[explorer] Add several commands to help with debugging

flags
: Print flags for the current board position. This prints the castling rights
and whether the player can castle (regardless of whether they have the right).

make
: Finally reimplement the make command. Change the format so it takes a move in
the UCI long algebraic style.

perft
: Run perft to a given depth on the current board position.

explorer/src/main.rs

@@ -1,12 +1,14 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use chessfriend_board::ZobristState;
+use chessfriend_board::castle::CastleEvaluationError;
 use chessfriend_board::{Board, fen::FromFenStr};
+use chessfriend_board::{CastleParameters, ZobristState};
 use chessfriend_core::random::RandomNumberGenerator;
-use chessfriend_core::{Color, Piece, Shape, Square};
-use chessfriend_moves::GeneratedMove;
+use chessfriend_core::{Color, Piece, Shape, Square, Wing};
+use chessfriend_moves::algebraic::AlgebraicMoveComponents;
+use chessfriend_moves::{GeneratedMove, ValidateMove};
 use chessfriend_position::{PlacePieceStrategy, Position, fen::ToFenStr};
-use clap::{Arg, Command};
+use clap::{Arg, Command, value_parser};
 use rustyline::DefaultEditor;
 use rustyline::error::ReadlineError;
 use std::sync::Arc;
@@ -45,6 +47,7 @@ fn command_line() -> Command {
         .subcommand_help_heading("COMMANDS")
         .help_template(PARSER_TEMPLATE)
         .subcommand(Command::new("fen").about("Print the current position as a FEN string"))
+        .subcommand(Command::new("flags").about("Print flags for the current position"))
         .subcommand(
             Command::new("load")
                 .arg(Arg::new("fen").required(true))
@@ -53,8 +56,7 @@ fn command_line() -> Command {
         )
         .subcommand(
             Command::new("make")
-                .arg(Arg::new("from").required(true))
-                .arg(Arg::new("to").required(true))
+                .arg(Arg::new("move").required(true))
                 .alias("m")
                 .about("Make a move"),
         )
@@ -81,6 +83,14 @@ fn command_line() -> Command {
                 .arg(Arg::new("square").required(true))
                 .about("Show moves of a piece on a square"),
         )
+        .subcommand(
+            Command::new("perft")
+                .arg(Arg::new("depth")
+                    .required(true)
+                    .value_parser(value_parser!(usize))
+                )
+                .about("Run Perft on the current position to the given depth")
+        )
         .subcommand(
             Command::new("reset")
                 .subcommand(Command::new("clear").about("Reset to a cleared board"))
@@ -107,6 +117,12 @@ enum CommandHandlingError<'a> {
 
     #[error("no piece on {0}")]
     NoPiece(Square),
+
+    #[error("{value:?} is not a valid value for {argument_name:?}")]
+    ValueError {
+        argument_name: &'static str,
+        value: String,
+    },
 }
 
 fn respond(line: &str, state: &mut State) -> anyhow::Result<CommandResult> {
@@ -116,6 +132,7 @@ fn respond(line: &str, state: &mut State) -> anyhow::Result<CommandResult> {
     let mut result = CommandResult::default();
 
     match matches.subcommand() {
+        Some(("flags", matches)) => result = do_flags_command(state, matches),
         Some(("load", matches)) => result = do_load_command(state, matches)?,
         Some(("print", _matches)) => {}
         Some(("quit", _matches)) => {
@@ -126,9 +143,8 @@ fn respond(line: &str, state: &mut State) -> anyhow::Result<CommandResult> {
             println!("{}", state.position.to_fen_str()?);
             result.should_print_position = false;
         }
-        Some(("make", _matches)) => {
-            unimplemented!()
-        }
+        Some(("make", matches)) => result = do_make_command(state, matches)?,
+        Some(("perft", matches)) => result = do_perft_command(state, matches)?,
         Some(("place", matches)) => {
             let color = matches
                 .get_one::<String>("color")
@@ -175,6 +191,34 @@ fn respond(line: &str, state: &mut State) -> anyhow::Result<CommandResult> {
     Ok(result)
 }
 
+fn do_flags_command(state: &mut State, _matches: &clap::ArgMatches) -> CommandResult {
+    let board = &state.position.board;
+
+    println!("Castling:");
+
+    for (color, wing) in [
+        (Color::White, Wing::KingSide),
+        (Color::White, Wing::QueenSide),
+        (Color::Black, Wing::KingSide),
+        (Color::Black, Wing::QueenSide),
+    ] {
+        let has_right = board.color_has_castling_right_unwrapped(color, wing);
+        let can_castle = board.color_can_castle(wing, Some(color));
+
+        let can_castle_message = match can_castle {
+            Ok(_) => "ok".to_string(),
+            Err(error) => format!("{error}"),
+        };
+
+        println!("  {color} {wing}: {has_right}, {can_castle_message}");
+    }
+
+    CommandResult {
+        should_continue: true,
+        should_print_position: false,
+    }
+}
+
 fn do_load_command(state: &mut State, matches: &clap::ArgMatches) -> anyhow::Result<CommandResult> {
     let fen_string = matches
         .get_one::<String>("fen")
@@ -191,6 +235,26 @@ fn do_load_command(state: &mut State, matches: &clap::ArgMatches) -> anyhow::Res
     })
 }
 
+fn do_make_command(state: &mut State, matches: &clap::ArgMatches) -> anyhow::Result<CommandResult> {
+    let move_string = matches
+        .get_one::<String>("move")
+        .ok_or(CommandHandlingError::MissingArgument("move"))?;
+
+    let algebraic_move: AlgebraicMoveComponents = move_string.parse()?;
+
+    let encoded_move = state
+        .position
+        .move_from_algebraic_components(algebraic_move)
+        .ok_or(CommandHandlingError::ValueError {
+            argument_name: "move",
+            value: move_string.to_string(),
+        })?;
+
+    state.position.make_move(encoded_move, ValidateMove::Yes)?;
+
+    Ok(CommandResult::default())
+}
+
 fn do_reset_command(
     state: &mut State,
     matches: &clap::ArgMatches,
@@ -282,6 +346,25 @@ fn do_movement_command(
     })
 }
 
+fn do_perft_command(
+    state: &mut State,
+    matches: &clap::ArgMatches,
+) -> anyhow::Result<CommandResult> {
+    let depth = *matches
+        .get_one::<usize>("depth")
+        .ok_or(CommandHandlingError::MissingArgument("depth"))?;
+
+    let mut position = state.position.clone();
+    let nodes_count = position.perft(depth);
+
+    println!("nodes {nodes_count}");
+
+    Ok(CommandResult {
+        should_continue: true,
+        should_print_position: false,
+    })
+}
+
 fn do_zobrist_command(state: &mut State, _matches: &clap::ArgMatches) -> CommandResult {
     if let Some(hash) = state.position.zobrist_hash() {
         println!("hash:{hash}");