import { useEffect, useRef, useState } from "react";
import type { RpcCommand, RpcField } from "../commands/rpc";

const controls = (container: HTMLElement | null) =>
	Array.from(
		container?.querySelectorAll<HTMLElement>("button, input, select, textarea") ??
			[],
	).filter((node) => !node.hasAttribute("disabled"));

function valueFor(field: RpcField, value: string | boolean): unknown {
	if (field.kind === "boolean") return value === true;
	if (field.kind === "json")
		return value ? JSON.parse(value as string) : undefined;
	return value || undefined;
}

export function CommandFormDialog({
	command,
	onSubmit,
	onCancel,
	pending = false,
	commandError,
}: {
	command?: RpcCommand;
	onSubmit: (input: Record<string, unknown>) => void;
	onCancel: () => void;
	pending?: boolean;
	commandError?: string;
}) {
	const ref = useRef<HTMLElement>(null);
	const opener = useRef<HTMLElement | null>(null);
	const [values, setValues] = useState<Record<string, string | boolean>>({});
	const [validationError, setValidationError] = useState<string>();
	useEffect(() => {
		if (!command) return;
		opener.current = document.activeElement as HTMLElement | null;
		setValues({});
		setValidationError(undefined);
		const frame = requestAnimationFrame(() => controls(ref.current)[0]?.focus());
		return () => {
			cancelAnimationFrame(frame);
			opener.current?.focus();
		};
	}, [command]);
	if (!command) return null;
	const fields = command.input ?? [];
	const submit = () => {
		if (pending) return;
		try {
			const input: Record<string, unknown> = {};
			for (const field of fields) {
				const value = valueFor(
					field,
					values[field.name] ?? (field.kind === "boolean" ? false : ""),
				);
				if (field.required && (value === undefined || value === ""))
					throw new Error(`${field.label} is required`);
				if (value !== undefined) input[field.name] = value;
			}
			onSubmit(input);
		} catch (cause) {
			setValidationError(cause instanceof Error ? cause.message : "Invalid input");
		}
	};
	return (
		<div className="extension-backdrop">
			<section
				ref={ref}
				className="extension"
				role="dialog"
				aria-modal="true"
				aria-labelledby="command-form-title"
				aria-busy={pending}
				onKeyDown={(event) => {
					if (event.key === "Escape") {
						event.preventDefault();
						onCancel();
					}
					if (event.key === "Tab") {
						const items = controls(ref.current),
							first = items[0],
							last = items[items.length - 1];
						if (!first || !last) return;
						if (event.shiftKey && document.activeElement === first) {
							event.preventDefault();
							last.focus();
						} else if (!event.shiftKey && document.activeElement === last) {
							event.preventDefault();
							first.focus();
						}
					}
				}}
			>
				<p className="extension-eyebrow">Pi RPC command</p>
				<h2 id="command-form-title">/{command.command}</h2>
				<p>{command.description}</p>
				{fields.map((field) => (
					<label key={field.name}>
						{field.label}
						{field.kind === "boolean" ? (
							<input
								aria-label={field.label}
								type="checkbox"
								checked={values[field.name] === true}
								disabled={pending}
								onChange={(event) =>
									setValues({
										...values,
										[field.name]: event.currentTarget.checked,
									})
								}
							/>
						) : field.kind === "enum" ? (
							<select
								aria-label={field.label}
								value={(values[field.name] as string) ?? ""}
								disabled={pending}
								onChange={(event) =>
									setValues({
										...values,
										[field.name]: event.currentTarget.value,
									})
								}
							>
								<option value="">Select…</option>
								{field.options?.map((option) => (
									<option key={option}>{option}</option>
								))}
							</select>
						) : field.kind === "json" ? (
							<textarea
								aria-label={field.label}
								value={(values[field.name] as string) ?? ""}
								disabled={pending}
								onChange={(event) =>
									setValues({
										...values,
										[field.name]: event.currentTarget.value,
									})
								}
							/>
						) : (
							<input
								aria-label={field.label}
								value={(values[field.name] as string) ?? ""}
								disabled={pending}
								onChange={(event) =>
									setValues({
										...values,
										[field.name]: event.currentTarget.value,
									})
								}
							/>
						)}
					</label>
				))}
				{(validationError || commandError) && (
					<p role="alert">{validationError || commandError}</p>
				)}
				<div className="extension-options">
					<button disabled={pending} onClick={submit}>
						{pending ? "Running…" : "Run command"}
					</button>
					<button className="quiet" disabled={pending} onClick={onCancel}>
						Cancel
					</button>
				</div>
			</section>
		</div>
	);
}