// Calculator — terse/elegant edition. Demonstrates:
//   - selective imports (bare `button("+")`, no `ui.` prefix)
//   - mutable captures (closures write straight to `num`, `prev`, `op`)
//   - closure-as-operator (`op` holds a |a,b| closure; equals dispatches
//     via `call(op, prev, num)` — no opcode ints or if/else chain)
//   - DSL-with-Scope surface: `window(…) { vstack(…) { grid(…) { … } } }` — the
//     window block builds the tree, then its builder body runs the loop.
//     No `root` handle, no trailing app_run: in-block modifiers
//     (`margin`, `enable_test_server`) act on the ambient element/surface.

import ui (
    window, vstack, grid, equal_cells, btn, button,
    bg_color, onclick, divider, text_bound,
    ui_state, ui_set, margin,
    enable_test_server
)
import std.os (os_getenv)

main() {
    num     = 0
    prev    = 0
    op      = |a: int, b: int| { return a }
    display = ui_state(0)

    digit    = |d: int|  { num = num * 10 + d; ui_set(display, num) }
    apply_op = |fn: fn|  { prev = num; num = 0; op = fn; ui_set(display, 0) }
    equals   = ||        { num = call(op, prev, num); prev = 0; ui_set(display, num) }
    clear    = ||        { num = 0; prev = 0; ui_set(display, 0) }

    window("Calculator", 280, 260) {
        vstack(4) {
            margin(12, 12, 12, 12)
            text_bound(display, " ", "")
            divider()
            // The keypad: a 4-column grid, filled a row at a time, every
            // key the same size.
            grid(4, 4, 4) {
                equal_cells()
                btn("7") callback { call(digit, 7) }
                btn("8") callback { call(digit, 8) }
                btn("9") callback { call(digit, 9) }
                button("+") {
                    bg_color(0.95, 0.85, 0.5, 1.0)
                    onclick() callback {
                        call(apply_op, |a: int, b: int| { return a + b })
                    }
                }
                btn("4") callback { call(digit, 4) }
                btn("5") callback { call(digit, 5) }
                btn("6") callback { call(digit, 6) }
                button("-") {
                    bg_color(0.95, 0.85, 0.5, 1.0)
                    onclick() callback {
                        call(apply_op, |a: int, b: int| { return a - b })
                    }
                }
                btn("1") callback { call(digit, 1) }
                btn("2") callback { call(digit, 2) }
                btn("3") callback { call(digit, 3) }
                button("*") {
                    bg_color(0.95, 0.85, 0.5, 1.0)
                    onclick() callback {
                        call(apply_op, |a: int, b: int| { return a * b })
                    }
                }
                btn("0") callback { call(digit, 0) }
                button("C") {
                    bg_color(0.9, 0.6, 0.6, 1.0)
                    onclick() callback { call(clear) }
                }
                btn("=") callback { call(equals) }
                button("/") {
                    bg_color(0.95, 0.85, 0.5, 1.0)
                    onclick() callback {
                        call(apply_op, |a: int, b: int| {
                            if b != 0 { return a / b }
                            return a
                        })
                    }
                }
            }
        }

        test_port = os_getenv("AETHER_UI_TEST_PORT")
        if test_port != null {
            enable_test_server(9222)
        }
    }
}