# -*- coding: utf-8 -*-
"""坐标转换: 站点坐标(行1-10) <-> 引擎 UCCI(行0-9), 以及 FEN 构建。"""
import re

MOVE_RE = re.compile(r'^([a-i])(\d+)([a-i])(\d+)$')

INITIAL_GRID = (
    'rnbakabnr'
    '.........'
    '.c.....c.'
    'p.p.p.p.p'
    '.........'
    '.........'
    'P.P.P.P.P'
    '.C.....C.'
    '.........'
    'RNBAKABNR'
)


def _sub(m, delta):
    return f'{m.group(1)}{int(m.group(2)) + delta}{m.group(3)}{int(m.group(4)) + delta}'


def site_to_ucci(m):
    """'b3e3'->'b2e2', 'h10g8'->'h9g7' (站点行号 1-10, 引擎行号 0-9)."""
    return MOVE_RE.sub(lambda x: _sub(x, -1), m)


def ucci_to_site(m):
    """'b2e2'->'b3e3', 'h9g7'->'h10g8'."""
    return MOVE_RE.sub(lambda x: _sub(x, +1), m)


def ucci_to_rc(m):
    """UCCI 'b2e2' -> ((row,col),(row,col)); row 0 = 黑方底线(FEN 首行) = 9 - rank."""
    g = MOVE_RE.match(m)
    if not g:
        raise ValueError(f'走法格式错误: {m}')
    return (9 - int(g.group(2)), ord(g.group(1)) - 97), (9 - int(g.group(4)), ord(g.group(3)) - 97)


def fen_from_moves(moves_ucci):
    """从初始局面盲走生成 FEN(不走法合法性校验, 走法来自服务器视为可信)。"""
    grid = list(INITIAL_GRID)
    turn = 'w'
    for m in moves_ucci:
        (r1, c1), (r2, c2) = ucci_to_rc(m)
        grid[r2 * 9 + c2] = grid[r1 * 9 + c1]
        grid[r1 * 9 + c1] = '.'
        turn = 'b' if turn == 'w' else 'w'
    rows = []
    for r in range(10):
        row, empty = '', 0
        for c in range(9):
            ch = grid[r * 9 + c]
            if ch == '.':
                empty += 1
            else:
                if empty:
                    row += str(empty)
                    empty = 0
                row += ch
        if empty:
            row += str(empty)
        rows.append(row)
    return '/'.join(rows) + f' {turn} - - 0 1'