"use client";

import { useEffect, useRef, useState } from "react";
import { useRouter } from "next/navigation";
import { useForm, Controller } from "react-hook-form";
import { zodResolver } from "@hookform/resolvers/zod";
import { toast } from "sonner";
import { Card, CardContent } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Textarea } from "@/components/ui/textarea";
import { Label } from "@/components/ui/label";
import {
  Select, SelectContent, SelectItem, SelectTrigger, SelectValue,
} from "@/components/ui/select";
import { PartiesField } from "@/components/wizard/parties-field";
import { useCreateCase } from "@/lib/api/cases";
import {
  caseCreateSchema, expectedOutcomes,
  type CaseCreateInput,
} from "@/lib/schemas/case";
import {
  PRACTICE_AREAS, APPEAL_SUBTYPES, deriveSubtype,
  type AppealSubtype,
} from "@/lib/practice-area";

const STEPS = [
  { key: "basics",  label: "פרטי יסוד" },
  { key: "parties", label: "צדדים"      },
  { key: "details", label: "השלמות"     },
] as const;

type StepKey = (typeof STEPS)[number]["key"];

/* Fields validated at each step — lets the user fix just what's on screen
 * before moving forward, instead of surfacing all errors from page 1. */
const STEP_FIELDS: Record<StepKey, (keyof CaseCreateInput)[]> = {
  basics:  ["case_number", "title", "practice_area", "appeal_subtype"],
  parties: ["appellants", "respondents"],
  details: ["subject", "hearing_date", "expected_outcome", "notes", "property_address", "permit_number"],
};

function FieldError({ message }: { message?: string }) {
  if (!message) return null;
  return <p className="text-[0.72rem] text-danger mt-1">{message}</p>;
}

export function CaseWizard() {
  const router = useRouter();
  const [step, setStep] = useState<StepKey>("basics");
  const mutate = useCreateCase();

  const form = useForm<CaseCreateInput>({
    resolver: zodResolver(caseCreateSchema),
    mode: "onBlur",
    defaultValues: {
      case_number: "",
      title: "",
      appellants: [],
      respondents: [],
      subject: "",
      property_address: "",
      permit_number: "",
      hearing_date: "",
      notes: "",
      expected_outcome: "",
      practice_area: "appeals_committee",
      appeal_subtype: "unknown",
    },
  });

  /*
   * Auto-fill appeal_subtype from the case number as the user types, but
   * stop the moment they manually pick a value from the dropdown. Mirrors
   * the wireSubtypeAutofill() behaviour of the vanilla UI
   * (legal-ai/web/static/index.html around line 2770).
   */
  const userTouchedSubtype = useRef(false);
  const caseNumber = form.watch("case_number");
  const practiceArea = form.watch("practice_area");
  useEffect(() => {
    if (userTouchedSubtype.current) return;
    const derived = deriveSubtype(caseNumber, practiceArea);
    if (derived !== form.getValues("appeal_subtype")) {
      form.setValue("appeal_subtype", derived, { shouldValidate: false });
    }
  }, [caseNumber, practiceArea, form]);

  const stepIndex = STEPS.findIndex((s) => s.key === step);
  const isLast = stepIndex === STEPS.length - 1;

  const goNext = async () => {
    const ok = await form.trigger(STEP_FIELDS[step]);
    if (!ok) return;
    setStep(STEPS[stepIndex + 1].key);
  };
  const goBack = () => setStep(STEPS[stepIndex - 1].key);

  const onSubmit = form.handleSubmit(async (values) => {
    try {
      const res = await mutate.mutateAsync(values);
      toast.success("תיק חדש נוצר");
      const created = res?.case_number || values.case_number;
      router.push(`/cases/${encodeURIComponent(created)}`);
    } catch (e) {
      toast.error(e instanceof Error ? e.message : "שגיאה ביצירת תיק");
    }
  });

  return (
    <Card className="bg-surface border-rule shadow-sm max-w-3xl">
      <CardContent className="px-6 py-6 space-y-6">
        {/* Stepper */}
        <ol className="flex items-center gap-2 text-sm">
          {STEPS.map((s, i) => {
            const active = i === stepIndex;
            const done = i < stepIndex;
            return (
              <li key={s.key} className="flex items-center gap-2">
                <span
                  className={`
                    inline-flex items-center justify-center w-7 h-7 rounded-full
                    font-display font-bold text-sm tabular-nums transition-colors
                    ${done ? "bg-success text-parchment" : active ? "bg-navy text-parchment" : "bg-rule text-ink-muted"}
                  `}
                >
                  {done ? "✓" : i + 1}
                </span>
                <span className={active ? "text-navy font-semibold" : "text-ink-muted"}>
                  {s.label}
                </span>
                {i < STEPS.length - 1 && (
                  <span className="w-8 h-px bg-rule mx-1" aria-hidden />
                )}
              </li>
            );
          })}
        </ol>

        <form onSubmit={onSubmit} className="space-y-5">
          {step === "basics" && (
            <div className="space-y-4">
              <div>
                <Label htmlFor="case_number" className="text-navy">
                  מספר תיק <span className="text-danger">*</span>
                </Label>
                <Input
                  id="case_number"
                  placeholder="1033-25 או 1000-04-26"
                  {...form.register("case_number")}
                  className="mt-1 tabular-nums"
                />
                <FieldError message={form.formState.errors.case_number?.message} />
              </div>
              <div>
                <Label htmlFor="title" className="text-navy">
                  כותרת <span className="text-danger">*</span>
                </Label>
                <Input id="title" {...form.register("title")} className="mt-1" />
                <FieldError message={form.formState.errors.title?.message} />
              </div>
              <div className="grid grid-cols-2 gap-3">
                <div>
                  <Label className="text-navy">תחום משפטי</Label>
                  <Controller
                    control={form.control}
                    name="practice_area"
                    render={({ field }) => (
                      <Select value={field.value} onValueChange={field.onChange} dir="rtl">
                        <SelectTrigger className="mt-1">
                          <SelectValue />
                        </SelectTrigger>
                        <SelectContent>
                          {PRACTICE_AREAS.map((p) => (
                            <SelectItem
                              key={p.value}
                              value={p.value}
                              disabled={!p.enabled}
                            >
                              {p.label}{!p.enabled && " (בקרוב)"}
                            </SelectItem>
                          ))}
                        </SelectContent>
                      </Select>
                    )}
                  />
                </div>
                <div>
                  <Label className="text-navy">סוג ערר</Label>
                  <Controller
                    control={form.control}
                    name="appeal_subtype"
                    render={({ field }) => (
                      <Select
                        value={field.value}
                        onValueChange={(v) => {
                          userTouchedSubtype.current = true;
                          field.onChange(v as AppealSubtype);
                        }}
                        dir="rtl"
                      >
                        <SelectTrigger className="mt-1">
                          <SelectValue />
                        </SelectTrigger>
                        <SelectContent>
                          {APPEAL_SUBTYPES.map((s) => (
                            <SelectItem key={s.value} value={s.value}>
                              {s.label}
                            </SelectItem>
                          ))}
                        </SelectContent>
                      </Select>
                    )}
                  />
                  <p className="text-[0.7rem] text-ink-muted mt-1">
                    מזוהה אוטומטית ממספר התיק
                  </p>
                </div>
              </div>
            </div>
          )}

          {step === "parties" && (
            <div className="space-y-5">
              <Controller
                control={form.control}
                name="appellants"
                render={({ field, fieldState }) => (
                  <PartiesField
                    label="עוררים *"
                    value={field.value}
                    onChange={field.onChange}
                    error={fieldState.error?.message}
                  />
                )}
              />
              <div className="h-px bg-rule" />
              <Controller
                control={form.control}
                name="respondents"
                render={({ field, fieldState }) => (
                  <PartiesField
                    label="משיבים *"
                    value={field.value}
                    onChange={field.onChange}
                    error={fieldState.error?.message}
                  />
                )}
              />
            </div>
          )}

          {step === "details" && (
            <div className="space-y-4">
              <div>
                <Label htmlFor="subject" className="text-navy">נושא</Label>
                <Input id="subject" {...form.register("subject")} className="mt-1" />
              </div>
              <div className="grid grid-cols-2 gap-3">
                <div>
                  <Label htmlFor="property_address" className="text-navy">כתובת הנכס</Label>
                  <Input id="property_address" {...form.register("property_address")} className="mt-1" />
                </div>
                <div>
                  <Label htmlFor="permit_number" className="text-navy">מס׳ תכנית/בקשה</Label>
                  <Input id="permit_number" {...form.register("permit_number")} className="mt-1" />
                </div>
              </div>
              <div className="grid grid-cols-2 gap-3">
                <div>
                  <Label htmlFor="hearing_date" className="text-navy">תאריך דיון</Label>
                  <Input
                    id="hearing_date"
                    type="date"
                    {...form.register("hearing_date")}
                    className="mt-1 tabular-nums"
                  />
                  <FieldError message={form.formState.errors.hearing_date?.message} />
                </div>
                <div>
                  <Label className="text-navy">תוצאה צפויה</Label>
                  <Controller
                    control={form.control}
                    name="expected_outcome"
                    render={({ field }) => (
                      <Select
                        value={field.value || "__none__"}
                        onValueChange={(v) => field.onChange(v === "__none__" ? "" : v)}
                        dir="rtl"
                      >
                        <SelectTrigger className="mt-1">
                          <SelectValue />
                        </SelectTrigger>
                        <SelectContent>
                          {expectedOutcomes.map((o) => (
                            <SelectItem key={o.value || "none"} value={o.value || "__none__"}>
                              {o.label}
                            </SelectItem>
                          ))}
                        </SelectContent>
                      </Select>
                    )}
                  />
                </div>
              </div>
              <div>
                <Label htmlFor="notes" className="text-navy">הערות</Label>
                <Textarea id="notes" rows={4} {...form.register("notes")} className="mt-1" />
              </div>
            </div>
          )}

          <div className="flex items-center justify-between gap-3 pt-2">
            <Button
              type="button"
              variant="ghost"
              onClick={goBack}
              disabled={stepIndex === 0 || mutate.isPending}
            >
              ← הקודם
            </Button>
            {isLast ? (
              <Button
                key="submit-btn"
                type="submit"
                disabled={mutate.isPending}
                className="bg-navy hover:bg-navy-soft text-parchment"
              >
                {mutate.isPending ? "יוצר תיק…" : "צור תיק"}
              </Button>
            ) : (
              <Button
                key="next-btn"
                type="button"
                onClick={goNext}
                className="bg-navy hover:bg-navy-soft text-parchment"
              >
                הבא →
              </Button>
            )}
          </div>
        </form>
      </CardContent>
    </Card>
  );
}