use crate::client::games::manager::GameManager;
use crate::client::games::response::parse_spin_response;
use crate::client::ui::{
    command_names, completion_lines, display_width, help_lines, input_cursor_column,
    parse_bet_arg, record_history,
};

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Key {
    Char(char),
    Enter,
    Backspace,
    Up,
    Down,
    Tab,
    Esc,
    CtrlC,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum InteractiveCommand {
    Login,
    Register,
    SetCred,
    Connect(Option<String>),
}

/// High-level actions produced by the client core. The terminal adapter is
/// responsible for turning these into crossterm calls and network writes.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Effect {
    /// Append lines to the scrolling transcript.
    Print(Vec<String>),
    /// Replace the game board region in place.
    ReplaceRegion(Vec<String>),
    /// Remove the game board region.
    ClearRegion,
    /// Redraw the command prompt. `text` is the input without the `> ` prefix.
    SetPrompt { text: String, cursor_col: u16 },
    /// Send one protocol line and feed the reply to `handle_reply`.
    SendLine(String),
    /// Delegate an interactive prompt flow to the terminal adapter.
    Interactive(InteractiveCommand),
    /// Drop the connection.
    Disconnect,
    /// Let the adapter read the host database.
    ListHosts,
    /// Let the adapter delete a host from the database.
    ForgetHost(String),
    /// Leave the program.
    Quit,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum Pending {
    Spin,
    Ping,
    Echo,
    Info,
}

pub struct ClientCore {
    input: String,
    history: Vec<String>,
    history_index: usize,
    game: GameManager,
    connected: bool,
    logged_in: Option<String>,
    pending: Option<Pending>,
    balance: Option<i64>,
    host: Option<String>,
    fingerprint: Option<String>,
}

impl ClientCore {
    pub fn new() -> Self {
        Self {
            input: String::new(),
            history: Vec::new(),
            history_index: 0,
            game: GameManager::new(),
            connected: false,
            logged_in: None,
            pending: None,
            balance: None,
            host: None,
            fingerprint: None,
        }
    }

    pub fn set_connected(&mut self, connected: bool) {
        self.connected = connected;
        if !connected {
            self.logged_in = None;
            self.pending = None;
        }
    }

    pub fn set_logged_in(&mut self, user: Option<String>) {
        self.logged_in = user;
    }

    pub fn set_balance(&mut self, balance: i64) {
        self.balance = Some(balance);
        self.game.set_balance(balance);
    }

    pub fn set_host_info(&mut self, host: Option<String>, fingerprint: Option<String>) {
        self.host = host;
        self.fingerprint = fingerprint;
    }

    pub fn is_in_game(&self) -> bool {
        self.game.is_in_game()
    }

    pub fn prompt_effect(&self) -> Option<Effect> {
        if self.is_in_game() {
            return None;
        }
        Some(Effect::SetPrompt {
            text: self.input.clone(),
            cursor_col: input_cursor_column(2, display_width(&self.input)),
        })
    }

    pub fn handle_key(&mut self, key: Key) -> Vec<Effect> {
        if self.game.is_in_game() {
            return self.handle_game_key(key);
        }

        match key {
            Key::CtrlC => vec![Effect::Quit],
            Key::Enter => self.submit(),
            Key::Backspace => {
                self.input.pop();
                self.prompt_effects()
            }
            Key::Char(c) => {
                self.input.push(c);
                self.prompt_effects()
            }
            Key::Up => self.history_previous(),
            Key::Down => self.history_next(),
            Key::Tab => self.complete(),
            Key::Esc => Vec::new(),
        }
    }

    pub fn handle_reply(&mut self, reply: &str) -> Vec<Effect> {
        match self.pending.take() {
            Some(Pending::Spin) => match parse_spin_response(reply) {
                Ok(result) => {
                    self.balance = Some(result.balance);
                    self.game.apply_result(result);
                    self.board_effects()
                }
                Err(message) => {
                    self.game.set_error(message);
                    self.board_effects()
                }
            },
            Some(Pending::Ping) => {
                if reply.trim() == "PONG" {
                    print_line("Pong")
                } else {
                    self.connected = false;
                    self.logged_in = None;
                    vec![
                        Effect::Disconnect,
                        Effect::Print(vec![
                            "Connection lost".to_string(),
                        ]),
                    ]
                }
            }
            Some(Pending::Echo) => print_line(format!("Echo: {}", reply.trim())),
            Some(Pending::Info) => {
                if self.game.is_in_game() {
                    // Balance fetch while entering a game. A failure is not
                    // fatal: the board keeps showing `?`.
                    if let Some(balance) = info_balance(reply) {
                        self.balance = Some(balance);
                        self.game.set_balance(balance);
                        return self.board_effects();
                    }
                    Vec::new()
                } else {
                    vec![Effect::Print(info_lines(reply))]
                }
            }
            None => print_line(reply.trim()),
        }
    }

    fn handle_game_key(&mut self, key: Key) -> Vec<Effect> {
        match key {
            Key::CtrlC => vec![Effect::Quit],
            Key::Esc | Key::Char('q') => {
                self.game.end_game();
                vec![
                    Effect::ClearRegion,
                    Effect::Print(vec!["Game exited.".to_string()]),
                ]
            }
            Key::Char(' ') => self.spin(),
            Key::Char('+') => {
                let _ = self.game.adjust_bet(10);
                self.board_effects()
            }
            Key::Char('-') => {
                let _ = self.game.adjust_bet(-10);
                self.board_effects()
            }
            _ => Vec::new(),
        }
    }

    fn spin(&mut self) -> Vec<Effect> {
        let Some(request) = self.game.spin_request() else {
            return Vec::new();
        };
        if self.game.begin_spin().is_err() {
            return Vec::new();
        }
        self.pending = Some(Pending::Spin);

        let mut effects = self.board_effects();
        effects.push(Effect::SendLine(request));
        effects
    }

    fn submit(&mut self) -> Vec<Effect> {
        let line = self.input.trim().to_string();
        self.input.clear();
        if line.is_empty() {
            return Vec::new();
        }

        record_history(&mut self.history, &line);
        self.history_index = self.history.len();

        let parts: Vec<&str> = line.splitn(3, ' ').collect();
        match parts[0] {
            "play" => self.cmd_play(&parts),
            "games" => self.available_games(None),
            "help" => vec![Effect::Print(help_lines())],
            "connect" => {
                if self.connected {
                    print_line("Already connected. Disconnect first.")
                } else {
                    let target = parts.get(1).map(|value| value.to_string());
                    vec![Effect::Interactive(InteractiveCommand::Connect(target))]
                }
            }
            "login" => {
                if !self.connected {
                    print_line("Not connected. Use 'connect <ip>:<port>' first.")
                } else if self.logged_in.is_some() {
                    print_line(format!(
                        "Already logged in as {}",
                        self.logged_in.as_deref().unwrap_or("?")
                    ))
                } else {
                    vec![Effect::Interactive(InteractiveCommand::Login)]
                }
            }
            "register" => {
                if !self.connected {
                    print_line("Not connected. Use 'connect <ip>:<port>' first.")
                } else {
                    vec![Effect::Interactive(InteractiveCommand::Register)]
                }
            }
            "setcred" => {
                if self.host.is_none() {
                    print_line("No host connected. Use 'connect <ip>:<port>' first.")
                } else {
                    vec![Effect::Interactive(InteractiveCommand::SetCred)]
                }
            }
            "logout" => {
                self.logged_in = None;
                print_line("Logged out")
            }
            "disconnect" => {
                self.connected = false;
                self.logged_in = None;
                self.pending = None;
                self.game.end_game();
                vec![
                    Effect::ClearRegion,
                    Effect::Disconnect,
                    Effect::Print(vec!["Disconnected".to_string()]),
                ]
            }
            "ping" => {
                if !self.connected {
                    print_line("Not connected. Use 'connect <ip>:<port>' first.")
                } else {
                    self.pending = Some(Pending::Ping);
                    vec![Effect::SendLine("PING".to_string())]
                }
            }
            "send" => {
                if !self.connected {
                    print_line("Not connected. Use 'connect <ip>:<port>' first.")
                } else if parts.len() < 2 {
                    print_line("Usage: send <message>")
                } else {
                    let message = parts[1..].join(" ");
                    self.pending = Some(Pending::Echo);
                    vec![Effect::SendLine(message)]
                }
            }
            "info" => self.cmd_info(),
            "hosts" => vec![Effect::ListHosts],
            "forget-host" => {
                let target = parts
                    .get(1)
                    .map(|value| value.to_string())
                    .or_else(|| self.host.clone());
                match target {
                    Some(target) => vec![Effect::ForgetHost(target)],
                    None => print_line("Usage: forget-host <ip>:<port> (or connect first)"),
                }
            }
            "quit" => vec![Effect::Quit],
            _ => vec![Effect::Print(help_lines())],
        }
    }

    fn cmd_play(&mut self, parts: &[&str]) -> Vec<Effect> {
        if !self.connected {
            return print_line("Not connected. Use 'connect <ip>:<port>' first.");
        }
        if self.logged_in.is_none() {
            return print_line("Not logged in. Use 'login' first.");
        }
        if parts.len() < 2 {
            return self.available_games(Some("Usage: play <game> [bet]"));
        }

        let bet = match parts.get(2) {
            Some(raw) => match parse_bet_arg(raw) {
                Ok(bet) => Some(bet),
                Err(message) => return print_line(message),
            },
            None => None,
        };

        if self.game.is_in_game() {
            return print_line("Already in a game. Use 'quit' to exit current game.");
        }

        match self.game.enter_game(parts[1]) {
            Ok(()) => {
                if let Some(bet) = bet {
                    let _ = self.game.set_bet(bet);
                }
                if let Some(balance) = self.balance {
                    self.game.set_balance(balance);
                }

                let mut effects = self.board_effects();
                self.pending = Some(Pending::Info);
                effects.push(Effect::SendLine("INFO".to_string()));
                effects
            }
            Err(_) => print_line("Failed to enter game"),
        }
    }

    fn available_games(&self, usage: Option<&str>) -> Vec<Effect> {
        let mut lines = vec!["Available games:".to_string()];
        for (game_type, name) in self.game.get_available_games() {
            lines.push(format!("  - {} ({})", game_type, name));
        }
        if let Some(usage) = usage {
            lines.push(String::new());
            lines.push(usage.to_string());
        }
        vec![Effect::Print(lines)]
    }

    fn cmd_info(&mut self) -> Vec<Effect> {
        if !self.connected {
            return print_line("Not connected to any host.");
        }

        let mut effects = Vec::new();
        match &self.host {
            Some(host) => effects.push(Effect::Print(vec![format!("Connected to: {host}")])),
            None => effects.push(Effect::Print(vec!["Connected to: (unknown)".to_string()])),
        }
        match &self.fingerprint {
            Some(fingerprint) => {
                effects.push(Effect::Print(vec![format!("Fingerprint: {fingerprint}")]))
            }
            None => effects.push(Effect::Print(vec![
                "Fingerprint: (not trusted)".to_string(),
            ])),
        }

        self.pending = Some(Pending::Info);
        effects.push(Effect::SendLine("INFO".to_string()));
        effects
    }

    fn history_previous(&mut self) -> Vec<Effect> {
        if self.history_index == 0 {
            return Vec::new();
        }
        self.history_index -= 1;
        self.input = self.history[self.history_index].clone();
        self.prompt_effects()
    }

    fn history_next(&mut self) -> Vec<Effect> {
        if self.history_index >= self.history.len() {
            return Vec::new();
        }
        self.history_index += 1;
        self.input = if self.history_index == self.history.len() {
            String::new()
        } else {
            self.history[self.history_index].clone()
        };
        self.prompt_effects()
    }

    fn complete(&mut self) -> Vec<Effect> {
        let prefix = self.input.trim();
        let matches: Vec<&'static str> = command_names()
            .into_iter()
            .filter(|command| command.starts_with(prefix))
            .collect();

        let mut effects = Vec::new();
        if matches.len() == 1 {
            self.input = matches[0].to_string();
        } else if matches.len() > 1 {
            effects.push(Effect::Print(completion_lines(&matches, 76)));
        }
        if let Some(prompt) = self.prompt_effect() {
            effects.push(prompt);
        }
        effects
    }

    fn board_lines(&self) -> Option<Vec<String>> {
        let game = self.game.get_current_game()?;
        let state = self.game.get_current_state()?;
        Some(game.render(state).lines().map(str::to_string).collect())
    }

    fn board_effects(&self) -> Vec<Effect> {
        self.board_lines()
            .map(Effect::ReplaceRegion)
            .into_iter()
            .collect()
    }

    fn prompt_effects(&self) -> Vec<Effect> {
        self.prompt_effect().into_iter().collect()
    }
}

fn print_line(message: impl Into<String>) -> Vec<Effect> {
    vec![Effect::Print(vec![message.into()])]
}

fn info_balance(reply: &str) -> Option<i64> {
    let parts: Vec<&str> = reply.split_whitespace().collect();
    if parts.first() == Some(&"INFO") && parts.len() == 4 {
        parts[3].parse().ok()
    } else {
        None
    }
}

fn info_lines(reply: &str) -> Vec<String> {
    let parts: Vec<&str> = reply.split_whitespace().collect();
    if parts.first() == Some(&"INFO") && parts.len() == 4 {
        vec![
            format!("User: {}", parts[1]),
            format!("Account: {}", parts[2]),
            format!("Balance: {} PLN", parts[3]),
        ]
    } else {
        vec![reply.trim().to_string()]
    }
}