/* ── Chess command handler ──────────────────────────────────── */

#include "hybbx/chess.h"
#include "hybbx/session.h"
#include "hybbx/service.h"
#include "hybbx/hybbx.h"

#include <string.h>
#include <strings.h>
#include <stdio.h>
#include <ctype.h>

static int str_ieq(const char *a, const char *b)
{
    if (a == NULL || b == NULL) return 0;
    while (*a != '\0' && *b != '\0') {
        char ca = (char)(*a >= 'A' && *a <= 'Z' ? *a + 32 : *a);
        char cb = (char)(*b >= 'A' && *b <= 'Z' ? *b + 32 : *b);
        if (ca != cb) return 0;
        a++; b++;
    }
    return *a == '\0' && *b == '\0';
}

hybbx_result_t cmd_chess(hybbx_service_t *service,
                         hybbx_session_t *session,
                         const hybbx_parsed_command_t *cmd)
{
    const char *sub;
    chess_game_t *game;
    char line[128];

    (void)service;

    if (!hybbx_session_logged_in(session)) {
        hybbx_session_write_line(session, "Log in to play chess.");
        return HYBBX_ERR_DENIED;
    }

    sub = (cmd->argc >= 1) ? cmd->argv[0] : "help";

    /* ── /chess help ───────────────────────────────────────── */
    if (str_ieq(sub, "help") || str_ieq(sub, "?")) {
        hybbx_session_write_line(session, "Chess commands:");
        hybbx_session_write_line(session,
            "  /chess new        - Create a new game (you are White)");
        hybbx_session_write_line(session,
            "  /chess join       - Join an open game as Black");
        hybbx_session_write_line(session,
            "  /chess join G2    - Join a specific game by ID");
        hybbx_session_write_line(session,
            "  /chess watch      - Watch a game as spectator");
        hybbx_session_write_line(session,
            "  /chess watch G2   - Watch a specific game");
        hybbx_session_write_line(session,
            "  /chess board      - Show current board");
        hybbx_session_write_line(session,
            "  /chess move e2 e4 - Move piece (alias: /mv e2 e4)");
        hybbx_session_write_line(session,
            "  /chess resign     - Resign the game");
        hybbx_session_write_line(session,
            "  /chess draw       - Offer/accept draw");
        hybbx_session_write_line(session,
            "  /chess list       - List games with board + spectators");
        hybbx_session_write_line(session,
            "  /chess leave      - Stop watching");
        hybbx_session_write_line(session,
            "Board auto-refreshes every 15 seconds for all.");
        return HYBBX_OK;
    }

    /* ── /chess list ───────────────────────────────────────── */
    if (str_ieq(sub, "list") || str_ieq(sub, "ls")) {
        unsigned found = 0;
        unsigned i;
        for (i = 0; i < hybbx_chess_max_games(); i++) {
            game = hybbx_chess_get_game(i);
            if (game == NULL || !game->active) continue;

            /* Header: game id, players, state */
            {
                const char *state =
                    (game->result != CHESS_RESULT_NONE) ? "finished" :
                    (game->black_session == NULL) ? "waiting for Black" : "playing";
                snprintf(line, sizeof(line),
                         "[%s] %s(W) vs %s(B)  %s  move %u",
                         game->game_id, game->white_name,
                         game->black_session ? game->black_name : "...",
                         state, game->move_number);
            }
            hybbx_session_write_line(session, line);

            /* Board */
            hybbx_chess_send_board(game, session);

            /* Spectators */
            if (game->spectator_count > 0) {
                unsigned j;
                int n = snprintf(line, sizeof(line), "  Spectators (%u): ",
                                 game->spectator_count);
                for (j = 0; j < game->spectator_count; j++) {
                    const char *sname = hybbx_session_display_name(
                                            game->spectators[j]);
                    if (j > 0)
                        n += snprintf(line + n, sizeof(line) - (size_t)n, ", ");
                    n += snprintf(line + n, sizeof(line) - (size_t)n, "%s",
                                  sname ? sname : "?");
                }
                hybbx_session_write_line(session, line);
            }

            hybbx_session_write_line(session, "");
            found++;
        }
        if (!found)
            hybbx_session_write_line(session, "  No active games.");
        return HYBBX_OK;
    }

    /* ── /chess new ────────────────────────────────────────── */
    if (str_ieq(sub, "new") || str_ieq(sub, "create")) {
        unsigned i;
        for (i = 0; i < hybbx_chess_max_games(); i++) {
            game = hybbx_chess_get_game(i);
            if (game && game->active &&
                hybbx_chess_is_player(game, session)) {
                hybbx_session_write_line(session,
                    "You are already in a game. /chess resign first.");
                return HYBBX_ERR_DENIED;
            }
        }
        game = hybbx_chess_create_game(session,
                                       hybbx_session_username(session));
        if (game == NULL) {
            hybbx_session_write_line(session, "No free game slots.");
            return HYBBX_ERR_DENIED;
        }
        snprintf(line, sizeof(line), "Game %s created. You are White.",
                 game->game_id);
        hybbx_session_write_line(session, line);
        hybbx_session_write_line(session,
            "Waiting for Black to /chess join...");
        hybbx_chess_send_board(game, session);
        return HYBBX_OK;
    }

    /* ── /chess join [id] ──────────────────────────────────── */
    if (str_ieq(sub, "join")) {
        const char *id = (cmd->argc >= 2) ? cmd->argv[1] : NULL;
        unsigned i;

        for (i = 0; i < hybbx_chess_max_games(); i++) {
            game = hybbx_chess_get_game(i);
            if (game && game->active &&
                hybbx_chess_is_player(game, session)) {
                hybbx_session_write_line(session,
                    "You are already in a game. /chess resign first.");
                return HYBBX_ERR_DENIED;
            }
        }

        if (id) {
            game = hybbx_chess_find_game_by_id(id);
            if (game == NULL || !game->active) {
                hybbx_session_write_line(session, "Game not found.");
                return HYBBX_ERR_NOT_FOUND;
            }
            if (game->black_session != NULL) {
                hybbx_session_write_line(session, "Game is full.");
                return HYBBX_ERR_DENIED;
            }
        } else {
            game = hybbx_chess_find_open_game();
            if (game == NULL) {
                hybbx_session_write_line(session,
                    "No open games. /chess new to create one.");
                return HYBBX_ERR_NOT_FOUND;
            }
        }

        hybbx_chess_join_game(game, session,
                              hybbx_session_username(session));
        snprintf(line, sizeof(line), "Joined %s as Black. Game on!",
                 game->game_id);
        hybbx_session_write_line(session, line);
        hybbx_chess_send_board(game, game->white_session);
        hybbx_chess_send_board(game, session);
        return HYBBX_OK;
    }

    /* ── /chess watch [id] ─────────────────────────────────── */
    if (str_ieq(sub, "watch") || str_ieq(sub, "spectate")) {
        const char *id = (cmd->argc >= 2) ? cmd->argv[1] : NULL;
        unsigned i;

        if (id) {
            game = hybbx_chess_find_game_by_id(id);
        } else {
            game = NULL;
            for (i = 0; i < hybbx_chess_max_games(); i++) {
                chess_game_t *g = hybbx_chess_get_game(i);
                if (g && g->active && g->black_session != NULL) {
                    game = g;
                    break;
                }
            }
        }
        if (game == NULL || !game->active) {
            hybbx_session_write_line(session, "No game to watch.");
            return HYBBX_ERR_NOT_FOUND;
        }
        if (!hybbx_chess_add_spectator(game, session)) {
            hybbx_session_write_line(session, "Spectator list full.");
            return HYBBX_ERR_DENIED;
        }
        snprintf(line, sizeof(line),
                 "Watching %s. Board refreshes every %ds.",
                 game->game_id, CHESS_REFRESH_SEC);
        hybbx_session_write_line(session, line);
        hybbx_chess_send_board(game, session);
        return HYBBX_OK;
    }

    /* ── /chess leave ──────────────────────────────────────── */
    if (str_ieq(sub, "leave") || str_ieq(sub, "unwatch")) {
        unsigned i;
        for (i = 0; i < hybbx_chess_max_games(); i++) {
            game = hybbx_chess_get_game(i);
            if (game && game->active &&
                hybbx_chess_is_spectator(game, session)) {
                hybbx_chess_remove_spectator(game, session);
                hybbx_session_write_line(session, "Stopped watching.");
                return HYBBX_OK;
            }
        }
        hybbx_session_write_line(session,
            "You are not watching any game.");
        return HYBBX_ERR_NOT_FOUND;
    }

    /* ── /chess board ──────────────────────────────────────── */
    if (str_ieq(sub, "board") || str_ieq(sub, "show")) {
        unsigned i;
        game = NULL;
        for (i = 0; i < hybbx_chess_max_games(); i++) {
            chess_game_t *g = hybbx_chess_get_game(i);
            if (g && g->active &&
                (hybbx_chess_is_player(g, session) ||
                 hybbx_chess_is_spectator(g, session))) {
                game = g;
                break;
            }
        }
        if (game == NULL) {
            hybbx_session_write_line(session,
                "Not in a game. /chess new, join, or watch.");
            return HYBBX_ERR_NOT_FOUND;
        }
        hybbx_chess_send_board(game, session);
        return HYBBX_OK;
    }

    /* ── /chess move e2 e4 ─────────────────────────────────── */
    if (str_ieq(sub, "move") || str_ieq(sub, "mv") || str_ieq(sub, "m")) {
        const char *from, *to;
        char err[64];
        unsigned i;

        if (cmd->argc < 3) {
            hybbx_session_write_line(session,
                "Usage: /chess move e2 e4");
            return HYBBX_ERR_INVALID;
        }
        from = cmd->argv[1];
        to   = cmd->argv[2];

        game = NULL;
        for (i = 0; i < hybbx_chess_max_games(); i++) {
            chess_game_t *g = hybbx_chess_get_game(i);
            if (g && g->active && g->result == CHESS_RESULT_NONE &&
                hybbx_chess_is_player(g, session)) {
                chess_color_t color = hybbx_chess_player_color(g, session);
                if (color == g->turn) {
                    game = g;
                    break;
                }
            }
        }
        if (game == NULL) {
            hybbx_session_write_line(session,
                "Not your turn or no active game.");
            return HYBBX_ERR_DENIED;
        }

        if (!hybbx_chess_make_move(game, from, to, 0, err, sizeof(err))) {
            snprintf(line, sizeof(line), "Illegal: %s", err);
            hybbx_session_write_line(session, line);
            return HYBBX_ERR_INVALID;
        }

        /* Broadcast to all */
        if (game->white_session)
            hybbx_chess_send_board(game, game->white_session);
        if (game->black_session)
            hybbx_chess_send_board(game, game->black_session);
        {
            unsigned j;
            for (j = 0; j < game->spectator_count; j++)
                hybbx_chess_send_board(game, game->spectators[j]);
        }

        if (game->result != CHESS_RESULT_NONE) {
            const char *res;
            unsigned j;
            switch (game->result) {
            case CHESS_WHITE_WINS:     res = "White wins!"; break;
            case CHESS_BLACK_WINS:     res = "Black wins!"; break;
            case CHESS_DRAW_STALEMATE: res = "Stalemate!"; break;
            case CHESS_DRAW_AGREEMENT: res = "Draw!"; break;
            default:                   res = "Game over."; break;
            }
            snprintf(line, sizeof(line), "[%s] %s", game->game_id, res);
            if (game->white_session)
                hybbx_session_write_line(game->white_session, line);
            if (game->black_session)
                hybbx_session_write_line(game->black_session, line);
            for (j = 0; j < game->spectator_count; j++)
                hybbx_session_write_line(game->spectators[j], line);
        }

        return HYBBX_OK;
    }

    /* ── /chess resign ─────────────────────────────────────── */
    if (str_ieq(sub, "resign")) {
        unsigned i;
        game = NULL;
        for (i = 0; i < hybbx_chess_max_games(); i++) {
            chess_game_t *g = hybbx_chess_get_game(i);
            if (g && g->active && hybbx_chess_is_player(g, session)) {
                game = g;
                break;
            }
        }
        if (game == NULL) {
            hybbx_session_write_line(session, "You are not in a game.");
            return HYBBX_ERR_NOT_FOUND;
        }
        hybbx_chess_resign(game, session);
        snprintf(line, sizeof(line), "[%s] %s resigned.",
                 game->game_id, hybbx_session_username(session));
        if (game->white_session)
            hybbx_session_write_line(game->white_session, line);
        if (game->black_session)
            hybbx_session_write_line(game->black_session, line);
        {
            unsigned j;
            for (j = 0; j < game->spectator_count; j++)
                hybbx_session_write_line(game->spectators[j], line);
        }
        return HYBBX_OK;
    }

    /* ── /chess draw ───────────────────────────────────────── */
    if (str_ieq(sub, "draw")) {
        unsigned i;
        game = NULL;
        for (i = 0; i < hybbx_chess_max_games(); i++) {
            chess_game_t *g = hybbx_chess_get_game(i);
            if (g && g->active && hybbx_chess_is_player(g, session)) {
                game = g;
                break;
            }
        }
        if (game == NULL) {
            hybbx_session_write_line(session, "You are not in a game.");
            return HYBBX_ERR_NOT_FOUND;
        }
        hybbx_chess_offer_draw(game, session);
        snprintf(line, sizeof(line), "[%s] Draw agreed.",
                 game->game_id);
        if (game->white_session)
            hybbx_session_write_line(game->white_session, line);
        if (game->black_session)
            hybbx_session_write_line(game->black_session, line);
        {
            unsigned j;
            for (j = 0; j < game->spectator_count; j++)
                hybbx_session_write_line(game->spectators[j], line);
        }
        return HYBBX_OK;
    }

    hybbx_session_write_line(session,
        "Unknown chess command. /chess help for list.");
    return HYBBX_ERR_NOT_FOUND;
}