bishop/src/evaluate.rs

use game::*;
use bitboard::*;
use movegen::*;

use std::f32::*;

pub type PosValue = f32;
pub const MIN_VALUE: PosValue = -1000000.0f32;
pub const MAX_VALUE: PosValue = 1000000.0f32;

fn value_castling_rights(game: &Game, side: Side) -> PosValue {
    let mut val: PosValue = 0.0f32;

    for i in 0..2 {
        if game.castling_rights[i] { val += 12.0f32; }
    }
    for i in 2..4 {
        if game.castling_rights[i] { val -= 12.0f32; }
    }
    
    if side == BLACK {
        return -val;
    }
    else {
        return val;
    }
}

fn side_value(game: &Game, side: Side) -> u32 {
    let knights = game.get_piece(KNIGHT, side);
    let ks = BitboardIterator(knights);
    let mut k_attacks: u32 = 0;

    for k in ks {
        let targets = get_knight_targets(square(k));
        k_attacks += targets.count_ones() * 4;
    }

    let adv_pawn_mask = match side { WHITE => ROW_7, BLACK => ROW_2 };
    let advanced_pawns = (game.get_piece(PAWN, side) & adv_pawn_mask).count_ones() * 200;

    advanced_pawns + k_attacks

}

fn material_value(game: &Game, side: Side) -> PosValue {
    (game.get_piece(PAWN, side).count_ones() * 100
        + game.get_piece(KNIGHT, side).count_ones() * 300
        + game.get_piece(BISHOP, side).count_ones() * 320
        + game.get_piece(ROOK, side).count_ones() * 400
        + game.get_piece(QUEEN, side).count_ones() * 700) as PosValue
}

pub fn evaluate(game: &Game) -> PosValue {
    let sv = side_value(game, game.turn) as PosValue - side_value(game, !game.turn) as PosValue;
    let material_value_us = material_value(game, game.turn);
    let material_value_them = material_value(game, !game.turn);
    let mat_val = material_value_us.powf(0.995f32) - material_value_them.powf(0.995f32);
    return mat_val + value_castling_rights(game, game.turn);
}