discounts

src/controllers/admin_discounts.rs

@@ -0,0 +1,185 @@
+//! Admin management of per-product discounts.
+//!
+//! Discounts live on the product (`sale_price_cents`) but are set here, in a
+//! place of their own, rather than on the product editor: an admin picks a
+//! product, enters a discounted price, and the storefront then shows it on sale.
+//! Editing a product never touches its discount, and vice versa.
+
+use axum_extra::extract::cookie::CookieJar;
+use loco_rs::prelude::*;
+use sea_orm::{ActiveModelTrait, EntityTrait, QueryOrder, Set};
+use serde::Deserialize;
+use serde_json::json;
+
+use crate::{
+    controllers::i18n::current_lang,
+    models::products,
+    shared::{
+        guard,
+        money::{format_price, parse_price_to_cents},
+    },
+};
+
+#[derive(Debug, Deserialize)]
+struct DiscountForm {
+    sale_price: String,
+}
+
+async fn product_by_id(ctx: &AppContext, id: i32) -> Result<products::Model> {
+    products::Entity::find_by_id(id)
+        .one(&ctx.db)
+        .await?
+        .ok_or_else(|| Error::NotFound)
+}
+
+/// Percent off the regular price, rounded to a whole number. `0` when there is
+/// no positive regular price to discount from.
+fn percent_off(regular_cents: i64, sale_cents: i64) -> i64 {
+    if regular_cents <= 0 {
+        return 0;
+    }
+    let off = (regular_cents - sale_cents) as f64 / regular_cents as f64 * 100.0;
+    off.round() as i64
+}
+
+/// Row shape for the discounts list.
+fn list_row(product: &products::Model) -> serde_json::Value {
+    json!({
+        "id": product.id,
+        "name": product.name,
+        "slug": product.slug,
+        "currency": product.currency,
+        "regular_price": format_price(product.price_cents),
+        "on_sale": product.on_sale(),
+        "sale_price": product.sale_price_cents.map(format_price),
+        "percent_off": product.sale_price_cents.map(|sale| percent_off(product.price_cents, sale)),
+    })
+}
+
+#[debug_handler]
+async fn index(
+    auth: auth::JWT,
+    jar: CookieJar,
+    ViewEngine(v): ViewEngine<TeraView>,
+    State(ctx): State<AppContext>,
+) -> Result<Response> {
+    guard::current_admin(auth, &ctx).await?;
+    let list = products::Entity::find()
+        .order_by_asc(products::Column::Name)
+        .all(&ctx.db)
+        .await?;
+    let rows: Vec<serde_json::Value> = list.iter().map(list_row).collect();
+    format::view(
+        &v,
+        "admin/catalog/discounts.html",
+        json!({ "products": rows, "lang": current_lang(&jar) }),
+    )
+}
+
+/// Render the single-product discount form, optionally with a validation error
+/// and the value the admin just typed (so a rejected submit isn't lost).
+fn render_form(
+    v: &TeraView,
+    jar: &CookieJar,
+    product: &products::Model,
+    entered: Option<String>,
+    error: Option<&str>,
+) -> Result<Response> {
+    let current = product.sale_price_cents.map(format_price);
+    let value = entered.or_else(|| current.clone()).unwrap_or_default();
+    format::view(
+        v,
+        "admin/catalog/discount_form.html",
+        json!({
+            "product": {
+                "id": product.id,
+                "name": product.name,
+                "currency": product.currency,
+                "regular_price": format_price(product.price_cents),
+                "on_sale": product.on_sale(),
+                "sale_price": current,
+            },
+            "value": value,
+            "error": error,
+            "lang": current_lang(jar),
+        }),
+    )
+}
+
+#[debug_handler]
+async fn edit(
+    auth: auth::JWT,
+    jar: CookieJar,
+    ViewEngine(v): ViewEngine<TeraView>,
+    Path(id): Path<i32>,
+    State(ctx): State<AppContext>,
+) -> Result<Response> {
+    guard::current_admin(auth, &ctx).await?;
+    let product = product_by_id(&ctx, id).await?;
+    render_form(&v, &jar, &product, None, None)
+}
+
+#[debug_handler]
+async fn update(
+    auth: auth::JWT,
+    jar: CookieJar,
+    ViewEngine(v): ViewEngine<TeraView>,
+    Path(id): Path<i32>,
+    State(ctx): State<AppContext>,
+    Form(form): Form<DiscountForm>,
+) -> Result<Response> {
+    guard::current_admin(auth, &ctx).await?;
+    let product = product_by_id(&ctx, id).await?;
+
+    let entered = form.sale_price.trim().to_string();
+
+    // An empty value clears the discount (same as the Remove action).
+    if entered.is_empty() {
+        return clear_discount(&ctx, product).await;
+    }
+
+    // A discount must be a valid, positive price strictly below the regular
+    // price — otherwise it isn't a discount. Reject inline, keeping the input.
+    let render_err = |key: &str| render_form(&v, &jar, &product, Some(entered.clone()), Some(key));
+    let sale_cents = match parse_price_to_cents(&entered) {
+        Ok(cents) => cents,
+        Err(_) => return render_err("discount-invalid"),
+    };
+    if sale_cents <= 0 {
+        return render_err("discount-must-be-positive");
+    }
+    if sale_cents >= product.price_cents {
+        return render_err("discount-below-regular");
+    }
+
+    let mut active = product.into_active_model();
+    active.sale_price_cents = Set(Some(sale_cents));
+    active.update(&ctx.db).await?;
+    format::redirect("/admin/catalog/discounts")
+}
+
+async fn clear_discount(ctx: &AppContext, product: products::Model) -> Result<Response> {
+    let mut active = product.into_active_model();
+    active.sale_price_cents = Set(None);
+    active.update(&ctx.db).await?;
+    format::redirect("/admin/catalog/discounts")
+}
+
+#[debug_handler]
+async fn remove(
+    auth: auth::JWT,
+    Path(id): Path<i32>,
+    State(ctx): State<AppContext>,
+) -> Result<Response> {
+    guard::current_admin(auth, &ctx).await?;
+    let product = product_by_id(&ctx, id).await?;
+    clear_discount(&ctx, product).await
+}
+
+pub fn routes() -> Routes {
+    Routes::new()
+        .add("/admin/catalog/discounts", get(index))
+        .add("/admin/catalog/discounts/{id}/edit", get(edit))
+        .add("/admin/catalog/discounts/{id}", post(update))
+        .add("/admin/catalog/discounts/{id}/remove", post(remove))
+}