"use client";

import React, { useState } from "react";
import Link from "next/link";
import {
  Layers,
  Calendar,
  Clock,
  Plus,
  Search,
  CheckCircle2,
  ChevronRight,
  Users,
  AlertCircle,
  X,
} from "lucide-react";
import { toast } from "sonner";

interface SemesterItem {
  id: string;
  semesterNumber: number;
  name: string;
  program: string;
  termType: "ODD" | "EVEN";
  startDate: string;
  endDate: string;
  workingDays: number;
  enrolledStudents: number;
  minAttendanceRequired: number;
  coordinator: string;
  status: "ACTIVE" | "UPCOMING" | "COMPLETED";
}

export default function DeptAdminSemestersPage() {
  const [semesters, setSemesters] = useState<SemesterItem[]>([
    {
      id: "sem_1",
      semesterNumber: 1,
      name: "Semester 1 (Freshman Foundation)",
      program: "B.Sc. in Hospitality & Hotel Administration",
      termType: "ODD",
      startDate: "15 Jul 2024",
      endDate: "20 Dec 2024",
      workingDays: 92,
      enrolledStudents: 138,
      minAttendanceRequired: 75,
      coordinator: "Chef Anirban Roy",
      status: "ACTIVE",
    },
    {
      id: "sem_3",
      semesterNumber: 3,
      name: "Semester 3 (Intermediate Culinary & Operations)",
      program: "B.Sc. in Hospitality & Hotel Administration",
      termType: "ODD",
      startDate: "15 Jul 2024",
      endDate: "20 Dec 2024",
      workingDays: 92,
      enrolledStudents: 124,
      minAttendanceRequired: 75,
      coordinator: "Chef Amit Sen",
      status: "ACTIVE",
    },
    {
      id: "sem_5",
      semesterNumber: 5,
      name: "Semester 5 (Advanced Culinary & Kitchen Management)",
      program: "B.Sc. in Hospitality & Hotel Administration",
      termType: "ODD",
      startDate: "15 Jul 2024",
      endDate: "20 Dec 2024",
      workingDays: 92,
      enrolledStudents: 122,
      minAttendanceRequired: 75,
      coordinator: "Chef Rajesh Sharma",
      status: "ACTIVE",
    },
    {
      id: "sem_2",
      semesterNumber: 2,
      name: "Semester 2 (Core Fundamentals)",
      program: "B.Sc. in Hospitality & Hotel Administration",
      termType: "EVEN",
      startDate: "06 Jan 2025",
      endDate: "30 May 2025",
      workingDays: 94,
      enrolledStudents: 138,
      minAttendanceRequired: 75,
      coordinator: "Chef Anirban Roy",
      status: "UPCOMING",
    },
  ]);

  const [termTab, setTermTab] = useState<"ALL" | "ODD" | "EVEN">("ODD");
  const [isModalOpen, setIsModalOpen] = useState(false);

  const [formSemNumber, setFormSemNumber] = useState(1);
  const [formProgram, setFormProgram] = useState("B.Sc. in Hospitality & Hotel Administration");
  const [formWorkingDays, setFormWorkingDays] = useState(90);
  const [formCoordinator, setFormCoordinator] = useState("Chef Anirban Roy");

  const filteredSemesters = semesters.filter(
    (s) => termTab === "ALL" || s.termType === termTab
  );

  const handleAddSemester = (e: React.FormEvent) => {
    e.preventDefault();
    const newSem: SemesterItem = {
      id: `sem_${Date.now()}`,
      semesterNumber: Number(formSemNumber),
      name: `Semester ${formSemNumber}`,
      program: formProgram,
      termType: formSemNumber % 2 === 1 ? "ODD" : "EVEN",
      startDate: "15 Jul 2025",
      endDate: "20 Dec 2025",
      workingDays: Number(formWorkingDays),
      enrolledStudents: 0,
      minAttendanceRequired: 75,
      coordinator: formCoordinator,
      status: "UPCOMING",
    };

    setSemesters([...semesters, newSem]);
    setIsModalOpen(false);
    toast.success(`Semester ${formSemNumber} registered`);
  };

  return (
    <div className="p-4 sm:p-6 lg:p-8 space-y-6 max-w-7xl mx-auto">
      {/* Header */}
      <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-4">
        <div>
          <div className="flex items-center gap-2 text-xs font-semibold text-slate-500 mb-1">
            <Link href="/dept-admin/dashboard" className="hover:text-[#1769E8]">
              Dashboard
            </Link>
            <ChevronRight className="w-3.5 h-3.5" />
            <span className="text-[#071A4D] font-bold">Semester Management</span>
          </div>
          <h1 className="text-xl sm:text-2xl font-black text-[#071A4D] tracking-tight">
            Semester Management
          </h1>
          <p className="text-xs text-slate-500 mt-0.5">
            Configure term progression, working days criteria, and attendance threshold policies
          </p>
        </div>

        <button
          onClick={() => setIsModalOpen(true)}
          className="inline-flex items-center gap-2 px-4 py-2.5 rounded-lg bg-[#C8A45D] hover:bg-[#B38F48] text-slate-950 font-bold text-xs shadow-sm transition-all"
        >
          <Plus className="w-4 h-4" />
          <span>Configure Semester</span>
        </button>
      </div>

      {/* Tabs */}
      <div className="flex items-center gap-2 border-b border-slate-200">
        {[
          { key: "ODD", label: "Odd Semesters (Currently Active: Sem 1, 3, 5)" },
          { key: "EVEN", label: "Even Semesters (Upcoming: Sem 2, 4, 6)" },
          { key: "ALL", label: "All Semesters" },
        ].map((tab) => (
          <button
            key={tab.key}
            onClick={() => setTermTab(tab.key as any)}
            className={`pb-3 px-3 text-xs font-bold border-b-2 transition-colors ${
              termTab === tab.key
                ? "border-[#C8A45D] text-[#071A4D]"
                : "border-transparent text-slate-500 hover:text-slate-800"
            }`}
          >
            {tab.label}
          </button>
        ))}
      </div>

      {/* Semesters List */}
      <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-5">
        {filteredSemesters.map((s) => (
          <div
            key={s.id}
            className="p-5 rounded-xl bg-white border border-slate-200 shadow-xs hover:shadow-md transition-all space-y-4"
          >
            <div className="flex items-start justify-between">
              <div>
                <span className="text-[10px] font-bold uppercase tracking-wider px-2 py-0.5 rounded-full bg-slate-100 text-slate-700">
                  {s.termType} Term
                </span>
                <h3 className="text-base font-bold text-[#071A4D] mt-1.5">{s.name}</h3>
                <p className="text-xs text-slate-500">{s.program}</p>
              </div>
              <span
                className={`text-[10px] font-bold px-2 py-0.5 rounded-full uppercase ${
                  s.status === "ACTIVE"
                    ? "bg-emerald-100 text-emerald-800"
                    : "bg-blue-100 text-blue-800"
                }`}
              >
                {s.status}
              </span>
            </div>

            <div className="space-y-2 py-3 border-y border-slate-100 text-xs">
              <div className="flex justify-between">
                <span className="text-slate-500">Term Timeline:</span>
                <span className="font-semibold text-slate-800">
                  {s.startDate} – {s.endDate}
                </span>
              </div>
              <div className="flex justify-between">
                <span className="text-slate-500">Working Days Target:</span>
                <span className="font-bold text-[#071A4D]">{s.workingDays} Days</span>
              </div>
              <div className="flex justify-between">
                <span className="text-slate-500">Enrolled Students:</span>
                <span className="font-bold text-[#785E2F]">{s.enrolledStudents} Students</span>
              </div>
              <div className="flex justify-between">
                <span className="text-slate-500">NCHMCT Attendance Mandate:</span>
                <span className="font-bold text-rose-600">&gt;= {s.minAttendanceRequired}%</span>
              </div>
            </div>

            <div className="flex items-center justify-between text-xs pt-1">
              <span className="text-slate-500">Coordinator:</span>
              <span className="font-bold text-slate-800">{s.coordinator}</span>
            </div>
          </div>
        ))}
      </div>

      {/* Modal */}
      {isModalOpen && (
        <div className="fixed inset-0 z-50 bg-slate-900/60 backdrop-blur-xs flex items-center justify-center p-4">
          <div className="bg-white rounded-2xl max-w-md w-full p-6 shadow-2xl border border-slate-200">
            <div className="flex items-center justify-between pb-3 border-b border-slate-100">
              <h3 className="font-bold text-base text-[#071A4D]">Configure Semester</h3>
              <button onClick={() => setIsModalOpen(false)}>
                <X className="w-5 h-5 text-slate-400" />
              </button>
            </div>

            <form onSubmit={handleAddSemester} className="space-y-4 pt-4 text-xs">
              <div>
                <label className="font-bold text-slate-800 block mb-1">Semester Number</label>
                <select
                  value={formSemNumber}
                  onChange={(e) => setFormSemNumber(Number(e.target.value))}
                  className="w-full px-3 py-2 border border-slate-200 rounded-lg focus:outline-hidden focus:border-[#C8A45D]"
                >
                  {[1, 2, 3, 4, 5, 6].map((n) => (
                    <option key={n} value={n}>
                      Semester {n} ({n % 2 === 1 ? "Odd Term" : "Even Term"})
                    </option>
                  ))}
                </select>
              </div>

              <div>
                <label className="font-bold text-slate-800 block mb-1">Program</label>
                <input
                  type="text"
                  value={formProgram}
                  onChange={(e) => setFormProgram(e.target.value)}
                  className="w-full px-3 py-2 border border-slate-200 rounded-lg focus:outline-hidden focus:border-[#C8A45D]"
                  required
                />
              </div>

              <div>
                <label className="font-bold text-slate-800 block mb-1">Working Days Target</label>
                <input
                  type="number"
                  value={formWorkingDays}
                  onChange={(e) => setFormWorkingDays(Number(e.target.value))}
                  className="w-full px-3 py-2 border border-slate-200 rounded-lg focus:outline-hidden focus:border-[#C8A45D]"
                />
              </div>

              <div>
                <label className="font-bold text-slate-800 block mb-1">Semester Coordinator</label>
                <input
                  type="text"
                  value={formCoordinator}
                  onChange={(e) => setFormCoordinator(e.target.value)}
                  className="w-full px-3 py-2 border border-slate-200 rounded-lg focus:outline-hidden focus:border-[#C8A45D]"
                />
              </div>

              <div className="pt-3 border-t border-slate-100 flex justify-end gap-2">
                <button
                  type="button"
                  onClick={() => setIsModalOpen(false)}
                  className="px-4 py-2 rounded-lg border border-slate-200 font-bold text-slate-600 hover:bg-slate-50"
                >
                  Cancel
                </button>
                <button
                  type="submit"
                  className="px-4 py-2 rounded-lg bg-[#C8A45D] text-slate-950 font-bold hover:bg-[#B38F48]"
                >
                  Save Semester
                </button>
              </div>
            </form>
          </div>
        </div>
      )}
    </div>
  );
}