/*
 * engine-cli -- interroge le moteur d'Ustagammon en ligne de commande.
 *
 * Copyright (C) 2026 les auteurs d'Ustagammon.
 * Licence : GPLv3 ou ultérieure (voir LICENSE).
 *
 * Usage :
 *   engine-cli [--ply N] [--data DOSSIER] COMMANDE ARGUMENTS
 *
 * Commandes :
 *   bestmove POSITION_ID MATCH_ID DÉS   meilleur coup (DÉS : ex. 31)
 *   moves    POSITION_ID MATCH_ID DÉS   coups légaux classés, évalués
 *   legal    POSITION_ID MATCH_ID DÉS   coups légaux, sans évaluation
 *   cube     POSITION_ID MATCH_ID       décision de videau
 *   eval     POSITION_ID MATCH_ID       évaluation de la position
 *   reference POSITION_ID MATCH_ID [DÉS]
 *                                       un niveau au format des positions de
 *                                       référence (tests/reference/README.md) :
 *                                       évaluation, puis classement des coups
 *                                       avec DÉS, décision de videau sans
 *
 * --ply : niveau de gnubg, de 0 (défaut) à 4.
 * --data : dossier des données ; par défaut « data » à côté du programme.
 *
 * En WebAssembly (engine-wasm/), le même programme sert d'interface : le
 * JavaScript appelle main pour chaque commande, sans recharger le moteur.
 * engine_init ne fait rien quand le moteur est déjà prêt, et main ne l'arrête
 * pas à la fin.
 *
 * Sortie : un objet JSON sur la sortie standard. En cas d'erreur, un objet
 * {"error": {"code": ..., "message": ...}} et un code de sortie non nul :
 * 1 pour une erreur du moteur, 2 pour une erreur d'utilisation.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "engine.h"

#define EXIT_ENGINE_ERROR 1
#define EXIT_USAGE_ERROR 2

/* Format des nombres : 9 chiffres significatifs redonnent exactement le
 * float32 calculé par gnubg. */
#define NUMBER "%.9g"

/* Coups gardés dans le classement de la commande reference (comme hint). */
#define REFERENCE_MAX_MOVES 10

/* Arguments de la ligne de commande, une fois lus. */
typedef struct {
    int ply;
    const char *data_dir;
    const char *command;
    const char *args[3];
    int arg_count;
} options;

/* Code d'erreur JSON pour chaque engine_status. */
static const char *
status_code(engine_status status)
{
    switch (status) {
    case ENGINE_OK:
        return "ok";
    case ENGINE_ERROR_NOT_INITIALISED:
        return "not_initialised";
    case ENGINE_ERROR_DATA:
        return "invalid_data";
    case ENGINE_ERROR_POSITION_ID:
        return "invalid_position_id";
    case ENGINE_ERROR_MATCH_ID:
        return "invalid_match_id";
    case ENGINE_ERROR_DICE:
        return "invalid_dice";
    case ENGINE_ERROR_PLY:
        return "invalid_ply";
    case ENGINE_ERROR_TOO_MANY_MOVES:
        return "too_many_moves";
    case ENGINE_ERROR_INTERNAL:
        return "internal_error";
    }
    return "unknown_error";
}

/* Les messages sont des constantes sans guillemets : pas d'échappement. */
static int
print_error(const char *code, const char *message, int exit_code)
{
    printf("{\"error\": {\"code\": \"%s\", \"message\": \"%s\"}}\n", code, message);
    return exit_code;
}

static int
print_engine_error(engine_status status)
{
    return print_error(status_code(status), engine_status_message(status), EXIT_ENGINE_ERROR);
}

static int
usage_error(const char *message)
{
    return print_error("usage", message, EXIT_USAGE_ERROR);
}

static void
print_probabilities(const float p[ENGINE_NUM_PROBABILITIES])
{
    printf("{\"win\": " NUMBER ", \"win_gammon\": " NUMBER ", \"win_backgammon\": " NUMBER ", "
           "\"lose_gammon\": " NUMBER ", \"lose_backgammon\": " NUMBER "}",
           p[ENGINE_WIN], p[ENGINE_WIN_GAMMON], p[ENGINE_WIN_BACKGAMMON],
           p[ENGINE_LOSE_GAMMON], p[ENGINE_LOSE_BACKGAMMON]);
}

static void
print_move(const engine_move *m, int with_evaluation)
{
    printf("{\"move\": \"%s\", \"position_id\": \"%s\"", m->notation, m->position_id);
    if (with_evaluation) {
        printf(", \"ply\": %d, \"equity\": " NUMBER ", \"probabilities\": ", m->ply, m->equity);
        print_probabilities(m->probabilities);
    }
    printf("}");
}

static void
print_match(const engine_match *m)
{
    printf("{\"match_length\": %d, \"score\": [%d, %d], \"cube_value\": %d, "
           "\"cube_owner\": %d, \"player_on_roll\": %d, \"crawford\": %s, \"jacoby\": %s}",
           m->match_length, m->score[0], m->score[1], m->cube_value, m->cube_owner,
           m->player_on_roll, m->crawford ? "true" : "false", m->jacoby ? "true" : "false");
}

/* Champs d'une décision de videau, sans les accolades. */
static void
print_cube_fields(const engine_cube *c)
{
    printf("\"no_double\": " NUMBER ", \"double_take\": " NUMBER ", \"double_pass\": " NUMBER
           ", \"optimal\": " NUMBER ", \"decision\": \"%s\", \"decision_text\": \"%s\"",
           c->no_double, c->double_take, c->double_pass, c->optimal, c->decision,
           c->decision_text);
}

/* Début d'un niveau de référence : {"evaluation": {...} (objet laissé ouvert). */
static void
print_reference_evaluation(const engine_evaluation *e)
{
    printf("{\"evaluation\": {\"probabilities\": ");
    print_probabilities(e->probabilities);
    printf(", \"equity\": " NUMBER "}", e->cubeless_equity);
}

/* Lit des dés au format « 31 » ; renvoie 0 si le format est faux. */
static int
parse_dice(const char *text, int *die1, int *die2)
{
    if (strlen(text) != 2 || text[0] < '0' || text[0] > '9' || text[1] < '0' || text[1] > '9')
        return 0;
    *die1 = text[0] - '0';
    *die2 = text[1] - '0';
    return 1;
}

/* bestmove, moves et legal. */
static int
run_moves_command(const options *opt)
{
    const char *position_id = opt->args[0], *match_id = opt->args[1];
    int best_only = strcmp(opt->command, "bestmove") == 0;
    int evaluate = strcmp(opt->command, "legal") != 0;
    int die1, die2, count, i;
    engine_move *moves;
    engine_status status;

    if (opt->arg_count != 3)
        return usage_error("arguments attendus : POSITION_ID MATCH_ID DÉS");
    if (!parse_dice(opt->args[2], &die1, &die2))
        return usage_error("dés attendus sous la forme 31");

    moves = malloc(sizeof *moves * ENGINE_MAX_MOVES);
    if (!moves)
        return print_error("out_of_memory", "mémoire insuffisante", EXIT_ENGINE_ERROR);
    if (evaluate)
        status = engine_best_moves(position_id, match_id, die1, die2, opt->ply,
                                   moves, ENGINE_MAX_MOVES, &count);
    else
        status = engine_legal_moves(position_id, match_id, die1, die2,
                                    moves, ENGINE_MAX_MOVES, &count);
    if (status != ENGINE_OK) {
        free(moves);
        return print_engine_error(status);
    }

    printf("{\"position_id\": \"%s\", \"match_id\": \"%s\", \"dice\": [%d, %d]",
           position_id, match_id, die1, die2);
    if (evaluate)
        printf(", \"ply\": %d", opt->ply);
    if (best_only) {
        printf(", \"best_move\": ");
        if (count > 0)
            print_move(&moves[0], 1);
        else
            printf("null");
    } else {
        printf(", \"count\": %d, \"moves\": [", count);
        for (i = 0; i < count; i++) {
            printf(i ? ", " : "");
            print_move(&moves[i], evaluate);
        }
        printf("]");
    }
    printf("}\n");
    free(moves);
    return EXIT_SUCCESS;
}

/* eval et cube. */
static int
run_position_command(const options *opt)
{
    const char *position_id = opt->args[0], *match_id = opt->args[1];
    engine_match match;
    engine_status status;

    if (opt->arg_count != 2)
        return usage_error("arguments attendus : POSITION_ID MATCH_ID");
    status = engine_decode_match(match_id, &match);
    if (status != ENGINE_OK)
        return print_engine_error(status);

    if (strcmp(opt->command, "eval") == 0) {
        engine_evaluation e;
        status = engine_evaluate(position_id, match_id, opt->ply, &e);
        if (status != ENGINE_OK)
            return print_engine_error(status);
        printf("{\"position_id\": \"%s\", \"match_id\": \"%s\", \"ply\": %d, \"match\": ",
               position_id, match_id, opt->ply);
        print_match(&match);
        printf(", \"probabilities\": ");
        print_probabilities(e.probabilities);
        printf(", \"cubeless_equity\": " NUMBER ", \"cubeful_equity\": " NUMBER "}\n",
               e.cubeless_equity, e.cubeful_equity);
    } else {
        engine_cube c;
        status = engine_cube_decision(position_id, match_id, opt->ply, &c);
        if (status != ENGINE_OK)
            return print_engine_error(status);
        printf("{\"position_id\": \"%s\", \"match_id\": \"%s\", \"ply\": %d, \"match\": ",
               position_id, match_id, opt->ply);
        print_match(&match);
        printf(", \"probabilities\": ");
        print_probabilities(c.probabilities);
        printf(", ");
        print_cube_fields(&c);
        printf("}\n");
    }
    return EXIT_SUCCESS;
}

/*
 * reference : un niveau d'un fichier de résultat de tests/reference/, de
 * même structure que plies["<n>"] (voir tests/reference/README.md).
 */
static int
run_reference_command(const options *opt)
{
    const char *position_id = opt->args[0], *match_id = opt->args[1];
    engine_evaluation e;
    engine_status status;
    int die1, die2, count, i;

    if (opt->arg_count != 2 && opt->arg_count != 3)
        return usage_error("arguments attendus : POSITION_ID MATCH_ID [DÉS]");
    if (opt->arg_count == 3 && !parse_dice(opt->args[2], &die1, &die2))
        return usage_error("dés attendus sous la forme 31");

    status = engine_evaluate(position_id, match_id, opt->ply, &e);
    if (status != ENGINE_OK)
        return print_engine_error(status);

    if (opt->arg_count == 3) {
        engine_move *moves = malloc(sizeof *moves * ENGINE_MAX_MOVES);
        if (!moves)
            return print_error("out_of_memory", "mémoire insuffisante", EXIT_ENGINE_ERROR);
        status = engine_best_moves(position_id, match_id, die1, die2, opt->ply,
                                   moves, ENGINE_MAX_MOVES, &count);
        if (status != ENGINE_OK) {
            free(moves);
            return print_engine_error(status);
        }
        print_reference_evaluation(&e);
        printf(", \"moves\": {\"legal_move_count\": %d, \"ranking\": [", count);
        for (i = 0; i < count && i < REFERENCE_MAX_MOVES; i++) {
            printf("%s{\"rank\": %d, \"move\": \"%s\", \"ply\": %d, \"equity\": " NUMBER
                   ", \"equity_diff\": " NUMBER ", \"probabilities\": ",
                   i ? ", " : "", i + 1, moves[i].notation, moves[i].ply, moves[i].equity,
                   moves[i].equity - moves[0].equity);
            print_probabilities(moves[i].probabilities);
            printf("}");
        }
        printf("]}}\n");
        free(moves);
    } else {
        engine_cube c;
        status = engine_cube_decision(position_id, match_id, opt->ply, &c);
        if (status != ENGINE_OK)
            return print_engine_error(status);
        print_reference_evaluation(&e);
        printf(", \"cube\": {");
        print_cube_fields(&c);
        printf("}}\n");
    }
    return EXIT_SUCCESS;
}

/* Dossier « data » à côté du programme. */
static char *
default_data_dir(const char *program)
{
    const char *slash = strrchr(program, '/');
    size_t dir_length = slash ? (size_t) (slash - program) : 1;
    char *dir = malloc(dir_length + sizeof "/data");

    if (!dir)
        return NULL;
    if (slash)
        memcpy(dir, program, dir_length);
    else
        dir[0] = '.';
    strcpy(dir + dir_length, "/data");
    return dir;
}

/* Lit les options ; renvoie un message d'erreur, ou NULL si tout va bien. */
static const char *
parse_options(int argc, char **argv, options *opt)
{
    int i;

    memset(opt, 0, sizeof *opt);
    for (i = 1; i < argc; i++) {
        if (strcmp(argv[i], "--ply") == 0 && i + 1 < argc) {
            char *end;
            opt->ply = (int) strtol(argv[++i], &end, 10);
            if (*end || end == argv[i])
                return "--ply attend un nombre";
        } else if (strcmp(argv[i], "--data") == 0 && i + 1 < argc) {
            opt->data_dir = argv[++i];
        } else if (argv[i][0] == '-' && argv[i][1] == '-') {
            return "option inconnue ou sans valeur";
        } else if (!opt->command) {
            opt->command = argv[i];
        } else if (opt->arg_count < 3) {
            opt->args[opt->arg_count++] = argv[i];
        } else {
            return "trop d'arguments";
        }
    }
    if (!opt->command)
        return "commande attendue : bestmove, moves, legal, cube, eval ou reference";
    return NULL;
}

int
main(int argc, char **argv)
{
    options opt;
    const char *problem = parse_options(argc, argv, &opt);
    char *data_dir = NULL;
    engine_status status;
    int result;

    if (problem)
        return usage_error(problem);
    if (!opt.data_dir) {
        data_dir = default_data_dir(argv[0]);
        if (!data_dir)
            return print_error("out_of_memory", "mémoire insuffisante", EXIT_ENGINE_ERROR);
        opt.data_dir = data_dir;
    }

    status = engine_init(opt.data_dir);
    free(data_dir);
    if (status != ENGINE_OK)
        return print_engine_error(status);

    if (strcmp(opt.command, "bestmove") == 0 || strcmp(opt.command, "moves") == 0
        || strcmp(opt.command, "legal") == 0)
        result = run_moves_command(&opt);
    else if (strcmp(opt.command, "eval") == 0 || strcmp(opt.command, "cube") == 0)
        result = run_position_command(&opt);
    else if (strcmp(opt.command, "reference") == 0)
        result = run_reference_command(&opt);
    else
        result = usage_error("commande inconnue : bestmove, moves, legal, cube, eval ou reference");

#ifndef __EMSCRIPTEN__
    engine_shutdown();
#endif
    return result;
}