"use client";

/**
 * THE CHAIN TABLE (chains overlay; owner redesign, 2026-09-29 evening):
 * every reasoning chain of the graph in one FULL-BLEED table — the blur
 * + translucent background IS the surface, no inner card (owner ruling:
 * "full width of the area"). The overlay's own top bar carries the info
 * + the close button (lh-no-drag — it lives inside home's 52px drag
 * mask, and being later in the DOM the carve-out sticks; that mask was
 * what ate the old card's X clicks).
 *
 * HIERARCHY (three levels, one click each): CLUSTER (the birth session —
 * a chat or a notes file; a chain lives where its CONCLUSION was born,
 * owner ruling) → REASONING CHAIN → PROPOSITION STATEMENTS. Expanding a
 * chain reveals its members' statement TEXT directly — the names already
 * live in the chain line, so they never render twice; a singleton chain
 * reveals its one statement in a single click. Everything starts
 * COLLAPSED (owner ruling — no arbitrary default expansion).
 *
 * THE TABLE LOOK: drawn hairline row + column lines; sortable column
 * headers (Name + Created clickable, owner ruling — the size column is
 * text, not a control). In the chain line every proposition name is a
 * faint-outlined CHIP and the → a clearly separated connector between
 * chips (owner ruling) — a lonely chip with no connector reads as a
 * standalone proposition; the "(no premises)" text annotation is dead.
 * Icons: clusters FolderIcon (opens when expanded), chains WaypointsIcon
 * (the sidebar's graph glyph), propositions chip-only. Chevrons rotate
 * with expansion state.
 *
 * SELECTION never shifts layout (owner ruling): a floating bottom bar —
 * the Google-Photos pattern — appears only when something is selected,
 * showing the agents' ACTUAL input (chainsForSelection over the flat
 * node-id selection: a premise without its conclusion counts as the
 * singleton it becomes) + Clear + Generate problem set (the one action
 * for now; the bar is a neutral action slot for future ones). The fuzzy
 * search (names, aliases, statements) filters chains; clusters with
 * matches auto-expand, others hide — the collapsed grouped view returns
 * when the query clears.
 *
 * Read-only toward the graph. Named neutrally (ChainTable, not
 * Practice*) — only the Generate handoff knows about practice.
 */

import { useEffect, useMemo, useState } from "react";
import {
	ChevronRightIcon,
	FolderIcon,
	FolderOpenIcon,
	ListTreeIcon,
	SearchIcon,
	WaypointsIcon,
	XIcon,
} from "lucide-react";
import { chainsForSelection, formatChainLine, fuzzyScore } from "@/src/core";
import type { GraphEdge, GraphNode } from "@/src/core";
import { PracticeDialog } from "@/components/practice-dialog";

/** The shared row grid: checkbox | chevron | icon | content | props | created. */
const ROW_COLS = "grid-cols-[1.75rem_1.25rem_1.5rem_minmax(0,1fr)_5.5rem_6rem]";

/** The sortable columns (owner ruling: Name + Created only — size is text). */
export type ChainSortCol = "name" | "created";
export interface ChainSort {
	col: ChainSortCol;
	/** 1 = ascending (A→Z, oldest-first), -1 = descending. */
	dir: 1 | -1;
}

/** A cluster's chains share the conclusion's birth (owner ruling). This
 *  record is assembled per render from the visible chains. */
interface ClusterGroup {
	key: string;
	birth: string | null;
	label: string | null;
	kind: "chat" | "notes" | null;
	chains: ReturnType<typeof chainsForSelection>;
	nodeIds: string[];
	newestCreatedAt: string;
}

/** The table's pure body — exported for SSR pins (the render-suite
 *  discipline). All state (query, sort, selection, expansion) arrives
 *  via props; the overlay wrapper below owns it. */
export function ChainTableBody({
	nodes,
	edges,
	sessions,
	fileSources,
	query,
	onQuery,
	sort,
	onSort,
	selection,
	expandedClusters,
	expandedChains,
	onToggleCluster,
	onToggleChain,
	onToggleNodes,
	onClear,
	onGenerate,
	onClose,
}: {
	nodes: GraphNode[];
	edges: GraphEdge[];
	sessions: Record<string, string>;
	fileSources: Record<string, string>;
	query: string;
	onQuery: (v: string) => void;
	sort: ChainSort;
	onSort: (col: ChainSortCol) => void;
	selection: ReadonlySet<string>;
	expandedClusters: ReadonlySet<string>;
	expandedChains: ReadonlySet<string>;
	onToggleCluster: (key: string) => void;
	onToggleChain: (id: string) => void;
	/** Selection is ALWAYS a flat node-id set — cluster, chain, and single
	 *  proposition checks all reduce to this. */
	onToggleNodes: (ids: string[], next: boolean) => void;
	onClear: () => void;
	onGenerate: () => void;
	onClose: () => void;
}) {
	const byId = useMemo(() => new Map(nodes.map((n) => [n.id, n])), [nodes]);
	const chains = useMemo(() => chainsForSelection(nodes, edges), [nodes, edges]);
	const searching = query.trim() !== "";

	// The fuzzy filter: a chain is visible when ANY member matches on
	// name, aliases, or statement; chains rank by best member score.
	const visibleChains = useMemo(() => {
		if (!searching) return chains;
		const scored = chains
			.map((chain) => {
				let best: number | null = null;
				for (const id of [...chain.premises, chain.conclusion]) {
					const node = byId.get(id);
					if (!node) continue;
					const s = fuzzyScore(query, node.name, node.statement, ...node.aliases);
					if (s === null) continue;
					if (best === null || s > best) best = s;
				}
				return best === null ? null : { chain, best };
			})
			.filter((r): r is { chain: (typeof chains)[number]; best: number } => r !== null);
		return scored
			.sort((a, b) => b.best - a.best || (a.chain.id < b.chain.id ? -1 : 1))
			.map(({ chain }) => chain);
	}, [chains, byId, query, searching]);

	// Group the visible chains by their CONCLUSION's birth (owner ruling).
	// Unlabeled births (provenance gone / never named) form one honest
	// muted group, sorted last under name-sort.
	const groups = useMemo(() => {
		const map = new Map<string, ClusterGroup>();
		for (const chain of visibleChains) {
			const conclusion = byId.get(chain.conclusion);
			const birth = conclusion?.provenance[0]?.chatId ?? null;
			const key = birth ?? "\0unlabeled";
			let group = map.get(key);
			if (!group) {
				const label = birth === null ? null : (sessions[birth] ?? fileSources[birth] ?? null);
				const kind = birth === null ? null : sessions[birth] !== undefined ? "chat" : fileSources[birth] !== undefined ? "notes" : null;
				group = { key, birth, label, kind, chains: [], nodeIds: [], newestCreatedAt: "" };
				map.set(key, group);
			}
			group.chains.push(chain);
			for (const id of [...chain.premises, chain.conclusion]) {
				if (!group.nodeIds.includes(id)) group.nodeIds.push(id);
				const createdAt = byId.get(id)?.createdAt ?? "";
				if (createdAt > group.newestCreatedAt) group.newestCreatedAt = createdAt;
			}
		}
		const collator = new Intl.Collator(undefined, { sensitivity: "base", numeric: true });
		const nameKey = (g: ClusterGroup) => g.label ?? "\uffff"; // unlabeled last
		const list = [...map.values()];
		if (sort.col === "created") {
			list.sort((a, b) =>
				sort.dir === -1
					? b.newestCreatedAt.localeCompare(a.newestCreatedAt)
					: a.newestCreatedAt.localeCompare(b.newestCreatedAt),
			);
		} else {
			list.sort((a, b) => collator.compare(nameKey(a), nameKey(b)) * sort.dir);
		}
		for (const group of list) {
			if (sort.col === "created") {
				group.chains.sort((a, b) => {
					const da = byId.get(a.conclusion)?.createdAt ?? "";
					const db = byId.get(b.conclusion)?.createdAt ?? "";
					return sort.dir === -1 ? db.localeCompare(da) : da.localeCompare(db);
				});
			} else {
				group.chains.sort((a, b) => {
					const na = byId.get(a.conclusion)?.name ?? a.conclusion;
					const nb = byId.get(b.conclusion)?.name ?? b.conclusion;
					return collator.compare(na, nb) * sort.dir;
				});
			}
		}
		return list;
	}, [visibleChains, byId, sessions, fileSources, sort]);

	// The derived shape under the floating bar (the agents' ACTUAL input).
	const derived = useMemo(() => {
		const selectedNodes = [...selection].map((id) => byId.get(id)).filter((n): n is GraphNode => n !== undefined);
		return chainsForSelection(selectedNodes, edges);
	}, [selection, byId, edges]);

	const nameOf = (id: string) => byId.get(id)?.name ?? id;
	const dateOf = (id: string) => byId.get(id)?.createdAt.slice(0, 10) ?? "";
	const sortArrow = (col: ChainSortCol) =>
		sort.col !== col ? "" : sort.dir === 1 ? "▲" : "▼";

	return (
		<div data-testid="chain-table" className="relative flex h-full min-h-0 flex-col">
			{/* The overlay's own top bar (owner ruling): info + search + close.
			    lh-no-drag — this strip sits inside home's 52px window-drag mask,
			    and being later in the DOM the carve-out sticks (the mask law,
			    home.tsx). pl-12 clears the floating sidebar toggle (top-left). */}
			<div className="lh-no-drag flex h-13 shrink-0 items-center gap-3 border-b border-border/60 pl-12 pr-3">
				<ListTreeIcon className="size-4 text-muted-foreground" />
				<span className="font-title text-lg tracking-tight">Chains</span>
				<span className="text-xs text-muted-foreground">
					{chains.length} {chains.length === 1 ? "chain" : "chains"} · {nodes.length} propositions
				</span>
				<div className="flex-1" />
				<div className="relative">
					<SearchIcon className="absolute left-2.5 top-1/2 size-3.5 -translate-y-1/2 text-muted-foreground" />
					<input
						value={query}
						data-testid="chain-table-search"
						onChange={(e) => onQuery(e.target.value)}
						placeholder="Search propositions…"
						aria-label="Search propositions"
						spellCheck={false}
						className="h-8 w-64 rounded-lg border bg-background pl-8 pr-3 text-xs outline-none placeholder:text-muted-foreground focus:border-ring"
					/>
				</div>
				<button
					type="button"
					data-testid="chain-table-close"
					onClick={onClose}
					aria-label="Close chains"
					className="flex size-8 items-center justify-center rounded-lg border border-border/70 bg-card/80 text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
				>
					<XIcon className="size-4" />
				</button>
			</div>

			{/* The table: hairline column + row lines (owner ruling — a real
			    table look). Sortable headers on Name + Created only. */}
			<div className="min-h-0 flex-1 overflow-y-auto">
				<div className={`sticky top-0 z-10 grid ${ROW_COLS} items-center gap-1 border-b border-border/60 bg-background/95 px-3 py-1.5 text-[11px] uppercase tracking-widest text-muted-foreground/70 backdrop-blur`}>
					<span />
					<span />
					<span />
					<button
						type="button"
						data-testid="sort-name"
						onClick={() => onSort("name")}
						aria-sort={sort.col === "name" ? (sort.dir === 1 ? "ascending" : "descending") : "none"}
						className="flex items-center gap-1 text-left uppercase tracking-widest transition-colors hover:text-foreground"
					>
						Name <span aria-hidden="true">{sortArrow("name")}</span>
					</button>
					<span className="border-l border-border/40 pl-2">Props</span>
					<button
						type="button"
						data-testid="sort-created"
						onClick={() => onSort("created")}
						aria-sort={sort.col === "created" ? (sort.dir === 1 ? "ascending" : "descending") : "none"}
						className="flex items-center gap-1 border-l border-border/40 pl-2 text-left uppercase tracking-widest transition-colors hover:text-foreground"
					>
						Created <span aria-hidden="true">{sortArrow("created")}</span>
					</button>
				</div>

				{groups.length === 0 && (
					<div data-testid="chain-table-nomatch" className="px-4 pt-3 text-xs text-muted-foreground">
						No matching chains.
					</div>
				)}

				{groups.map((group) => {
					const open = searching || expandedClusters.has(group.key);
					const selectedCount = group.nodeIds.filter((id) => selection.has(id)).length;
					return (
						<div key={group.key} data-testid={`cluster-group-${group.key}`}>
							{/* The cluster row: birth-session group header. */}
							<div className={`grid ${ROW_COLS} items-center gap-1 border-b border-border/40 px-3 py-1.5`}>
								<span>
									<RowCheckbox
										checked={selectedCount === group.nodeIds.length && group.nodeIds.length > 0}
										indeterminate={selectedCount > 0 && selectedCount < group.nodeIds.length}
										onToggle={(next) => onToggleNodes(group.nodeIds, next)}
										testid={`cluster-checkbox-${group.key}`}
										label={`Select everything born in ${group.label ?? "unlabeled"}`}
									/>
								</span>
								<Expander open={open} onClick={() => onToggleCluster(group.key)} testid={`cluster-toggle-${group.key}`} label={`Expand cluster ${group.label ?? "unlabeled"}`} />
								<span className="flex items-center justify-center text-muted-foreground">
									{open ? <FolderOpenIcon className="size-3.5" /> : <FolderIcon className="size-3.5" />}
								</span>
								<span className="min-w-0 truncate text-sm font-medium">
									{group.label ?? <span className="text-muted-foreground/60">unlabeled</span>}
									{group.kind === "notes" && <span className="ml-2 text-[11px] uppercase tracking-widest text-muted-foreground/60">notes</span>}
								</span>
								<span className="border-l border-border/40 pl-2 text-xs tabular-nums text-muted-foreground">
									{group.nodeIds.length}
								</span>
								<span className="border-l border-border/40 pl-2 text-xs tabular-nums text-muted-foreground">
									{group.newestCreatedAt.slice(0, 10)}
								</span>
							</div>

							{/* The chain rows (visible only when the cluster is open —
							    searching auto-expands, owner ruling). */}
							{open &&
								group.chains.map((chain) => {
									const memberIds = [...chain.premises, chain.conclusion];
									const chainOpen = expandedChains.has(chain.id);
									const selectedInChain = memberIds.filter((id) => selection.has(id)).length;
									return (
										<div key={chain.id} data-testid={`chain-block-${chain.id}`}>
											<div
												data-testid={`chain-row-${chain.id}`}
												aria-label={formatChainLine(chain, Object.fromEntries([...byId.entries()].map(([id, n]) => [id, { name: n.name }])))}
												className={`grid ${ROW_COLS} items-center gap-1 border-b border-border/40 px-3 py-1.5`}
											>
												<span>
													<RowCheckbox
														checked={selectedInChain === memberIds.length && memberIds.length > 0}
														indeterminate={selectedInChain > 0 && selectedInChain < memberIds.length}
														onToggle={(next) => onToggleNodes(memberIds, next)}
														testid={`chain-checkbox-${chain.id}`}
														label={`Select chain ${nameOf(chain.conclusion)}`}
													/>
												</span>
												<Expander open={chainOpen} onClick={() => onToggleChain(chain.id)} testid={`chain-toggle-${chain.id}`} label={`Expand chain ${nameOf(chain.conclusion)}`} />
												<span className="flex items-center justify-center text-muted-foreground">
													<WaypointsIcon className="size-3.5" />
												</span>
												{/* The chain line: proposition names as faint-outlined
												    chips, → the connector BETWEEN them (owner ruling) — a
												    lonely chip reads as a standalone proposition. */}
												<span className="flex min-w-0 flex-wrap items-center gap-x-0.5 gap-y-1 text-[13px] leading-tight">
													{memberIds.map((id, i) => (
														<span key={id} className="flex items-center">
															{i > 0 && <span data-testid={`chain-arrow-${chain.id}-${i}`} className="px-1.5 text-muted-foreground/50">→</span>}
															<span
																data-testid={`prop-chip-${id}`}
																className="rounded border border-border/70 bg-muted/30 px-1.5 py-0.5"
															>
																{nameOf(id)}
															</span>
														</span>
													))}
												</span>
												<span className="border-l border-border/40 pl-2 text-xs tabular-nums text-muted-foreground">
													{memberIds.length}
												</span>
												<span className="border-l border-border/40 pl-2 text-xs tabular-nums text-muted-foreground">
													{dateOf(chain.conclusion)}
												</span>
											</div>

											{/* The propositions — their STATEMENT text directly (owner
											    ruling: names already live in the line; never shown twice;
											    a singleton reveals its one statement in a single click).
											    Deep indent under the chain. */}
											{chainOpen &&
												memberIds.map((id) => {
													const node = byId.get(id);
													if (!node) return null;
													const isConclusion = id === chain.conclusion;
													return (
														<div
															key={id}
															data-testid={`prop-row-${id}`}
															className={`grid ${ROW_COLS} items-start gap-1 border-b border-border/40 bg-muted/10 px-3 py-1.5`}
														>
															<span>
																<RowCheckbox
																	checked={selection.has(id)}
																	onToggle={(next) => onToggleNodes([id], next)}
																	testid={`prop-checkbox-${id}`}
																	label={`Select proposition ${node.name}`}
																/>
															</span>
															<span />
															<span />
															<span className="min-w-0 pl-10 text-xs leading-relaxed text-muted-foreground">
																{isConclusion && <span data-testid={`prop-conclusion-${id}`} className="mr-1.5 text-foreground/60">→</span>}
																{node.statement}
															</span>
															<span className="border-l border-border/40" />
															<span className="border-l border-border/40" />
														</div>
													);
												})}
										</div>
									);
								})}
						</div>
					);
				})}
			</div>

			{/* The floating selection bar (owner ruling: never shifts layout —
			    the Google-Photos pattern). Appears only when something is
			    selected; floats over the table's bottom edge. */}
			{selection.size > 0 && (
				<div className="pointer-events-none absolute inset-x-0 bottom-0 z-10 flex justify-center pb-4">
					<div
						data-testid="chain-selection-bar"
						className="pointer-events-auto flex items-center gap-3 rounded-full border bg-card px-4 py-2 shadow-lg"
					>
						<span data-testid="chain-selected-summary" className="text-xs font-medium">
							{selection.size} {selection.size === 1 ? "proposition" : "propositions"} →{" "}
							{derived.length} {derived.length === 1 ? "chain" : "chains"}
						</span>
						<button
							type="button"
							data-testid="chain-clear"
							onClick={onClear}
							className="rounded-full px-2.5 py-1 text-xs text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
						>
							Clear
						</button>
						<button
							type="button"
							data-testid="chain-generate"
							onClick={onGenerate}
							className="rounded-full bg-primary px-3 py-1.5 text-xs font-medium text-primary-foreground transition-colors hover:bg-primary/90"
						>
							Generate problem set
						</button>
					</div>
				</div>
			)}
		</div>
	);
}

/** The rotating chevron — collapsed points right, expanded rotates down
 *  (owner ruling: the affordance must read on every expandable row). */
function Expander({ open, onClick, testid, label }: { open: boolean; onClick: () => void; testid: string; label: string }) {
	return (
		<button
			type="button"
			data-testid={testid}
			onClick={onClick}
			aria-label={label}
			aria-expanded={open}
			className="flex size-5 items-center justify-center rounded text-muted-foreground/70 transition-colors hover:bg-accent hover:text-foreground"
		>
			<ChevronRightIcon className={`size-3.5 transition-transform ${open ? "rotate-90" : ""}`} />
		</button>
	);
}

/** The checkbox — checked/indeterminate (partial chains/clusters); DOM
 *  property set via ref (React does not expose `indeterminate`). */
function RowCheckbox({
	checked,
	indeterminate = false,
	onToggle,
	testid,
	label,
}: {
	checked: boolean;
	indeterminate?: boolean;
	onToggle: (next: boolean) => void;
	testid: string;
	label: string;
}) {
	return (
		<input
			type="checkbox"
			checked={checked}
			ref={(el) => {
				if (el) el.indeterminate = indeterminate;
			}}
			data-testid={testid}
			aria-label={label}
			onChange={(e) => onToggle(e.target.checked)}
			className="size-3.5 accent-primary"
		/>
	);
}

/** The graph view's overlay wrapper: owns query + sort + selection +
 *  expansion + the custom practice dialog; mounts ABSOLUTE INSIDE the
 *  graph area, full-bleed (owner ruling: the translucent blurred surface
 *  IS the overlay — no inner card). Esc + the top-bar X dismiss (there
 *  is no backdrop margin to click anymore). Read-only toward the graph. */
export function ChainTableOverlay({
	open,
	nodes,
	edges,
	sessions,
	fileSources,
	onClose,
}: {
	open: boolean;
	nodes: GraphNode[];
	edges: GraphEdge[];
	sessions: Record<string, string>;
	fileSources: Record<string, string>;
	onClose: () => void;
}) {
	const [query, setQuery] = useState("");
	const [sort, setSort] = useState<ChainSort>({ col: "name", dir: 1 });
	const [selection, setSelection] = useState<ReadonlySet<string>>(() => new Set());
	const [expandedClusters, setExpandedClusters] = useState<ReadonlySet<string>>(() => new Set());
	const [expandedChains, setExpandedChains] = useState<ReadonlySet<string>>(() => new Set());
	const [dialogOpen, setDialogOpen] = useState(false);

	// Esc dismisses (unless the practice dialog has focus — its own Esc
	// owns that layer; both listen on window, so the guard is explicit).
	useEffect(() => {
		if (!open || dialogOpen) return;
		const onKeyDown = (e: KeyboardEvent) => {
			if (e.key === "Escape") onClose();
		};
		window.addEventListener("keydown", onKeyDown);
		return () => window.removeEventListener("keydown", onKeyDown);
	}, [open, dialogOpen, onClose]);

	if (!open) return null;

	const byId = new Map(nodes.map((n) => [n.id, n]));
	const selectedNodes = [...selection].map((id) => byId.get(id)).filter((n): n is GraphNode => n !== undefined);
	const derived = chainsForSelection(selectedNodes, edges);
	const nodeIds = [...selection].sort();

	const toggleNodes = (ids: string[], next: boolean) =>
		setSelection((prev) => {
			const s = new Set(prev);
			for (const id of ids) {
				if (next) s.add(id);
				else s.delete(id);
			}
			return s;
		});
	const toggleIn = (set: ReadonlySet<string>, id: string) => {
		const s = new Set(set);
		if (s.has(id)) s.delete(id);
		else s.add(id);
		return s;
	};

	return (
		<>
			<div
				data-testid="chain-table-overlay"
				className="absolute inset-0 z-40 flex flex-col bg-background/80 backdrop-blur-sm"
			>
				<ChainTableBody
					nodes={nodes}
					edges={edges}
					sessions={sessions}
					fileSources={fileSources}
					query={query}
					onQuery={setQuery}
					sort={sort}
					onSort={(col) =>
						setSort((prev) =>
							prev.col === col
								? { col, dir: prev.dir === 1 ? -1 : 1 }
								: { col, dir: col === "created" ? -1 : 1 },
						)
					}
					selection={selection}
					expandedClusters={expandedClusters}
					expandedChains={expandedChains}
					onToggleCluster={(key) => setExpandedClusters((prev) => toggleIn(prev, key))}
					onToggleChain={(id) => setExpandedChains((prev) => toggleIn(prev, id))}
					onToggleNodes={toggleNodes}
					onClear={() => setSelection(new Set())}
					onGenerate={() => setDialogOpen(true)}
					onClose={onClose}
				/>
			</div>
			{dialogOpen && (
				<PracticeDialog
					mode="custom"
					selection={{ nodeIds, propositions: selectedNodes.length, chains: derived.length }}
					onClose={() => setDialogOpen(false)}
				/>
			)}
		</>
	);
}