//! Pure text/history helpers for the client TUI.
//!
//! Nothing here touches the terminal, so it is unit-tested from `tests/`
//! without a PTY.

struct CommandHelp {
    name: &'static str,
    usage: &'static str,
    description: &'static str,
}

const COMMANDS: &[CommandHelp] = &[
    CommandHelp {
        name: "connect",
        usage: "connect <ip>:<port>",
        description: "connect to the server",
    },
    CommandHelp {
        name: "send",
        usage: "send <message>",
        description: "send a message to the server",
    },
    CommandHelp {
        name: "disconnect",
        usage: "disconnect",
        description: "disconnect from the server",
    },
    CommandHelp {
        name: "ping",
        usage: "ping",
        description: "ping the server",
    },
    CommandHelp {
        name: "login",
        usage: "login",
        description: "login to the server",
    },
    CommandHelp {
        name: "register",
        usage: "register",
        description: "register a new user",
    },
    CommandHelp {
        name: "setcred",
        usage: "setcred",
        description: "set credentials for a host",
    },
    CommandHelp {
        name: "logout",
        usage: "logout",
        description: "logout from the server",
    },
    CommandHelp {
        name: "info",
        usage: "info",
        description: "show account and connection info",
    },
    CommandHelp {
        name: "play",
        usage: "play <game> [bet]",
        description: "start a game (e.g. play slots 50)",
    },
    CommandHelp {
        name: "games",
        usage: "games",
        description: "list available games",
    },
    CommandHelp {
        name: "help",
        usage: "help",
        description: "show this message",
    },
    CommandHelp {
        name: "forget-host",
        usage: "forget-host [ip:port]",
        description: "clear saved trust fingerprint and credentials",
    },
    CommandHelp {
        name: "hosts",
        usage: "hosts",
        description: "list remembered hosts",
    },
    CommandHelp {
        name: "quit",
        usage: "quit",
        description: "quit the program",
    },
];

pub fn command_names() -> Vec<&'static str> {
    COMMANDS.iter().map(|command| command.name).collect()
}

pub fn help_lines() -> Vec<String> {
    let mut lines = vec!["Available commands:".to_string()];
    for command in COMMANDS {
        lines.push(format!(
            "  {:<28} - {}",
            command.usage, command.description
        ));
    }
    lines
}

/// Wrap a completion list to `width` columns, one space between names.
pub fn completion_lines(commands: &[&str], width: usize) -> Vec<String> {
    let mut lines = vec!["Possible completions:".to_string()];
    let mut current = String::new();

    for command in commands {
        let needed = if current.is_empty() {
            command.len()
        } else {
            current.len() + 1 + command.len()
        };
        if !current.is_empty() && needed > width {
            lines.push(current.clone());
            current.clear();
        }
        if !current.is_empty() {
            current.push(' ');
        }
        current.push_str(command);
    }

    if !current.is_empty() {
        lines.push(current);
    }
    lines
}

/// Add a command to the history, skipping blanks and consecutive duplicates.
pub fn record_history(history: &mut Vec<String>, line: &str) {
    let line = line.trim();
    if line.is_empty() {
        return;
    }
    if history.last().is_some_and(|last| last == line) {
        return;
    }
    history.push(line.to_string());
}

/// Parse the optional bet argument of `play <game> [bet]`.
pub fn parse_bet_arg(raw: &str) -> Result<u64, String> {
    let bet = raw
        .trim()
        .parse::<u64>()
        .map_err(|_| format!("Invalid bet: {raw}"))?;
    if bet < 10 {
        return Err("Bet must be at least 10 PLN".to_string());
    }
    Ok(bet)
}

/// Lines to move the cursor up to reach the first line of a region that ends
/// on the current line. `render()` has no trailing newline, so a 7-line board
/// needs `MoveUp(6)`.
pub fn lines_to_move_up(previous_lines: usize) -> u16 {
    previous_lines
        .saturating_sub(1)
        .min(u16::MAX as usize) as u16
}

/// Column (0-based) to move to after the given prompt and input text.
pub fn input_cursor_column(prompt_len: usize, input_len: usize) -> u16 {
    prompt_len
        .saturating_add(input_len)
        .min(u16::MAX as usize) as u16
}