turbo_vision/core/

command_set.rs

// (C) 2025 - Enzo Lombardi
//! Command Set System
//!
//! Implements Borland Turbo Vision's command enable/disable system.
//! Commands are stored as a bitfield allowing efficient enable/disable operations.
//!
//! ## Architecture
//!
//! - **`CommandSet`**: Bitfield storing enabled/disabled state for up to 65,536 commands
//! - **Global State**: Stored in Application, accessible via View trait methods
//! - **Automatic Updates**: Buttons auto-enable/disable when command set changes
//! - **Broadcast Pattern**: cmCommandSetChanged notifies all views of changes
//!
//! ## Reference
//!
//! Based on Borland's implementation:
//! - `/include/tv/cmdset.h` (lines 14-84)
//! - `/classes/tcommand.cc` (lines 1-268)

use crate::core::command::CommandId;
use std::cell::RefCell;

/// Maximum number of commands supported (65,536)
/// Matches Borland: `MAX_COMMANDS` = 32 * 2048
pub const MAX_COMMANDS: usize = 32 * 2048;

// Global command set - matches Borland's TView::curCommandSet (tview.cc:67)
// Uses thread_local to avoid Sync requirement while maintaining global accessibility
//
// ## Thread-Local Global Command Set
//
// For compatibility with Borland TV, commands are managed through a thread-local
// global command set. This design has the following implications:
//
// - **Per-thread state**: Each thread has its own independent command set
// - **Test isolation**: Multiple Application instances in different threads don't interfere
// - **No synchronization overhead**: No need for Mutex/Arc since state is thread-local
// - **Single-threaded TUI**: Appropriate for terminal applications (always single-threaded)
//
// **Usage:**
// ```rust
// use turbo_vision::core::command_set::{enable_command, disable_command, command_enabled};
// use turbo_vision::core::command::CM_SAVE;
//
// // Enable a command
// enable_command(CM_SAVE);
//
// // Check if command is enabled
// if command_enabled(CM_SAVE) {
//     // Save operation is available
// }
//
// // Disable a command
// disable_command(CM_SAVE);
// ```
//
// **Alternative Design (Future):**
// For applications requiring explicit command set management, consider
// passing CommandSet through Application:
// ```rust,ignore
// pub struct Application {
//     command_set: CommandSet,
//     // ...
// }
// ```
thread_local! {
    static GLOBAL_COMMAND_SET: RefCell<CommandSet> = RefCell::new(CommandSet::with_all_enabled());
    static COMMAND_SET_CHANGED: RefCell<bool> = const { RefCell::new(false) };
}

/// Check if a command is currently enabled (global query)
/// Matches Borland: `TView::commandEnabled(ushort` command) (tview.cc:142-147)
pub fn command_enabled(command: CommandId) -> bool {
    GLOBAL_COMMAND_SET.with(|cs| cs.borrow().has(command))
}

/// Enable a command in the global command set
/// Matches Borland: `TView::enableCommand(ushort` command) (tview.cc:384-389)
pub fn enable_command(command: CommandId) {
    GLOBAL_COMMAND_SET.with(|cs| {
        let mut set = cs.borrow_mut();
        if !set.has(command) {
            COMMAND_SET_CHANGED.with(|changed| *changed.borrow_mut() = true);
        }
        set.enable_command(command);
    });
}

/// Disable a command in the global command set
/// Matches Borland: `TView::disableCommand(ushort` command) (tview.cc:161-166)
pub fn disable_command(command: CommandId) {
    GLOBAL_COMMAND_SET.with(|cs| {
        let mut set = cs.borrow_mut();
        if set.has(command) {
            COMMAND_SET_CHANGED.with(|changed| *changed.borrow_mut() = true);
        }
        set.disable_command(command);
    });
}

/// A copy of the global command set, to put back later with
/// [`set_commands`]. Matches Borland: `TView::getCommands`.
pub fn get_commands() -> CommandSet {
    GLOBAL_COMMAND_SET.with(|cs| cs.borrow().clone())
}

/// Replace the global command set, flagging a change if it differs.
/// Matches Borland: `TView::setCommands`.
pub fn set_commands(commands: CommandSet) {
    GLOBAL_COMMAND_SET.with(|cs| {
        let mut set = cs.borrow_mut();
        if *set != commands {
            COMMAND_SET_CHANGED.with(|changed| *changed.borrow_mut() = true);
        }
        *set = commands;
    });
}

/// Check if command set has changed (needs broadcast)
/// Matches Borland: `TView::commandSetChanged` (tview.cc:51)
pub fn command_set_changed() -> bool {
    COMMAND_SET_CHANGED.with(|changed| *changed.borrow())
}

/// Clear the command set changed flag
/// Called after broadcasting `CM_COMMAND_SET_CHANGED`
pub fn clear_command_set_changed() {
    COMMAND_SET_CHANGED.with(|changed| *changed.borrow_mut() = false);
}

/// Initialize the global command set with specific disabled commands
/// Matches Borland: `initCommands()` (tview.cc:58-68)
pub fn init_command_set() {
    use crate::core::command::{CM_CLOSE, CM_NEXT, CM_PREV, CM_RESIZE, CM_ZOOM};

    GLOBAL_COMMAND_SET.with(|cs| {
        let mut set = cs.borrow_mut();
        *set = CommandSet::with_all_enabled();
        // Matches Borland initCommands (tview.cc): window commands start
        // disabled and are enabled when a window can accept them
        for cmd in [CM_CLOSE, CM_ZOOM, CM_RESIZE, CM_NEXT, CM_PREV] {
            set.disable_command(cmd);
        }
    });
    COMMAND_SET_CHANGED.with(|changed| *changed.borrow_mut() = false);
}

/// Number of 32-bit words needed to store command bits
const COMMANDS_COUNT: usize = MAX_COMMANDS / 32;

/// Command set bitfield for tracking enabled/disabled commands
///
/// Matches Borland's `TCommandSet` (cmdset.h:14-84)
/// Uses a bitfield array where each command ID is a bit position
#[derive(Clone, PartialEq)]
pub struct CommandSet {
    /// Bitfield storage: 2048 words * 32 bits = 65,536 command bits
    /// Matches Borland: uint32 *cmds
    cmds: Box<[u32; COMMANDS_COUNT]>,
}

impl CommandSet {
    /// Create a new command set with all commands disabled
    ///
    /// Matches Borland: `TCommandSet::TCommandSet()` (tcommand.cc:41-48)
    pub fn new() -> Self {
        Self {
            cmds: Box::new([0; COMMANDS_COUNT]),
        }
    }

    /// Create a command set with all commands enabled
    ///
    /// Matches Borland: `TCommandSet::enableAllCommands()` (tcommand.cc:132-137)
    pub fn with_all_enabled() -> Self {
        Self {
            cmds: Box::new([0xFFFFFFFF; COMMANDS_COUNT]),
        }
    }

    /// Check if a command is enabled
    ///
    /// Matches Borland: `TCommandSet::has(int` cmd) (tcommand.cc:108-112)
    pub fn has(&self, command: CommandId) -> bool {
        let cmd = command as usize;
        if cmd >= MAX_COMMANDS {
            // Commands >= MAX_COMMANDS are always enabled
            return true;
        }
        let word_index = cmd / 32;
        let bit_mask = 1u32 << (cmd & 0x1F);
        (self.cmds[word_index] & bit_mask) != 0
    }

    /// Enable a single command
    ///
    /// Matches Borland: `TCommandSet::enableCmd(int` cmd) (tcommand.cc:139-145)
    pub fn enable_command(&mut self, command: CommandId) {
        let cmd = command as usize;
        if cmd >= MAX_COMMANDS {
            return;
        }
        let word_index = cmd / 32;
        let bit_mask = 1u32 << (cmd & 0x1F);
        self.cmds[word_index] |= bit_mask;
    }

    /// Disable a single command
    ///
    /// Matches Borland: `TCommandSet::disableCmd(int` cmd) (tcommand.cc:180-186)
    pub fn disable_command(&mut self, command: CommandId) {
        let cmd = command as usize;
        if cmd >= MAX_COMMANDS {
            return;
        }
        let word_index = cmd / 32;
        let bit_mask = 1u32 << (cmd & 0x1F);
        self.cmds[word_index] &= !bit_mask;
    }

    /// Enable a range of commands (inclusive)
    ///
    /// Matches Borland: `TCommandSet::enableCmd(int` cmdStart, int cmdEnd) (tcommand.cc:147-179)
    pub fn enable_range(&mut self, cmd_start: CommandId, cmd_end: CommandId) {
        let start = cmd_start as usize;
        let end = cmd_end as usize;

        // Inclusive range like Borland's loops: a single-command range
        // (start == end) is valid, and end is clamped rather than rejected
        if start >= MAX_COMMANDS || end < start {
            return;
        }
        let end = end.min(MAX_COMMANDS - 1);

        let word_start = start / 32;
        let word_end = end / 32;

        // Both in the same word
        if word_start == word_end {
            for bit in (start & 0x1F)..=(end & 0x1F) {
                self.cmds[word_start] |= 1u32 << bit;
            }
            return;
        }

        // Set partial bits in first word
        for bit in (start & 0x1F)..32 {
            self.cmds[word_start] |= 1u32 << bit;
        }

        // Set all bits in middle words
        for word in (word_start + 1)..word_end {
            self.cmds[word] = 0xFFFFFFFF;
        }

        // Set partial bits in last word
        for bit in 0..=(end & 0x1F) {
            self.cmds[word_end] |= 1u32 << bit;
        }
    }

    /// Disable a range of commands (inclusive)
    ///
    /// Matches Borland: `TCommandSet::disableCmd(int` cmdStart, int cmdEnd) (tcommand.cc:188-220)
    pub fn disable_range(&mut self, cmd_start: CommandId, cmd_end: CommandId) {
        let start = cmd_start as usize;
        let end = cmd_end as usize;

        // Inclusive range like Borland's loops: a single-command range
        // (start == end) is valid, and end is clamped rather than rejected
        if start >= MAX_COMMANDS || end < start {
            return;
        }
        let end = end.min(MAX_COMMANDS - 1);

        let word_start = start / 32;
        let word_end = end / 32;

        // Both in the same word
        if word_start == word_end {
            for bit in (start & 0x1F)..=(end & 0x1F) {
                self.cmds[word_start] &= !(1u32 << bit);
            }
            return;
        }

        // Clear partial bits in first word
        for bit in (start & 0x1F)..32 {
            self.cmds[word_start] &= !(1u32 << bit);
        }

        // Clear all bits in middle words
        for word in (word_start + 1)..word_end {
            self.cmds[word] = 0;
        }

        // Clear partial bits in last word
        for bit in 0..=(end & 0x1F) {
            self.cmds[word_end] &= !(1u32 << bit);
        }
    }

    /// Enable all commands in another command set
    ///
    /// Matches Borland: `TCommandSet::enableCmd(const` `TCommandSet`&) (tcommand.cc:222-228)
    pub fn enable_set(&mut self, other: &CommandSet) {
        for i in 0..COMMANDS_COUNT {
            self.cmds[i] |= other.cmds[i];
        }
    }

    /// Disable all commands in another command set
    ///
    /// Matches Borland: `TCommandSet::disableCmd(const` `TCommandSet`&) (tcommand.cc:230-236)
    pub fn disable_set(&mut self, other: &CommandSet) {
        for i in 0..COMMANDS_COUNT {
            self.cmds[i] &= !other.cmds[i];
        }
    }

    /// Enable all commands
    ///
    /// Matches Borland: `TCommandSet::enableAllCommands()` (tcommand.cc:132-137)
    pub fn enable_all(&mut self) {
        self.cmds.fill(0xFFFFFFFF);
    }

    /// Check if command set is empty (all commands disabled)
    ///
    /// Matches Borland: `TCommandSet::isEmpty()` (tcommand.cc:114-125)
    pub fn is_empty(&self) -> bool {
        self.cmds.iter().all(|&word| word == 0)
    }

    /// Perform bitwise AND with another command set
    ///
    /// Matches Borland: `TCommandSet::operator&=(const` `TCommandSet`&) (tcommand.cc:259-268)
    pub fn intersect(&mut self, other: &CommandSet) {
        for i in 0..COMMANDS_COUNT {
            self.cmds[i] &= other.cmds[i];
        }
    }

    /// Perform bitwise OR with another command set
    ///
    /// Matches Borland: `TCommandSet::operator|=(const` `TCommandSet`&) (tcommand.cc:249-257)
    pub fn union(&mut self, other: &CommandSet) {
        for i in 0..COMMANDS_COUNT {
            self.cmds[i] |= other.cmds[i];
        }
    }
}

impl Default for CommandSet {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_enable_disable_single() {
        let mut cs = CommandSet::new();
        assert!(!cs.has(10));

        cs.enable_command(10);
        assert!(cs.has(10));

        cs.disable_command(10);
        assert!(!cs.has(10));
    }

    #[test]
    fn test_enable_range() {
        let mut cs = CommandSet::new();
        cs.enable_range(10, 20);

        assert!(!cs.has(9));
        assert!(cs.has(10));
        assert!(cs.has(15));
        assert!(cs.has(20));
        assert!(!cs.has(21));
    }

    #[test]
    fn test_enable_all() {
        let mut cs = CommandSet::new();
        cs.enable_all();

        assert!(cs.has(0));
        assert!(cs.has(100));
        assert!(cs.has(65535));
    }

    #[test]
    fn test_is_empty() {
        let mut cs = CommandSet::new();
        assert!(cs.is_empty());

        cs.enable_command(50);
        assert!(!cs.is_empty());
    }

    #[test]
    fn test_commands_default_disabled() {
        // New command set has all commands disabled by default
        let cs = CommandSet::new();
        assert!(!cs.has(0));
        assert!(!cs.has(100));
        assert!(!cs.has(1000));
        assert!(!cs.has(60000));
        assert!(!cs.has(65535)); // Maximum u16 value
    }

    #[test]
    fn test_single_command_range_and_clamped_end() {
        // Regression: enable_range(n, n) used to be a silent no-op
        let mut set = CommandSet::new();
        set.enable_range(42, 42);
        assert!(set.has(42));
        set.disable_range(42, 42);
        assert!(!set.has(42));

        // A range ending at the last command is clamped, not rejected
        let mut set = CommandSet::new();
        set.enable_range(65530, 65535);
        assert!(set.has(65530));
        assert!(set.has(65535));
    }

    #[test]
    fn test_init_command_set_disables_window_commands() {
        use crate::core::command::{CM_CLOSE, CM_NEXT, CM_PREV, CM_RESIZE, CM_ZOOM};
        init_command_set();
        for cmd in [CM_CLOSE, CM_ZOOM, CM_RESIZE, CM_NEXT, CM_PREV] {
            assert!(!command_enabled(cmd), "cmd {cmd} should start disabled");
        }
        assert!(command_enabled(crate::core::command::CM_QUIT));
        // Restore a fully-enabled set for other tests sharing the thread-local
        init_command_set();
        enable_command(CM_CLOSE);
    }
}