// frontend/src/components/admin/ClassForm.jsx
import React, { useState, useEffect } from "react";
import { Plus, Trash2, Loader2, Save, X, MapPin } from "lucide-react";
import { useQuery } from "@tanstack/react-query";
import api from "../../api/client";

const DAYS = [
  "Monday",
  "Tuesday",
  "Wednesday",
  "Thursday",
  "Friday",
  "Saturday",
  "Sunday",
];

export default function ClassForm({ classData, onSave, onCancel, isLoading }) {
  // Fetch membership plans if not provided
  const { data: plans = [], isLoading: plansLoading } = useQuery({
    queryKey: ["membership-plans"],
    queryFn: async () => {
      const res = await api.get("/admin/plans");
      return Array.isArray(res.data) ? res.data : [];
    },
    initialData: [],
  });

  // schedule: [{ day, start_time, end_time }]
  const [formData, setFormData] = useState({
    name: "",
    description: "",
    coach_email: "",
    location: "",
    membership_plan_ids: [],
    schedule: [{ day: "Monday", start_time: "", end_time: "" }],
    is_active: true,
  });

  useEffect(() => {
    if (!classData) return;
    setFormData({
      name: classData.name || "",
      description: classData.description || "",
      coach_email: classData.coach_email || "",
      location: classData.location || "",
      membership_plan_ids: Array.isArray(classData.membership_plan_ids) 
        ? classData.membership_plan_ids 
        : (classData.membership_plans?.map(p => p.id) || []),
      schedule:
        Array.isArray(classData.schedule) && classData.schedule.length > 0
          ? classData.schedule.map((slot) => ({
              day: slot.day || "Monday",
              start_time: slot.start_time || "",
              end_time: slot.end_time || "",
            }))
          : [{ day: "Monday", start_time: "", end_time: "" }],
      is_active:
        classData.is_active !== undefined ? classData.is_active : true,
    });
  }, [classData]);

  const addScheduleSlot = () => {
    setFormData((prev) => ({
      ...prev,
      schedule: [
        ...prev.schedule,
        { day: "Monday", start_time: "", end_time: "" },
      ],
    }));
  };

  const removeScheduleSlot = (index) => {
    setFormData((prev) => ({
      ...prev,
      schedule: prev.schedule.filter((_, i) => i !== index),
    }));
  };

  const updateScheduleSlot = (index, field, value) => {
    setFormData((prev) => {
      const schedule = [...prev.schedule];
      schedule[index] = { ...schedule[index], [field]: value };
      return { ...prev, schedule };
    });
  };

  const handleSubmit = (e) => {
    e.preventDefault();

    // Transform schedule to a simple structure that backend can later map
    const transformedSchedule = formData.schedule.map((slot) => ({
      day: slot.day,
      start_time: slot.start_time,
      end_time: slot.end_time,
      time:
        slot.start_time && slot.end_time
          ? `${slot.start_time}-${slot.end_time}`
          : "",
    }));

    const payload = {
      name: formData.name,
      description: formData.description,
      coach_email: formData.coach_email || null,
      location: formData.location || null,
      membership_plan_ids: formData.membership_plan_ids || [],
      schedule: transformedSchedule,
      is_active: formData.is_active,
    };

    onSave(payload);
  };

  const handlePlanToggle = (planId) => {
    setFormData((prev) => {
      const currentIds = prev.membership_plan_ids || [];
      const newIds = currentIds.includes(planId)
        ? currentIds.filter((id) => id !== planId)
        : [...currentIds, planId];
      return { ...prev, membership_plan_ids: newIds };
    });
  };

  return (
    <form onSubmit={handleSubmit} className="space-y-6">
      {/* Class Name */}
      <div className="space-y-1">
        <label className="block text-sm font-medium text-stone-800">
          Class Name
        </label>
        <input
          type="text"
          className="w-full rounded-md border border-stone-300 px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-red-600"
          value={formData.name}
          onChange={(e) =>
            setFormData((prev) => ({ ...prev, name: e.target.value }))
          }
          placeholder="e.g., Beginner Karate"
          required
        />
      </div>

      {/* Description */}
      <div className="space-y-1">
        <label className="block text-sm font-medium text-stone-800">
          Description
        </label>
        <textarea
          className="w-full rounded-md border border-stone-300 px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-red-600"
          rows={2}
          value={formData.description}
          onChange={(e) =>
            setFormData((prev) => ({
              ...prev,
              description: e.target.value,
            }))
          }
          placeholder="Class description..."
        />
      </div>

      {/* Coach Email and Location - Side by Side */}
      <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
        {/* Coach Email */}
        <div className="space-y-1">
          <label className="block text-sm font-medium text-stone-800">
            Coach Email (Optional)
          </label>
          <input
            type="email"
            className="w-full rounded-md border border-stone-300 px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-red-600"
            value={formData.coach_email}
            onChange={(e) =>
              setFormData((prev) => ({ ...prev, coach_email: e.target.value }))
            }
            placeholder="coach@dojo.com"
          />
          <p className="text-xs text-stone-500 mt-1">
            Assign a coach to manage attendance.
          </p>
        </div>

        {/* Location */}
        <div className="space-y-1">
          <label className="block text-sm font-medium text-stone-800">
            Location
          </label>
          <div className="relative">
            <MapPin className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-stone-400" />
            <input
              type="text"
              className="w-full rounded-md border border-stone-300 pl-10 pr-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-red-600"
              value={formData.location}
              onChange={(e) =>
                setFormData((prev) => ({ ...prev, location: e.target.value }))
              }
              placeholder="Address or Zoom meeting link"
            />
          </div>
          <p className="text-xs text-stone-500 mt-1">
            Physical address or online meeting details.
          </p>
        </div>
      </div>

      {/* Membership Plans */}
      <div className="space-y-2">
        <label className="block text-sm font-medium text-stone-800">
          Membership Plans
        </label>
        <p className="text-xs text-stone-500 mb-3">
          Select which membership plans can access this class. Members under these plans will be able to see and enroll in this class.
        </p>
        {plansLoading ? (
          <div className="text-sm text-stone-500">Loading plans...</div>
        ) : plans.length === 0 ? (
          <div className="text-sm text-stone-500">No membership plans available.</div>
        ) : (
          <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-3">
            {plans
              .filter((plan) => plan.is_active)
              .map((plan) => (
                <label
                  key={plan.id}
                  className="flex items-start gap-3 p-3 border border-stone-200 rounded-lg hover:bg-stone-50 cursor-pointer transition-colors"
                >
                  <input
                    type="checkbox"
                    checked={formData.membership_plan_ids?.includes(plan.id) || false}
                    onChange={() => handlePlanToggle(plan.id)}
                    className="mt-0.5 h-4 w-4 rounded border-stone-300 text-red-600 focus:ring-red-600"
                  />
                  <div className="flex-1 min-w-0">
                    <div className="text-sm font-medium text-stone-900">
                      {plan.name}
                    </div>
                    <div className="text-xs text-stone-500 mt-0.5">
                      ${plan.price} / {plan.billing_period}
                    </div>
                  </div>
                </label>
              ))}
          </div>
        )}
      </div>

      {/* Schedule */}
      <div>
        <div className="flex items-center justify-between mb-3">
          <span className="text-sm font-medium text-stone-800">
            Class Schedule
          </span>
          <button
            type="button"
            onClick={addScheduleSlot}
            className="inline-flex items-center gap-2 rounded-md border border-stone-300 px-2.5 py-1 text-xs font-medium text-stone-800 hover:bg-stone-50"
          >
            <Plus className="w-4 h-4" />
            Add Time Slot
          </button>
        </div>

        <div className="space-y-3">
          {formData.schedule.map((slot, index) => (
            <div
              key={index}
              className="rounded-lg border border-stone-200 bg-stone-50 px-3 py-3"
            >
              <div className="flex flex-col gap-3 md:flex-row md:items-center">
                {/* Day */}
                <div className="w-full md:w-40">
                  <label className="block text-xs font-medium text-stone-700 mb-1">
                    Day
                  </label>
                  <select
                    className="w-full rounded-md border border-stone-300 px-2 py-1.5 text-sm focus:outline-none focus:ring-2 focus:ring-red-600"
                    value={slot.day}
                    onChange={(e) =>
                      updateScheduleSlot(index, "day", e.target.value)
                    }
                  >
                    {DAYS.map((day) => (
                      <option key={day} value={day}>
                        {day}
                      </option>
                    ))}
                  </select>
                </div>

                {/* From / To */}
                <div className="flex flex-1 flex-col gap-3 md:flex-row">
                  <div className="flex-1">
                    <label className="block text-xs font-medium text-stone-700 mb-1">
                      From
                    </label>
                    <input
                      type="time"
                      className="w-full rounded-md border border-stone-300 px-2 py-1.5 text-sm focus:outline-none focus:ring-2 focus:ring-red-600"
                      value={slot.start_time}
                      onChange={(e) =>
                        updateScheduleSlot(index, "start_time", e.target.value)
                      }
                    />
                  </div>
                  <div className="flex-1">
                    <label className="block text-xs font-medium text-stone-700 mb-1">
                      To
                    </label>
                    <input
                      type="time"
                      className="w-full rounded-md border border-stone-300 px-2 py-1.5 text-sm focus:outline-none focus:ring-2 focus:ring-red-600"
                      value={slot.end_time}
                      onChange={(e) =>
                        updateScheduleSlot(index, "end_time", e.target.value)
                      }
                    />
                  </div>
                </div>

                {/* Remove */}
                {formData.schedule.length > 1 && (
                  <button
                    type="button"
                    onClick={() => removeScheduleSlot(index)}
                    className="self-start rounded-md p-2 text-red-600 hover:bg-red-50"
                  >
                    <Trash2 className="w-4 h-4" />
                  </button>
                )}
              </div>
            </div>
          ))}
        </div>
      </div>

      {/* Actions */}
      <div className="flex gap-3 pt-2">
        <button
          type="submit"
          disabled={isLoading}
          className="inline-flex items-center gap-2 rounded-md bg-red-600 px-4 py-2 text-sm font-medium text-white hover:bg-red-700 disabled:opacity-60"
        >
          {isLoading ? (
            <Loader2 className="w-4 h-4 animate-spin" />
          ) : (
            <Save className="w-4 h-4" />
          )}
          {classData ? "Update Class" : "Create Class"}
        </button>

        <button
          type="button"
          onClick={onCancel}
          disabled={isLoading}
          className="inline-flex items-center gap-2 rounded-md border border-stone-300 px-4 py-2 text-sm font-medium text-stone-800 hover:bg-stone-50 disabled:opacity-60"
        >
          <X className="w-4 h-4" />
          Cancel
        </button>
      </div>
    </form>
  );
}