"use client";

import { useState, useEffect } from "react";
import { useRouter } from "next/navigation";
import { useSession, signIn, signOut } from "next-auth/react";
import Link from "next/link";
import {
  Search,
  Settings,
  LogIn,
  LogOut,
  X,
  Plus,
  MessageSquare,
  Loader2,
  Menu,
} from "lucide-react";

export default function HomeDashboard() {
  const router = useRouter();
  const { data: session, status: authStatus } = useSession();

  // Core data states
  const [characters, setCharacters] = useState([]);
  const [chats, setChats] = useState([]);
  const [loading, setLoading] = useState(true);
  const [searchQuery, setSearchQuery] = useState("");
  const [showUpgradeModal, setShowUpgradeModal] = useState(false);
  const [userCredits, setUserCredits] = useState(50);
  const [showSidebar, setShowSidebar] = useState(false);

  // Create Character Modal states
  const [showCreateModal, setShowCreateModal] = useState(false);
  const [newChar, setNewChar] = useState({
    name: "",
    avatar: "🤖",
    profile_url: "",
    description: "",
    personality: "",
    systemPrompt: "",
    greeting: "",
    is_public: true,
  });
  const [isCreating, setIsCreating] = useState(false);

  useEffect(() => {
    fetchInitialData();
  }, [authStatus]);

  useEffect(() => {
    if (session?.user) {
      setUserCredits(session.user.credits);
    }
  }, [session]);

  const fetchInitialData = async () => {
    try {
      setLoading(true);
      // Fetch all characters from DB
      const charRes = await fetch("/api/characters");
      const charData = await charRes.json();
      if (charData.characters) {
        setCharacters(charData.characters);
      }

      if (authStatus === "authenticated") {
        // Sync active chats from SQLite/DB
        const chatRes = await fetch("/api/chats");
        const chatData = await chatRes.json();
        if (chatData.chats) {
          setChats(chatData.chats);
        }
      }
    } catch (err) {
      console.error("Failed to load initial workspace data", err);
    } finally {
      setLoading(false);
    }
  };

  // Triggers creation of a chat session
  const handleStartChat = async (characterId, characterName) => {
    if (authStatus !== "authenticated") {
      signIn("google");
      return;
    }
    try {
      const res = await fetch("/api/chats", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ character_id: characterId }),
      });
      const data = await res.json();
      if (data.chat) {
        const slug = characterName.toLowerCase().replace(/ /g, "-");
        router.push(`/${slug}/${data.chat.id}`);
      }
    } catch (err) {
      console.error("Failed to instantiate chat thread", err);
    }
  };

  const handleCreateCharacter = async (e) => {
    e.preventDefault();
    if (authStatus !== "authenticated") {
      signIn("google");
      return;
    }
    try {
      setIsCreating(true);
      const res = await fetch("/api/characters", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(newChar),
      });
      const data = await res.json();
      if (data.character) {
        setCharacters((prev) => [...prev, data.character]);
        setShowCreateModal(false);
        setNewChar({
          name: "",
          avatar: "🤖",
          profile_url: "",
          description: "",
          personality: "",
          systemPrompt: "",
          greeting: "",
          is_public: true,
        });
        await handleStartChat(data.character.id, data.character.name);
      }
    } catch (error) {
      console.error(error);
    } finally {
      setIsCreating(false);
    }
  };

  const executeUpgrade = () => {
    setUserCredits((prev) => prev + 100);
    setShowUpgradeModal(false);
    alert(
      "Successfully upgraded to c.ai+! Added 100 premium credits to your balance.",
    );
  };

  // Derive unique recent characters from chat history
  const recentCharactersMap = new Map();
  chats.forEach((c) => {
    if (c.character && !recentCharactersMap.has(c.character.id)) {
      recentCharactersMap.set(c.character.id, c.character);
    }
  });
  const recentCharacters = Array.from(recentCharactersMap.values());

  // Filter characters based on search
  const filteredCharacters = characters.filter((c) => {
    const q = searchQuery.toLowerCase();
    return (
      c.name.toLowerCase().includes(q) ||
      c.description.toLowerCase().includes(q)
    );
  });

  return (
    <div className="flex h-dvh overflow-hidden bg-bg-page text-primary-text font-sans antialiased">
      {/* MOBILE BACKDROP */}
      {showSidebar && (
        <div
          className="fixed inset-0 bg-black/60 z-30 md:hidden backdrop-blur-sm transition-opacity"
          onClick={() => setShowSidebar(false)}
        />
      )}
      {/* 1. SIDE NAVIGATION BAR */}
      <aside
        className={`fixed inset-y-0 left-0 z-40 transform transition-transform duration-300 md:relative md:translate-x-0 w-64 bg-bg-card border-r border-divider/50 p-5 flex flex-col shrink-0 select-none ${showSidebar ? "translate-x-0 shadow-2xl shadow-black" : "-translate-x-full"}`}
      >
        {/* BRAND LOGO HEADER */}
        <div className="flex items-center justify-between mb-6">
          <Link
            href="/"
            className="flex items-center gap-2 hover:opacity-85 transition"
          >
            <h1 className="text-[17px] font-bold text-primary-text tracking-tight">
              (character.ai)
            </h1>
          </Link>
          <button
            onClick={() => setShowCreateModal(true)}
            className="p-1.5 rounded text-secondary-text hover:text-primary-text transition cursor-pointer bg-bg-card-hover hover:bg-bg-elevated border border-divider/50"
            title="Create Character"
          >
            <Plus className="w-4 h-4" />
          </button>
        </div>

        {/* RECENT DIALOGUE LIST */}
        <div className="flex-1 flex flex-col overflow-hidden">
          <h3 className="text-[10px] font-bold text-secondary-text mb-3 uppercase tracking-wider">
            Recent Chats
          </h3>
          <div className="flex-1 overflow-y-auto custom-scrollbar">
            {recentCharacters.length === 0 &&
              !loading &&
              authStatus === "authenticated" &&
              session?.user && (
                <p className="text-xs text-secondary-text italic px-1">
                  No recent chats found.
                </p>
              )}
            {recentCharacters.map((ch, idx) => (
              <button
                key={idx}
                onClick={() => {
                  handleStartChat(ch.id, ch.name);
                  setShowSidebar(false);
                }}
                className="w-full p-2.5 rounded flex items-center gap-3.5 text-left bg-transparent text-secondary-text hover:bg-bg-card-hover transition duration-150 cursor-pointer group"
              >
                <div className="h-8.5 w-8.5 rounded-full bg-bg-card border border-divider/50 flex items-center justify-center text-lg shrink-0 shadow-sm overflow-hidden relative">
                  {ch.profileUrl ||
                  (ch.avatar.length > 2 && ch.avatar.startsWith("http")) ? (
                    <img
                      src={ch.profileUrl || ch.avatar}
                      alt="avatar"
                      className="w-full h-full object-cover"
                    />
                  ) : (
                    ch.avatar
                  )}
                </div>
                <div className="overflow-hidden">
                  <h4 className="font-semibold text-[13px] truncate text-primary-text tracking-wide group-hover:text-white transition">
                    {ch.name}
                  </h4>
                </div>
              </button>
            ))}
          </div>
        </div>

        {/* BOTTOM UPGRADE CAPSULE */}
        <div className="mt-4 pt-4 border-t border-divider/50">
          <button
            onClick={() => router.push("/pricing")}
            className="w-full mb-4 py-2.5 px-4 rounded-full border border-divider/50 bg-bg-page text-secondary-text hover:text-primary-text font-bold text-xs tracking-wider transition hover:bg-bg-card-hover cursor-pointer active:scale-[0.98]"
          >
            Upgrade to (c.ai+)
          </button>

          {/* DYNAMIC USER SECTION */}
          {authStatus === "authenticated" && session?.user ? (
            <div className="flex items-center justify-between p-2 rounded bg-transparent select-none">
              <div className="flex items-center gap-3 overflow-hidden">
                {session.user.image ? (
                  <img
                    src={session.user.image}
                    alt=""
                    className="w-9 h-9 rounded-full border border-divider/50 shrink-0"
                  />
                ) : (
                  <div className="w-9 h-9 rounded-full bg-primary flex items-center justify-center font-bold text-sm text-white shrink-0">
                    {session.user.name?.[0] || "U"}
                  </div>
                )}
                <div className="overflow-hidden">
                  <h4 className="font-bold text-xs truncate leading-tight text-primary-text">
                    {session.user.name || "User"}
                  </h4>
                  <p className="text-[10px] text-secondary-text truncate mt-0.5">
                    Premium Credits: {userCredits}
                  </p>
                </div>
              </div>
              <button
                onClick={() => signOut()}
                type="button"
                title="Logout"
                className="p-1 hover:bg-bg-card-hover rounded text-secondary-text hover:text-primary-text transition"
              >
                <LogOut className="w-4 h-4" />
              </button>
            </div>
          ) : (
            <button
              onClick={() => signIn("google")}
              className="w-full py-2.5 px-4 rounded bg-primary hover:bg-primary-hover font-bold text-xs tracking-wider uppercase shadow-md flex items-center justify-center gap-2 cursor-pointer transition active:scale-[0.98]"
            >
              <LogIn className="w-4 h-4" />
              <span>Login with Google</span>
            </button>
          )}
        </div>
      </aside>
      {/* 2. MAIN CORE VIEWPORT */}
      <section className="flex-1 overflow-hidden bg-bg-page custom-scrollbar relative w-full py-6 sm:py-8">
        {/* HEADER BAR */}
        <header className="flex items-center justify-between mb-6 sm:mb-8 flex-wrap gap-4 px-4 sm:px-10">
          <div className="flex items-center gap-3">
            <button
              className="md:hidden p-2 bg-bg-card-hover hover:bg-bg-elevated rounded-lg text-secondary-text hover:text-primary-text border border-divider/50 transition shrink-0"
              onClick={() => setShowSidebar(true)}
            >
              <Menu className="w-5 h-5" />
            </button>
            <div className="min-w-0">
              <span className="text-secondary-text text-[10px] sm:text-xs font-semibold hidden sm:block">
                Welcome back,
              </span>
              <h2 className="text-base sm:text-xl font-bold text-primary-text tracking-tight sm:mt-0.5 truncate max-w-[140px] sm:max-w-xs">
                {session?.user?.name || "Guest"}
              </h2>
            </div>
          </div>

          <div className="flex items-center gap-3 w-full sm:w-auto">
            <div className="relative w-full sm:w-80">
              <div className="absolute inset-y-0 left-4 flex items-center pointer-events-none text-secondary-text">
                <Search className="w-4 h-4" />
              </div>
              <input
                type="text"
                value={searchQuery}
                onChange={(e) => setSearchQuery(e.target.value)}
                placeholder="Search characters..."
                className="w-full pl-10 pr-4 py-2.5 bg-bg-card border border-divider/50 rounded-full text-xs focus:outline-none focus:bg-bg-card-hover focus:border-primary/50 text-primary-text placeholder-secondary-text transition duration-150"
              />
            </div>
          </div>
        </header>
        {/* CHARACTER GRID */}
        <div className="flex flex-col gap-2 w-full h-full overflow-y-auto px-4 sm:px-10 pb-20">
          <div className="flex items-center justify-between mb-4">
            <h3 className="text-sm font-bold text-primary-text flex items-center gap-2">
              <span>Explore Characters</span>
            </h3>
            <button
              onClick={() => setShowCreateModal(true)}
              className="text-xs font-bold text-primary hover:text-primary-hover transition flex items-center gap-1.5 bg-primary/10 hover:bg-primary/20 px-3 py-1.5 rounded-full border border-primary/25"
            >
              <Plus className="w-3 h-3" />
              Create Own
            </button>
          </div>

          <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 lg:grid-cols-4 gap-3">
            {filteredCharacters.map((char, idx) => (
              <div
                key={idx}
                onClick={() => handleStartChat(char.id, char.name)}
                className="bg-bg-card border border-divider/50 rounded p-2 flex gap-4 hover:border-primary/50 hover:bg-bg-card-hover transition duration-200 cursor-pointer shadow-lg"
              >
                {/* Character visual image */}
                <div className="h-full w-20 aspect-[3/4] rounded overflow-hidden flex-shrink-0 bg-bg-page border border-divider/50 shadow flex items-center justify-center text-4xl">
                  {char.profileUrl ||
                  (char.avatar.length > 2 && char.avatar.startsWith("http")) ? (
                    <img
                      src={char.profileUrl || char.avatar}
                      alt={char.name}
                      className="w-full h-full object-cover"
                    />
                  ) : (
                    char.avatar
                  )}
                </div>

                {/* Info block */}
                <div className="flex-1 flex flex-col justify-between overflow-hidden">
                  <div>
                    <h4 className="font-extrabold text-[13px] text-primary-text truncate leading-tight">
                      {char.name}
                    </h4>
                    <span className="text-[10px] text-primary block font-semibold truncate mt-0.5">
                      {char.isCustom
                        ? "Community Character"
                        : "Official Preset"}
                    </span>
                    <p className="text-[11px] text-secondary-text mt-1.5 leading-relaxed line-clamp-2 font-medium">
                      {char.description}
                    </p>
                  </div>

                  {/* Bottom metrics */}
                  <div className="flex items-center gap-1.5 text-[10px] text-secondary-text font-bold mt-2.5">
                    <MessageSquare className="w-3.5 h-3.5 text-primary" />
                    <span>Chat Now</span>
                  </div>
                </div>
              </div>
            ))}
          </div>

          {filteredCharacters.length === 0 && !loading && (
            <div className="text-center py-20 text-secondary-text">
              <p>No characters found matching "{searchQuery}".</p>
            </div>
          )}

          {loading && (
            <div className="flex items-center justify-center py-20 text-secondary-text gap-3">
              <Loader2 className="w-5 h-5 animate-spin text-primary" />
              <span>Loading characters...</span>
            </div>
          )}
        </div>
      </section>
      {/* CREATE CHARACTER MODAL */}
      {showCreateModal && (
        <div className="fixed inset-0 bg-black/85 backdrop-blur-sm flex items-center justify-center p-4 z-50 animate-fadeIn select-none">
          <div className="bg-bg-card border border-divider/50 rounded w-full max-w-xl shadow-2xl relative flex flex-col max-h-[90vh]">
            <div className="flex items-center justify-between p-5 border-b border-divider/50">
              <h2 className="text-lg font-bold text-primary-text flex items-center gap-2">
                <Plus className="w-5 h-5 text-primary" />
                Create Custom Character
              </h2>
              <button
                onClick={() => setShowCreateModal(false)}
                className="p-1 hover:bg-bg-card-hover rounded text-secondary-text hover:text-primary-text transition"
              >
                <X className="w-5 h-5" />
              </button>
            </div>

            <form
              onSubmit={handleCreateCharacter}
              className="p-5 overflow-y-auto custom-scrollbar flex-1 space-y-4"
            >
              <div className="grid grid-cols-2 gap-4">
                <div className="space-y-1.5">
                  <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider">
                    Name
                  </label>
                  <input
                    required
                    value={newChar.name}
                    onChange={(e) =>
                      setNewChar({ ...newChar, name: e.target.value })
                    }
                    type="text"
                    className="w-full bg-bg-page border border-divider/50 rounded p-2.5 text-sm text-primary-text focus:outline-none focus:border-primary/50 transition placeholder-secondary-text"
                    placeholder="e.g. Master Chief"
                  />
                </div>
                <div className="space-y-1.5">
                  <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider">
                    Avatar Emoji
                  </label>
                  <input
                    required
                    value={newChar.avatar}
                    onChange={(e) =>
                      setNewChar({ ...newChar, avatar: e.target.value })
                    }
                    type="text"
                    className="w-full bg-bg-page border border-divider/50 rounded p-2.5 text-sm text-primary-text focus:outline-none focus:border-primary/50 transition placeholder-secondary-text"
                    placeholder="🤖"
                  />
                </div>
              </div>

              <div className="space-y-1.5">
                <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider">
                  Image URL (Optional)
                </label>
                <input
                  value={newChar.profile_url}
                  onChange={(e) =>
                    setNewChar({ ...newChar, profile_url: e.target.value })
                  }
                  type="text"
                  className="w-full bg-bg-page border border-divider/50 rounded p-2.5 text-sm text-primary-text focus:outline-none focus:border-primary/50 transition placeholder-secondary-text"
                  placeholder="https://example.com/image.png"
                />
              </div>

              <div className="space-y-1.5">
                <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider">
                  Short Description
                </label>
                <input
                  required
                  value={newChar.description}
                  onChange={(e) =>
                    setNewChar({ ...newChar, description: e.target.value })
                  }
                  type="text"
                  className="w-full bg-bg-page border border-divider/50 rounded p-2.5 text-sm text-primary-text focus:outline-none focus:border-primary/50 transition placeholder-secondary-text"
                  placeholder="A brief tagline shown in the UI."
                />
              </div>

              <div className="space-y-1.5">
                <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider">
                  Personality Traits
                </label>
                <input
                  required
                  value={newChar.personality}
                  onChange={(e) =>
                    setNewChar({ ...newChar, personality: e.target.value })
                  }
                  type="text"
                  className="w-full bg-bg-page border border-divider/50 rounded p-2.5 text-sm text-primary-text focus:outline-none focus:border-primary/50 transition placeholder-secondary-text"
                  placeholder="e.g. Sarcastic, brave, funny, protective."
                />
              </div>

              <div className="space-y-1.5">
                <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider">
                  Opening Greeting
                </label>
                <textarea
                  required
                  value={newChar.greeting}
                  onChange={(e) =>
                    setNewChar({ ...newChar, greeting: e.target.value })
                  }
                  className="w-full bg-bg-page border border-divider/50 rounded p-3 text-sm text-primary-text focus:outline-none focus:border-primary/50 transition h-20 resize-none placeholder-secondary-text"
                  placeholder="The very first message they send when someone starts a chat."
                />
              </div>

              <div className="space-y-1.5">
                <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider">
                  System Prompt (AI Brain)
                </label>
                <textarea
                  required
                  value={newChar.systemPrompt}
                  onChange={(e) =>
                    setNewChar({ ...newChar, systemPrompt: e.target.value })
                  }
                  className="w-full bg-bg-page border border-divider/50 rounded p-3 text-sm text-primary-text focus:outline-none focus:border-primary/50 transition h-32 resize-none placeholder-secondary-text"
                  placeholder="You are [Name]. Act like... Follow these rules..."
                />
              </div>

              <div className="space-y-1.5 flex items-center justify-between p-3 bg-bg-page/40 border border-divider/50 rounded mt-2 select-none">
                <div>
                  <label className="text-[10px] font-bold text-secondary-text uppercase tracking-wider block">
                    Visibility Settings
                  </label>
                  <p className="text-[11px] text-secondary-text mt-0.5 font-semibold">
                    {newChar.is_public
                      ? "Public: Published to all users."
                      : "Private: Only you can chat with this character."}
                  </p>
                </div>
                <button
                  type="button"
                  onClick={() =>
                    setNewChar((prev) => ({
                      ...prev,
                      is_public: !prev.is_public,
                    }))
                  }
                  className={`relative inline-flex h-6 w-11 shrink-0 cursor-pointer rounded-full border-2 border-transparent transition-colors duration-200 ease-in-out focus:outline-none ${newChar.is_public ? "bg-primary" : "bg-bg-card-hover"}`}
                >
                  <span
                    className={`pointer-events-none inline-block h-5 w-5 transform rounded-full bg-white shadow ring-0 transition duration-200 ease-in-out ${newChar.is_public ? "translate-x-5" : "translate-x-0"}`}
                  />
                </button>
              </div>

              <div className="pt-5 border-t border-divider/50 flex justify-end gap-3 mt-2">
                <button
                  type="button"
                  onClick={() => setShowCreateModal(false)}
                  className="px-5 py-2 text-xs font-bold text-secondary-text hover:text-primary-text transition"
                >
                  Cancel
                </button>
                <button
                  type="submit"
                  disabled={isCreating}
                  className="px-5 py-2 bg-primary hover:bg-primary-hover text-white rounded text-xs font-bold tracking-wide transition flex items-center gap-2 shadow-lg shadow-primary/20 active:scale-95 disabled:opacity-50"
                >
                  {isCreating ? (
                    <Loader2 className="w-3.5 h-3.5 animate-spin" />
                  ) : (
                    <Plus className="w-3.5 h-3.5" />
                  )}
                  {isCreating ? "Deploying..." : "Create Character"}
                </button>
              </div>
            </form>
          </div>
        </div>
      )}

      {/* 6. PREMIUM PAYMENT / UPGRADE MODAL */}
      {showUpgradeModal && (
        <div className="fixed inset-0 bg-black/85 backdrop-blur-md flex items-center justify-center p-4 z-50 animate-fadeIn select-none">
          <div className="bg-bg-card border border-divider/55 rounded w-full max-w-md overflow-hidden shadow-2xl relative">
            <div className="absolute top-0 left-0 right-0 h-1 bg-gradient-to-r from-amber-500 via-orange-500 to-yellow-500" />
            <div className="p-6 pt-8 text-center">
              <div className="h-16 w-16 bg-amber-500/10 border border-amber-500/30 rounded flex items-center justify-center text-4xl mx-auto mb-4 animate-bounce">
                👑
              </div>
              <span className="px-3.5 py-1 text-[10px] uppercase font-black tracking-widest text-amber-500 bg-amber-950/30 rounded-full border border-amber-800/40 shadow-inner">
                c.ai+ Premium tier
              </span>
              <h3 className="font-black text-2xl mt-4 mb-2 text-primary-text tracking-tight">
                Upgrade to character.ai+
              </h3>
              <p className="text-xs text-secondary-text max-w-sm mx-auto leading-relaxed mb-6 font-semibold">
                Gain instant access to unlimited thinking engine telemetry,
                zero-wait premium response models (GPT-4o, DeepSeek R1), and
                +100 bonus credits!
              </p>
              <div className="flex gap-3">
                <button
                  onClick={() => setShowUpgradeModal(false)}
                  className="flex-1 py-3.5 bg-bg-page hover:bg-bg-card-hover text-secondary-text hover:text-primary-text rounded font-bold text-xs uppercase tracking-wider transition border border-divider/50 cursor-pointer"
                >
                  Go Back
                </button>
                <button
                  onClick={executeUpgrade}
                  className="flex-1 py-3.5 bg-gradient-to-r from-amber-500 via-orange-500 to-yellow-500 hover:from-amber-600 hover:to-yellow-600 text-black font-extrabold text-xs uppercase tracking-wider transition cursor-pointer shadow-lg active:scale-95"
                >
                  Upgrade Now
                </button>
              </div>
            </div>
          </div>
        </div>
      )}
    </div>
  );
}