import { Soma } from '../../core/soma.svelte';
import { FieldProvider } from '../field';
import { buttonMorfo } from '../../../morfo/components/button';
import type { OptsFromProps } from '../../provider';
import type { OnChangeFn, SomaMouseEvent } from '../../types';
import type { ButtonProps, ButtonIntent } from './types';
import type { SomaRuntime, SomaRuntimePart } from '../../runtime.svelte';

// ── Provider ───────────────────────────────────────────────────────────────

/**
 * Provider's reactive contract derived from `ButtonProps`.
 */
type ButtonOpts = OptsFromProps<
	ButtonProps,
	| 'intent'
	| 'color'
	| 'type'
	| 'disabled'
	| 'loading'
	| 'loadingText'
	| 'spinnerPlacement'
	| 'aria-label'
	| 'onPress',
	never
>;

/**
 * Button provider — runtime-direct.
 *
 * Owns the press → `commit-action` flow. Sequence is `pre` so the
 * perceptual signal lands at the moment of the click; the consumer's
 * onclick may then run async work without blocking it.
 */
export class ButtonProvider {
	static create(opts: ButtonOpts) {
		return new ButtonProvider(opts);
	}

	readonly opts: ButtonOpts;
	readonly field = FieldProvider.get();
	readonly runtime: SomaRuntime;
	readonly runtimePart: SomaRuntimePart;
	readonly soma: Soma;

	private constructor(opts: ButtonOpts) {
		this.opts = opts;

		this.soma = Soma.require();
		this.runtime = this.soma.runtime(buttonMorfo, {
			states: {
				loading: () => opts.loading.current ?? false
			},
			props: {
				disabled: () => this.isDisabled,
				loading: () => opts.loading.current ?? false,
				intent: () => opts.intent.current ?? 'neutral',
				type: () => opts.type.current ?? 'button',
				/**
				 * Resolved visual color. Doctrine: aesthetic must not
				 * contradict semantic. When intent is evaluative
				 * (affirm/fulfill/risk/threat/loss), it WINS over any
				 * hierarchy override. When intent is neutral, `color` may
				 * promote the visual to primary/secondary; if neither,
				 * default 'primary' (Button's default is promoted because
				 * actions are typically the focal point of their surface).
				 */
				color: () => {
					const intent = opts.intent.current ?? 'neutral';
					if (intent !== 'neutral') return intent;
					return opts.color.current ?? 'primary';
				},
				'aria-label': () => opts['aria-label'].current
			},
			events: {
				'commit-action': () => {
					// The consumer's onclick has already been (or will be)
					// invoked by native button click dispatch. We only fire
					// onPress for diagnostic / analytics consumers.
					opts.onPress.current?.({ intent: opts.intent.current ?? 'neutral' });
				}
			}
		});
		this.runtimePart = this.runtime.part('provider', {
			id: opts.id,
			ref: opts.ref,
			owner: this,
			syncAttrs: true
		});
	}

	readonly isDisabled = $derived.by(
		() => (this.opts.disabled.current ?? false) || (this.field?.isDisabled ?? false)
	);
	readonly isLoading = $derived.by(() => this.opts.loading.current ?? false);

	readonly snippetProps = $derived.by(() => ({
		loading: this.isLoading,
		disabled: this.isDisabled
	}));

	readonly onclick = (_e: SomaMouseEvent<HTMLButtonElement>) => {
		if (this.isDisabled || this.isLoading) return;
		// Sequence 'pre' — the perceptual signal fires synchronously with
		// the click; consumer's onclick runs in parallel.
		void this.runtime.trigger('commit-action');
	};

	/**
	 * Render-time props. Composed of:
	 * - identity from the runtime (`id`, `data-button`, ref attachment)
	 * - the HTML `disabled` attribute
	 * - the `onclick` handler
	 */
	readonly props = $derived.by(() => ({
		...this.runtimePart.props,
		disabled: this.isDisabled || undefined,
		onclick: this.onclick
	}));
}

export type { OnChangeFn, ButtonIntent };