import React from "react";
import { motion, AnimatePresence } from "framer-motion";
import {
  MessageSquare,
  Plus,
  Trash2,
  Moon,
  Sun,
  Bot,
  History,
  FlaskConical
} from "lucide-react";
import { clsx } from "clsx";
import { twMerge } from "tailwind-merge";

function cn(...inputs) {
  return twMerge(clsx(inputs));
}

export default function ChatSidebar({
  open,
  setOpen,
  models,
  selectedModelId,
  onSelectModel,
  isModelsLoading,
  modelsError,
  modelsIssues,
  onReloadModels,
  mode,
  modes,
  onModeChange,
  onNewChat,
  onClearHistory,
  historyList,
  activeSessionId,
  onSelectSession,
  isSessionLocked = false,
  theme,
  onToggleTheme,
  activeView = "chat",
  onNavigateToLabs,
  onNavigateToChat,
}) {
  const selectedModel = models?.find((item) => item.id === selectedModelId);
  const uploadsStatus = selectedModel?.features?.status || "unknown";
  const uploadsEnabled = Boolean(selectedModel?.features?.uploads);
  const historyScrollRef = React.useRef(null);

  React.useEffect(() => {
    const el = historyScrollRef.current;
    if (!el) return;

    let timeoutId = null;
    const onScroll = () => {
      el.classList.add("scrolling");
      if (timeoutId) clearTimeout(timeoutId);
      timeoutId = setTimeout(() => el.classList.remove("scrolling"), 150);
    };

    el.addEventListener("scroll", onScroll, { passive: true });
    return () => {
      el.removeEventListener("scroll", onScroll);
      if (timeoutId) clearTimeout(timeoutId);
    };
  }, []);

  return (
    <AnimatePresence mode="wait">
      {open && (
        <>
          <motion.button
            type="button"
            initial={{ opacity: 0 }}
            animate={{ opacity: 1 }}
            exit={{ opacity: 0 }}
            transition={{ duration: 0.2 }}
            className="fixed inset-0 z-40 bg-[rgba(15,17,23,0.75)] md:hidden"
            onClick={() => setOpen?.(false)}
            aria-label="Close sidebar overlay"
          />
          <motion.aside
            initial={{ x: -300, opacity: 0 }}
            animate={{ x: 0, opacity: 1 }}
            exit={{ x: -300, opacity: 0 }}
            transition={{ duration: 0.3, ease: "easeInOut" }}
            className="fixed left-0 top-0 bottom-0 z-50 w-[280px] border-r border-[rgba(255,255,255,0.04)] bg-popover flex flex-col p-4"
          >
            {/* Header & Logo */}
            <div className="flex items-center justify-between mb-6 px-2">
              <div className="flex items-center gap-2">
                <div className="w-8 h-8 rounded-xl bg-foreground/5 border border-border flex items-center justify-center text-foreground">
                  <Bot size={18} />
                </div>
                <h1 className="text-xl font-display font-bold text-foreground">
                  Vector
                </h1>
              </div>
              <button
                onClick={() => setOpen?.(false)}
                className="md:hidden p-2 rounded-lg text-muted-foreground hover:text-foreground hover:bg-foreground/5 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/50"
                aria-label="Close sidebar"
              >
                <span className="text-lg leading-none">×</span>
              </button>
            </div>

            {/* View Navigation */}
            <div className="space-y-2 mb-6">
              <div className="px-2 text-xs font-semibold text-muted-foreground uppercase tracking-wider">
                Navigate
              </div>
              <div className="space-y-1">
                <button
                  onClick={onNavigateToChat}
                  className={cn(
                    "flex items-center gap-3 w-full px-3 py-2.5 rounded-lg text-sm font-medium transition-colors focus-visible:outline-none",
                    activeView === "chat"
                      ? "bg-foreground/10 text-foreground"
                      : "text-muted-foreground hover:bg-foreground/5 hover:text-foreground"
                  )}
                >
                  <MessageSquare size={16} />
                  <span>Chat</span>
                </button>
                <button
                  onClick={onNavigateToLabs}
                  className={cn(
                    "flex items-center gap-3 w-full px-3 py-2.5 rounded-lg text-sm font-medium transition-colors focus-visible:outline-none",
                    activeView === "labs"
                      ? "bg-foreground/10 text-foreground"
                      : "text-muted-foreground hover:bg-foreground/5 hover:text-foreground"
                  )}
                >
                  <FlaskConical size={16} />
                  <span>Labs</span>
                  <span className="ml-auto text-[10px] px-1.5 py-0.5 rounded bg-primary/20 text-primary font-medium">New</span>
                </button>
              </div>
            </div>

            {/* New Chat Button - only in chat view */}
            {activeView === "chat" && (
              <button
                onClick={onNewChat}
                className="group flex items-center gap-3 w-full px-4 py-3 rounded-xl bg-transparent border border-border transition-[background-color,border-color] duration-[120ms] ease-out mb-6 text-sm font-medium text-foreground hover:bg-foreground/5 hover:border-[var(--input-border-focus)] active:bg-foreground/8 focus-visible:outline-none"
              >
                <div className="bg-foreground/5 p-1.5 rounded-lg text-[#22D3EE] transition-colors group-hover:bg-foreground/8">
                  <Plus size={18} />
                </div>
                <span>New Thread</span>
                <div className="ml-auto text-xs text-muted-foreground border border-border rounded px-1.5 py-0.5 opacity-0 group-hover:opacity-100 transition-opacity">
                  Ctrl+N
                </div>
              </button>
            )}

            {/* Models Selection - only in chat view */}
            {activeView === "chat" && (
              <div className="mb-6 space-y-2">
                <div className="px-2 text-xs font-semibold text-muted-foreground uppercase tracking-wider flex items-center justify-between">
                  <span>{isSessionLocked ? "Model (Locked)" : "Model"}</span>
                  <button
                    type="button"
                    onClick={onReloadModels}
                    className="text-[11px] font-medium text-muted-foreground hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/50 rounded px-1"
                  >
                    Refresh
                  </button>
                </div>
                <div className="relative">
                  <select
                    className={cn(
                      "w-full appearance-none bg-foreground/5 text-foreground text-sm rounded-lg pl-3 pr-8 py-2.5 border border-border focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/50 transition-all hover:bg-foreground/8 disabled:opacity-60",
                      isSessionLocked && "cursor-not-allowed opacity-70"
                    )}
                    value={selectedModelId}
                    onChange={(e) => onSelectModel(e.target.value)}
                    disabled={isModelsLoading || !models?.length || isSessionLocked}
                    title={isSessionLocked ? "Model is locked to this chat session. Start a new chat to change models." : ""}
                  >
                    {isModelsLoading && (
                      <option value="" className="bg-background">
                        Loading models…
                      </option>
                    )}
                    {!isModelsLoading && models?.length > 0 && (
                      <>
                        <option value="" disabled className="bg-background">
                          Select a model
                        </option>
                        {models.map((m) => (
                          <option key={m.id} value={m.id} className="bg-background">
                            {m.name}
                          </option>
                        ))}
                      </>
                    )}
                    {!isModelsLoading && !models?.length && (
                      <option value="" className="bg-background">
                        No models configured
                      </option>
                    )}
                  </select>
                  <div className="absolute right-3 top-1/2 -translate-y-1/2 pointer-events-none text-muted-foreground">
                    <svg width="10" height="6" viewBox="0 0 10 6" fill="none" xmlns="http://www.w3.org/2000/svg">
                      <path d="M1 1L5 5L9 1" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
                    </svg>
                  </div>
                </div>
                {selectedModel && (
                  <div className="px-2 flex items-center gap-2 text-[11px]">
                    <span className={cn(
                      "inline-flex items-center rounded-full border px-2 py-0.5 font-medium",
                      uploadsStatus === "ok"
                        ? uploadsEnabled
                          ? "border-emerald-500/40 text-emerald-400 bg-emerald-500/10"
                          : "border-border text-muted-foreground bg-foreground/5"
                        : "border-amber-500/40 text-amber-400 bg-amber-500/10"
                    )}>
                      {uploadsStatus === "ok"
                        ? uploadsEnabled
                          ? "Uploads enabled"
                          : "Uploads off"
                        : "Uploads unknown"}
                    </span>
                  </div>
                )}
                {(modelsError || (modelsIssues && modelsIssues.length > 0) || (!isModelsLoading && !models?.length)) && (
                  <div className="px-2 text-xs text-muted-foreground space-y-1">
                    {modelsError && <div className="text-destructive">{modelsError}</div>}
                    {!modelsError && !isModelsLoading && !models?.length && (
                      <div>
                        Add MODEL_1_NAME / MODEL_1_ID / MODEL_1_HOST to your environment.
                      </div>
                    )}
                    {modelsIssues?.slice(0, 3).map((issue) => (
                      <div key={issue}>{issue}</div>
                    ))}
                  </div>
                )}
              </div>
            )}

            {/* History List - only in chat view */}
            {activeView === "chat" && (
              <div ref={historyScrollRef} className="flex-1 overflow-y-auto -mx-2 px-2 custom-scrollbar">
                <div className="mb-2 px-2 text-xs font-semibold text-muted-foreground uppercase tracking-wider flex items-center gap-2">
                  <History size={12} />
                  Recent
                </div>
                <div className="space-y-1">
                  {historyList.length === 0 ? (
                    <div className="flex flex-col items-center justify-center py-8 text-muted-foreground/70 gap-2">
                      <MessageSquare size={24} className="opacity-20" />
                      <span className="text-xs">No history yet</span>
                    </div>
                  ) : (
                    historyList.map((session, i) => (
                      <button
                        key={session.id}
                        onClick={() => onSelectSession(session.id)}
                        className={cn(
                          "w-full text-left px-3 py-2.5 rounded-lg text-sm transition-colors group flex items-center gap-3 relative overflow-hidden focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/50 stagger-item",
                          activeSessionId === session.id
                            ? "bg-[#202338] text-foreground"
                            : "text-muted-foreground hover:bg-[#1A1D29] hover:text-foreground"
                        )}
                        style={{ animationDelay: `${Math.min(i * 30, 300)}ms` }}
                      >
                        {activeSessionId === session.id && (
                          <span className="absolute left-0 top-2 bottom-2 w-[2px] bg-[#22D3EE] rounded-full" />
                        )}
                        <MessageSquare size={16} className={cn(
                          "shrink-0 transition-colors",
                          activeSessionId === session.id ? "text-foreground" : "text-muted-foreground/70 group-hover:text-muted-foreground"
                        )} />
                        <span className="truncate flex-1 z-10 relative">{session.title || "New Thread"}</span>
                      </button>
                    ))
                  )}
                </div>
              </div>
            )}

            {/* Spacer for Labs view */}
            {activeView === "labs" && <div className="flex-1" />}

            {/* Footer Actions */}
            <div className="pt-4 mt-4 border-t border-[rgba(255,255,255,0.04)] space-y-2">
              {activeView === "chat" && (
                <button
                  onClick={onClearHistory}
                  className="flex items-center gap-3 w-full px-3 py-2 rounded-lg text-sm text-muted-foreground hover:bg-destructive/10 hover:text-destructive transition-all group focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/50"
                >
                  <Trash2 size={16} />
                  <span>Clear History</span>
                </button>
              )}
              <button
                onClick={onToggleTheme}
                className="flex items-center gap-3 w-full px-3 py-2 rounded-lg text-sm text-muted-foreground hover:bg-foreground/5 hover:text-foreground transition-all focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/50"
              >
                {theme === "dark" ? <Sun size={16} /> : <Moon size={16} />}
                <span>{theme === "dark" ? "Light Mode" : "Dark Mode"}</span>
              </button>
            </div>
          </motion.aside>
        </>
      )}
    </AnimatePresence>
  );
}