use maud::{DOCTYPE, Markup, html};
use pulldown_cmark::{Options, Parser, html as cmark_html};

use crate::{
    domain::PresenceUser,
    domain::{Category, GroceryList, Item, Meal, MealIngredient, User},
};

pub fn login_page(error: Option<&str>, invite: Option<&str>) -> Markup {
    page(
        "Sign in",
        None,
        html! {
            div class="auth-card" {
                p class="eyebrow" { "SUSTENANCE" }
                h1 { "Welcome back" }
                p class="lede" { "Keep the shopping list in sync." }
                @if let Some(error) = error {
                    div class="alert alert-error" role="alert" { (error) }
                }
                form method="post" action="/login" class="stack" {
                    @if let Some(invite) = invite {
                        input type="hidden" name="invite" value=(invite);
                    }
                    label for="email" { "Email" }
                    input id="email" name="email" type="email" autocomplete="email" required autofocus;
                    label for="password" { "Password" }
                    input id="password" name="password" type="password" autocomplete="current-password" required;
                    button class="button button-primary" type="submit" { "Sign in" }
                }
                p class="auth-switch" { "Need an account? " a href="/register" { "Create one" } }
            }
        },
    )
}

pub fn register_page(error: Option<&str>, invite: Option<&str>) -> Markup {
    page(
        "Create account",
        None,
        html! {
            div class="auth-card" {
                p class="eyebrow" { "SUSTENANCE" }
                h1 { "Make a shared list" }
                p class="lede" { "A simple grocery list for the people you shop with." }
                @if let Some(error) = error {
                    div class="alert alert-error" role="alert" { (error) }
                }
                form method="post" action="/register" class="stack" {
                    @if let Some(invite) = invite {
                        input type="hidden" name="invite" value=(invite);
                    }
                    label for="display-name" { "Your name" }
                    input id="display-name" name="display_name" type="text" autocomplete="name" maxlength="50" required autofocus;
                    label for="email" { "Email" }
                    input id="email" name="email" type="email" autocomplete="email" required;
                    label for="password" { "Password" }
                    input id="password" name="password" type="password" autocomplete="new-password" required;
                    button class="button button-primary" type="submit" { "Create account" }
                }
                p class="auth-switch" { "Already have an account? " a href="/login" { "Sign in" } }
            }
        },
    )
}

pub fn registration_closed_page() -> Markup {
    page(
        "Registration closed",
        None,
        html! {
            div class="auth-card" {
                p class="eyebrow" { "PRIVATE LISTS" }
                h1 { "Registration is invite-only" }
                p class="lede" { "Ask someone who uses the app to send you an invitation link." }
                a class="button button-primary" href="/login" { "Back to sign in" }
            }
        },
    )
}

pub fn lists_page(user: &User, lists: &[GroceryList], csrf_token: &str) -> Markup {
    page(
        "Your lists",
        Some(user),
        html! {
            div class="page-heading" {
                div {
                    p class="eyebrow" { "SHARED LISTS" }
                    h1 { "Grocery lists" }
                    p class="lede" { "Everything you need, in one place." }
                }
            }
            div class="dashboard-grid" {
                section class="panel" {
                    div class="panel-heading" {
                        h2 { "Lists" }
                        span class="count-badge" { (lists.len()) }
                    }
                    @if lists.is_empty() {
                        div class="empty-state" {
                            div class="empty-mark" { "+" }
                            h3 { "Start your first list" }
                            p { "Create a list for the weekly shop, a party, or anything else." }
                        }
                    } @else {
                        div class="list-cards" {
                            @for list in lists {
                                a class="list-card" href=(format!("/lists/{}", list.id)) {
                                    span class="list-card-icon" { "✓" }
                                    span class="list-card-copy" {
                                        strong { (list.name) }
                                    }
                                    span class="list-card-arrow" { "→" }
                                }
                            }
                        }
                    }
                }
                section class="panel create-panel" {
                    div class="panel-heading" { h2 { "New list" } }
                    form method="post" action="/lists" class="stack" {
                        input type="hidden" name="csrf" value=(csrf_token);
                        label for="list-name" { "List name" }
                        input id="list-name" name="name" type="text" maxlength="80" placeholder="Weekly shop" required;
                        button class="button button-primary" type="submit" { "Create list" }
                    }
                }
                section id="sharing" class="panel sharing-panel" {
                    div class="panel-heading" { h2 { "Invite someone" } }
                    p { "Create a one-time invite link so a new person can join." }
                    form
                        hx-post="/invitations"
                        hx-target="#invite-result"
                        hx-swap="innerHTML"
                        class="stack"
                    {
                        input type="hidden" name="csrf" value=(csrf_token);
                        button class="button button-secondary" type="submit" { "Create invite link" }
                    }
                    div id="invite-result" class="invite-result" {}
                }
            }
        },
    )
}

pub fn meals_page(user: &User, meals: &[Meal]) -> Markup {
    page(
        "Meals",
        Some(user),
        html! {
            div class="page-heading" {
                div {
                    p class="eyebrow" { "MEAL LIBRARY" }
                    h1 { "Meals" }
                    p class="lede" { "Save a meal and add its ingredients to any list." }
                }
                a class="button button-primary" href="/meals/new" { "New meal" }
            }
            div class="dashboard-grid" {
                section class="panel" {
                    div class="panel-heading" {
                        h2 { "All meals" }
                        span class="count-badge" { (meals.len()) }
                    }
                    @if meals.is_empty() {
                        div class="empty-state" {
                            div class="empty-mark" { "🍽" }
                            h3 { "No meals yet" }
                            p { "Create a meal to reuse its ingredients across your lists." }
                        }
                    } @else {
                        div class="list-cards" {
                            @for meal in meals {
                                a class="list-card" href=(format!("/meals/{}", meal.id)) {
                                    span class="list-card-icon" { "🍽" }
                                    span class="list-card-copy" {
                                        strong { (meal.name) }
                                        small { (meal.ingredients.len()) " ingredients" }
                                    }
                                    span class="list-card-arrow" { "→" }
                                }
                            }
                        }
                    }
                }
            }
        },
    )
}

pub fn meal_picker(meals: &[Meal], list_id: i64, csrf_token: &str) -> Markup {
    html! {
        div class="meal-picker-backdrop" onclick="if (event.target === this) this.remove()" {
            div class="meal-picker-modal" role="dialog" aria-modal="true" aria-label="Add a meal" {
                div class="meal-picker-header" {
                    div {
                        p class="eyebrow" { "ADD TO LIST" }
                        h2 { "Add a meal" }
                    }
                    button class="meal-picker-close" type="button" aria-label="Close" onclick="this.closest('.meal-picker-backdrop').remove()" { "✕" }
                }
                @if meals.is_empty() {
                    div class="meal-picker-empty" {
                        span class="empty-mark" { "🍽" }
                        h3 { "No meals yet" }
                        p { "Create a meal first, then add it to any list." }
                        a class="button button-primary" href="/meals/new" { "Create a meal" }
                    }
                } @else {
                    div class="meal-picker-list" {
                        @for meal in meals {
                            form
                                hx-post=(format!("/lists/{}/add-meal", list_id))
                                hx-target="#list-items"
                                hx-swap="outerHTML"
                                hx-on::after-request="if (event.detail.successful) this.closest('.meal-picker-backdrop').remove()"
                                class="meal-picker-row"
                            {
                                input type="hidden" name="csrf" value=(csrf_token);
                                input type="hidden" name="meal_id" value=(meal.id);
                                button class="meal-picker-button" type="submit" {
                                    span class="meal-picker-icon" { "🍽" }
                                    span class="meal-picker-copy" {
                                        strong { (meal.name) }
                                        small { (meal.ingredients.len()) " ingredients" }
                                    }
                                    span class="meal-picker-add" { "Add" }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

pub fn meal_form_page(user: &User, meal: Option<&Meal>, csrf_token: &str) -> Markup {
    let (title, action, name, description) = match meal {
        Some(meal) => (
            "Edit meal",
            format!("/meals/{}/edit", meal.id),
            meal.name.clone(),
            meal.description.clone(),
        ),
        None => ("New meal", "/meals".into(), String::new(), String::new()),
    };
    page(
        title,
        Some(user),
        html! {
            div class="page-heading" {
                a class="back-link" href="/meals" { "← All meals" }
                h1 { (title) }
            }
            section class="panel" {
                form method="post" action=(action) class="stack" {
                    input type="hidden" name="csrf" value=(csrf_token);
                    label for="meal-name" { "Name" }
                    input id="meal-name" name="name" type="text" maxlength="120" value=(name) required;
                    label for="meal-description" { "Description (markdown)" }
                    textarea id="meal-description" name="description" rows="8" { (description) }
                    button class="button button-primary" type="submit" { "Save meal" }
                }
            }
            @if meal.is_none() {
                p class="muted" { "You can add ingredients after creating the meal." }
            }
        },
    )
}

pub fn meal_page(user: &User, meal: &Meal, categories: &[Category], csrf_token: &str) -> Markup {
    page(
        &meal.name,
        Some(user),
        html! {
            div class="page-heading" {
                a class="back-link" href="/meals" { "← All meals" }
                div class="list-topbar-actions" {
                    button type="button" class="button button-small button-quiet" onclick="document.getElementById('meal-edit-modal').showModal()" { "Edit" }
                    form method="post" action=(format!("/meals/{}/delete", meal.id)) {
                        input type="hidden" name="csrf" value=(csrf_token);
                        button class="danger-link" type="submit" { "Delete" }
                    }
                }
            }
            dialog id="meal-edit-modal" class="item-modal" {
                div class="item-modal-card" {
                    div class="item-modal-header" {
                        h3 { "Edit meal" }
                        button type="button" class="meal-picker-close" aria-label="Close" onclick="this.closest('dialog').close()" { "✕" }
                    }
                    form method="post" action=(format!("/meals/{}/edit", meal.id)) class="stack" {
                        input type="hidden" name="csrf" value=(csrf_token);
                        label { "Name" }
                        input id="meal-edit-name" name="name" value=(meal.name) maxlength="120" required;
                        label { "Description (markdown)" }
                        textarea id="meal-edit-description" name="description" rows="8" { (meal.description) }
                        button id="meal-edit-save" class="button button-primary" type="submit" { "Save meal" }
                    }
                }
            }
            div class="list-layout" {
                section class="panel list-panel" {
                    div class="list-heading" {
                        div {
                            p class="eyebrow" { "MEAL" }
                            h1 { (meal.name) }
                        }
                    }
                    @if meal.description.is_empty() {
                        p class="muted" { "No description." }
                    } @else {
                        div class="markdown" { (render_markdown(&meal.description)) }
                    }
                    h2 class="category-heading" { "Ingredients" }
                    @if meal.ingredients.is_empty() {
                        p class="muted" { "No ingredients yet." }
                    } @else {
                        div class="item-list" {
                            @for group in ingredient_groups(&meal.ingredients, categories) {
                                (ingredient_category_group(&group.0, &group.1, meal.id, categories, csrf_token))
                            }
                        }
                    }
                }
                aside class="side-column" {
                    section class="panel" {
                        div class="panel-heading" { h2 { "Add ingredient" } }
                        form id="add-ingredient-form" method="post" action=(format!("/meals/{}/ingredients", meal.id)) class="stack" {
                            input type="hidden" name="csrf" value=(csrf_token);
                            label { "Name" }
                            input id="ingredient-name" name="name" type="text" maxlength="120" required;
                            label { "Quantity" }
                            input id="ingredient-quantity" name="quantity" type="text" maxlength="40";
                            label { "Note" }
                            input id="ingredient-note" name="note" type="text" maxlength="120";
                            label { "Category" }
                            select id="ingredient-category" name="category_id" {
                                (category_options(categories, None))
                            }
                            button id="add-ingredient-button" class="button button-primary" type="submit" { "Add ingredient" }
                        }
                    }
                }
            }
        },
    )
}

fn ingredient_row(
    ingredient: &MealIngredient,
    meal_id: i64,
    categories: &[Category],
    csrf_token: &str,
) -> Markup {
    html! {
        div class="item-copy" {
            @if !ingredient.quantity.is_empty() {
                span class="item-qty" { "(" (ingredient.quantity) ")" }
            }
            strong { (ingredient.name) }
            @if !ingredient.note.is_empty() {
                small { (ingredient.note) }
            }
        }
        button type="button" class="item-actions-button" aria-label="Ingredient actions" onclick=(format!("document.getElementById('ingredient-edit-{}').showModal()", ingredient.id)) { "•••" }
        dialog id=(format!("ingredient-edit-{}", ingredient.id)) class="item-modal" {
            div class="item-modal-card" {
                div class="item-modal-header" {
                    h3 { (ingredient.name) }
                    button type="button" class="meal-picker-close" aria-label="Close" onclick="this.closest('dialog').close()" { "✕" }
                }
                form
                    hx-post=(format!("/meals/{}/ingredients/{}/edit", meal_id, ingredient.id))
                    hx-target="body"
                    hx-swap="outerHTML"
                    class="stack"
                {
                    input type="hidden" name="csrf" value=(csrf_token);
                    label { "Name" }
                    input id=(format!("ingredient-edit-name-{}", ingredient.id)) name="name" value=(ingredient.name) maxlength="120" required;
                    label { "Quantity" }
                    input id=(format!("ingredient-edit-quantity-{}", ingredient.id)) name="quantity" value=(ingredient.quantity) maxlength="40";
                    label { "Note" }
                    input id=(format!("ingredient-edit-note-{}", ingredient.id)) name="note" value=(ingredient.note) maxlength="120";
                    label { "Category" }
                    select id=(format!("ingredient-edit-category-{}", ingredient.id)) name="category_id" {
                        (category_options(categories, ingredient.category_id))
                    }
                    button id=(format!("ingredient-edit-save-{}", ingredient.id)) class="button button-primary" type="submit" { "Save" }
                }
                form method="post" action=(format!("/meals/{}/ingredients/{}/delete", meal_id, ingredient.id)) {
                    input type="hidden" name="csrf" value=(csrf_token);
                    button id=(format!("ingredient-edit-delete-{}", ingredient.id)) class="danger-link" type="submit" { "Remove" }
                }
            }
        }
    }
}

fn ingredient_groups<'a>(
    ingredients: &'a [MealIngredient],
    categories: &[Category],
) -> Vec<(String, Vec<&'a MealIngredient>)> {
    let mut groups = Vec::new();
    for category in categories {
        let in_category = ingredients
            .iter()
            .filter(|ingredient| ingredient.category_id == Some(category.id))
            .collect::<Vec<_>>();
        if !in_category.is_empty() {
            groups.push((category.name.clone(), in_category));
        }
    }

    let uncategorized = ingredients
        .iter()
        .filter(|ingredient| ingredient.category_id.is_none())
        .collect::<Vec<_>>();
    if !uncategorized.is_empty() {
        groups.push(("Uncategorized".into(), uncategorized));
    }
    groups
}

fn ingredient_category_group(
    name: &str,
    ingredients: &[&MealIngredient],
    meal_id: i64,
    categories: &[Category],
    csrf_token: &str,
) -> Markup {
    html! {
        section class="category-group" {
            h2 class="category-heading" { (name) }
            ul class="ingredient-list" {
                @for ingredient in ingredients {
                    li {
                        (ingredient_row(ingredient, meal_id, categories, csrf_token))
                    }
                }
            }
        }
    }
}

fn render_markdown(source: &str) -> Markup {
    let mut options = Options::empty();
    options.insert(Options::ENABLE_STRIKETHROUGH);
    let parser = Parser::new_ext(source, options);
    let mut buffer = String::new();
    cmark_html::push_html(&mut buffer, parser);
    html! {
        (maud::PreEscaped(buffer))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn render_markdown_turns_bullets_into_list_html() {
        let html = render_markdown("- one\n- two\n").into_string();
        assert!(html.contains("<ul>"), "expected <ul>, got: {html}");
        assert!(html.contains("<li>"), "expected <li>, got: {html}");
        assert!(!html.contains("* one"), "raw bullet leaked through: {html}");
    }

    #[test]
    fn render_markdown_renders_emphasis() {
        let html = render_markdown("**bold** and *italic*").into_string();
        assert!(html.contains("<strong>"), "expected <strong>, got: {html}");
        assert!(html.contains("<em>"), "expected <em>, got: {html}");
    }
}

pub fn list_page(
    user: &User,
    list: &GroceryList,
    items: &[Item],
    categories: &[Category],
    presence: &[PresenceUser],
    csrf_token: &str,
) -> Markup {
    page(
        &list.name,
        Some(user),
        html! {
            div class="list-topbar" {
                a class="back-link" href="/lists" { "← All lists" }
                div class="list-topbar-actions" {
                    span class="live-pill" { span class="live-dot" {} "Live" }
                    button class="button button-small add-meal-button" hx-get=(format!("/meals?picker={}", list.id)) hx-target="#meal-picker" hx-swap="innerHTML" { "+ Add meal" }
                }
            }
            div id="meal-picker" class="meal-picker" {}
            div class="list-layout" {
                section class="panel list-panel" {
                    div class="list-heading" {
                        div {
                            p class="eyebrow" { "SHARED LIST" }
                            h1 { (list.name) }
                            p class="list-meta" { (items.iter().filter(|item| !item.checked).count()) " items to get" }
                        }
                    }
                    (list_content_fragment(list, items, categories, csrf_token, false))
                }
                aside class="side-column" {
                    (presence_panel(presence, false))
                    (categories_panel(categories, csrf_token, false))
                    section class="panel tip-panel" {
                        span class="tip-label" { "TIP" }
                        p { "Check items off as you go. Everyone viewing this list will see it instantly." }
                    }
                }
            }
            div id="live-stream" class="live-stream" hx-ext="ws" ws-connect=(format!("/lists/{}/stream", list.id)) {}
        },
    )
}

pub fn list_content_fragment(
    list: &GroceryList,
    items: &[Item],
    categories: &[Category],
    csrf_token: &str,
    out_of_band: bool,
) -> Markup {
    if out_of_band {
        html! {
            div id="list-content" hx-swap-oob="outerHTML" {
                (list_content(list, items, categories, csrf_token))
            }
        }
    } else {
        html! {
            div id="list-content" {
                (list_content(list, items, categories, csrf_token))
            }
        }
    }
}

fn list_content(
    list: &GroceryList,
    items: &[Item],
    categories: &[Category],
    csrf_token: &str,
) -> Markup {
    html! {
        form
            id="add-item-form"
            class="add-item-form"
            hx-post=(format!("/lists/{}/items", list.id))
            hx-target="#list-items"
            hx-swap="outerHTML"
            hx-on::after-request="if (event.detail.successful) this.reset()"
        {
            input type="hidden" name="csrf" value=(csrf_token);
            label class="sr-only" for="item-name" { "Item name" }
            input id="item-name" name="name" type="text" maxlength="120" placeholder="Add an item..." autocomplete="off" required;
            input id="item-quantity" name="quantity" type="text" maxlength="40" placeholder="Qty" aria-label="Quantity";
            select id="item-category" name="category_id" aria-label="Category" {
                (category_options(categories, None))
            }
            button id="add-item-button" class="button button-primary add-button" type="submit" { "+ Add" }
        }
        (list_items_fragment(list, items, categories, csrf_token, false))
    }
}

pub fn list_items_fragment(
    list: &GroceryList,
    items: &[Item],
    categories: &[Category],
    csrf_token: &str,
    out_of_band: bool,
) -> Markup {
    if out_of_band {
        html! {
            div id="list-items" class="items" data-revision=(list.revision) hx-swap-oob="outerHTML" {
                (list_items_content(items, categories, csrf_token))
            }
        }
    } else {
        html! {
            div id="list-items" class="items" data-revision=(list.revision) {
                (list_items_content(items, categories, csrf_token))
            }
        }
    }
}

fn list_items_content(items: &[Item], categories: &[Category], csrf_token: &str) -> Markup {
    html! {
        @if items.is_empty() {
            div class="empty-items" {
                span class="empty-items-icon" { "✦" }
                p { "Your list is clear." }
                small { "Add the first thing you need above." }
            }
        } @else {
            div class="item-list" {
                @for group in item_groups(items, categories) {
                    (category_group(&group.0, &group.1, categories, csrf_token))
                }
            }
        }
    }
}

fn item_groups<'a>(items: &'a [Item], categories: &[Category]) -> Vec<(String, Vec<&'a Item>)> {
    let mut groups = Vec::new();
    for category in categories {
        let items_in_category = items
            .iter()
            .filter(|item| item.category_id == Some(category.id))
            .collect::<Vec<_>>();
        if !items_in_category.is_empty() {
            groups.push((category.name.clone(), items_in_category));
        }
    }

    let uncategorized = items
        .iter()
        .filter(|item| item.category_id.is_none())
        .collect::<Vec<_>>();
    if !uncategorized.is_empty() {
        groups.push(("Uncategorized".into(), uncategorized));
    }
    groups
}

fn category_group(
    name: &str,
    items: &[&Item],
    categories: &[Category],
    csrf_token: &str,
) -> Markup {
    html! {
        section class="category-group" {
            h2 class="category-heading" { (name) }
            @for item in items {
                (item_row(item, categories, csrf_token))
            }
        }
    }
}

fn item_row(item: &Item, categories: &[Category], csrf_token: &str) -> Markup {
    let next_checked = if item.checked { "0" } else { "1" };
    html! {
        article class=(if item.checked { "item-row is-checked" } else { "item-row" }) id=(format!("item-{}", item.id)) data-version=(item.version) {
            form
                class="check-form"
                hx-post=(format!("/lists/{}/items/{}/check", item.list_id, item.id))
                hx-target="#list-items"
                hx-swap="outerHTML"
            {
                input type="hidden" name="csrf" value=(csrf_token);
                input type="hidden" name="checked" value=(next_checked);
                button id=(format!("item-check-{}", item.id)) class="check-button" type="submit" aria-label=(if item.checked { "Mark unchecked" } else { "Mark complete" }) {
                    @if item.checked { "✓" } @else { "" }
                }
            }
            label class="item-copy" for=(format!("item-check-{}", item.id)) {
                @if !item.quantity.is_empty() {
                    span class="item-qty" { "(" (item.quantity) ")" }
                }
                strong { (item.name) }
                @if !item.note.is_empty() {
                    small { (item.note) }
                }
            }
            button type="button" class="item-actions-button" aria-label="Item actions" onclick=(format!("document.getElementById('item-edit-{}').showModal()", item.id)) { "•••" }
            dialog id=(format!("item-edit-{}", item.id)) class="item-modal" {
                div class="item-modal-card" {
                    div class="item-modal-header" {
                        h3 { (item.name) }
                        button type="button" class="meal-picker-close" aria-label="Close" onclick="this.closest('dialog').close()" { "✕" }
                    }
                    form
                        hx-post=(format!("/lists/{}/items/{}/edit", item.list_id, item.id))
                        hx-target="#list-items"
                        hx-swap="outerHTML"
                        class="stack"
                    {
                        input type="hidden" name="csrf" value=(csrf_token);
                        label { "Name" }
                        input id=(format!("item-edit-name-{}", item.id)) name="name" value=(item.name) maxlength="120" required;
                        label { "Quantity" }
                        input id=(format!("item-edit-quantity-{}", item.id)) name="quantity" value=(item.quantity) maxlength="40";
                        label { "Note" }
                        input id=(format!("item-edit-note-{}", item.id)) name="note" value=(item.note) maxlength="120";
                        label { "Category" }
                        select id=(format!("item-edit-category-{}", item.id)) name="category_id" {
                            (category_options(categories, item.category_id))
                        }
                        button id=(format!("item-edit-save-{}", item.id)) class="button button-primary" type="submit" { "Save" }
                    }
                    form
                        hx-post=(format!("/lists/{}/items/{}/delete", item.list_id, item.id))
                        hx-target="#list-items"
                        hx-swap="outerHTML"
                    {
                        input type="hidden" name="csrf" value=(csrf_token);
                        button id=(format!("item-edit-delete-{}", item.id)) class="danger-link" type="submit" { "Remove item" }
                    }
                }
            }
        }
    }
}

fn category_options(categories: &[Category], selected: Option<i64>) -> Markup {
    html! {
        @if selected.is_none() {
            option value="" selected { "No category" }
        } @else {
            option value="" { "No category" }
        }
        @for category in categories {
            @if selected == Some(category.id) {
                option value=(category.id) selected { (category.name) }
            } @else {
                option value=(category.id) { (category.name) }
            }
        }
    }
}

pub fn categories_panel(categories: &[Category], csrf_token: &str, out_of_band: bool) -> Markup {
    let panel = html! {
        div class="panel-heading" {
            h2 { "Categories" }
            span class="count-badge" { (categories.len()) }
        }
        p { "Organize items by aisle or shopping area." }
        form
            hx-post="/categories"
            hx-target="#category-result"
            hx-swap="innerHTML"
            hx-on::after-request="if (event.detail.successful) window.location.reload()"
            class="category-form"
        {
            input type="hidden" name="csrf" value=(csrf_token);
            input id="category-name" name="name" type="text" maxlength="60" placeholder="Add a category" required;
            button id="add-category-button" class="button button-small button-secondary" type="submit" { "Add" }
        }
        @if categories.is_empty() {
            p class="muted category-empty" { "No categories yet." }
        } @else {
            div class="category-list" {
                @for category in categories {
                    span class="category-chip" { (category.name) }
                }
            }
        }
        div id="category-result" class="category-result" {}
    };

    if out_of_band {
        html! {
            section id="categories-panel" class="panel categories-panel" hx-swap-oob="outerHTML" { (panel) }
        }
    } else {
        html! {
            section id="categories-panel" class="panel categories-panel" { (panel) }
        }
    }
}

pub fn live_list_fragments(
    list: &GroceryList,
    items: &[Item],
    categories: &[Category],
    csrf_token: &str,
) -> Markup {
    html! {
        (list_content_fragment(list, items, categories, csrf_token, true))
        (categories_panel(categories, csrf_token, true))
    }
}

pub fn presence_panel(presence: &[PresenceUser], out_of_band: bool) -> Markup {
    if out_of_band {
        html! {
            section id="presence" class="panel presence-panel" hx-swap-oob="outerHTML" {
                (presence_content(presence))
            }
        }
    } else {
        html! {
            section id="presence" class="panel presence-panel" {
                (presence_content(presence))
            }
        }
    }
}

fn presence_content(presence: &[PresenceUser]) -> Markup {
    html! {
        div class="panel-heading" {
            h2 { "Viewing now" }
            span class="count-badge" { (presence.len()) }
        }
        @if presence.is_empty() {
            p class="muted" { "Just you for now." }
        } @else {
            div class="presence-list" {
                @for person in presence {
                        div class="presence-person" data-user-id=(person.user_id) {
                        span class="avatar" { (initials(&person.display_name)) }
                        span { (person.display_name) }
                    }
                }
            }
        }
    }
}

pub fn invite_page(
    user: Option<&User>,
    token: &str,
    error: Option<&str>,
    csrf_token: Option<&str>,
) -> Markup {
    page(
        "Join a list",
        user,
        html! {
            div class="auth-card invite-card" {
                p class="eyebrow" { "YOU'RE INVITED" }
                h1 { "Join the shared lists" }
                p class="lede" { "Shop together and keep all the lists in sync." }
                @if let Some(error) = error {
                    div class="alert alert-error" role="alert" { (error) }
                }
                @if let Some(user) = user {
                    p { "Signed in as " strong { (user.display_name) } "." }
                    form method="post" action=(format!("/invite/{}/accept", token)) class="stack" {
                        @if let Some(csrf_token) = csrf_token {
                            input type="hidden" name="csrf" value=(csrf_token);
                        }
                        button class="button button-primary" type="submit" { "Join lists" }
                    }
                    p class="muted" { "Want to join as a different person? Create a new account below." }
                } @else {
                    p { "Sign in or create an account to accept this invite." }
                }
                div class="invite-actions" {
                    a class="button button-primary" href=(format!("/register?invite={}", token)) { "Create account" }
                    a class="button button-secondary" href=(format!("/login?invite={}", token)) { "Sign in" }
                }
            }
        },
    )
}

pub fn invite_result(url: &str) -> Markup {
    html! {
        div class="invite-link-result" {
            p { "Copy this invite link:" }
            input readonly value=(url) aria-label="Invitation URL";
        }
    }
}

pub fn error_page(status: &str, message: &str) -> Markup {
    page(
        status,
        None,
        html! {
            div class="auth-card" {
                p class="eyebrow" { "SOMETHING WENT WRONG" }
                h1 { (status) }
                p class="lede" { (message) }
                a class="button button-primary" href="/lists" { "Back to lists" }
            }
        },
    )
}

fn page(title: &str, user: Option<&User>, content: Markup) -> Markup {
    html! {
        (DOCTYPE)
        html lang="en" {
            head {
                meta charset="utf-8";
                meta name="viewport" content="width=device-width, initial-scale=1";
                title { (title) " · Sustenance" }
                link rel="stylesheet" href="/static/style.css";
                script src="https://unpkg.com/htmx.org@2.0.4" {}
                script src="https://unpkg.com/htmx-ext-ws@2.0.2/ws.js" {}
            }
            body {
                header class="site-header" {
                    a class="brand" href="/lists" { span class="brand-mark" { "S" } "Sustenance" }
                    @if let Some(user) = user {
                        nav class="site-nav" {
                            a href="/lists" { "Lists" }
                            a href="/meals" { "Meals" }
                        }
                        div class="account-nav" {
                            span class="user-name" { (user.display_name) }
                            form method="post" action="/logout" {
                                button class="text-button" type="submit" { "Sign out" }
                            }
                        }
                    }
                }
                main class="site-main" { (content) }
                footer class="site-footer" { "A small, shared grocery list." }
            }
        }
    }
}

fn initials(name: &str) -> String {
    name.split_whitespace()
        .filter_map(|part| part.chars().next())
        .take(2)
        .collect::<String>()
        .to_uppercase()
}