"use client";

import Link from "next/link";
import { usePathname } from "next/navigation";
import { useAuth } from "./auth-provider";
import { useTheme } from "next-themes";
import type { LucideIcon } from "lucide-react";
import {
  LayoutDashboard,
  Users,
  Building2,
  Truck,
  FileText,
  ShoppingCart,
  LogOut,
  Sun,
  Moon,
  Menu,
  CheckCircle,
  Archive,
  Package,
  ClipboardList,
  Wrench,
  ChevronDown,
  MapPinned,
  Settings as SettingsIcon,
} from "lucide-react";
import { Button } from "@/components/ui/button";
import { Avatar, AvatarFallback } from "@/components/ui/avatar";
import { Separator } from "@/components/ui/separator";
import { ScrollArea } from "@/components/ui/scroll-area";
import { Sheet, SheetContent, SheetTrigger, SheetTitle } from "@/components/ui/sheet";
import { useEffect, useState, type ReactNode } from "react";

/* ============================================================================
 * CATEGORY SYSTEM
 *
 * Sidebar nav is grouped into 4 categories, each with a fixed brand color
 * so users can scan by color. Colors are intentionally hard-coded — they
 * stay the same regardless of which theme is active, so the sidebar reads
 * consistently.
 *
 *   dashboard   → blue  (brand)
 *   management  → blue  (brand)
 *   quotes      → gold  (brand)
 *   operations  → red   (brand)
 * ========================================================================== */
type CategoryId = "dashboard" | "management" | "quotes" | "operations";

const CATEGORY_COLORS: Record<CategoryId, string> = {
  dashboard: "#4C96D7",
  management: "#4C96D7",
  quotes: "#F2AF58",
  operations: "#E94E49",
};

// Helper — produce 8-digit hex with alpha (browser-portable, no color-mix needed)
function withAlpha(hex: string, alphaPercent: number): string {
  const a = Math.round((alphaPercent / 100) * 255)
    .toString(16)
    .padStart(2, "0");
  return `${hex}${a}`;
}

type NavEntry = {
  href: string;
  label: string;
  icon: LucideIcon;
  category: CategoryId;
};

const dashboardItems: NavEntry[] = [
  { href: "/dashboard", label: "Dashboard", icon: LayoutDashboard, category: "dashboard" },
];

const managementItems: NavEntry[] = [
  { href: "/customers", label: "Customers", icon: Users, category: "management" },
  { href: "/companies", label: "Companies", icon: Building2, category: "management" },
  { href: "/suppliers", label: "Suppliers", icon: Truck, category: "management" },
  { href: "/supplier-map", label: "Supplier Map", icon: MapPinned, category: "management" },
];

const quoteItems: NavEntry[] = [
  { href: "/quotes", label: "All Quotes", icon: FileText, category: "quotes" },
  { href: "/quotes/approvals", label: "Pending Approvals", icon: CheckCircle, category: "quotes" },
  { href: "/quotes/archived", label: "Archived", icon: Archive, category: "quotes" },
];

const operationsItems: NavEntry[] = [
  { href: "/orders", label: "Orders", icon: ShoppingCart, category: "operations" },
  { href: "/collection-pool", label: "Collection Pool", icon: Package, category: "operations" },
  { href: "/delivery-notes", label: "Delivery Notes", icon: ClipboardList, category: "operations" },
  { href: "/repairs", label: "Repairs", icon: Wrench, category: "operations" },
];

const CATEGORY_LABELS: Record<CategoryId, string> = {
  dashboard: "Dashboard",
  management: "Management",
  quotes: "Quotes",
  operations: "Operations",
};

/* ============================================================================
 * NavItem — single nav link with category-colored icon
 * ========================================================================== */
function NavItem({
  item,
  active,
  onClick,
  indent = false,
}: {
  item: NavEntry;
  active: boolean;
  onClick?: () => void;
  indent?: boolean;
}) {
  const color = CATEGORY_COLORS[item.category];
  // Inactive: subtle category tint. Active: white-on-primary from theme.
  const inactiveStyle = active
    ? undefined
    : { color: withAlpha(color, 78) };
  return (
    <Link
      href={item.href}
      onClick={onClick}
      style={inactiveStyle}
      className={`group flex items-center gap-3 rounded-xl ${
        indent ? "px-2.5 py-2 text-sm" : "px-3 py-2.5 text-sm"
      } font-medium transition-all duration-150 ${
        active
          ? "bg-primary text-primary-foreground shadow-sm"
          : "hover:opacity-80"
      }`}
    >
      <item.icon
        className={`${indent ? "h-4 w-4" : "h-[18px] w-[18px]"} shrink-0`}
        style={active ? { color: "var(--primary-foreground)" } : { color }}
      />
      {item.label}
    </Link>
  );
}

/* ============================================================================
 * NavGroup — accordion wrapper tinted with category color
 * ========================================================================== */
function NavGroup({
  category,
  open,
  onToggle,
  headerActive,
  headerIcon,
  items,
  pathname,
  onLinkClick,
}: {
  category: CategoryId;
  open: boolean;
  onToggle: () => void;
  headerActive: boolean;
  headerIcon: LucideIcon;
  items: NavEntry[];
  pathname: string;
  onLinkClick?: () => void;
}) {
  const color = CATEGORY_COLORS[category];
  const HeaderIcon = headerIcon;
  return (
    <div
      className="rounded-xl border p-1.5"
      style={{
        background: withAlpha(color, open ? 10 : 6),
        borderColor: withAlpha(color, open ? 28 : 18),
      }}
    >
      <button
        type="button"
        onClick={onToggle}
        className={`flex w-full items-center gap-2 rounded-lg px-2 py-1.5 text-xs font-semibold uppercase tracking-wide transition-colors ${
          headerActive ? "" : "hover:opacity-80"
        }`}
        style={{
          color: headerActive ? color : withAlpha(color, 78),
        }}
      >
        <HeaderIcon
          className="h-3.5 w-3.5"
          style={{ color: headerActive ? color : color }}
        />
        {CATEGORY_LABELS[category]}
        <ChevronDown
          className={`ml-auto h-3.5 w-3.5 transition-transform ${open ? "rotate-180" : ""}`}
          style={{ color: withAlpha(color, 60) }}
        />
      </button>
      {open && (
        <div className="mt-1 space-y-0.5">
          {items.map((item) => {
            const isActive =
              item.href === "/quotes"
                ? pathname === "/quotes"
                : pathname === item.href || pathname.startsWith(item.href + "/");
            return (
              <NavItem
                key={item.href}
                item={item}
                active={isActive}
                onClick={onLinkClick}
                indent
              />
            );
          })}
        </div>
      )}
    </div>
  );
}

/* ============================================================================
 * NavContent — the actual sidebar body
 * ========================================================================== */
function NavContent({ onLinkClick }: { onLinkClick?: () => void }) {
  const pathname = usePathname();
  const { user, logout } = useAuth();
  const { theme, setTheme } = useTheme();

  const isManagementActive = managementItems.some(
    (item) => pathname === item.href || pathname.startsWith(item.href + "/")
  );
  const isQuotesActive =
    pathname === "/quotes" || pathname.startsWith("/quotes/");
  const isOperationsActive = operationsItems.some(
    (item) => pathname === item.href || pathname.startsWith(item.href + "/")
  );

  const [managementOpen, setManagementOpen] = useState(isManagementActive);
  const [quotesOpen, setQuotesOpen] = useState(isQuotesActive);

  // Auto-open accordion when route inside it becomes active
  useEffect(() => {
    if (isManagementActive) setManagementOpen(true);
    if (isQuotesActive) setQuotesOpen(true);
  }, [isManagementActive, isQuotesActive]);

  const isDashboardActive =
    pathname === "/dashboard" || pathname.startsWith("/dashboard/");

  return (
    <div className="flex flex-col h-full">
      {/* Brand block */}
      <div className="px-5 pt-6 pb-4">
        <div className="flex items-center gap-3">
          <div className="grid size-10 place-items-center rounded-xl bg-primary text-primary-foreground shadow-sm">
            <Package className="h-5 w-5" />
          </div>
          <div>
            <h1 className="text-lg font-semibold tracking-tight text-foreground font-heading-theme">
              WFDASH
            </h1>
            <p className="text-xs text-muted-foreground mt-0.5">
              Westcott Fasteners
            </p>
          </div>
        </div>
        {/* Brand color stripe */}
        <div className="mt-4 grid grid-cols-3 gap-1">
          <span className="h-1.5 rounded-full" style={{ background: "#4C96D7" }} />
          <span className="h-1.5 rounded-full" style={{ background: "#F2AF58" }} />
          <span className="h-1.5 rounded-full" style={{ background: "#E94E49" }} />
        </div>
      </div>
      <Separator className="mx-3" />

      {/* Main nav */}
      <ScrollArea className="flex-1 px-3 py-3">
        <nav className="space-y-1.5">
          {/* Dashboard — flat top item, no accordion */}
          <NavItem
            item={dashboardItems[0]}
            active={isDashboardActive}
            onClick={onLinkClick}
          />

          {/* Management — accordion */}
          <NavGroup
            category="management"
            open={managementOpen}
            onToggle={() => setManagementOpen((o) => !o)}
            headerActive={isManagementActive}
            headerIcon={Users}
            items={managementItems}
            pathname={pathname}
            onLinkClick={onLinkClick}
          />

          {/* Quotes — accordion */}
          <NavGroup
            category="quotes"
            open={quotesOpen}
            onToggle={() => setQuotesOpen((o) => !o)}
            headerActive={isQuotesActive}
            headerIcon={FileText}
            items={quoteItems}
            pathname={pathname}
            onLinkClick={onLinkClick}
          />

          {/* Operations — flat items, but with a tiny colored gutter on the left */}
          <OperationsList
            active={isOperationsActive}
            pathname={pathname}
            onLinkClick={onLinkClick}
          />
        </nav>
      </ScrollArea>

      <Separator className="mx-3" />

      {/* Bottom block: settings (icon-only) + theme + avatar + logout */}
      <div className="p-3 space-y-2">
        {/* Settings — small icon-only button bottom-left */}
        <Link
          href="/settings"
          onClick={onLinkClick}
          aria-label="Settings"
          title="Settings"
          className="grid size-9 place-items-center rounded-xl text-muted-foreground transition-colors hover:bg-accent hover:text-accent-foreground"
        >
          <SettingsIcon className="h-[18px] w-[18px]" />
        </Link>

        {/* Theme toggle */}
        <Button
          variant="ghost"
          size="sm"
          className="w-full justify-start gap-3 text-muted-foreground hover:text-foreground h-9 px-2.5 rounded-xl"
          onClick={() => setTheme(theme === "dark" ? "warm" : "dark")}
        >
          {theme === "dark" ? (
            <>
              <Sun className="h-[18px] w-[18px]" />
              <span className="text-sm">Light Mode</span>
            </>
          ) : (
            <>
              <Moon className="h-[18px] w-[18px]" />
              <span className="text-sm">Dark Mode</span>
            </>
          )}
        </Button>

        {/* User */}
        <div className="flex items-center gap-3 px-2.5 py-2">
          <Avatar className="h-9 w-9 shrink-0 ring-2 ring-border/50">
            <AvatarFallback className="text-xs font-medium bg-muted">
              {user?.name?.charAt(0)?.toUpperCase() ||
                user?.email?.charAt(0)?.toUpperCase() ||
                "U"}
            </AvatarFallback>
          </Avatar>
          <div className="flex-1 min-w-0">
            <p className="text-sm font-medium truncate">
              {user?.name || "User"}
            </p>
            <p className="text-xs text-muted-foreground truncate">
              {user?.email}
            </p>
          </div>
        </div>

        {/* Logout */}
        <Button
          variant="ghost"
          size="sm"
          className="w-full justify-start gap-3 text-destructive hover:text-destructive hover:bg-destructive/8 h-9 px-2.5 rounded-xl"
          onClick={logout}
        >
          <LogOut className="h-[18px] w-[18px]" />
          <span className="text-sm">Logout</span>
        </Button>
      </div>
    </div>
  );
}

/* ============================================================================
 * OperationsList — flat items with a 4px red left gutter
 *
 * Operations is the only flat category. To make it visually consistent with
 * the accordion groups above, we wrap it in a thin red gutter that hints
 * at the category color without painting a full background.
 * ========================================================================== */
function OperationsList({
  active,
  pathname,
  onLinkClick,
}: {
  active: boolean;
  pathname: string;
  onLinkClick?: () => void;
}): ReactNode {
  const color = CATEGORY_COLORS.operations;
  return (
    <div
      className="rounded-xl border p-1.5 space-y-0.5"
      style={{
        background: withAlpha(color, active ? 10 : 6),
        borderColor: withAlpha(color, active ? 28 : 18),
      }}
    >
      {/* Tiny header label so the category is identifiable */}
      <div
        className="px-2 py-1 text-xs font-semibold uppercase tracking-wide flex items-center gap-2"
        style={{ color: withAlpha(color, 78) }}
      >
        <ShoppingCart className="h-3.5 w-3.5" style={{ color }} />
        Operations
      </div>
      {operationsItems.map((item) => {
        const isActive =
          pathname === item.href || pathname.startsWith(item.href + "/");
        return (
          <NavItem
            key={item.href}
            item={item}
            active={isActive}
            onClick={onLinkClick}
            indent
          />
        );
      })}
    </div>
  );
}

/* ============================================================================
 * Sidebar — desktop + mobile (Sheet) wrappers
 * ========================================================================== */
export function Sidebar() {
  const [open, setOpen] = useState(false);

  return (
    <>
      <aside className="hidden lg:flex lg:w-60 lg:flex-col bg-sidebar border-r border-sidebar-border">
        <NavContent />
      </aside>

      <div className="lg:hidden fixed top-0 left-0 right-0 z-40 flex items-center gap-3 border-b bg-background/95 backdrop-blur-sm px-4 h-14">
        <Sheet open={open} onOpenChange={setOpen}>
          <SheetTrigger
            render={<Button variant="ghost" size="icon" className="h-9 w-9" />}
          >
            <Menu className="h-5 w-5" />
          </SheetTrigger>
          <SheetContent side="left" className="w-60 p-0">
            <SheetTitle className="sr-only">Navigation</SheetTitle>
            <NavContent onLinkClick={() => setOpen(false)} />
          </SheetContent>
        </Sheet>
        <h1 className="text-lg font-semibold font-heading-theme">WFDASH</h1>
      </div>
    </>
  );
}