# TimePicker

A styled time selector with separate dropdowns for hours and minutes (and optionally AM/PM). The selected time is always stored in a hidden input as `HH:MM` in 24-hour format, regardless of whether you show the 12-hour display mode.

---

## Quick example

```csharp
new TimePicker(name: "startTime", label: "Start time")
```

---

## All the options

```csharp
public TimePicker(
    string  name,
    string? selected    = null,
    string  label       = "",
    string  description = "",
    bool    use12h      = false)
```

| Parameter | What it does |
|---|---|
| `name` | Form field name. The hidden input gets this name and always holds a `HH:MM` value. The visible selects get `{name}-h`, `{name}-m`, `{name}-ampm`. |
| `selected` | Pre-selected time as `"HH:MM"` in 24-hour format. Defaults to the current time. |
| `label` | Visible text label above the picker. |
| `description` | Small hint text below the picker. |
| `use12h` | Show 12-hour mode with an AM/PM dropdown. The hidden input still stores 24h format. |

---

## Real-world examples

### Appointment booking with start and end times

```html
<!-- ScheduleForm.htmx -->
<form method="post" action="/schedule" class="space-y-4">
  $$Token$$
  $$StartTime$$
  $$EndTime$$
  <button type="submit">Save</button>
</form>
```

```csharp
// ScheduleForm.htmx.cs
_startTime = new TimePicker(name: "startTime", label: "Start", selected: "09:00");
_endTime   = new TimePicker(name: "endTime",   label: "End",   selected: "17:00");
```

Reading on the server:

```csharp
public record Command(
    [property: FromForm] string StartTime,  // "HH:MM"
    [property: FromForm] string EndTime
);

var start = TimeOnly.ParseExact(command.StartTime, "HH:mm");
var end   = TimeOnly.ParseExact(command.EndTime,   "HH:mm");
```

### 12-hour display mode with a pre-selected time

```csharp
new TimePicker(
    name:     "alarmTime",
    selected: "07:30",
    label:    "Alarm time",
    use12h:   true)
```

The user sees `7:30 AM` in the dropdowns, but `07:30` is what gets submitted.

---

## How it works

TimePicker renders three `<select>` elements (hours, minutes, and optionally AM/PM) styled to look like a single field, plus a hidden `<input>` that holds the combined value. JavaScript in `components.js` listens for changes on any of the three selects and writes the correctly formatted `HH:MM` value to the hidden input, converting from 12h to 24h when needed.
public record Command(
    [property: FromForm] string StartTime,  // "09:00"
    [property: FromForm] string EndTime     // "17:00"
);

var start = TimeOnly.ParseExact(command.StartTime, "HH:mm");
var end   = TimeOnly.ParseExact(command.EndTime,   "HH:mm");
```

---

## Tips and tricks

- The hidden input always stores 24h `HH:MM` regardless of `use12h` — parse with `"HH:mm"` format on the server.
- `selected` defaults to the current server time if not specified — pass `"00:00"` if you want the picker to start at midnight.
- The visible hour/minute selects are independent form fields (`{name}-h`, `{name}-m`) — only the hidden input with `name` is needed in your command record. Ignore the `-h`, `-m`, and `-ampm` fields server-side.
- For a date+time combination, pair `Calendar` (for date) with `TimePicker` (for time) and combine their values in the handler.
- For a date+time combination, pair `Calendar` (for date) with `TimePicker` (for time) and combine their values in the handler.

---

## Complete page example

**`Templates/ScheduleMeetingPage.htmx`**
```html
<div class="max-w-lg mx-auto py-10">
  <h1 class="text-2xl font-bold mb-2">Schedule a meeting</h1>
  <p class="text-sm text-muted-foreground mb-8">Pick a date and time that works for you.</p>
  <form method="post" action="/meetings/new">
    $$AntiforgeryToken$$
    <div class="grid grid-cols-2 gap-6 mb-8">
      <div>
        <label class="block text-sm font-medium mb-2">Date</label>
        $$DatePicker$$
      </div>
      <div>
        <label class="block text-sm font-medium mb-2">Time</label>
        $$TimePicker$$
      </div>
    </div>
    $$TitleInput$$
    <div class="mt-6">
      $$SubmitBtn$$
    </div>
  </form>
  $$SuccessAlert$$
</div>
```

**`Templates/ScheduleMeetingPage.htmx.cs`**
```csharp
namespace Htmx.ApiDemo.Templates;

public sealed class ScheduleMeetingPage : ScheduleMeetingPageBase
{
    private readonly IHtmxComponent _calendar;
    private readonly IHtmxComponent _timePicker;
    private readonly IHtmxComponent _title;
    private readonly IHtmxComponent _submit;
    private readonly IHtmxComponent _success;
    private readonly byte[] _afToken;

    public ScheduleMeetingPage(
        IAntiforgery af,
        HttpContext ctx,
        DateOnly?   selectedDate = null,
        string      selectedTime = "",
        bool        booked       = false)
    {
        var tokens = af.GetAndStoreTokens(ctx);
        _afToken = $"""<input type="hidden" name="{tokens.FormFieldName}" value="{tokens.RequestToken}">""".ToUtf8Bytes();

        _calendar   = new Components.Calendar(name: "date", selectedDate: selectedDate);
        _timePicker = new Components.TimePicker(name: "time", value: selectedTime, placeholder: "09:00");
        _title      = new Components.Input(id: "title", name: "title", label: "Meeting title", placeholder: "Sync call");
        _submit     = new Components.Button("Book meeting", type: "submit");
        _success    = booked
            ? new Components.Alert(title: "Meeting booked!", description: $"Scheduled for {selectedDate:d} at {selectedTime}.")
            : HtmxEmpty.Instance;
    }

    protected override void RenderAntiforgeryToken(HtmxRenderContext ctx) => ctx.Writer.WriteUtf8(_afToken);
    protected override void RenderDatePicker(HtmxRenderContext ctx)       => _calendar.Render(ctx.Next());
    protected override void RenderTimePicker(HtmxRenderContext ctx)       => _timePicker.Render(ctx.Next());
    protected override void RenderTitleInput(HtmxRenderContext ctx)       => _title.Render(ctx.Next());
    protected override void RenderSubmitBtn(HtmxRenderContext ctx)        => _submit.Render(ctx.Next());
    protected override void RenderSuccessAlert(HtmxRenderContext ctx)     => _success.Render(ctx.Next());
}
```

**POST handler**
```csharp
[Handler]
[MapPost("/meetings/new")]
public static partial class PostScheduleMeetingHandler
{
    public record Command(
        [property: FromForm] DateOnly Date,
        [property: FromForm] string   Time,
        [property: FromForm] string   Title);

    private static Task<IResult> HandleAsync(
        [AsParameters] Command cmd, HttpContext ctx, IAntiforgery af, CancellationToken ct)
    {
        // Persist meeting…
        return ctx.WriteHtmxPage(
            new ScheduleMeetingPage(af, ctx, cmd.Date, cmd.Time, booked: true),
            title: "Schedule meeting");
    }
}
```

**`AppJsonSerializerContext.cs`**
```csharp
[JsonSerializable(typeof(PostScheduleMeetingHandler.Command), TypeInfoPropertyName = "ScheduleMeetingCommand")]
```