import { useState, useEffect, useCallback } from "react";
import { useNavigate } from "react-router-dom";
import { useLang } from "@/contexts/LanguageContext";
import { isAdminSession, clearAdminSession } from "@/lib/adminSession";
import { toast } from "sonner";
import {
  type CourseVideo,
  fetchAllCourseVideos,
  createCourseVideo,
  deleteCourseVideo,
  updateCourseVideoStatus,
} from "@/lib/api";
import { motion, AnimatePresence } from "framer-motion";
import {
  Upload, Video, Trash2, ArrowLeft, Eye,
  Plus, FileVideo, Clock, Users, Search, Filter,
  CheckCircle2, AlertCircle, Sparkles
} from "lucide-react";
import heroBg from "@/assets/hero-bg.jpg";
import logo from "@/assets/logo.png";

interface VideoItem {
  id: string;
  title: string;
  course: string;
  courseKey: string;
  module: string;
  duration: string;
  uploadDate: string;
  status: "published" | "draft" | "processing";
  views: number;
  thumbnail: string;
  videoUrl?: string;
}

function thumbForCourseKey(key: string): string {
  const m: Record<string, string> = {
    biz: "📊",
    product: "💡",
    marketing: "📢",
    ops: "⚙️",
  };
  return m[key] || "🎞";
}

function mapCourseVideoToItem(v: CourseVideo, lang: "en" | "zh"): VideoItem {
  return {
    id: v.id,
    title: v.title,
    course: lang === "zh" ? v.courseLabelZh : v.courseLabelEn,
    courseKey: v.courseKey,
    module: v.moduleName,
    duration: v.duration,
    uploadDate: v.uploadDate,
    status: v.status as VideoItem["status"],
    views: v.views,
    thumbnail: thumbForCourseKey(v.courseKey),
    videoUrl: v.videoUrl,
  };
}

const courseOptions = [
  { key: "biz", label: { zh: "商业模式设计", en: "Business Model Design" } },
  { key: "product", label: { zh: "产品开发方法论", en: "Product Development" } },
  { key: "marketing", label: { zh: "营销策略", en: "Marketing Strategy" } },
  { key: "ops", label: { zh: "运营管理体系", en: "Operations Management" } },
];

export default function Admin() {
  const { lang } = useLang();
  const navigate = useNavigate();

  useEffect(() => {
    if (!isAdminSession()) {
      navigate("/admin", { replace: true });
    }
  }, [navigate]);

  const [videos, setVideos] = useState<VideoItem[]>([]);
  const [listLoading, setListLoading] = useState(true);
  const [showUpload, setShowUpload] = useState(false);
  const [searchQuery, setSearchQuery] = useState("");
  const [filterCourse, setFilterCourse] = useState("all");
  const [dragActive, setDragActive] = useState(false);

  const [uploadTitle, setUploadTitle] = useState("");
  const [uploadCourse, setUploadCourse] = useState("biz");
  const [uploadModule, setUploadModule] = useState("");
  const [uploadFile, setUploadFile] = useState<File | null>(null);
  const [uploadBusy, setUploadBusy] = useState(false);

  const refreshVideos = useCallback(async () => {
    setListLoading(true);
    try {
      const list = await fetchAllCourseVideos();
      setVideos(list.map((v) => mapCourseVideoToItem(v, lang)));
    } catch {
      toast.error(lang === "zh" ? "无法加载视频列表" : "Could not load videos");
    } finally {
      setListLoading(false);
    }
  }, [lang]);

  useEffect(() => {
    refreshVideos();
  }, [refreshVideos]);

  const resetUploadForm = () => {
    setUploadTitle("");
    setUploadCourse("biz");
    setUploadModule(lang === "zh" ? "模块1" : "Module 1");
    setUploadFile(null);
  };

  const buildUploadFormData = (status: "published" | "draft"): FormData => {
    const co = courseOptions.find((c) => c.key === uploadCourse);
    const fd = new FormData();
    fd.append("file", uploadFile as File);
    fd.append("title", uploadTitle.trim());
    fd.append("courseKey", uploadCourse);
    fd.append("courseLabelZh", co?.label.zh ?? "");
    fd.append("courseLabelEn", co?.label.en ?? "");
    fd.append("moduleName", uploadModule || (lang === "zh" ? "模块1" : "Module 1"));
    fd.append("status", status);
    return fd;
  };

  const handleSaveAsDraft = async () => {
    if (!uploadFile) {
      toast.error(lang === "zh" ? "请选择视频文件" : "Choose a video file");
      return;
    }
    setUploadBusy(true);
    try {
      const r = await createCourseVideo(buildUploadFormData("draft"));
      if (!r.ok) {
        toast.error(r.error || (lang === "zh" ? "保存失败" : "Save failed"));
        return;
      }
      toast.success(lang === "zh" ? "已保存草稿" : "Draft saved");
      setShowUpload(false);
      resetUploadForm();
      await refreshVideos();
    } catch {
      toast.error(lang === "zh" ? "上传失败" : "Upload failed");
    } finally {
      setUploadBusy(false);
    }
  };

  const handleUpload = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!uploadFile) {
      toast.error(lang === "zh" ? "请选择视频文件" : "Choose a video file");
      return;
    }
    setUploadBusy(true);
    try {
      const r = await createCourseVideo(buildUploadFormData("published"));
      if (!r.ok) {
        toast.error(r.error || (lang === "zh" ? "发布失败" : "Publish failed"));
        return;
      }
      toast.success(lang === "zh" ? "已发布，学员可在对应课程页观看" : "Published — visible on the course page");
      setShowUpload(false);
      resetUploadForm();
      await refreshVideos();
    } catch {
      toast.error(lang === "zh" ? "上传失败" : "Upload failed");
    } finally {
      setUploadBusy(false);
    }
  };

  const handleDelete = async (id: string) => {
    const ok = await deleteCourseVideo(id);
    if (!ok) {
      toast.error(lang === "zh" ? "删除失败" : "Delete failed");
      return;
    }
    setVideos((prev) => prev.filter((v) => v.id !== id));
    toast.success(lang === "zh" ? "已删除" : "Deleted");
  };

  const handlePublish = async (id: string) => {
    const r = await updateCourseVideoStatus(id, "published");
    if (!r.ok) {
      toast.error(lang === "zh" ? "发布失败" : "Publish failed");
      return;
    }
    toast.success(lang === "zh" ? "已发布" : "Published");
    await refreshVideos();
  };

  const filteredVideos = videos.filter(v => {
    const matchSearch = v.title.toLowerCase().includes(searchQuery.toLowerCase()) ||
      v.course.toLowerCase().includes(searchQuery.toLowerCase());
    const matchCourse = filterCourse === "all" || v.courseKey === filterCourse;
    return matchSearch && matchCourse;
  });

  const statusConfig = {
    published: { color: "text-emerald-600 bg-emerald-500/10", icon: CheckCircle2, label: { zh: "已发布", en: "Published" } },
    draft: { color: "text-amber-600 bg-amber-500/10", icon: AlertCircle, label: { zh: "草稿", en: "Draft" } },
    processing: { color: "text-blue-600 bg-blue-500/10", icon: Clock, label: { zh: "处理中", en: "Processing" } },
  };

  // Admin Dashboard
  return (
    <div className="min-h-screen bg-background">
      {/* Header */}
      <div className="relative">
        <img src={heroBg} alt="" className="absolute inset-0 w-full h-full object-cover" />
        <div className="absolute inset-0 bg-gradient-to-b from-background/20 to-background" />
        <div className="relative z-10 max-w-6xl mx-auto px-4 pt-4 pb-16">
          <nav className="glass-nav rounded-2xl px-5 py-2.5 flex items-center justify-between mb-8">
            <div className="flex items-center gap-2">
              <img src={logo} alt="有维商学" className="w-7 h-7 rounded-xl object-contain" />
              <span className="font-semibold text-foreground text-sm">
                {lang === "zh" ? "管理后台" : "Admin Dashboard"}
              </span>
            </div>
            <div className="flex items-center gap-3">
              <span className="section-tag !py-1">
                <Sparkles className="w-3 h-3" />
                Admin
              </span>
              <button
                onClick={() => {
                  clearAdminSession();
                  navigate("/home");
                }}
                className="glass-pill px-4 py-1.5 text-xs font-medium text-foreground hover:scale-105 transition-transform"
              >
                <ArrowLeft className="w-3 h-3 inline mr-1" />
                {lang === "zh" ? "返回前台" : "Back to Site"}
              </button>
            </div>
          </nav>

          {/* Stats */}
          <div className="grid grid-cols-2 md:grid-cols-4 gap-4">
            {[
              { label: lang === "zh" ? "总视频数" : "Total Videos", value: videos.length, icon: Video, color: "from-primary to-accent" },
              { label: lang === "zh" ? "已发布" : "Published", value: videos.filter(v => v.status === "published").length, icon: CheckCircle2, color: "from-emerald-500 to-teal-400" },
              { label: lang === "zh" ? "草稿" : "Drafts", value: videos.filter(v => v.status === "draft").length, icon: AlertCircle, color: "from-amber-500 to-orange-400" },
              { label: lang === "zh" ? "总播放量" : "Total Views", value: videos.reduce((sum, v) => sum + v.views, 0).toLocaleString(), icon: Users, color: "from-violet-500 to-purple-400" },
            ].map((stat, i) => (
              <motion.div
                key={i}
                initial={{ opacity: 0, y: 20 }}
                animate={{ opacity: 1, y: 0 }}
                transition={{ delay: i * 0.1 }}
                className="glass-card p-5"
              >
                <div className={`w-10 h-10 rounded-xl bg-gradient-to-br ${stat.color} flex items-center justify-center text-white mb-3`}>
                  <stat.icon className="w-5 h-5" />
                </div>
                <p className="text-2xl font-bold text-foreground">{stat.value}</p>
                <p className="text-xs text-muted-foreground mt-1">{stat.label}</p>
              </motion.div>
            ))}
          </div>
        </div>
      </div>

      {/* Main Content */}
      <div className="max-w-6xl mx-auto px-4 -mt-6 pb-16">
        {/* Toolbar */}
        <div className="glass-card rounded-2xl p-4 mb-6 flex flex-col sm:flex-row items-stretch sm:items-center gap-3">
          <div className="relative flex-1">
            <Search className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-muted-foreground" />
            <input
              type="text"
              value={searchQuery}
              onChange={(e) => setSearchQuery(e.target.value)}
              placeholder={lang === "zh" ? "搜索视频..." : "Search videos..."}
              className="w-full h-10 rounded-xl border border-border/50 bg-muted/20 pl-10 pr-4 text-sm text-foreground placeholder:text-muted-foreground focus:outline-none focus:ring-2 focus:ring-primary/30 transition-all"
            />
          </div>
          <div className="flex items-center gap-2">
            <div className="relative">
              <Filter className="absolute left-3 top-1/2 -translate-y-1/2 w-3 h-3 text-muted-foreground" />
              <select
                value={filterCourse}
                onChange={(e) => setFilterCourse(e.target.value)}
                className="h-10 rounded-xl border border-border/50 bg-muted/20 pl-8 pr-4 text-sm text-foreground focus:outline-none focus:ring-2 focus:ring-primary/30 transition-all appearance-none cursor-pointer"
              >
                <option value="all">{lang === "zh" ? "全部课程" : "All Courses"}</option>
                {courseOptions.map(c => (
                  <option key={c.key} value={c.key}>{c.label[lang]}</option>
                ))}
              </select>
            </div>
            <motion.button
              whileHover={{ scale: 1.05 }}
              whileTap={{ scale: 0.95 }}
              onClick={() => {
                resetUploadForm();
                setShowUpload(true);
              }}
              className="h-10 px-5 rounded-xl bg-gradient-to-r from-primary to-accent text-primary-foreground text-sm font-medium shadow-lg shadow-primary/20 flex items-center gap-2"
            >
              <Plus className="w-4 h-4" />
              {lang === "zh" ? "上传视频" : "Upload Video"}
            </motion.button>
          </div>
        </div>

        {/* Video Grid */}
        <div className="grid md:grid-cols-2 lg:grid-cols-3 gap-4">
          {listLoading && (
            <div className="col-span-full glass-card p-12 text-center text-muted-foreground text-sm">
              {lang === "zh" ? "加载中…" : "Loading…"}
            </div>
          )}
          {!listLoading && filteredVideos.map((video, i) => {
            const status = statusConfig[video.status];
            return (
              <motion.div
                key={video.id}
                initial={{ opacity: 0, y: 20 }}
                animate={{ opacity: 1, y: 0 }}
                transition={{ delay: i * 0.05 }}
                className="glass-card overflow-hidden group"
                whileHover={{ y: -4 }}
              >
                {/* Thumbnail */}
                <div className="aspect-video bg-gradient-to-br from-muted/50 to-muted/30 flex items-center justify-center relative">
                  <span className="text-4xl">{video.thumbnail}</span>
                  <div className="absolute inset-0 bg-black/0 group-hover:bg-black/20 transition-colors flex items-center justify-center">
                    <motion.div
                      initial={{ opacity: 0, scale: 0.5 }}
                      whileHover={{ opacity: 1, scale: 1 }}
                      className="w-12 h-12 rounded-full bg-primary/90 flex items-center justify-center opacity-0 group-hover:opacity-100 transition-opacity"
                    >
                      <FileVideo className="w-5 h-5 text-primary-foreground" />
                    </motion.div>
                  </div>
                  <span className="absolute bottom-2 right-2 glass-pill px-2 py-0.5 text-[10px] font-medium text-foreground">
                    {video.duration}
                  </span>
                </div>

                {/* Info */}
                <div className="p-4">
                  <div className="flex items-start justify-between gap-2 mb-2">
                    <h4 className="text-sm font-semibold text-foreground line-clamp-2">{video.title}</h4>
                    <button
                      onClick={() => handleDelete(video.id)}
                      className="p-1.5 rounded-lg hover:bg-destructive/10 text-muted-foreground hover:text-destructive transition-colors shrink-0"
                    >
                      <Trash2 className="w-3.5 h-3.5" />
                    </button>
                  </div>

                  <p className="text-xs text-muted-foreground mb-3">
                    {video.course} · {video.module}
                  </p>

                  <div className="flex items-center justify-between gap-2 flex-wrap">
                    <span className={`inline-flex items-center gap-1 px-2 py-0.5 rounded-full text-[10px] font-medium ${status.color}`}>
                      <status.icon className="w-3 h-3" />
                      {status.label[lang]}
                    </span>
                    <div className="flex items-center gap-3 text-[10px] text-muted-foreground">
                      <span className="flex items-center gap-1">
                        <Eye className="w-3 h-3" /> {video.views}
                      </span>
                      <span>{video.uploadDate}</span>
                    </div>
                  </div>
                  {(video.status === "draft" || video.status === "processing") && (
                    <button
                      type="button"
                      onClick={() => handlePublish(video.id)}
                      className="mt-3 w-full h-9 rounded-lg text-xs font-medium bg-emerald-500/15 text-emerald-700 dark:text-emerald-400 hover:bg-emerald-500/25 transition-colors"
                    >
                      {lang === "zh" ? "发布到学员端" : "Publish to learners"}
                    </button>
                  )}
                </div>
              </motion.div>
            );
          })}
        </div>

        {!listLoading && filteredVideos.length === 0 && (
          <div className="glass-card p-12 text-center">
            <Video className="w-12 h-12 text-muted-foreground/30 mx-auto mb-4" />
            <p className="text-muted-foreground">
              {lang === "zh" ? "暂无视频" : "No videos found"}
            </p>
          </div>
        )}
      </div>

      {/* Upload Modal */}
      <AnimatePresence>
        {showUpload && (
          <motion.div
            initial={{ opacity: 0 }}
            animate={{ opacity: 1 }}
            exit={{ opacity: 0 }}
            className="fixed inset-0 z-50 bg-black/60 flex items-center justify-center p-4"
            onClick={() => {
              setShowUpload(false);
              resetUploadForm();
            }}
          >
            <motion.div
              initial={{ scale: 0.9, opacity: 0 }}
              animate={{ scale: 1, opacity: 1 }}
              exit={{ scale: 0.9, opacity: 0 }}
              className="w-full max-w-lg p-8 rounded-2xl border border-white/30 bg-white/80 dark:bg-white/15 backdrop-blur-2xl shadow-2xl shadow-primary/10"
              onClick={(e) => e.stopPropagation()}
            >
              <h3 className="text-lg font-bold text-foreground mb-6 flex items-center gap-2">
                <Upload className="w-5 h-5 text-primary" />
                {lang === "zh" ? "上传新视频" : "Upload New Video"}
              </h3>

              <form onSubmit={handleUpload} className="space-y-4">
                {/* Video Title */}
                <div className="space-y-2">
                  <label className="text-sm font-medium text-foreground">
                    {lang === "zh" ? "视频标题" : "Video Title"}
                  </label>
                  <input
                    type="text"
                    value={uploadTitle}
                    onChange={(e) => setUploadTitle(e.target.value)}
                    placeholder={lang === "zh" ? "输入视频标题" : "Enter video title"}
                    className="w-full h-11 rounded-xl border border-border bg-background px-4 text-sm text-foreground placeholder:text-muted-foreground focus:outline-none focus:ring-2 focus:ring-primary/30 shadow-sm transition-all"
                    required
                  />
                </div>

                {/* Course Selection */}
                <div className="space-y-2">
                  <label className="text-sm font-medium text-foreground">
                    {lang === "zh" ? "所属课程" : "Course"}
                  </label>
                  <select
                    value={uploadCourse}
                    onChange={(e) => setUploadCourse(e.target.value)}
                    className="w-full h-11 rounded-xl border border-border bg-background px-4 text-sm text-foreground focus:outline-none focus:ring-2 focus:ring-primary/30 shadow-sm transition-all"
                  >
                    {courseOptions.map(c => (
                      <option key={c.key} value={c.key}>{c.label[lang]}</option>
                    ))}
                  </select>
                </div>

                {/* Module */}
                <div className="space-y-2">
                  <label className="text-sm font-medium text-foreground">
                    {lang === "zh" ? "所属模块" : "Module"}
                  </label>
                  <select
                    value={uploadModule}
                    onChange={(e) => setUploadModule(e.target.value)}
                    className="w-full h-11 rounded-xl border border-border bg-background px-4 text-sm text-foreground focus:outline-none focus:ring-2 focus:ring-primary/30 shadow-sm transition-all"
                  >
                    {[1, 2, 3, 4, 5, 6].map(n => (
                      <option key={n} value={lang === "zh" ? `模块${n}` : `Module ${n}`}>
                        {lang === "zh" ? `模块${n}` : `Module ${n}`}
                      </option>
                    ))}
                  </select>
                </div>

                {/* File Upload */}
                <div className="space-y-2">
                  <label className="text-sm font-medium text-foreground">
                    {lang === "zh" ? "视频文件" : "Video File"}
                  </label>
                  <div
                    onDragOver={(e) => { e.preventDefault(); setDragActive(true); }}
                    onDragLeave={() => setDragActive(false)}
                    onDrop={(e) => {
                      e.preventDefault();
                      setDragActive(false);
                      if (e.dataTransfer.files[0]) setUploadFile(e.dataTransfer.files[0]);
                    }}
                    className={`relative border-2 border-dashed rounded-xl p-6 text-center transition-all cursor-pointer ${
                      dragActive
                        ? "border-primary bg-primary/10"
                        : "border-border hover:border-primary/40 bg-background shadow-sm"
                    }`}
                  >
                    <input
                      type="file"
                      accept="video/*"
                      onChange={(e) => e.target.files?.[0] && setUploadFile(e.target.files[0])}
                      className="absolute inset-0 opacity-0 cursor-pointer"
                    />
                    {uploadFile ? (
                      <div className="flex items-center justify-center gap-2">
                        <FileVideo className="w-5 h-5 text-primary" />
                        <span className="text-sm text-foreground font-medium">{uploadFile.name}</span>
                      </div>
                    ) : (
                      <>
                        <Upload className="w-8 h-8 text-muted-foreground/40 mx-auto mb-2" />
                        <p className="text-sm text-muted-foreground">
                          {lang === "zh" ? "拖拽文件到这里或点击上传" : "Drag & drop or click to upload"}
                        </p>
                        <p className="text-xs text-muted-foreground/60 mt-1">MP4, MOV, AVI (max 2GB)</p>
                      </>
                    )}
                  </div>
                </div>

                {/* Draft Preview */}
                {(uploadTitle || uploadFile) && (
                  <div className="rounded-xl border border-border bg-muted/30 p-4 space-y-2">
                    <p className="text-xs font-semibold text-muted-foreground uppercase tracking-wider">
                      {lang === "zh" ? "📋 上传预览" : "📋 Upload Preview"}
                    </p>
                    <div className="flex items-start gap-3">
                      <div className="w-20 h-14 rounded-lg bg-gradient-to-br from-muted/60 to-muted/30 flex items-center justify-center text-2xl shrink-0">
                        {courseOptions.find(c => c.key === uploadCourse)?.label.zh.charAt(0) === "商" ? "📊" : "📋"}
                      </div>
                      <div className="flex-1 min-w-0">
                        <p className="text-sm font-semibold text-foreground truncate">
                          {uploadTitle || (lang === "zh" ? "未命名视频" : "Untitled Video")}
                        </p>
                        <p className="text-xs text-muted-foreground">
                          {courseOptions.find(c => c.key === uploadCourse)?.label[lang]} · {uploadModule || (lang === "zh" ? "模块1" : "Module 1")}
                        </p>
                        {uploadFile && (
                          <p className="text-xs text-primary mt-1 flex items-center gap-1">
                            <FileVideo className="w-3 h-3" />
                            {uploadFile.name} ({(uploadFile.size / 1024 / 1024).toFixed(1)} MB)
                          </p>
                        )}
                      </div>
                    </div>
                  </div>
                )}

                {/* Actions */}
                <div className="flex gap-3 pt-2">
                  <button
                    type="button"
                    disabled={uploadBusy}
                    onClick={() => {
                      setShowUpload(false);
                      resetUploadForm();
                    }}
                    className="h-11 px-4 rounded-xl border border-border bg-background text-sm font-medium text-foreground hover:bg-muted/40 shadow-sm transition-colors disabled:opacity-50"
                  >
                    {lang === "zh" ? "取消" : "Cancel"}
                  </button>
                  <button
                    type="button"
                    disabled={uploadBusy}
                    onClick={handleSaveAsDraft}
                    className="flex-1 h-11 rounded-xl border border-amber-500/50 bg-amber-500/10 text-sm font-medium text-amber-700 dark:text-amber-400 hover:bg-amber-500/20 shadow-sm transition-colors flex items-center justify-center gap-2 disabled:opacity-50"
                  >
                    <AlertCircle className="w-4 h-4" />
                    {lang === "zh" ? "保存草稿" : "Save as Draft"}
                  </button>
                  <button
                    type="submit"
                    disabled={uploadBusy}
                    className="flex-1 h-11 rounded-xl bg-gradient-to-r from-primary to-accent text-primary-foreground text-sm font-medium shadow-lg shadow-primary/20 hover:shadow-xl transition-all flex items-center justify-center gap-2 disabled:opacity-50"
                  >
                    <Upload className="w-4 h-4" />
                    {uploadBusy ? (lang === "zh" ? "上传中…" : "Uploading…") : lang === "zh" ? "上传发布" : "Publish"}
                  </button>
                </div>
              </form>
            </motion.div>
          </motion.div>
        )}
      </AnimatePresence>
    </div>
  );
}