// modules/admin/components/courses/CreateLessonDialog.jsx
// Lightweight "create a brand-new lesson and attach it to this unit" dialog —
// the create-new counterpart to AttachLessonsDialog's attach-existing flow.

import { useEffect } from "react";
import { useForm, useFieldArray } from "react-hook-form";
import { z } from "zod";
import { zodResolver } from "@hookform/resolvers/zod";
import { Plus, Trash2 } from "lucide-react";

import { useCourses } from "@/contexts/AdminCoursesContext";
import { useAuth } from "@/contexts/AuthContext";
import {
  Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter, DialogClose,
} from "@/components/ui/dialog";
import { Input } from "@/components/ui/input";
import { Textarea } from "@/components/ui/textarea";
import { Button } from "@/components/ui/button";
import { Label } from "@/components/ui/label";
import { Spinner } from "@/components/ui/spinner";

const schema = z.object({
  title: z.string().min(1, "Title is required."),
  description: z.string().optional(),
  order: z.coerce.number().min(0).default(0),
  objectives: z.array(z.object({ value: z.string().min(1, "Objective cannot be empty.") })).default([]),
});

export default function CreateLessonDialog({ open, onOpenChange, courseId, unitId, nextOrder = 0, onCreated, draftMode = false }) {
  const { createLesson, loading } = useCourses();
  const { user } = useAuth();

  const { register, handleSubmit, reset, control, formState: { errors } } = useForm({
    resolver: zodResolver(schema),
    defaultValues: { title: "", description: "", order: nextOrder, objectives: [] },
  });

  const { fields, append, remove } = useFieldArray({ control, name: "objectives" });

  useEffect(() => {
    if (open) reset({ title: "", description: "", order: nextOrder, objectives: [] });
  }, [open, nextOrder, reset]);

  const onValid = async (values) => {
    const objectives = values.objectives.map((o) => o.value);

    if (draftMode) {
      onCreated?.({
        lesson_id: null,
        key: crypto.randomUUID(),
        title: values.title,
        description: values.description,
        order_index: values.order,
        objectives,
      });
      onOpenChange(false);
      return;
    }

    const result = await createLesson(courseId, unitId, {
      ...values,
      objectives,
      createdBy: user?.user_id,
    });
    const lesson = result?.data?.data ?? null;
    if (!lesson) return;
    onCreated?.(lesson);
    onOpenChange(false);
  };

  return (
    <Dialog open={open} onOpenChange={onOpenChange}>
      <DialogContent className="sm:max-w-[440px]">
        <DialogHeader>
          <DialogTitle>New Lesson</DialogTitle>
        </DialogHeader>

        <form onSubmit={handleSubmit(onValid)} className="space-y-4">
          <div className="space-y-1.5">
            <Label htmlFor="lesson_title">
              Title <span className="text-destructive">*</span>
            </Label>
            <Input id="lesson_title" placeholder="e.g. Welcome to the Course" {...register("title")} />
            {errors.title && <p className="text-sm text-destructive">{errors.title.message}</p>}
          </div>

          <div className="space-y-1.5">
            <Label htmlFor="lesson_description">Description</Label>
            <Textarea id="lesson_description" placeholder="Optional lesson description" rows={3} {...register("description")} />
          </div>

          <div className="space-y-1.5 max-w-[120px]">
            <Label htmlFor="lesson_order">Order</Label>
            <Input id="lesson_order" type="number" min={0} {...register("order")} />
          </div>

          <div className="space-y-2">
            <div className="flex items-center justify-between">
              <Label className="text-xs text-muted-foreground">Objectives</Label>
              <Button type="button" variant="outline" size="sm" onClick={() => append({ value: "" })}>
                <Plus className="h-3.5 w-3.5 mr-1" /> Add
              </Button>
            </div>
            {fields.map((field, index) => (
              <div key={field.id} className="flex items-start gap-2">
                <div className="flex-1 space-y-1">
                  <Input placeholder={`Objective ${index + 1}`} {...register(`objectives.${index}.value`)} />
                  {errors.objectives?.[index]?.value && (
                    <p className="text-xs text-destructive">{errors.objectives[index].value.message}</p>
                  )}
                </div>
                <Button
                  type="button" variant="ghost" size="icon"
                  className="mt-0.5 text-muted-foreground hover:text-destructive"
                  onClick={() => remove(index)}
                >
                  <Trash2 className="h-4 w-4" />
                </Button>
              </div>
            ))}
          </div>

          <DialogFooter>
            <DialogClose asChild>
              <Button type="button" variant="outline" disabled={loading}>Cancel</Button>
            </DialogClose>
            <Button type="submit" disabled={loading}>
              {loading && <Spinner className="h-4 w-4 mr-2" />}
              Create Lesson
            </Button>
          </DialogFooter>
        </form>
      </DialogContent>
    </Dialog>
  );
}