#include "kknd.h"

/* =========================================================================
 * engine.c - Match setup, main simulation step and win/lose logic.
 * ========================================================================= */

int g_headless = 0;
int g_auto = 0;

void engine_log(const char *fmt, ...) {
    va_list ap;
    va_start(ap, fmt);
    char buf[512];
    vsnprintf(buf, sizeof buf, fmt, ap);
    va_end(ap);
    printf("[kknd] %s\n", buf);
    fflush(stdout);
}

void game_log(Game *g, const char *fmt, ...) {
    va_list ap;
    va_start(ap, fmt);
    vsnprintf(g->log_msg[g->log_next], 96, fmt, ap);
    va_end(ap);
    g->log_next = (g->log_next + 1) % 32;
    if (g->log_count < 32) g->log_count++;
}

void engine_init(Game *g, const char *title) {
    memset(g, 0, sizeof(Game));
    g->wrecks = (Wreck *)calloc(MAX_WRECKS, sizeof(Wreck));
    config_init();
    if (!g_headless) {
        audio_init();
        if (!render_init(g)) {
            fprintf(stderr, "Failed to initialise renderer\n");
            exit(1);
        }
    } else {
        (void)title;
    }
    g->state = GAME_MENU;
    g->human = FACTION_SURVIVOR;
    g->diff = DIFF_NORMAL;
    g->speed_mul = 1.0f;
    g->unlocked = 1;
    g->menu_sel = 0;
}

void engine_shutdown(Game *g) {
    free(g->wrecks);
    sprites_free(&g->spr);
    if (g->ren) SDL_DestroyRenderer(g->ren);
    if (g->win) SDL_DestroyWindow(g->win);
    audio_shutdown();
    SDL_Quit();
    map_free(&g->map);
}

static void place_start(Game *g, Faction f) {
    int sx = g->map.spawn_x[f], sy = g->map.spawn_y[f];
    int bx = sx - 1, by = sy - 1;
    bld_spawn(g, BT_BASE, f, bx, by);
    bld_spawn(g, BT_REFINERY, f, bx, sy + 2);
    bld_spawn(g, BT_WARFACTORY, f, sx + 2, by);
    bld_spawn(g, BT_POWER, f, sx + 2, sy + 2);

    float wx, wy; map_tile_to_world(sx, sy, &wx, &wy);
    /* harvesters */
    for (int i = 0; i < 2; i++)
        unit_spawn(g, UT_HARVESTER, f, wx + (i*24-12), wy + 30);
    /* starting infantry */
    for (int i = 0; i < 4; i++)
        unit_spawn(g, (f==FACTION_SURVIVOR?UT_INFANTRY:UT_INFANTRY), f,
                   wx - 40 + i*20, wy - 20);
    /* a couple of buggies */
    for (int i = 0; i < 2; i++)
        unit_spawn(g, (f==FACTION_SURVIVOR?UT_BUGGY:UT_BUGGY), f,
                   wx - 30 + i*30, wy - 40);
}

void engine_setup_match(Game *g, int mission_id) {
    const Mission *m = mission_get(mission_id);
    g->mission_id = m->id;
    g->objective = m->objective;
    g->diff = (Difficulty)m->diff;
    g->obj_timer = 0;

    /* resolve the enemy faction (never the player's own side) */
    Faction enemy = m->enemy;
    if (enemy == g->human)
        enemy = (g->human == FACTION_SURVIVOR) ? FACTION_EVOLVED : FACTION_SURVIVOR;
    g->enemy = enemy;

    RNG rng;
    rng_seed(&rng, (uint64_t)m->seed ^ 0x4B4B4E44ULL);
    g->map.style = m->map_style;
    map_init(&g->map, &rng);

    g->unit_count = 0; g->unit_next_id = 1;
    g->bld_count = 0; g->bld_next_id = 1;
    g->bullet_count = 0; g->particle_count = 0;
    g->sel_count = 0; g->placing = 0;
    g->time = 0; g->frames = 0; g->winner = 0;
    g->ai_timer = 5.0f;
    g->log_count = 0; g->log_next = 0;

    for (int f = 1; f < MAX_FACTIONS; f++) {
        g->scrap[f] = START_SCRAP;
        g->power[f] = 0; g->pop[f] = 0; g->pop_cap[f] = 0;
        for (int u = 0; u < UP_COUNT; u++) g->upg[f].lvl[u] = 0;
        g->research_lab[f] = 0;
        g->research_cur[f] = -1;
        g->research_prog[f] = 0;
    }

    place_start(g, g->human);
    place_start(g, enemy);

    /* fortress theme: wall the enemy base (leave a gate on the far edge) */
    if (m->map_style == 3) {
        int sx = g->map.spawn_x[enemy], sy = g->map.spawn_y[enemy];
        for (int dx = -2; dx <= 4; dx++)
            for (int dy = -2; dy <= 4; dy++) {
                int perimeter = (dx == -2 || dx == 4 || dy == -2 || dy == 4);
                if (!perimeter) continue;
                if (dy == 4) continue;          /* gate on the far edge */
                bld_spawn(g, BT_WALL, enemy, sx + dx, sy + dy);
            }
    }

    /* centre camera on player base */
    int hx = g->map.spawn_x[g->human], hy = g->map.spawn_y[g->human];
    g->cam.x = (float)(hx*TILE - VIEW_W/2);
    g->cam.y = (float)(hy*TILE - VIEW_H/2);
    if (g->cam.x < 0) g->cam.x = 0;
    if (g->cam.y < 0) g->cam.y = 0;

    g->state = GAME_PLAYING;
    engine_log("Mission %d '%s': %s vs %s (%s)",
        m->id, m->name, faction_name(g->human), faction_name(enemy),
        m->diff==DIFF_EASY?"Easy":m->diff==DIFF_HARD?"Hard":"Normal");
}

void engine_check_win(Game *g) {
    Faction human = g->human;
    Faction enemy = g->enemy;
    int human_base = 0, enemy_base = 0;
    int human_bld = 0, enemy_bld = 0;
    for (int i = 0; i < g->bld_count; i++) {
        Building *b = &g->buildings[i];
        if (b->dead) continue;
        if (b->faction == human) { human_bld++; if (b->type==BT_BASE) human_base=1; }
        if (b->faction == enemy) { enemy_bld++; if (b->type==BT_BASE) enemy_base=1; }
    }
    if (!human_base || human_bld == 0) { g->state = GAME_LOST; g->winner = enemy; return; }

    switch (g->objective) {
        case OBJ_SURVIVE:
            if (g->time >= ((const Mission*)mission_get(g->mission_id))->survive_time)
                { g->state = GAME_WON; g->winner = human; }
            break;
        case OBJ_GATHER:
            if (g->scrap[human] >= ((const Mission*)mission_get(g->mission_id))->scrap_goal)
                { g->state = GAME_WON; g->winner = human; }
            break;
        default: /* OBJ_DESTROY_ALL */
            if (!enemy_base || enemy_bld == 0) { g->state = GAME_WON; g->winner = human; }
            break;
    }
}

void engine_update(Game *g, float dt) {
    if (g->state != GAME_PLAYING) return;
    dt *= g->speed_mul;
    g->time += dt;
    g->frames++;

    unit_update(g, dt);
    bld_update(g, dt);
    bullet_update(g, dt);
    particle_update(g, dt);
    ai_update(g, dt);
    map_update_fog(g, g->human);
    audio_music_tick(dt);
    if (g->cam.shake > 0) { g->cam.shake -= dt * 24.0f; if (g->cam.shake < 0) g->cam.shake = 0; }
    engine_check_win(g);
}