【Functions】法人ランク別・購入点数別の動的ディスカウント＆掛率適用

use shopify_function::prelude::*;
use shopify_function::Result;

#[shopify_function_target(query_file = "src/run.graphql")]
fn run(input: input::ResponseData) -> Result<output::FunctionResult> {
    let vip_tier = input.cart.buyer_identity
        .as_ref()
        .and_then(|buyer| buyer.customer.as_ref())
        .and_then(|cust| cust.metafield.as_ref())
        .map(|m| m.value.as_str());

    let discount_percentage = match vip_tier {
        Some("TIER_GOLD") => 30.0,
        Some("TIER_SILVER") => 15.0,
        _ => 0.0,
    };

    if discount_percentage > 0.0 {
        return Ok(output::FunctionResult {
            discounts: vec![output::Discount {
                message: Some(format!("会員ランク特別割引 ({:.0}% OFF)", discount_percentage)),
                targets: vec![output::Target::ProductVariant(output::ProductVariantTarget {
                    id: "all".to_string(),
                    quantity: None,
                })],
                value: output::Value::Percentage(output::Percentage { value: discount_percentage }),
            }],
            discount_application_strategy: output::DiscountApplicationStrategy::First,
        });
    }

    Ok(output::FunctionResult { discounts: vec![], discount_application_strategy: output::DiscountApplicationStrategy::First })
}