"use client";

import { useMemo, useState } from "react";
import { ArrowDownIcon, ChevronRightIcon, PlayIcon } from "lucide-react";
import { Button } from "@/components/ui/button";
import { MessageResponse } from "@/components/ai-elements/message";
import { cn } from "@/lib/utils";
import {
	buildAnswer,
	coerceCorrectAnswer,
	emptyDockSelection,
	normalizeOptions,
	resolveCorrect,
	seededRandom,
	shuffleOptions,
	toggleOption,
	toggleOther,
	type AnswerRequest,
	type AskToolInput,
	type DockSelection,
	type QuestionAnswerData,
	type QuestionData,
	type QuestionMode,
	type QuizToolInput,
	type SelectMode,
	type Phase3,
} from "@/src/core";

/**
 * The question dock — a pending quiz/ask REPLACES the chat composer: the
 * persistent bottom blob morphs into the question. Two voices meet here:
 * the teacher's (question, options, explanation) and the learner's —
 * "Your thinking", a labeled composer-twin field for dumping reasoning,
 * with Submit docked inside it exactly like the chat composer's send.
 *
 * The thinking field is the transfer channel of the whole product (wave-2):
 * never called "optional", Enter makes a NEWLINE (it is for dumping — soon
 * dictated, not typed), submission is the button only, and its size scales
 * with the phase (probing stays quick; teaching invites depth). The
 * "Other…" option is an editable option ROW — circle + inline input,
 * styled like its siblings — so picking Other never displaces thinking.
 *
 * Collapse behavior (scroll-up → slim bar) is owned by the DockOverlay in the
 * chat view, which also owns the persistent shell and its height morph. This
 * component is content only. The expanded form stays MOUNTED while collapsed
 * (hidden, not unmounted) so a half-made selection survives scrolling.
 */

export interface QuestionDockProps {
	toolName: "quiz" | "ask_user_question";
	toolCallId: string;
	input: QuizToolInput | AskToolInput;
	/** Collapse state, owned by the DockOverlay (it drives the shell's height morph). */
	expanded: boolean;
	/**
	 * Teach-phase check awaiting its reveal (vision §2, W5): while collapsed,
	 * the bar is the "Check your understanding" invitation instead of the
	 * scroll-collapse strip. Owned by the DockOverlay; false once the learner
	 * has revealed (afterwards the normal collapse machine rules apply).
	 */
	reveal?: boolean;
	onExpand: () => void;
	onSubmit: (output: QuestionAnswerData) => void;
	/** Session phase at the question — scales the thinking field: probing
	 *  stays quick (one row), teaching invites dumping (three rows). */
	phase?: Phase3;
}

export function QuestionDock({
	toolName,
	toolCallId,
	input,
	expanded,
	reveal = false,
	onExpand,
	onSubmit,
	phase = "probe",
}: QuestionDockProps) {
	return (
		<>
			{!expanded && (
				<QuestionDockBar
					toolName={toolName}
					question={input.question}
					onExpand={onExpand}
					variant={reveal ? "reveal" : "collapsed"}
				/>
			)}
			<div className={expanded ? "dock-variant" : "invisible h-0 overflow-hidden"}>
				<QuestionDockForm
					toolName={toolName}
					toolCallId={toolCallId}
					input={input}
					phase={phase}
					onSubmit={onSubmit}
				/>
			</div>
		</>
	);
}

/** A plain-text teaser of a question for the collapsed bar: unwrap math, flatten common LaTeX. */
function teaserText(q: string): string {
	return q
		.replace(/\\\(([\s\S]*?)\\\)/g, "$1") // \(...\) inline math
		.replace(/\\\[([\s\S]*?)\\\]/g, "$1") // \[...\] display math
		.replace(/\$\$?([^$]*)\$\$?/g, "$1") // legacy $...$ (pre-switch sessions)
		.replace(/\\frac\{([^{}]*)\}\{([^{}]*)\}/g, "$1/$2")
		.replace(/\\([a-zA-Z]+)/g, "$1")
		.replace(/[{}]/g, "")
		.replace(/\s+/g, " ")
		.trim();
}

/** The collapsed strip. Two species (W5): "collapsed" is the scroll minimization
 *  (kind chip + one-liner + Answer ↓); "reveal" is the teach-check invitation —
 *  a distinct, more inviting affordance, because it asks the learner to start
 *  something, not to resume something. */
export function QuestionDockBar({
	toolName,
	question,
	onExpand,
	variant = "collapsed",
}: {
	toolName: "quiz" | "ask_user_question";
	question: string;
	onExpand: () => void;
	variant?: "collapsed" | "reveal";
}) {
	if (variant === "reveal") {
		return (
			<button
				type="button"
				data-testid="teach-check-reveal"
				onClick={onExpand}
				className="dock-variant flex w-full items-center gap-3 px-4 py-3 text-left transition-colors hover:bg-accent/40"
			>
				<span className="flex size-7 shrink-0 items-center justify-center rounded-full bg-primary/15 text-primary">
					<PlayIcon className="size-3.5" />
				</span>
				<span className="min-w-0 flex-1">
					<span className="block text-sm font-medium">Check your understanding</span>
					<span className="block truncate text-xs text-muted-foreground">{teaserText(question)}</span>
				</span>
				<span className="flex shrink-0 items-center gap-1 text-xs font-medium text-primary">
					Open <ChevronRightIcon className="size-3.5" />
				</span>
			</button>
		);
	}
	return (
		<button
			type="button"
			data-testid="question-dock-bar"
			onClick={onExpand}
			className="dock-variant flex w-full items-center gap-2.5 px-4 py-2.5 text-left text-sm transition-colors hover:bg-accent/40"
		>
			<span className="shrink-0 text-xs font-medium uppercase tracking-wide text-muted-foreground">
				{toolName === "quiz" ? "Quiz" : "Question"}
			</span>
			<span className="min-w-0 flex-1 truncate text-muted-foreground">{teaserText(question)}</span>
			<span className="flex shrink-0 items-center gap-1 text-xs font-medium">
				Answer <ArrowDownIcon className="size-3.5" />
			</span>
		</button>
	);
}

/** The expanded question: label, question, options, and the unified bottom row. */
function QuestionDockForm({
	toolName,
	toolCallId,
	input,
	phase = "probe",
	onSubmit,
}: Omit<QuestionDockProps, "expanded" | "onExpand">) {
	const kind = toolName === "quiz" ? ("quiz" as const) : ("ask" as const);

	// Canonical QuestionData, built once per question. Quiz options are
	// deterministically shuffled (seeded by toolCallId) so position never leaks
	// correctness AND server/client render the same order (hydration-safe);
	// the display order is snapshotted into the answer record at submit time.
	const qd = useMemo<QuestionData>(() => {
		const quizInput = kind === "quiz" ? (input as QuizToolInput) : null;
		const askInput = kind === "ask" ? (input as AskToolInput) : null;
		const multi = input.multiSelect === true;
		const mode: QuestionMode =
			kind === "quiz"
				? multi
					? "multi-select"
					: "single-select"
				: askInput?.options?.length
					? multi
						? "multi-select"
						: "single-select"
						: "text";
		const options = normalizeOptions(
			(quizInput?.options ?? askInput?.options ?? []) as { label: string; value?: string }[],
		);
		const ordered = kind === "quiz" && options.length > 0 ? shuffleOptions(options, seededRandom(toolCallId)) : options;
		const q: QuestionData = {
			id: toolCallId,
			kind,
			question: input.question,
			context: input.details,
			mode,
			options: ordered,
			createdAt: new Date().toISOString(),
		};
		if (quizInput) {
			const resolved = resolveCorrect(coerceCorrectAnswer(quizInput.correctAnswer), ordered);
			if (resolved.error) console.error("[quiz] correctAnswer did not resolve:", resolved.error);
			q.correctIndices = resolved.indices;
			q.explanation = quizInput.explanation;
		}
		return q;
	}, [toolCallId, kind, input]);

	// The selection state machine lives in question-core (pure, tested):
	// single-select displaces, multi-select coexists — picking the ask
	// "Other…" row in a multi-select must never clear already-picked
	// options, and picking an option must never clear a typed custom answer.
	const [sel, setSel] = useState<DockSelection>(emptyDockSelection());
	// The learner's transfer channel — thinking, never "a note".
	const [thinking, setThinking] = useState("");
	const [other, setOther] = useState("");
	const [text, setText] = useState("");
	const selectMode: SelectMode = qd.mode === "multi-select" ? "multi-select" : "single-select";

	const toggle = (idx: number) => setSel(toggleOption(selectMode, sel, idx));

	const canSubmit =
		qd.mode === "text"
			? text.trim().length > 0
			: sel.dontKnow || (sel.otherSelected && other.trim().length > 0) || sel.selected.size > 0;

	const submit = () => {
		if (!canSubmit) return;
		const req: AnswerRequest = {
			dontKnow: sel.dontKnow,
			values: [...sel.selected].map((i) => qd.options[i]!.value),
			other: sel.otherSelected ? other : undefined,
			text: qd.mode === "text" ? text : undefined,
			note: qd.mode !== "text" ? thinking.trim() || undefined : undefined,
		};
		onSubmit(buildAnswer(qd, req));
	};

	// Selecting Other never clears the thinking field — two channels, the
	// answer and the reasoning behind it, side by side.
	const selectOther = () => setSel(toggleOther(selectMode, sel));

	return (
		<div data-testid="question-dock">
			{/* Question area — scrolls internally if very tall; the bottom row stays put. */}
			<div className="max-h-[55dvh] overflow-y-auto px-4 pt-3">
				<div className="mb-1 text-xs font-medium uppercase tracking-wide text-muted-foreground">
					{kind === "quiz" ? "Quiz" : "Question"}
					{qd.mode === "multi-select" && " · select all that apply"}
				</div>
				<div className="mb-3 font-medium">
					<MessageResponse>{qd.question}</MessageResponse>
				</div>
				{qd.context && (
					<div className="mb-3 text-sm text-muted-foreground">
						<MessageResponse>{qd.context}</MessageResponse>
					</div>
				)}

				{qd.mode !== "text" && (
					<div className="flex flex-col gap-2 pb-1" role={qd.mode === "multi-select" ? "group" : "radiogroup"}>
						{qd.options.map((opt, i) => {
							const isSel = sel.selected.has(i);
							return (
								<button
									key={opt.value}
									type="button"
									role={qd.mode === "multi-select" ? "checkbox" : "radio"}
									aria-checked={isSel}
									onClick={() => toggle(i)}
									className={cn(
										"flex items-start gap-3 rounded-lg border px-3 py-2 text-left text-sm transition-colors",
										isSel ? "border-primary bg-accent" : "hover:bg-accent/50",
									)}
								>
									<span
										className={cn(
											"mt-0.5 flex size-4 shrink-0 items-center justify-center border",
											qd.mode === "multi-select" ? "rounded-sm" : "rounded-full",
											isSel ? "border-primary bg-primary text-primary-foreground" : "border-muted-foreground/40",
										)}
									>
										{isSel && (
											<span className={cn(qd.mode === "multi-select" ? "text-[10px]" : "size-1.5 rounded-full bg-current")}>
												{qd.mode === "multi-select" ? "✓" : ""}
											</span>
										)}
									</span>
									<span>
										<MessageResponse>{opt.label}</MessageResponse>
										{opt.description && <span className="block text-xs text-muted-foreground">{opt.description}</span>}
									</span>
								</button>
							);
						})}

						{kind === "quiz" && (
							<button
								type="button"
								onClick={() =>
									setSel((prev) => ({ ...prev, selected: new Set(), otherSelected: false, dontKnow: !prev.dontKnow }))
								}
								aria-pressed={sel.dontKnow}
								className={cn(
									"rounded-lg border border-dashed px-3 py-2 text-left text-sm text-muted-foreground transition-colors",
									sel.dontKnow && "border-primary text-foreground",
								)}
							>
								I don't know
							</button>
						)}

						{kind === "ask" && (
							<div
								role={qd.mode === "multi-select" ? "checkbox" : "radio"}
								aria-checked={sel.otherSelected}
								data-testid="other-option"
								onClick={selectOther}
								className={cn(
									"flex items-start gap-3 rounded-lg border px-3 py-2 text-left text-sm transition-colors",
									sel.otherSelected ? "border-primary bg-accent" : "border-dashed hover:bg-accent/50",
								)}
							>
								<span
									className={cn(
										"mt-0.5 flex size-4 shrink-0 items-center justify-center border",
										qd.mode === "multi-select" ? "rounded-sm" : "rounded-full",
										sel.otherSelected
											? "border-primary bg-primary text-primary-foreground"
											: "border-muted-foreground/40",
									)}
								>
									{sel.otherSelected && (
										<span className={cn(qd.mode === "multi-select" ? "text-[10px]" : "size-1.5 rounded-full bg-current")}>
											{qd.mode === "multi-select" ? "✓" : ""}
										</span>
									)}
								</span>
								<input
									value={other}
									onChange={(e) => {
										setOther(e.target.value);
										// Typing selects the row — displacing in
										// single-select, alongside the siblings in multi.
										setSel((prev) => (prev.otherSelected ? prev : toggleOther(selectMode, prev)));
									}}
									placeholder="Type your own answer…"
									className="w-full min-w-0 flex-1 bg-transparent text-sm outline-none placeholder:text-muted-foreground"
									onClick={(e) => e.stopPropagation()}
								/>
							</div>
						)}
					</div>
				)}
			</div>

			{/* The learner's half of the dock — a composer TWIN: a labeled, bordered
			    field with Submit docked inside, exactly like the chat composer's
			    send. Select modes get "Your thinking" (Enter makes a newline — it
			    is for dumping, soon dictated; the button submits); text mode
			    keeps "Your answer" with Enter-to-submit. */}
			<form
				className="border-t border-border/60 p-1.5"
				onSubmit={(e) => {
					e.preventDefault();
					submit();
				}}
			>
				<div
					data-testid={qd.mode === "text" ? "answer-field" : "thinking-field"}
					className="rounded-xl border border-border/70 bg-background/60 transition-colors focus-within:border-primary/50"
				>
					<div className="px-2.5 pt-2 text-[10px] font-medium uppercase tracking-wide text-muted-foreground">
						{qd.mode === "text" ? "Your answer" : "Your thinking"}
					</div>
					{qd.mode === "text" ? (
						<textarea
							value={text}
							onChange={(e) => setText(e.target.value)}
							onKeyDown={(e) => {
								// Chat convention: Enter submits, Shift+Enter is a newline;
								// ⌘/Ctrl+Enter also submits (universal across the app).
								if (e.key === "Enter" && (e.metaKey || e.ctrlKey || !e.shiftKey)) {
									e.preventDefault();
									submit();
								}
							}}
							placeholder="Type your answer…"
							rows={1}
							className="field-sizing-content max-h-48 min-h-10 w-full resize-none bg-transparent px-2.5 py-2 text-sm outline-none placeholder:text-muted-foreground"
						/>
					) : (
						<textarea
							value={thinking}
							onChange={(e) => setThinking(e.target.value)}
							onKeyDown={(e) => {
								// ⌘↵ on macOS, Ctrl↵ elsewhere — the Gmail convention; plain
								// Enter stays a newline (this field is for dumping).
								if (e.key === "Enter" && (e.metaKey || e.ctrlKey)) {
									e.preventDefault();
									submit();
								}
							}}
							placeholder="Why this answer? What are you unsure about? Say as much as you like — the teacher reads all of this."
							rows={1}
							className={cn(
								"field-sizing-content max-h-48 w-full resize-none bg-transparent px-2.5 py-2 text-sm outline-none placeholder:text-muted-foreground/70",
								// Phase-scaled prominence: teaching invites depth,
								// probing stays quick.
								phase === "teach" ? "min-h-[4.5rem]" : "min-h-10",
							)}
						/>
					)}
					<div className="flex items-center justify-between gap-2 p-1">
						{qd.mode !== "text" && (
							<span aria-hidden className="pl-1.5 text-[10px] text-muted-foreground">
								⌘/Ctrl + ↵ submits
							</span>
						)}
						<Button
							type="submit"
							disabled={!canSubmit}
							className="ml-auto h-9 rounded-[10px] px-3.5 text-sm font-medium"
						>
							Submit answer
						</Button>
					</div>
				</div>
			</form>
		</div>
	);
}