> = std::result::Result<T, Box<dyn error::Error>>;

/// Application exit reasons
#[derive(Debug, Default)]
pub enum QuitReason {
    #[default]
    Exit,
    Poweroff,
    Restart,
}

/// Config
#[derive(Debug, Deserialize)]
pub struct Config {
    con_emu: String,
    tools: Vec<Tool>,
}

impl Config {
    /// # Panics
    ///
    /// Will panic for many reasons
    #[must_use]
    pub fn load() -> Option<Config> {
        // Main config
        let exe_path = env::current_exe().expect("Failed to find main executable");
        let contents = fs::read_to_string(exe_path.with_file_name("pe-menu.toml"))
            .expect("Failed to load config file");
        let mut new_config: Config =
            toml::from_str(&contents).expect("Failed to parse config file");

        // Tools
        let tool_config_path = exe_path.parent().unwrap().join("menu_entries");
        let mut entries: Vec<PathBuf> = std::fs::read_dir(tool_config_path)
            .expect("Failed to find any tool configs")
            .map(|res| res.map(|e| e.path()))
            .filter_map(Result::ok)
            .collect();
        entries.sort();
        for entry in entries {
            let contents = fs::read_to_string(&entry).expect("Failed to read tool config file");
            let tool: Tool = toml::from_str(&contents).expect("Failed to parse tool config file");
            new_config.tools.push(tool);
        }

        // Done
        Some(new_config)
    }
}

/// `PopUp`
#[derive(Debug, Clone, PartialEq)]
pub struct PopUp {
    pub title: String,
    pub body: String,
}

impl PopUp {
    #[must_use]
    pub fn new(title: &str, body: &str) -> PopUp {
        PopUp {
            title: String::from(title),
            body: String::from(body),
        }
    }
}

/// `Tool`
#[derive(Debug, Deserialize)]
pub struct Tool {
    name: String,
    command: String,
    args: Option<Vec<String>>,
    use_conemu: bool,
    separator: bool,
}

/// `MenuEntry`
#[derive(Default, Debug, Clone, PartialEq)]
pub struct MenuEntry {
    pub name: String,
    pub command: String,
    pub args: Vec<String>,
    pub use_conemu: bool,
    pub separator: bool,
}

impl MenuEntry {
    #[must_use]
    pub fn new(
        name: &str,
        command: &str,
        args: Option<Vec<String>>,
        use_conemu: bool,
        separator: bool,
    ) -> MenuEntry {
        let mut my_args = Vec::new();
        if let Some(a) = args {
            my_args.clone_from(&a);
        }
        MenuEntry {
            name: String::from(name),
            command: String::from(command),
            args: my_args,
            use_conemu,
            separator,
        }
    }
}

/// `StatefulList`
#[derive(Default, Debug, Clone, PartialEq)]
pub struct StatefulList<T> {
    pub state: ListState,
    pub items: Vec<T>,
    pub last_selected: Option<usize>,
}

impl<T: Clone> StatefulList<T> {
    #[must_use]
    pub fn new() -> StatefulList<T> {
        StatefulList {
            state: ListState::default(),
            items: Vec::new(),
            last_selected: None,
        }
    }

    #[must_use]
    pub fn get_selected(&self) -> Option<&T> {
        if let Some(i) = self.state.selected() {
            self.items.get(i)
        } else {
            None
        }
    }

    pub fn pop_selected(&mut self) -> Option<T> {
        if let Some(i) = self.state.selected() {
            Some(self.items[i].clone())
        } else {
            None
        }
    }

    fn select_first_item(&mut self) {
        if self.items.is_empty() {
            self.state.select(None);
        } else {
            self.state.select(Some(0));
        }
        self.last_selected = None;
    }

    pub fn set_items(&mut self, items: Vec<T>) {
        // Clear list and rebuild with provided items
        self.items.clear();
        for item in items {
            self.items.push(item);
        }

        // Reset state and select first item (if available)
        self.state = ListState::default();
        self.select_first_item();
    }

    pub fn next(&mut self) {
        if self.items.is_empty() {
            return;
        }
        let i = match self.state.selected() {
            Some(i) => {
                if i >= self.items.len() - 1 {
                    0
                } else {
                    i + 1
                }
            }
            None => self.last_selected.unwrap_or(0),
        };
        self.state.select(Some(i));
    }

    pub fn previous(&mut self) {
        if self.items.is_empty() {
            return;
        }
        let i = match self.state.selected() {
            Some(i) => {
                if i == 0 {
                    self.items.len() - 1
                } else {
                    i - 1
                }
            }
            None => self.last_selected.unwrap_or(0),
        };
        self.state.select(Some(i));
    }
}

/// Application.
#[derive(Debug)]
pub struct App {
    pub config: Config,
    pub main_menu: StatefulList<MenuEntry>,
    pub popup: Option<PopUp>,
    pub quit_reason: QuitReason,
    pub running: bool,
    pub thread_pool: Vec<JoinHandle<Result<Output, io::Error>>>,
}

impl Default for App {
    fn default() -> Self {
        let config = Config::load();
        Self {
            config: config.unwrap(),
            running: true,
            quit_reason: QuitReason::Exit,
            main_menu: StatefulList::new(),
            popup: None,
            thread_pool: Vec::new(),
        }
    }
}

impl App {
    /// Constructs a new instance of [`App`].
    #[must_use]
    pub fn new() -> Self {
        let mut app = Self::default();

        // Add MenuEntries
        for tool in &app.config.tools {
            app.main_menu.items.push(MenuEntry::new(
                &tool.name,
                &tool.command,
                tool.args.clone(),
                tool.use_conemu,
                tool.separator,
            ));
        }
        app.main_menu.select_first_item();

        // Done
        app
    }

    /// Handles the tick event of the terminal.
    pub fn tick(&self) {}

    /// Actually exit application
    ///
    /// # Errors
    /// # Panics
    ///
    /// Will panic if wpeutil fails to reboot or shutdown
    pub fn exit(&self) -> Result<(), &'static str> {
        let mut argument: Option<String> = None;
        match self.quit_reason {
            QuitReason::Exit => {}
            QuitReason::Poweroff => argument = Some(String::from("shutdown")),
            QuitReason::Restart => argument = Some(String::from("reboot")),
        }
        if let Some(a) = argument {
            Command::new("wpeutil")
                .arg(a)
                .output()
                .expect("Failed to run exit command");
        }
        Ok(())
    }

    /// Set running to false to quit the application.
    pub fn quit(&mut self, reason: QuitReason) {
        self.running = false;
        self.quit_reason = reason;
    }

    /// # Panics
    ///
    /// Will panic if command fails to run
    pub fn open_terminal(&mut self) {
        Command::new("cmd.exe")
            .arg("-new_console:n")
            .output()
            .expect("Failed to run command");
    }

    /// # Panics
    ///
    /// Will panic if menu entry isn't found
    pub fn run_tool(&mut self) {
        // Command
        let tool: &MenuEntry;
        if let Some(index) = self.main_menu.state.selected() {
            tool = &self.main_menu.items[index];
        } else {
            self.popup = Some(PopUp::new(
                "Failed to find menu entry",
                "Check for an updated version of Deja-Vu",
            ));
            return;
        }
        let command = if tool.use_conemu {
            self.config.con_emu.clone()
        } else {
            tool.command.clone()
        };

        // Separators
        if tool.separator {
            return;
        }

        // Args
        let mut args = tool.args.clone();
        if tool.use_conemu {
            args.insert(0, tool.command.clone());
            args.push(String::from("-new_console:n"));
        }

        // Check path
        let command_path = PathBuf::from(&command);
        if let Ok(true) = command_path.try_exists() {
            // File path exists
        } else {
            // File path doesn't exist or is a broken symlink/etc
            // The latter case would be Ok(false) rather than Err(_)
            self.popup = Some(PopUp::new("Tool Missing", &format!("Tool path: {command}")));
            return;
        }

        // Run
        // TODO: This really needs refactored to use channels so we can properly check if the
        // command fails.
        let new_thread = thread::spawn(move || Command::new(command_path).args(args).output());
        self.thread_pool.push(new_thread);
    }
}