#include <stdio.h>

typedef struct {
    char type;
    float price;
    char *name;
} st_product;

static st_product vagitables[] = {
    { 'a', 1.25, "朝鲜蓟" },
    { 'b', 0.65, "甜菜"   },
    { 'c', 0.89, "胡萝卜" },
    { 0, 0, 0 }
};

#define MAX (sizeof (vagitables) / sizeof (st_product))

typedef struct {
    float pounds[MAX];
} st_order;


void menu_weight(float *pounds)
{
    float need;
    for (;;) {
        printf("请输入需要的数量：");
        scanf("%f", &need); getchar();
        if (need > 0.01 || need < -0.01) {
            if (need + *pounds >= 0) {
                *pounds += need;
                return;
            }
        }
        printf("您的输入有误，请重新输入！\n");
    }
}


void menu_show()
{
    st_product *v = vagitables;
    printf("有以下蔬菜可供您选择：\n");
    for (; v->type; v++) {
        printf("    %c. %s (%.2f 美元/磅)\n", v->type, v->name, v->price);
    }
    printf(
"您还可以进行进行以下操作：\n"
"   x. 计算总价\n"
"   q. 退出\n"
"请您选择："
    );
}


float *match_product(st_order *order, char type)
{
    st_product *v = vagitables;
    int i = 0;
    for (; v->type; v++, i++) {
        if (type == v->type) return order->pounds + i;
    }
    return 0;
}


void calc_order(st_order *order)
{
    float weights = 0;
    float cost = 0;
    float off = 0;
    float fare = 0;
    float total = 0;
    
    printf("\n ----- \n");

    int i = 0;
    st_product *v = vagitables;
    for (; v->type; v++, i++) {
        if (order->pounds[i]) {
            float price = vagitables[i].price * order->pounds[i];
            weights += order->pounds[i];
            cost += price;
            printf("%s %.2f 磅，共 %.2f 美元\n",
                v->name, order->pounds[i], price);
        }
    }

    if (cost >= 100) off = cost * 0.05;

    if (weights <= 5) {
        fare = 3.5;
    } else if (weights < 20) {
        fare = 10;
    } else {
        fare = 8 + 0.1 * weights;
    }

    total = cost - off + fare;

    printf("所有商品总计：%.2f 美元\n", cost);
    printf("折扣：%.2f 美元\n", off);
    printf("运费：%.2f 美元\n", fare);
    printf("总计：%.2f 美元\n", total);
    printf("----- \n\n");
}


void order_process()
{
    char type;
    st_order order = {0,};
    for (;;) {
        menu_show();
        scanf("%c", &type); getchar();
        switch (type) {
            case 'q':
                return;
            case 'x': {
                calc_order(&order);
                break;
            }
            default: {
                float *match = match_product(&order, type);
                if (match) {
                    menu_weight(match);
                } else {
                    printf("输入错误，请重新输入！\n");
                }
                break;
            }
        }
        
    }
}

int main()
{
    order_process();
    return 0;
}