#include "cglm/call/vec2.h"

#include "game.h"
#include "scufeng/engine.h"
#include "scufeng/util.h"

typedef enum {
    BCR_PADDLE_L_GOAL,
    BCR_PADDLE_R_GOAL,
} BALL_COLLISION_RESULT;

const GameStateParameters game_default_params = {
    .paddles_w = 0.01f,
    .paddles_h = 0.10f,
    .paddle_l_x = (1.0f / 16),
    .ball_w = 0.005f,
    .ball_pos = { 0.5f, 0.5f },
    .paddle_speed = 0.7f,
    .ball_speed = 0.7f,
};

const char *GameStateEvent_to_str(const GameStateEvent evt) {
#define X(evt) \
    case evt: \
        return #evt;

    switch (evt) {
        XGameStateEvent(X)
    }

#undef X
}

GameState GameState_new(
    const GameStateParameters params,
    const bool ai_enabled
) {

#define BALL_START_DIR { -1.0f, 0.0f }

    // clang-format off
    GameState state = {
        .ai_enabled = ai_enabled,
        .paddle_l = {
            .pos = { params.paddle_l_x, 0.5f },
            .w = params.paddles_w,
            .h = params.paddles_h,
            .dirv = GLM_VEC2_ZERO_INIT,
            .speed = params.paddle_speed
        },
        .paddle_r = {
            .pos = { 1.0f - params.paddle_l_x, 0.5f },
            .w = params.paddles_w,
            .h = params.paddles_h,
            .dirv = GLM_VEC2_ZERO_INIT,
            .speed = params.paddle_speed
        },
        .ball = {
            // .pos = { 0.5f, 0.5f },
            .pos = { params.ball_pos[0], params.ball_pos[1] },
            .w = params.ball_w,
            .h = params.ball_w,
            .dirv = BALL_START_DIR,
            .speed = params.ball_speed
        },
        .ball_start_pos = { params.ball_pos[0], params.ball_pos[1] },
        .ball_start_dir = BALL_START_DIR,
        .score_l = 0,
        .score_r = 0
    };
    // clang-format on

    return state;
}

static void paddle_collision_check(MovingObject *const paddle) {
    if (paddle->pos[1] - paddle->h / 2.0f < 0.0f) {
        paddle->pos[1] = paddle->h / 2.0f;
    }
    if (paddle->pos[1] + paddle->h / 2.0f > 1.0f) {
        paddle->pos[1] = 1.0f - paddle->h / 2.0f;
    }
}

static void paddle_r_change_dir_ai(GameState *const state) {
    const float ball_y = state->ball.pos[1];

    const float target_zone_range = state->paddle_r.h / 2.0f;
    const float target_zone_top = state->paddle_r.pos[1] - target_zone_range;
    const float target_zone_middle = state->paddle_r.pos[1];
    const float target_zone_bottom = state->paddle_r.pos[1] + target_zone_range;

    const bool ball_is_below = ball_y > target_zone_bottom;
    const bool ball_is_above = ball_y < target_zone_top;
    const bool ball_is_centered = ball_y <= target_zone_middle + target_zone_range / 2.0f
        && ball_y >= target_zone_middle - target_zone_range / 2.0f;
    // printf("%d%d\n", ball_is_below, ball_is_above);

    if (ball_is_below) {
        state->paddle_r.dirv[1] = 1.0f;
    } else if (ball_is_above) {
        state->paddle_r.dirv[1] = -1.0f;
    } else if (ball_is_centered) {
        state->paddle_r.dirv[1] = 0.0f;
    }
}

static void game_next_round(GameState *const state) {
    glmc_vec2_copy(state->ball_start_pos, state->ball.pos);
    glmc_vec2_copy(state->ball_start_dir, state->ball.dirv);
}

static GameStateEvent ball_bounds_collision_check(GameState *const state, vec2 new_pos) {
    MovingObject *const ball = &state->ball;

    const float wd2 = ball->w / 2.0f;
    const float hd2 = ball->h / 2.0f;

    if (new_pos[0] + wd2 <= 0.0f) {
        return GSEVENT_R_SCORE;
    } else if (new_pos[0] - wd2 >= 1.0f) {
        return GSEVENT_L_SCORE;
    }

    if (new_pos[1] - hd2 < 0.0f) {
        new_pos[1] = hd2;
        glmc_vec2_reflect(ball->dirv, (vec2) { 0.0f, -1.0f }, ball->dirv);
        return GSEVENT_BALL_DIR_CHANGE;
    }
    if (new_pos[1] + hd2 > 1.0f) {
        new_pos[1] = 1.0f - hd2;
        glmc_vec2_reflect(ball->dirv, (vec2) { 0.0f, 1.0f }, ball->dirv);
        return GSEVENT_BALL_DIR_CHANGE;
    }

    return GSEVENT_NONE;
}

static GameStateEvent ball_paddles_collision_check(GameState *const state, vec2 new_pos) {
    static const float possible_y_directions[] = {
        0.0f,
        0.5f,
        -0.5f
    };

    MovingObject *const ball = &state->ball;
    const MovingObject *const paddle_l = &state->paddle_l;
    const MovingObject *const paddle_r = &state->paddle_r;

    const float ball_wd2 = ball->w / 2.0f;
    const float ball_hd2 = ball->h / 2.0f;
    const float paddle_wd2 = paddle_l->w / 2.0f;
    const float paddle_hd2 = paddle_l->h / 2.0f;
    vec2 paddle_side_top;
    vec2 paddle_side_bottom;
    vec2 ball_side_top;
    vec2 ball_side_bottom;
    float paddle_back_x;
    vec2 ball_pos;
    vec2 new_pos_adj;
    paddle_side_top[0] = paddle_l->pos[0] + paddle_wd2;
    paddle_side_top[1] = paddle_l->pos[1] - paddle_hd2;
    paddle_side_bottom[0] = paddle_side_top[0];
    paddle_side_bottom[1] = paddle_l->pos[1] + paddle_hd2;
    ball_side_top[0] = ball->pos[0] - ball_wd2;
    ball_side_top[1] = ball->pos[1] - ball_hd2;
    ball_side_bottom[0] = ball_side_top[0];
    ball_side_bottom[1] = ball->pos[1] + ball_hd2;
    paddle_back_x = paddle_l->pos[0] - paddle_wd2;
    glmc_vec2_copy(ball->pos, ball_pos);
    glmc_vec2_copy(new_pos, new_pos_adj);

    bool collision = false;
    bool mirror_ip = false;
    vec2 ip;

    if (state->ball.dirv[0] > 0.0f) {
        mirror_ip = true;
        paddle_side_top[0] = 1.0f - (paddle_r->pos[0] - paddle_r->w / 2.0f);
        paddle_side_top[1] = (paddle_r->pos[1] - paddle_r->h / 2.0f);
        paddle_side_bottom[0] = paddle_side_top[0];
        paddle_side_bottom[1] = paddle_side_top[1] + paddle_r->h;
        ball_pos[0] = 1.0f - ball_pos[0];
        ball_side_top[0] = ball_pos[0] - ball_wd2;
        ball_side_bottom[0] = ball_side_top[0];
        paddle_back_x = 1.0f - (paddle_r->pos[0] + paddle_r->w / 2.0f);
        new_pos_adj[0] = 1.0f - new_pos_adj[0];
    }

    // SEResult res = se_render_line_segment_norm_coord(
    //     paddle_side_top,
    //     paddle_side_bottom,
    //     (vec4) { 0.0f, 1.0f, 0.0f, 1.0f }
    // );
    // if (res != SE_SUCCESS) {
    //     SE_LOG_ERRORF("Failed to draw segment: %d", res);
    // }
    // res = se_render_line_segment_norm_coord(
    //     ball_side_top,
    //     ball_side_bottom,
    //     (vec4) { 1.0f, 0.0f, 0.0f, 1.0f }
    // );
    // if (res != SE_SUCCESS) {
    //     SE_LOG_ERRORF("Failed to draw segment: %d", res);
    // }
    // res = se_render_line_segment_norm_coord(
    //     (vec2) { paddle_back_x, 0.0f },
    //     (vec2) { paddle_back_x, 1.0f },
    //     (vec4) { 0.0f, 1.0f, 0.0f, 1.0f }
    // );
    // if (res != SE_SUCCESS) {
    //     SE_LOG_ERRORF("Failed to draw segment: %d", res);
    // }

    const bool inside_paddle = (ball_side_top[0] <= paddle_side_top[0] && ball_side_top[0] >= paddle_back_x)
        && ((ball_side_top[1] <= paddle_side_bottom[1] && ball_side_top[1] >= paddle_side_top[1])
            || (ball_side_bottom[1] <= paddle_side_bottom[1] && ball_side_bottom[1] >= paddle_side_top[1]));

    if (inside_paddle) {
        ball->dirv[0] *= -1.0f;
        ball->dirv[1] = possible_y_directions[se_rand_int() % 3];
        return GSEVENT_BALL_DIR_CHANGE;
    };

    collision = se_line_segments_intersect(
        ball_pos,
        new_pos_adj,
        paddle_side_top,
        paddle_side_bottom,
        ip
    );

    if (collision) {
        new_pos[0] = mirror_ip ? 1.0f - ip[0] : ip[0];
        new_pos[1] = ip[1];
        state->ball.dirv[0] *= -1.0f;
        state->ball.dirv[1] = possible_y_directions[se_rand_int() % 3];
        // state->ball.dirv[1] = 0.0f;
        return GSEVENT_BALL_DIR_CHANGE;
    }

    return GSEVENT_NONE;
}

static GameStateEvent ball_move(GameState *const state, const double delta) {
    vec2 ball_movement;
    const float ball_movement_scale = delta * state->ball.speed;
    // glmc_vec2_normalize(state->ball.dirv);
    glmc_vec2_scale(state->ball.dirv, ball_movement_scale, ball_movement);

    vec2 new_pos;
    glmc_vec2_add(state->ball.pos, ball_movement, new_pos);

    GameStateEvent event = ball_bounds_collision_check(state, new_pos);
    if (event != GSEVENT_NONE) {
        return event;
    }
    event = ball_paddles_collision_check(state, new_pos);

    glmc_vec2_copy(new_pos, state->ball.pos);

    return event;
}

void GameState_paddle_l_change_dir(GameState *const state, const SEDirection dir) {
    switch (dir) {
    case SE_UP:
        state->paddle_l.dirv[1] = -1.0f;
        break;
    case SE_DOWN:
        state->paddle_l.dirv[1] = 1.0f;
        break;
    case SE_NONE:
        state->paddle_l.dirv[1] = 0.0f;
    default:
        break;
    }
}

void GameState_paddle_r_change_dir(GameState *const state, const SEDirection dir) {
    switch (dir) {
    case SE_UP:
        state->paddle_r.dirv[1] = -1.0f;
        break;
    case SE_DOWN:
        state->paddle_r.dirv[1] = 1.0f;
        break;
    case SE_NONE:
        state->paddle_r.dirv[1] = 0.0f;
    default:
        break;
    }
}

GameStateEvent GameState_update(GameState *const state, const double delta) {
    // Paddles
    vec2 paddle_movement;
    const float paddle_movement_scale = delta * state->paddle_l.speed;
    glmc_vec2_scale(state->paddle_l.dirv, paddle_movement_scale, paddle_movement);
    glmc_vec2_add(state->paddle_l.pos, paddle_movement, state->paddle_l.pos);
    paddle_collision_check(&state->paddle_l);

    if (state->ai_enabled) {
        paddle_r_change_dir_ai(state);
    }
    glmc_vec2_scale(state->paddle_r.dirv, paddle_movement_scale, paddle_movement);
    glmc_vec2_add(state->paddle_r.pos, paddle_movement, state->paddle_r.pos);
    paddle_collision_check(&state->paddle_r);

    // Ball
    const GameStateEvent event = ball_move(state, delta);
    switch (event) {
    case GSEVENT_L_SCORE:
        state->score_l++;
        game_next_round(state);
        if (state->score_l > 5) {
            return GSEVENT_L_WIN;
        } else {
            return event;
        }
    case GSEVENT_R_SCORE:
        state->score_r++;
        game_next_round(state);
        if (state->score_r > 5) {
            return GSEVENT_R_WIN;
        } else {
            return event;
        }
    case GSEVENT_NONE:
    case GSEVENT_BALL_DIR_CHANGE:
        break;
    default:
        break;
    }

    return event;
}

SEDirection GameState_paddle_l_dir_get(const GameState *const state) {
    if (state->paddle_l.dirv[1] == -1.0f) {
        return SE_UP;
    } else if (state->paddle_l.dirv[1] == 1.0f) {
        return SE_DOWN;
    } else {
        return SE_NONE;
    }
}