// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0

export component ComboBoxBase {
    in property <[string]> model;
    in property <bool> enabled <=> i-focus-scope.enabled;
    out property <bool> has-focus: (i-focus-scope.has-focus || popup-has-focus) && root.enabled;
    out property <bool> pressed <=> i-touch-area.pressed;
    out property <bool> has-hover: i-touch-area.has-hover;
    in-out property <int> current-index: 0;
    in-out property <string> current-value: root.model[root.current-index];

    // Set from the ComboBox when the popup has the focus
    in-out property <bool> popup-has-focus;

    callback selected(current-value: string);
    callback show-popup();
    callback close-popup();

    public function select(index: int) {
        if !root.enabled {
            return;
        }
        root.current-index = index;

        if root.current-value != root.model[root.current-index] {
            root.update-current-value();
        }

        root.selected(root.current-value);
    }

    public function move-selection-up() {
        root.select(Math.max(root.current-index - 1, 0));
    }

    public function move-selection-down() {
        root.select(Math.min(root.current-index + 1, root.model.length - 1));
    }

    public function popup-key-handler(event: KeyEvent) -> EventResult {
        if (event.text == Key.UpArrow) {
            root.move-selection-up();
            return accept;
        } else if (event.text == Key.DownArrow) {
            root.move-selection-down();
            return accept;
        } else if (event.text == Key.Return || event.text == Key.Escape) {
            root.close-popup();
            return accept;
        }
        return reject;

    }

    function reset-current() {
        root.current-index = 0;
    }

    function update-current-value() {
        if root.current-index < 0 || root.current-index >= root.model.length {
            root.current-value = "";
            return;
        }
        root.current-value = root.model[root.current-index];
    }

    changed model => {
        root.reset-current();
    }

    changed current-index => {
        root.update-current-value();
    }

    /// Minimum scroll delta so that the scroll wheel changes the value.
    in property <length> scroll-delta: 2px;

    forward-focus: i-focus-scope;

    i-focus-scope := FocusScope {
        changed has-focus => {
            if self.has-focus {
                // this means the popup was closed and we get back the focus
                root.popup-has-focus = false;
            }
        }
        key-pressed(event) => {
            if (!self.enabled) {
                return reject;
            }
            if (event.text == Key.UpArrow) {
                root.move-selection-up();
                return accept;
            } else if (event.text == Key.DownArrow) {
                root.move-selection-down();
                return accept;
            } else if (event.text == Key.Return) {
                root.show-popup();
            }
            return reject;
        }

        i-touch-area := TouchArea {
            enabled: root.enabled;

            clicked => {
                root.focus();
                root.show-popup();
            }

            scroll-event(event) => {
                if (!root.has-focus) {
                    return reject;
                }
                if (event.delta-y < -root.scroll-delta) {
                    root.move-selection-down();
                    return accept;
                }
                if (event.delta-y > root.scroll-delta) {
                    root.move-selection-up();
                    return accept;
                }
                reject
            }
        }
    }
}