# Hiccup Views

Clojure TUI uses Hiccup-style syntax for declarative UI definitions. Views are pure functions that return nested data structures representing the UI.

## Basic Syntax

Views use vectors with keywords as element tags:

```clojure
[:element-type {attributes} children...]
```

Examples:
```clojure
[:text "Hello"]                           ;; Simple text
[:text {:fg :red} "Error"]                ;; Text with attributes
[:col [:text "Line 1"] [:text "Line 2"]]  ;; Nested elements
```

## Elements

### `:text` - Styled Text

The basic building block for displaying text.

```clojure
;; Simple text
[:text "Hello, World!"]

;; Styled text
[:text {:fg :cyan :bold true} "Important"]

;; Multiple style attributes
[:text {:fg :white :bg :red :bold true :underline true} "Alert!"]
```

**Output:**
```
Hello, World!
Important
Alert!
```

**Attributes:**

| Attribute | Type | Description |
|-----------|------|-------------|
| `:fg` | keyword/int | Foreground color |
| `:bg` | keyword/int | Background color |
| `:bold` | boolean | Bold text |
| `:dim` | boolean | Dimmed text |
| `:italic` | boolean | Italic text |
| `:underline` | boolean | Underlined text |
| `:inverse` | boolean | Swap fg/bg colors |
| `:strike` | boolean | Strikethrough text |

### `:row` - Horizontal Layout

Arranges children horizontally (left to right).

```clojure
;; Basic row
[:row "Left" "Middle" "Right"]

;; Row with gap
[:row {:gap 2} "A" "B" "C"]

;; Nested elements in row
[:row
 [:text {:fg :green} "Status:"]
 [:text {:bold true} "OK"]]
```

**Output:**
```
LeftMiddleRight

A  B  C

Status:OK
```

**Attributes:**

| Attribute | Type | Description |
|-----------|------|-------------|
| `:gap` | integer | Spaces between children (default: 0) |

### `:col` - Vertical Layout

Arranges children vertically (top to bottom).

```clojure
;; Basic column
[:col "Line 1" "Line 2" "Line 3"]

;; Column with gap
[:col {:gap 1}
 [:text "Section 1"]
 [:text "Section 2"]]

;; Nested layouts
[:col
 [:text {:bold true} "Header"]
 [:row "Col A" "Col B" "Col C"]
 [:text {:fg :gray} "Footer"]]
```

**Output:**
```
Line 1
Line 2
Line 3

Section 1

Section 2

Header
Col ACol BCol C
Footer
```

**Attributes:**

| Attribute | Type | Description |
|-----------|------|-------------|
| `:gap` | integer | Blank lines between children (default: 0) |

### `:box` - Bordered Container

Wraps content in a bordered box.

```clojure
;; Simple box
[:box "Content"]

;; Box with title
[:box {:title "Settings"} "Options go here"]

;; Box with padding
[:box {:padding 1} "Padded content"]

;; Box with custom border style
[:box {:border :double} "Important!"]
```

**Output:**
```
╭─────────╮
│Content  │
╰─────────╯

╭─Settings─╮
│Options go here│
╰──────────╯

╭──────────────────╮
│                  │
│ Padded content   │
│                  │
╰──────────────────╯

╔═══════════╗
║Important! ║
╚═══════════╝
```

**Attributes:**

| Attribute | Type | Description |
|-----------|------|-------------|
| `:border` | keyword | Border style (see below) |
| `:title` | string | Title in top border |
| `:padding` | int/vec | Inner padding (see below) |
| `:width` | integer | Fixed width |

**Border Styles:**

| Style | Characters | Example |
|-------|------------|---------|
| `:rounded` | `╭╮╰╯─│` | `╭───╮` (default) |
| `:single` | `┌┐└┘─│` | `┌───┐` |
| `:double` | `╔╗╚╝═║` | `╔═══╗` |
| `:heavy` | `┏┓┗┛━┃` | `┏━━━┓` |
| `:ascii` | `++--\|` | `+---+` |

**Padding:**

```clojure
;; All sides
[:box {:padding 2} "Content"]

;; Vertical and horizontal [v h]
[:box {:padding [1 2]} "Content"]

;; Individual [top right bottom left]
[:box {:padding [1 2 1 2]} "Content"]
```

### `:space` - Empty Space

Creates empty space for layout purposes.

```clojure
;; Default 1x1 space
[:space]

;; Horizontal space
[:row "Left" [:space {:width 10}] "Right"]

;; Vertical space
[:col "Top" [:space {:height 3}] "Bottom"]
```

**Output:**
```
Left          Right

Top



Bottom
```

**Attributes:**

| Attribute | Type | Description |
|-----------|------|-------------|
| `:width` | integer | Width in characters (default: 1) |
| `:height` | integer | Height in lines (default: 1) |

## Colors

### Named Colors

Basic 16-color palette supported by all terminals:

| Color | Keyword | Bright Version |
|-------|---------|----------------|
| Black | `:black` | `:bright-black` |
| Red | `:red` | `:bright-red` |
| Green | `:green` | `:bright-green` |
| Yellow | `:yellow` | `:bright-yellow` |
| Blue | `:blue` | `:bright-blue` |
| Magenta | `:magenta` | `:bright-magenta` |
| Cyan | `:cyan` | `:bright-cyan` |
| White | `:white` | `:bright-white` |
| Default | `:default` | - |

Aliases: `:gray` and `:grey` map to `:bright-black`

```clojure
[:text {:fg :red} "Error"]
[:text {:fg :bright-green} "Success"]
[:text {:bg :blue :fg :white} "Highlighted"]
```

### 256 Colors

Use integers 0-255 for extended color support:

```clojure
[:text {:fg 208} "Orange (256-color)"]
[:text {:bg 236} "Dark gray background"]
```

**Color ranges:**
- 0-7: Standard colors
- 8-15: Bright colors
- 16-231: 6x6x6 color cube
- 232-255: Grayscale (dark to light)

### True Color (24-bit)

For true color, use the `tui.ansi` namespace directly:

```clojure
(require '[tui.ansi :as ansi])

[:text (ansi/fg-rgb 255 128 0 "Orange text")]
[:text (ansi/bg-rgb 30 30 30 "Dark background")]
```

## Text Styles

Combine multiple styles:

```clojure
[:text {:bold true :underline true} "Bold and underlined"]
[:text {:fg :red :bold true :inverse true} "Inverted error"]
[:text {:dim true :italic true} "Subtle italic"]
```

**Available styles:**

| Style | Attribute | Description |
|-------|-----------|-------------|
| Bold | `:bold true` | Heavier font weight |
| Dim | `:dim true` | Lighter/faded text |
| Italic | `:italic true` | Slanted text |
| Underline | `:underline true` | Line under text |
| Inverse | `:inverse true` | Swap foreground/background |
| Strikethrough | `:strike true` | Line through text |

## Layout Examples

### Two-Column Layout

```clojure
[:row {:gap 4}
 [:col
  [:text {:bold true} "Left Column"]
  [:text "Item 1"]
  [:text "Item 2"]]
 [:col
  [:text {:bold true} "Right Column"]
  [:text "Item A"]
  [:text "Item B"]]]
```

**Output:**
```
Left Column    Right Column
Item 1         Item A
Item 2         Item B
```

### Nested Boxes

```clojure
[:box {:title "Outer" :padding 1}
 [:row {:gap 2}
  [:box {:border :single :title "Box A"}
   [:text "Content A"]]
  [:box {:border :single :title "Box B"}
   [:text "Content B"]]]]
```

**Output:**
```
╭─Outer────────────────────────────╮
│                                  │
│  ┌─Box A─────┐  ┌─Box B─────┐    │
│  │Content A  │  │Content B  │    │
│  └───────────┘  └───────────┘    │
│                                  │
╰──────────────────────────────────╯
```

### Status Bar

```clojure
[:col
 [:box {:border :rounded :padding [0 1]}
  [:text {:bold true} "My Application"]]
 [:space {:height 1}]
 [:text "Main content here..."]
 [:space {:height 1}]
 [:row {:gap 2}
  [:text {:fg :gray} "Status: Ready"]
  [:text {:fg :gray} "|"]
  [:text {:fg :gray} "Press q to quit"]]]
```

**Output:**
```
╭──────────────────╮
│ My Application   │
╰──────────────────╯

Main content here...

Status: Ready  |  Press q to quit
```

### Menu with Selection

```clojure
(defn menu-item [label selected?]
  [:row
   [:text (if selected? "> " "  ")]
   [:text {:fg (if selected? :cyan :white)
           :bold selected?}
    label]])

(defn view [{:keys [items cursor]}]
  [:col
   [:text {:bold true} "Select an option:"]
   [:space {:height 1}]
   [:col {:gap 0}
    (for [[idx item] (map-indexed vector items)]
      (menu-item item (= idx cursor)))]])
```

**Output (cursor on second item):**
```
Select an option:

  First Option
> Second Option
  Third Option
```

### Progress Indicator

```clojure
(defn progress-bar [percent width]
  (let [filled (int (* width (/ percent 100)))
        empty (- width filled)]
    [:row
     [:text "["]
     [:text {:fg :green} (apply str (repeat filled "="))]
     [:text {:fg :gray} (apply str (repeat empty "-"))]
     [:text "]"]
     [:text " "]
     [:text (str percent "%")]]))

(defn view [{:keys [progress]}]
  [:col
   [:text "Downloading..."]
   (progress-bar progress 20)])
```

**Output (at 65%):**
```
Downloading...
[=============-------] 65%
```

## Helper Functions

The `tui.render` namespace provides helper functions:

```clojure
(require '[tui.render :refer [text row col box]])

;; These are equivalent:
[:text {:fg :red} "Error"]
(text {:fg :red} "Error")

[:row {:gap 2} "A" "B"]
(row {:gap 2} "A" "B")

[:col [:text "Line 1"] [:text "Line 2"]]
(col (text "Line 1") (text "Line 2"))

[:box {:title "Info"} "Content"]
(box {:title "Info"} "Content")
```

## Conditional Rendering

Use standard Clojure conditionals:

```clojure
(defn view [{:keys [loading? error data]}]
  [:col
   [:text {:bold true} "Status"]
   (cond
     loading?
     [:text {:fg :yellow} "Loading..."]

     error
     [:text {:fg :red} (str "Error: " error)]

     :else
     [:text {:fg :green} (str "Data: " data)])])
```

## Dynamic Views with `for`

Generate repeated elements:

```clojure
(defn view [{:keys [items selected]}]
  [:col
   (for [[idx item] (map-indexed vector items)]
     [:row
      [:text (if (= idx selected) "> " "  ")]
      [:text {:fg (if (= idx selected) :cyan :white)} item]])])
```

## String Shortcuts

Plain strings are automatically wrapped in `:text`:

```clojure
;; These are equivalent:
[:col "Line 1" "Line 2"]
[:col [:text "Line 1"] [:text "Line 2"]]

;; In rows too:
[:row "A" "B" "C"]
[:row [:text "A"] [:text "B"] [:text "C"]]
```

## Common Patterns

### Styled Labels

```clojure
(defn label [text]
  [:text {:fg :gray} (str text ": ")])

(defn value [text]
  [:text {:fg :white :bold true} text])

[:row (label "Name") (value "John")]
```

### Conditional Styling

```clojure
(defn status-text [status]
  [:text {:fg (case status
                :ok :green
                :warning :yellow
                :error :red
                :white)
          :bold (= status :error)}
   (name status)])
```

### Reusable Components

```clojure
(defn card [{:keys [title]} & children]
  [:box {:border :rounded :title title :padding [0 1]}
   (into [:col] children)])

;; Usage
(card {:title "User Info"}
  [:row (label "Name") (value "Alice")]
  [:row (label "Email") (value "alice@example.com")])
```

## Next Steps

- [API Reference](api-reference.md) - Complete API documentation
- [Examples](examples.md) - Full example applications