zeyn 0.0.3

//! Form controls: every field kind gets a Zeyn control, with the native element underneath so the
//! form still works without JavaScript and still submits plain values.
//!
//! | Field | Default control | Other controls |
//! |---|---|---|
//! | `bool` | checkbox | [`Control::Switch`] |
//! | `#[choice]` | select (ARIA select only combobox) | [`Control::Radio`], [`Control::Segmented`], [`Control::Listbox`] |
//! | `i32`, `i64`, `Money`, `Decimal` | number input formatted while typing, with step buttons | [`Control::Percent`] |
//! | `String` | text input; a growing text area with a counter above 255 characters; a masked input with the `mask` rule | [`Control::Password`], [`Control::NewPassword`], [`Control::PasswordMeter`], [`Control::OneTimeCode`] |

use crate::i18n::{NumberFormat, Text};
use crate::model::FieldMeta;
use crate::render::{Render, escape};
use crate::value::{FieldKind, Value};

/// A control other than the default for a field. See the table in the module docs.
///
/// ```ignore
/// Form::of(order).field(Order::urgent).control(Order::urgent, Control::Switch)
/// ```
#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize)]
#[serde(rename_all = "snake_case")]
pub enum Control {
    Checkbox,
    /// An on and off switch for `bool` fields (ARIA switch).
    Switch,
    /// A drop down list for `#[choice]` fields (ARIA select only combobox).
    Select,
    /// Radio buttons for short `#[choice]` lists.
    Radio,
    /// Radio buttons drawn as one row of buttons, for two to five short options.
    Segmented,
    /// An always open list with a search box for long `#[choice]` lists.
    Listbox,
    /// A password input for text fields: never shown, never kept in drafts, `autocomplete` set
    /// to `current-password`.
    Password,
    /// A new password input for text fields (`autocomplete="new-password"`), for sign up and
    /// password changes.
    NewPassword,
    /// A one time code input for text fields: numeric keyboard, `autocomplete="one-time-code"`,
    /// never kept in drafts.
    OneTimeCode,
    /// A number shown as a percentage, for `Decimal` and whole number fields. The value is in
    /// percent points: `12.5` is shown as `12.5 %` (`%12,5` in Turkish) and stored as `12.5`.
    Percent,
    /// A new password input with a strength meter. The meter is a hint computed in the browser;
    /// the field's rules (`min_len`, a model `validate` function) are what the server enforces.
    PasswordMeter,
}

/// What a control needs to render one field.
pub(crate) struct Slot<'a> {
    pub m: &'static FieldMeta,
    pub value: &'a Value,
    /// Id, name, test id and validation attributes of the main input.
    pub common: &'a str,
    pub id: &'a str,
    /// The `<label>` element.
    pub label: &'a str,
    pub control: Option<Control>,
}

fn ui(r: &Render, key: &str) -> String {
    r.text(&Text::key(format!("zeyn.ui.{key}")))
}

/// `bool` fields: a checkbox, or a switch.
pub(crate) fn render_bool(out: &mut String, s: &Slot) {
    let checked = if *s.value == Value::Bool(true) { " checked" } else { "" };
    let common = s.common;
    if s.control == Some(Control::Switch) {
        out.push_str(&format!(
            r#"<span class="z-check z-switch-wrap"><input type="checkbox" role="switch" class="z-switch" {common}{checked}><span class="z-switch-track" aria-hidden="true"></span>{}</span>"#,
            s.label
        ));
    } else {
        out.push_str(&format!(
            r#"<span class="z-check"><input type="checkbox" class="z-checkbox" {common}{checked}>{}</span>"#,
            s.label
        ));
    }
}

/// `#[choice]` fields: select, radio buttons, segmented buttons or an open list.
pub(crate) fn render_choice(out: &mut String, r: &Render, s: &Slot) {
    let FieldKind::Choice(options) = s.m.kind else { return };
    let label_of = |key: &'static str, fallback: &'static str| r.text(&Text::key_or(key, fallback));
    match s.control {
        Some(Control::Radio | Control::Segmented) => {
            let class = if s.control == Some(Control::Segmented) { "z-radios z-segmented" } else { "z-radios" };
            let star = if s.m.is_required() { r#"<span class="z-required" aria-hidden="true">*</span>"# } else { "" };
            out.push_str(&format!(
                r#"<fieldset class="{class}" aria-describedby="{}-error"><legend>{}{star}</legend><div class="z-radios-list">"#,
                s.id,
                r.label(s.m)
            ));
            let required = if s.m.is_required() { " required" } else { "" };
            for (i, o) in options.iter().enumerate() {
                let id = if i == 0 { s.id.to_string() } else { format!("{}-{i}", s.id) };
                let checked = if *s.value == Value::Choice(o.value) { " checked" } else { "" };
                out.push_str(&format!(
                    r#"<label class="z-radio" for="{id}"><input type="radio" id="{id}" name="{}" value="{}" data-testid="{}.field.{}.{}"{checked}{required}><span>{}</span></label>"#,
                    s.m.name,
                    o.value,
                    r.scope,
                    s.m.name,
                    o.value,
                    label_of(o.key, o.label)
                ));
            }
            out.push_str("</div></fieldset>");
        }
        _ => {
            let listbox = s.control == Some(Control::Listbox);
            out.push_str(s.label);
            let (class, attr) = if listbox {
                (
                    "z-listbox-field",
                    format!(r#" data-zeyn-listbox size="{}""#, options.len().clamp(2, 8) + usize::from(s.m.optional)),
                )
            } else {
                ("z-select", " data-zeyn-select".to_string())
            };
            out.push_str(&format!(
                r#"<div class="{class}" data-text-none="{}" data-text-search="{}" data-text-no-results="{}"><select {}{attr}>"#,
                ui(r, "select.none"),
                ui(r, "select.search"),
                ui(r, "lookup.no_results"),
                s.common
            ));
            if s.m.optional {
                out.push_str(&format!(r#"<option value="">{}</option>"#, ui(r, "select.none")));
            }
            for o in options {
                let selected = if *s.value == Value::Choice(o.value) { " selected" } else { "" };
                out.push_str(&format!(
                    r#"<option value="{}"{selected}>{}</option>"#,
                    o.value,
                    label_of(o.key, o.label)
                ));
            }
            out.push_str("</select></div>");
        }
    }
}

/// Whole numbers, money and decimals: formatted while typing in the user's language, with step
/// buttons. Key fields are not grouped (`10234`, not `10.234`). Decimals keep their field's scale.
pub(crate) fn render_number(out: &mut String, r: &Render, s: &Slot) {
    let f = NumberFormat::for_locale(r.locale);
    let money = s.m.kind == FieldKind::Money;
    let group = s.m.kind != FieldKind::Id;
    let scale = match s.m.kind {
        FieldKind::Money => 2,
        FieldKind::Decimal => s.m.decimal_limits().1,
        _ => 0,
    };
    let percent = s.control == Some(Control::Percent);
    let text = match s.value {
        Value::Money(m) => m.format_plain(r.locale),
        Value::Number(d) => d.format(r.locale),
        Value::Int(n) if group => crate::value::Money::new(n.saturating_mul(100), Default::default())
            .format_plain(r.locale)
            .rsplit_once(f.decimal)
            .map(|(a, _)| a.to_string())
            .unwrap_or_default(),
        Value::Int(n) => n.to_string(),
        _ => String::new(),
    };
    let limits = [("min", s.m.min()), ("max", s.m.max())]
        .iter()
        .filter_map(|(k, v)| v.map(|n| format!(r#" data-{k}="{n}" aria-value{k}="{n}""#)))
        .collect::<String>();
    let _ = money;
    out.push_str(s.label);
    let (class, common) = if percent {
        let unit = format!("{}-unit", s.id);
        let common = s.common.replacen(r#"aria-describedby=""#, &format!(r#"aria-describedby="{unit} "#), 1);
        (
            if NumberFormat::percent_first(r.locale) {
                "z-number z-percent z-affix-first"
            } else {
                "z-number z-percent"
            },
            common,
        )
    } else {
        ("z-number", s.common.to_string())
    };
    out.push_str(&format!(
        r#"<div class="{class}" data-zeyn-number data-decimal="{}" data-group="{}" data-scale="{scale}" data-grouped="{group}"><input type="text" role="spinbutton" inputmode="{}" autocomplete="off" class="z-num" {common}{limits} value="{}">"#,
        escape(&f.decimal.to_string()),
        escape(&f.group.to_string()),
        if scale > 0 { "decimal" } else { "numeric" },
        escape(&text)
    ));
    if percent {
        out.push_str(&format!(
            r#"<span class="z-affix" aria-hidden="true">%</span><span class="z-sr-only" id="{}-unit">{}</span>"#,
            s.id,
            ui(r, "number.percent")
        ));
    }
    if !s.m.readonly {
        out.push_str(&format!(
            r#"<span class="z-steppers"><button type="button" tabindex="-1" data-zeyn-step="1" aria-label="{}"><span aria-hidden="true">+</span></button><button type="button" tabindex="-1" data-zeyn-step="-1" aria-label="{}"><span aria-hidden="true">&#8722;</span></button></span>"#,
            ui(r, "number.up"),
            ui(r, "number.down")
        ));
    }
    out.push_str("</div>");
}

/// Text: an input, an email input, or a growing text area with a counter for long texts.
pub(crate) fn render_text(out: &mut String, r: &Render, s: &Slot) {
    if let Some(pattern) = s.m.mask_pattern()
        && s.control.is_none()
    {
        crate::ui::inputs::render_mask(out, s, pattern);
        return;
    }
    let text = match s.value {
        Value::Text(t) => escape(t),
        _ => String::new(),
    };
    let max = s.m.max_len();
    let maxlength = max.map(|n| format!(r#" maxlength="{n}""#)).unwrap_or_default();
    let minlength = s.m.min_len().map(|n| format!(r#" minlength="{n}""#)).unwrap_or_default();
    out.push_str(s.label);
    match max {
        Some(n)
            if n > 255
                && !matches!(s.control, Some(Control::Password | Control::NewPassword | Control::OneTimeCode)) =>
        {
            let id = s.id;
            let common = s.common.replace(
                &format!(r#"aria-describedby="{id}-error""#),
                &format!(r#"aria-describedby="{id}-count {id}-error""#),
            );
            let count = match s.value {
                Value::Text(t) => t.chars().count(),
                _ => 0,
            };
            out.push_str(&format!(
                r#"<textarea rows="3" class="z-textarea" data-zeyn-autosize {common}{minlength}{maxlength}>{text}</textarea><p class="z-counter" id="{id}-count" data-zeyn-counter="{n}" data-text="{}">{}</p>"#,
                ui(r, "text.count"),
                escape(&r.i18n.text(r.locale, &Text::key("zeyn.ui.text.count").arg("n", count.to_string()).arg("max", n.to_string())))
            ));
        }
        _ if matches!(s.control, Some(Control::Password | Control::NewPassword | Control::PasswordMeter)) => {
            let auto = if s.control == Some(Control::Password) { "current-password" } else { "new-password" };
            let meter = s.control == Some(Control::PasswordMeter);
            let id = s.id;
            let common = if meter {
                s.common.replacen(r#"aria-describedby=""#, &format!(r#"aria-describedby="{id}-strength "#), 1)
            } else {
                s.common.to_string()
            };
            out.push_str(&format!(
                r#"<div class="z-password" data-zeyn-password><input type="password" autocomplete="{auto}" spellcheck="false" {common}{minlength}{maxlength} value=""><button type="button" class="z-password-toggle" aria-pressed="false" aria-controls="{id}" aria-label="{}" data-testid="{}.field.{}.toggle" hidden><span class="z-eye" aria-hidden="true"></span></button></div>"#,
                ui(r, "password.show"),
                r.scope,
                s.m.name
            ));
            if meter {
                let levels = ["weak", "fair", "good", "strong"].map(|k| ui(r, &format!("password.{k}")));
                out.push_str(&format!(
                    r#"<div class="z-strength" data-zeyn-strength="{id}" data-levels="{}" hidden><span class="z-strength-bar" aria-hidden="true"><span></span><span></span><span></span><span></span></span><span class="z-strength-text" id="{id}-strength" aria-live="polite"></span></div>"#,
                    crate::render::attr(&levels)
                ));
            }
        }

        _ if s.control == Some(Control::OneTimeCode) => {
            out.push_str(&format!(r#"<input type="text" inputmode="text" autocomplete="one-time-code" spellcheck="false" {}{maxlength} value="">"#, s.common));
        }
        _ => {
            let kind = if s.m.rules.contains(&crate::model::Rule::Email) { "email" } else { "text" };
            out.push_str(&format!(r#"<input type="{kind}" {}{minlength}{maxlength} value="{text}">"#, s.common));
        }
    }
}

/// Several options of a `#[choice]`: a native multiple select (what works without JavaScript)
/// that the runtime turns into chips and a multi select list (APG listbox, `aria-multiselectable`).
pub(crate) fn render_choices(out: &mut String, r: &Render, s: &Slot) {
    let FieldKind::Choices(options) = s.m.kind else { return };
    let chosen: Vec<&str> = match s.value {
        Value::Text(t) => t.split(',').filter(|v| !v.is_empty()).collect(),
        _ => Vec::new(),
    };
    let texts = serde_json::json!({
        "none": ui(r, "select.none"),
        "remove": ui(r, "lookup.remove"),
        "selected": ui(r, "lookup.selected"),
        "count": ui(r, "multi.count"),
        "open": ui(r, "lookup.open"),
    });
    out.push_str(s.label);
    out.push_str(&format!(
        r#"<div class="z-multi" data-zeyn-multi data-texts="{}"><select multiple size="{}" {}>"#,
        crate::render::attr(&texts),
        options.len().clamp(2, 8),
        s.common
    ));
    for o in options {
        let selected = if chosen.contains(&o.value) { " selected" } else { "" };
        out.push_str(&format!(
            r#"<option value="{}"{selected}>{}</option>"#,
            o.value,
            r.text(&Text::key_or(o.key, o.label))
        ));
    }
    out.push_str("</select></div>");
}

/// Reads several choices sent as a JSON array or as values joined with commas. Every value must
/// be an option; repeats are dropped. `None` when a value is unknown.
pub(crate) fn read_choices(
    options: &[crate::value::ChoiceOption],
    raw: &serde_json::Value,
) -> Option<serde_json::Value> {
    let parts: Vec<String> = match raw {
        serde_json::Value::Array(items) => {
            items.iter().map(|v| v.as_str().map(str::to_string)).collect::<Option<_>>()?
        }
        serde_json::Value::String(s) => s.split(',').map(|p| p.trim().to_string()).filter(|p| !p.is_empty()).collect(),
        serde_json::Value::Null => Vec::new(),
        _ => return None,
    };
    let mut values: Vec<&str> = Vec::with_capacity(parts.len().min(options.len()));
    for p in &parts {
        let option = options.iter().find(|o| o.value == p.trim())?;
        if !values.contains(&option.value) {
            values.push(option.value);
        }
    }
    Some(serde_json::json!(values))
}

/// Several choices as the user reads them: their labels in the user's language, joined with
/// commas.
pub(crate) fn choices_text(value: &str, kind: &FieldKind, r: &Render) -> String {
    let FieldKind::Choices(options) = kind else { return value.to_string() };
    value
        .split(',')
        .filter(|v| !v.is_empty())
        .map(|v| match options.iter().find(|o| o.value == v) {
            Some(o) => r.i18n.text(r.locale, &Text::key_or(o.key, o.label)),
            None => v.to_string(),
        })
        .collect::<Vec<_>>()
        .join(", ")
}