"use client";

import { CornerDownLeftIcon, SquareIcon } from "lucide-react";
import { cn } from "@/lib/utils";
import { Hint } from "@/components/ui/hint";

/**
 * The chat composer — content row ONLY (the persistent rounded shell lives in
 * the chat view's overlay, so the shell can later morph chat → question
 * without remounting).
 *
 * Corner-radius math (concentric with the shell): shell rounded-2xl (16px) −
 * row padding p-1.5 (6px) = button rounded-[10px] = 25% of the 40px button.
 */
/** What one Enter press does, in precedence order: stop a busy stream,
 *  otherwise send the message. (The plan-verdict accept branch died
 *  2026-09-26 with the verdict itself.) Pure so the static-render harness
 *  can pin the decision (key events can't be simulated in
 *  renderToStaticMarkup). */
export function enterAction(state: { busy: boolean; canSend: boolean }): "stop" | "send" | "none" {
	if (state.busy) return "stop";
	if (state.canSend) return "send";
	return "none";
}

export function Composer({
	busy,
	value,
	onChange,
	onSend,
	onStop,
	canSend,
	autoFocus,
	onEscape,
	placeholder = "Ask, answer, or steer the lesson…",
}: {
	busy: boolean;
	value: string;
	onChange: (v: string) => void;
	onSend: () => void;
	onStop: () => void;
	canSend: boolean;
	autoFocus?: boolean;
	/** Escape while a dictation runs stops it (STT wave, 2026-09-17). No-op
	 *  when absent — Esc otherwise means nothing in the composer. */
	onEscape?: () => void;
	/** The textarea's placeholder (owner refinement round, 2026-09-24):
	 *  active sessions read "Ask, answer, or steer the lesson…"; the fresh
	 *  new-session page asks the graph view's opening question instead. */
	placeholder?: string;
}) {
	return (
		<form
			data-testid="composer"
			className="flex items-end gap-1.5 p-1.5"
			onSubmit={(e) => {
				e.preventDefault();
				const action = enterAction({ busy, canSend });
				if (action === "stop") onStop();
				else if (action === "send") onSend();
			}}
		>
			<textarea
				value={value}
				onChange={(e) => onChange(e.target.value)}
				onKeyDown={(e) => {
					// Esc ends dictation before anything else Esc might someday mean
					// here (the dictate decisions: click-again or Esc to stop).
					// stopPropagation claims the Esc (keyboard wave A): the
					// window-level chain must not also abort a turn under us.
					if (e.key === "Escape" && onEscape) {
						e.preventDefault();
						e.stopPropagation();
						onEscape();
						return;
					}
					// Chat convention: Enter sends, Shift+Enter is a newline.
					// ⌘/Ctrl+Enter also sends — the universal submit shortcut
					// across every input in the app (thinking field, answers).
					if (e.key === "Enter" && (e.metaKey || e.ctrlKey || !e.shiftKey)) {
						e.preventDefault();
						const action = enterAction({ busy, canSend });
						if (action === "stop") onStop();
						else if (action === "send") onSend();
					}
				}}
				placeholder={placeholder}
				autoFocus={autoFocus}
				rows={1}
				className="field-sizing-content lh-input max-h-48 min-h-10 flex-1 resize-none bg-transparent px-2.5 py-2 outline-none placeholder:text-muted-foreground"
			/>
			{/* No tooltip on the send square — the ↵ glyph is the
				 affordance and Enter is obvious (owner, subtlety
				 round 2026-09-25). */}
				<button
					type="submit"
					aria-label={busy ? "Stop" : "Send"}
					disabled={!busy && !canSend}
					className={cn(
						"flex size-10 shrink-0 items-center justify-center rounded-[10px] transition-colors",
						busy
							? "bg-secondary text-foreground hover:bg-accent"
							: "bg-primary text-primary-foreground hover:opacity-90 disabled:opacity-40",
					)}
				>
					{busy ? <SquareIcon className="size-4" /> : <CornerDownLeftIcon className="size-5" />}
				</button>
		</form>
	);
}