import { useEffect, useState } from "react"
import { useForm } from "react-hook-form"
import { z } from "zod/v4"
import { zodResolver } from "@hookform/resolvers/zod"
import { useNavigate } from "react-router"
import { Button } from "@/components/ui/button"
import { Input } from "@/components/ui/input"
import { Label } from "@/components/ui/label"
import { Textarea } from "@/components/ui/textarea"
import { Separator } from "@/components/ui/separator"
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select"
import { DistractorEditor } from "@/components/question/DistractorEditor"
import { KnowledgeCardFields } from "@/components/question/KnowledgeCardFields"
import { fetchCategories } from "@/lib/api/category-api"
import { DIFFICULTY_LABELS, QUESTION_STATUSES } from "@/lib/constants"
import type { Question, Difficulty, QuestionStatus } from "@/types/question"
import type { Category } from "@/types/category"

const questionSchema = z.object({
  stem: z.string().min(1, "请输入题干").max(500),
  correctAnswer: z.string().min(1, "请输入正确答案"),
  distractors: z
    .array(z.string().min(1, "干扰项不能为空"))
    .min(4, "至少 4 个干扰项")
    .max(6, "最多 6 个干扰项"),
  categoryId: z.string().min(1, "请选择分类"),
  difficulty: z.number().min(1).max(5),
  status: z.enum(["draft", "reviewing", "published", "archived"]),
  knowledgeCardBasic: z.string().min(1, "请填写基础知识卡").max(100),
  knowledgeCardDeep: z.string().max(300).optional(),
  sourceRef: z.string().max(500).optional(),
})

type FormValues = z.infer<typeof questionSchema>

interface QuestionFormProps {
  question?: Question
}

export function QuestionForm({ question }: QuestionFormProps) {
  const navigate = useNavigate()
  const isEditing = !!question
  const [submitting, setSubmitting] = useState(false)
  const [categories, setCategories] = useState<Category[]>([])

  const {
    register,
    handleSubmit,
    formState: { errors },
    setValue,
    watch,
  } = useForm<FormValues>({
    resolver: zodResolver(questionSchema),
    defaultValues: question
      ? {
          stem: question.stem,
          correctAnswer: question.correctAnswer,
          distractors: question.distractors,
          categoryId: question.categoryId,
          difficulty: question.difficulty,
          status: question.status,
          knowledgeCardBasic: question.knowledgeCardBasic,
          knowledgeCardDeep: question.knowledgeCardDeep ?? "",
          sourceRef: question.sourceRef ?? "",
        }
      : {
          stem: "",
          correctAnswer: "",
          distractors: ["", "", "", ""],
          categoryId: "",
          difficulty: 3,
          status: "draft",
          knowledgeCardBasic: "",
          knowledgeCardDeep: "",
          sourceRef: "",
        },
  })

  useEffect(() => {
    fetchCategories({ limit: 100 }).then((res) => setCategories(res.data))
  }, [])

  async function onSubmit(data: FormValues) {
    setSubmitting(true)
    try {
      // TODO: 接入 API
      console.log("submit", isEditing ? "update" : "create", data)
      navigate("/questions")
    } finally {
      setSubmitting(false)
    }
  }

  const distractorsValue = watch("distractors")

  return (
    <form onSubmit={handleSubmit(onSubmit)} className="max-w-2xl space-y-6">
      {/* 题干 */}
      <div className="space-y-2">
        <Label htmlFor="stem">题干</Label>
        <Textarea
          id="stem"
          placeholder="输入题目文字"
          rows={3}
          {...register("stem")}
        />
        {errors.stem && (
          <p className="text-sm text-destructive">{errors.stem.message}</p>
        )}
      </div>

      {/* 正确答案 */}
      <div className="space-y-2">
        <Label htmlFor="correctAnswer">正确答案</Label>
        <Input
          id="correctAnswer"
          placeholder="正确选项文本"
          {...register("correctAnswer")}
        />
        {errors.correctAnswer && (
          <p className="text-sm text-destructive">
            {errors.correctAnswer.message}
          </p>
        )}
      </div>

      {/* 干扰项 */}
      <DistractorEditor
        value={distractorsValue}
        onChange={(items) =>
          setValue("distractors", items, { shouldValidate: true })
        }
        errors={
          errors.distractors?.message ? [errors.distractors.message] : undefined
        }
      />

      <Separator />

      {/* 分类 + 难度 + 状态 */}
      <div className="grid grid-cols-3 gap-4">
        <div className="space-y-2">
          <Label>分类</Label>
          <Select
            value={watch("categoryId")}
            onValueChange={(val) => setValue("categoryId", val)}
          >
            <SelectTrigger>
              <SelectValue placeholder="选择分类" />
            </SelectTrigger>
            <SelectContent>
              {categories.map((cat) => (
                <SelectItem key={cat.id} value={cat.id}>
                  {cat.name}
                </SelectItem>
              ))}
            </SelectContent>
          </Select>
          {errors.categoryId && (
            <p className="text-sm text-destructive">
              {errors.categoryId.message}
            </p>
          )}
        </div>

        <div className="space-y-2">
          <Label>难度</Label>
          <Select
            value={String(watch("difficulty"))}
            onValueChange={(val) =>
              setValue("difficulty", Number(val) as Difficulty)
            }
          >
            <SelectTrigger>
              <SelectValue />
            </SelectTrigger>
            <SelectContent>
              {Object.entries(DIFFICULTY_LABELS).map(([value, label]) => (
                <SelectItem key={value} value={value}>
                  {label}
                </SelectItem>
              ))}
            </SelectContent>
          </Select>
        </div>

        <div className="space-y-2">
          <Label>状态</Label>
          <Select
            value={watch("status")}
            onValueChange={(val) => setValue("status", val as QuestionStatus)}
          >
            <SelectTrigger>
              <SelectValue />
            </SelectTrigger>
            <SelectContent>
              {Object.entries(QUESTION_STATUSES).map(([value, label]) => (
                <SelectItem key={value} value={value}>
                  {label}
                </SelectItem>
              ))}
            </SelectContent>
          </Select>
        </div>
      </div>

      <Separator />

      {/* 知识卡 */}
      <KnowledgeCardFields
        basicRegister={register("knowledgeCardBasic")}
        deepRegister={register("knowledgeCardDeep")}
        sourceRefRegister={register("sourceRef")}
        basicError={errors.knowledgeCardBasic?.message}
        deepError={errors.knowledgeCardDeep?.message}
        watchBasic={watch("knowledgeCardBasic") ?? ""}
        watchDeep={watch("knowledgeCardDeep") ?? ""}
      />

      {/* 提交 */}
      <div className="flex justify-end gap-2 pt-2">
        <Button
          type="button"
          variant="outline"
          onClick={() => navigate("/questions")}
        >
          取消
        </Button>
        <Button type="submit" disabled={submitting}>
          {submitting
            ? "保存中..."
            : isEditing
              ? "更新题目"
              : "创建题目"}
        </Button>
      </div>
    </form>
  )
}