use crate::client::ChatGptClient;
use crate::config::{Config, Role};
use crate::editor;
use crate::render::{self, MarkdownRender};
use crate::utils::{copy, dump};
use anyhow::{anyhow, Result};
use crossbeam::channel::{unbounded, Sender};
use crossbeam::sync::WaitGroup;
use reedline::{
    default_emacs_keybindings, ColumnarMenu, DefaultCompleter, DefaultPrompt, DefaultPromptSegment,
    Emacs, FileBackedHistory, KeyCode, KeyModifiers, Keybindings, Reedline, ReedlineEvent,
    ReedlineMenu, Signal,
};
use std::cell::RefCell;
use std::fs::File;
use std::path::Path;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread::spawn;

const REPL_COMMANDS: [(&str, &str); 10] = [
    (".clear", "Clear the screen"),
    (".clear-history", "Clear the history"),
    (".clear-role", "Clear the currently selected role"),
    (".copy", "Copy last reply message"),
    (".editor", "Enter multiline editor"),
    (".exit", "Exit the REPL"),
    (".help", "Print this help message"),
    (".history", "Print the history"),
    (".info", "Print the information"),
    (".role", "Specify the role that the AI will play"),
];

const MENU_NAME: &str = "completion_menu";

pub struct Repl {
    editor: Reedline,
    prompt: DefaultPrompt,
}

impl Repl {
    pub fn init(config: Arc<Config>) -> Result<Self> {
        let completer = Self::create_completer(config);
        let keybindings = Self::create_keybindings();
        let history = Self::create_history()?;
        let menu = Self::create_menu();
        let edit_mode = Box::new(Emacs::new(keybindings));
        let editor = Reedline::create()
            .with_completer(Box::new(completer))
            .with_history(history)
            .with_menu(menu)
            .with_edit_mode(edit_mode)
            .with_quick_completions(true)
            .with_partial_completions(true);
        let prompt = Self::create_prompt();
        Ok(Self { editor, prompt })
    }

    pub fn run(&mut self, handler: ReplCmdHandler) -> Result<()> {
        dump(
            format!("Welcome to aichat {}", env!("CARGO_PKG_VERSION")),
            1,
        );
        dump("Type \".help\" for more information.", 1);
        let mut current_ctrlc = false;
        let handler = Arc::new(handler);
        loop {
            if handler.ctrlc.load(Ordering::SeqCst) {
                handler.ctrlc.store(false, Ordering::SeqCst);
                current_ctrlc = true
            }
            let sig = self.editor.read_line(&self.prompt);
            match sig {
                Ok(Signal::Success(line)) => {
                    current_ctrlc = false;
                    match self.handle_line(handler.clone(), line) {
                        Ok(quit) => {
                            if quit {
                                break;
                            }
                        }
                        Err(err) => {
                            dump(format!("{err:?}"), 1);
                        }
                    }
                }
                Ok(Signal::CtrlC) => {
                    if !current_ctrlc {
                        current_ctrlc = true;
                        dump("(To exit, press Ctrl+C again or Ctrl+D or type .exit)", 2);
                    } else {
                        break;
                    }
                }
                Ok(Signal::CtrlD) => {
                    break;
                }
                _ => {}
            }
        }
        Ok(())
    }

    fn handle_line(&mut self, handler: Arc<ReplCmdHandler>, line: String) -> Result<bool> {
        if line.starts_with('.') {
            let (cmd, args) = match line.split_once(' ') {
                Some((head, tail)) => (head, Some(tail.trim())),
                None => (line.as_str(), None),
            };
            match cmd {
                ".exit" => {
                    return Ok(true);
                }
                ".help" => {
                    dump_repl_help();
                }
                ".clear" => {
                    self.editor.clear_scrollback()?;
                }
                ".clear-history" => {
                    let history = Box::new(self.editor.history_mut());
                    history
                        .clear()
                        .map_err(|err| anyhow!("Failed to clear history, {err}"))?;
                    dump("", 1);
                }
                ".history" => {
                    self.editor.print_history()?;
                    dump("", 1);
                }
                ".role" => match args {
                    Some(name) => handler.handle(ReplCmd::SetRole(name.to_string()))?,
                    None => dump("Usage: .role <name>", 2),
                },
                ".clear-role" => {
                    handler.handle(ReplCmd::UnsetRole)?;
                    dump("", 1);
                }
                ".editor" => {
                    dump(
                        "// Entering editor mode (Ctrl+D to finish, Ctrl+C to cancel)",
                        1,
                    );
                    let content = editor::edit()?;
                    dump("", 1);
                    handler.handle(ReplCmd::Input(content))?;
                }
                ".copy" => {
                    let reply = handler.get_reply();
                    if reply.is_empty() {
                        dump("No reply messages that can be copied", 1)
                    } else {
                        copy(&reply)?;
                        dump("Pasted", 1);
                    }
                }
                ".info" => {
                    handler.handle(ReplCmd::Info)?;
                    dump("", 1);
                }
                _ => dump_unknown_command(),
            }
        } else {
            handler.handle(ReplCmd::Input(line))?;
        }

        Ok(false)
    }

    fn create_prompt() -> DefaultPrompt {
        DefaultPrompt::new(DefaultPromptSegment::Empty, DefaultPromptSegment::Empty)
    }

    fn create_completer(config: Arc<Config>) -> DefaultCompleter {
        let mut commands: Vec<String> = REPL_COMMANDS
            .into_iter()
            .map(|(v, _)| v.to_string())
            .collect();
        commands.extend(config.roles.iter().map(|v| format!(".role {}", v.name)));
        let mut completer = DefaultCompleter::with_inclusions(&['.', '-']).set_min_word_len(2);
        completer.insert(commands.clone());
        completer
    }

    fn create_keybindings() -> Keybindings {
        let mut keybindings = default_emacs_keybindings();
        keybindings.add_binding(
            KeyModifiers::NONE,
            KeyCode::Tab,
            ReedlineEvent::UntilFound(vec![
                ReedlineEvent::Menu(MENU_NAME.to_string()),
                ReedlineEvent::MenuNext,
            ]),
        );
        keybindings
    }

    fn create_menu() -> ReedlineMenu {
        let completion_menu = ColumnarMenu::default().with_name(MENU_NAME);
        ReedlineMenu::EngineCompleter(Box::new(completion_menu))
    }

    fn create_history() -> Result<Box<FileBackedHistory>> {
        Ok(Box::new(
            FileBackedHistory::with_file(1000, Config::history_file()?)
                .map_err(|err| anyhow!("Failed to setup history file, {err}"))?,
        ))
    }
}

pub struct ReplCmdHandler {
    client: ChatGptClient,
    config: Arc<Config>,
    state: RefCell<ReplCmdHandlerState>,
    ctrlc: Arc<AtomicBool>,
    render: Option<Arc<MarkdownRender>>,
}

struct ReplCmdHandlerState {
    reply: String,
    role: Option<Role>,
    save_file: Option<File>,
}

impl ReplCmdHandler {
    pub fn init(client: ChatGptClient, config: Arc<Config>, role: Option<Role>) -> Result<Self> {
        let render = if config.no_highlight {
            None
        } else {
            Some(Arc::new(MarkdownRender::init()?))
        };
        let save_file = config.open_message_file()?;
        let ctrlc = Arc::new(AtomicBool::new(false));
        let state = RefCell::new(ReplCmdHandlerState {
            role,
            save_file,
            reply: String::new(),
        });
        Ok(Self {
            client,
            config,
            state,
            ctrlc,
            render,
        })
    }
    fn handle(&self, cmd: ReplCmd) -> Result<()> {
        match cmd {
            ReplCmd::Input(input) => {
                if input.is_empty() {
                    self.state.borrow_mut().reply.clear();
                    return Ok(());
                }
                let prompt = self
                    .state
                    .borrow()
                    .role
                    .as_ref()
                    .map(|v| v.prompt.to_string())
                    .unwrap_or_default();
                let prompt = if prompt.is_empty() {
                    None
                } else {
                    Some(prompt)
                };
                let wg = WaitGroup::new();
                let mut receiver = if let Some(markdown_render) = self.render.clone() {
                    let (tx, rx) = unbounded();
                    let ctrlc = self.ctrlc.clone();
                    let wg = wg.clone();
                    spawn(move || {
                        let _ = render::render_stream(rx, ctrlc, markdown_render);
                        drop(wg);
                    });
                    ReplyReceiver::new(Some(tx))
                } else {
                    ReplyReceiver::new(None)
                };
                self.client
                    .acquire_stream(&input, prompt, &mut receiver, self.ctrlc.clone())?;
                let role = self
                    .state
                    .borrow_mut()
                    .role
                    .as_ref()
                    .map(|v| v.name.to_string());
                Config::save_message(
                    self.state.borrow_mut().save_file.as_mut(),
                    &input,
                    &receiver.output,
                    &role,
                );
                wg.wait();
                self.state.borrow_mut().reply = receiver.output;
            }
            ReplCmd::SetRole(name) => match self.config.find_role(&name) {
                Some(role) => {
                    self.state.borrow_mut().role = Some(role);
                    dump("", 1);
                }
                None => {
                    dump("Unknown role", 2);
                }
            },
            ReplCmd::UnsetRole => {
                self.state.borrow_mut().role = None;
            }
            ReplCmd::Info => {
                let state = self.state.borrow();
                let file_info = |path: &Path| {
                    let state = if path.exists() { "" } else { " [not found]" };
                    format!("{}{state}", path.display())
                };
                let items = vec![
                    ("config file", file_info(&Config::config_file()?)),
                    ("roles file", file_info(&Config::roles_file()?)),
                    ("messages file", file_info(&Config::messages_file()?)),
                    (
                        "current role",
                        state
                            .role
                            .as_ref()
                            .map(|v| v.name.to_string())
                            .unwrap_or_default(),
                    ),
                    (
                        "proxy",
                        self.config
                            .proxy
                            .as_ref()
                            .map(|v| v.to_string())
                            .unwrap_or_default(),
                    ),
                    ("save messages", self.config.save.to_string()),
                    ("highlight", (!self.config.no_highlight).to_string()),
                ];
                let mut info = String::new();
                for (name, value) in items {
                    info.push_str(&format!("{name:<20}{value}\n"));
                }
                dump(info, 0);
            }
        }
        Ok(())
    }

    fn get_reply(&self) -> String {
        self.state.borrow().reply.to_string()
    }
}

pub struct ReplyReceiver {
    output: String,
    sender: Option<Sender<RenderStreamEvent>>,
}

impl ReplyReceiver {
    pub fn new(sender: Option<Sender<RenderStreamEvent>>) -> Self {
        Self {
            output: String::new(),
            sender,
        }
    }

    pub fn text(&mut self, text: &str) {
        match self.sender.as_ref() {
            Some(tx) => {
                let _ = tx.send(RenderStreamEvent::Text(text.to_string()));
            }
            None => {
                dump(text, 0);
            }
        }
        self.output.push_str(text);
    }

    pub fn done(&mut self) {
        match self.sender.as_ref() {
            Some(tx) => {
                let _ = tx.send(RenderStreamEvent::Done);
            }
            None => {
                dump("", 2);
            }
        }
    }
}

pub enum RenderStreamEvent {
    Text(String),
    Done,
}

enum ReplCmd {
    UnsetRole,
    Input(String),
    SetRole(String),
    Info,
}

fn dump_repl_help() {
    let head = REPL_COMMANDS
        .iter()
        .map(|(name, desc)| format!("{name:<15} {desc}"))
        .collect::<Vec<String>>()
        .join("\n");
    dump(
        format!("{head}\n\nPress Ctrl+C to abort session, Ctrl+D to exit the REPL"),
        2,
    );
}

fn dump_unknown_command() {
    dump("Unknown command. Type \".help\" for more information.", 2);
}