import { render, hitTest } from './ui';

type UIValue = any;

type ComponentInstance = {
    state: any;
    update: (state: any) => (event: any) => any;
    view: (state: any) => any;
};

export function runAppCompiled(canvas: HTMLCanvasElement, store: any) {
    const componentInstances = new Map<string, ComponentInstance>();
    let focusedComponentKey: string | null = null;

    function setupCanvas() {
        const dpr = window.devicePixelRatio || 1;
        canvas.width = window.innerWidth * dpr;
        canvas.height = window.innerHeight * dpr;
        canvas.style.width = window.innerWidth + 'px';
        canvas.style.height = window.innerHeight + 'px';
    }

    setupCanvas();

    function setFocus(componentKey: string | null) {
        if (focusedComponentKey === componentKey) return;

        const oldFocus = focusedComponentKey;
        focusedComponentKey = componentKey;

        // Blur event to the previous
        if (oldFocus && componentInstances.has(oldFocus)) {
            handleComponentEvent(oldFocus, { _tag: 'Blurred' });
        }

        // Focus event to the new
        if (componentKey && componentInstances.has(componentKey)) {
            handleComponentEvent(componentKey, { _tag: 'Focused' });
        }

        // Notify ancestors
        if (componentKey) {
            for (const key of componentInstances.keys()) {
                if (key !== componentKey && componentKey.startsWith(key + '.')) {
                    handleComponentEvent(key, { _tag: 'ChildFocused' });
                }
            }
        }
    }

    function handleComponentEvent(componentKey: string, event: any) {
        const instance = componentInstances.get(componentKey);
        if (!instance) return;

        try {
            const result = instance.update(instance.state)(event);
            instance.state = result.state;

            if (result.emit && Array.isArray(result.emit)) {
                for (const e of result.emit) {
                    handleEvent(e);
                }
            }
        } catch(error) {
            console.error('Component event error:', error);
        }
    }

    function expandStateful(ui: UIValue, path: number[], renderedKeys: Set<string>): UIValue {
        switch (ui.kind) {
            case 'stateful': {
                const fullKey = [...path, ui.key].join('.');
                renderedKeys.add(fullKey);

                let instance = componentInstances.get(fullKey);
                const isNew = !instance;

                if (!instance) {
                    instance = {
                        state: ui.init,
                        update: ui.update,
                        view: ui.view
                    };
                    componentInstances.set(fullKey, instance);
                } else {
                    // refresh closures, pick up new values
                    instance.update = ui.update;
                    instance.view = ui.view;
                }

                if (ui.autoFocus?._tag === 'True' && isNew) {
                    setFocus(fullKey);
                }

                const viewResult = instance.view(instance.state);
                let viewUI = viewResult;

                if (ui.focusable) {
                    viewUI = {
                        kind: 'clickable',
                        child: viewUI,
                        event: { _tag: 'FocusAndClick', _0: fullKey }
                    };
                }
                return expandStateful(viewUI, [...path, ui.key], renderedKeys);
            }

            case 'stack':
            case 'row':
            case 'column': {
                return {
                    ...ui,
                    children: ui.children.map((child: UIValue, i: number) =>
                        expandStateful(child, [...path, i], renderedKeys)
                    )
                }
            }

            case 'clickable':
            case 'padding':
            case 'positioned':
            case 'opacity':
            case 'clip': {
                return {
                    ...ui,
                    child: expandStateful((ui as any).child, [...path, 0], renderedKeys)
                };
            }

            default:
                // leaf nodes
                return ui;
        }

    }

    function rerender() {
        const renderedKeys = new Set<string>();

        try {
            const expandedUI = expandStateful(store.os, [], renderedKeys);

            // clean up unrendered instances
            for (const key of componentInstances.keys()) {
                if (!renderedKeys.has(key)) {
                   componentInstances.delete(key);
                }
            }

            if (focusedComponentKey && !renderedKeys.has(focusedComponentKey)) {
                const parts = focusedComponentKey.split('.');
                focusedComponentKey = null;
                while (parts.length > 0) {
                    parts.pop();
                    const ancestor = parts.join('.');
                    if (ancestor && renderedKeys.has(ancestor)) {
                        focusedComponentKey = ancestor;
                        break;
                    }
                }
            }

            render(expandedUI, canvas);
        } catch (error) {
            console.error('Render error:', error);
        }
    }

    function handleEvent(event: any) {
        // Thunk
        if (typeof event === 'function') {
            handleEvent(event(null));
            return;
        }

        if (!event || !event._tag) return;

        if (event._tag === 'Batch' && event._0) {
            for (const e of event._0) {
                handleEvent(e);
            }
            return;
        }

        if (event._tag === 'FocusAndClick') {
            const componentKey = event._0;
            const coords = event._1;
            setFocus(componentKey);
            handleComponentEvent(componentKey, { _tag: 'Clicked', _0: coords });
            return;
        }

        if (event._tag === 'Rebind') {
            store.rebind(event._0, event._1, event._2);
            return;
        }

        if (event._tag === 'Focus') {
            setFocus(event._0);
            return;
        }

        if (event._tag === 'NoOp')
            return;
    }

    canvas.addEventListener('click', (e) => {
        const rect = canvas.getBoundingClientRect();
        const x = e.clientX - rect.left;
        const y = e.clientY - rect.top;

        const hitResult = hitTest(x, y);
        if (hitResult) {
            const { event, relativeX, relativeY } = hitResult;

            if (event._tag === 'FocusAndClick') {
                handleEvent({
                    _tag: 'FocusAndClick',
                    _0: event._0,
                    _1: { x: Math.floor(relativeX), y: Math.floor(relativeY) }
                });
            } else {
                handleEvent(event);
            }
        }

        rerender();
    });

    window.addEventListener('keydown', (e) => {
        const event = {
            _tag: 'Key',
            _0: {
                key: e.key,
                ctrl: { _tag: e.ctrlKey ? 'True' : 'False' },
                meta: { _tag: e.metaKey ? 'True' : 'False' },
                alt: { _tag: e.altKey ? 'True' : 'False' },
                shift: { _tag: e.shiftKey ? 'True' : 'False' },
                printable: { _tag: e.key.length === 1 ? 'True' : 'False' }
            }
        };

        if (focusedComponentKey) {
            // send to focused component
            handleComponentEvent(focusedComponentKey, event);

            // bubble up to ancestors
            for (const key of componentInstances.keys()) {
                if (key !== focusedComponentKey && focusedComponentKey.startsWith(key + '.')) {
                    handleComponentEvent(key, event);
                }
            }
        }

        e.preventDefault();
        rerender();
    });

    let resizeRAF = 0;
    window.addEventListener('resize', () => {
        cancelAnimationFrame(resizeRAF);
        resizeRAF = requestAnimationFrame(() => {
            setupCanvas();
            store.viewport = { width: window.innerWidth, height: window.innerHeight };
            rerender();
        });
    });

    rerender();
}