use crate::board::Board;
use crate::strategy::{NakedSingle, Strategy, StrategyFn};
use crate::validator;

fn try_strategies(strategies: &[StrategyFn], sudoku_board: &Board) -> Option<Box<dyn Strategy>> {
    for strategy in strategies {
        if let Some(strat) = strategy(&sudoku_board) {
            return Some(strat);
        }
    }
    None
}

pub fn solve_board(mut sudoku_board: Board) -> Result<Board, Board> {
    if let validator::BoardState::Broken(ind) = validator::validate_board(&sudoku_board) {
        println!("{}", sudoku_board.to_url());
        panic!(
            "Error invalid number at row {} col {}",
            (ind / 9) + 1,
            (ind % 9) + 1
        );
    }

    let strategies: [StrategyFn; 1] = [NakedSingle::find_instance];

    while let Some(ns) = try_strategies(&strategies, &sudoku_board) {
        sudoku_board = ns.apply(sudoku_board);

        if let validator::BoardState::Broken(ind) = validator::validate_board(&sudoku_board) {
            println!("{}", sudoku_board.to_url());
            panic!(
                "Error invalid number at row {} col {}",
                (ind / 9) + 1,
                (ind % 9) + 1
            );
        }
    }

    match validator::validate_board(&sudoku_board) {
        validator::BoardState::Finished => Ok(sudoku_board),
        validator::BoardState::InProgress => Err(sudoku_board),
        _ => unreachable!(),
    }
}