"use client";

import type { Ajuda, Anexo, Pergunta, Resposta } from "@prisma/client";
import { useEffect, useRef, useState, useTransition } from "react";
import { useRouter } from "next/navigation";
import { FormProvider, useForm } from "react-hook-form";
import { PerguntaField } from "@/components/form/PerguntaField";
import { Button } from "@/components/ui/button";
import { salvarRespostas } from "./actions";

type PerguntaComDados = Pergunta & {
  ajuda: Ajuda | null;
  anexos?: Anexo[];
  respostas: Resposta[];
};

type Props = {
  briefingId: string;
  secaoId: string;
  perguntas: PerguntaComDados[];
  readOnly?: boolean;
};

type FormValues = {
  perguntas: Record<
    string,
    {
      texto?: string;
      selecionadas?: string[];
      complemento?: string;
    }
  >;
};

function getDefaultValues(perguntas: PerguntaComDados[]): FormValues {
  return {
    perguntas: perguntas.reduce<FormValues["perguntas"]>((acc, pergunta) => {
      const resposta = pergunta.respostas[0];
      const selecionadas = Array.isArray(resposta?.selecionadas)
        ? resposta.selecionadas.filter((item): item is string => typeof item === "string")
        : [];

      acc[pergunta.id] = {
        texto: resposta?.texto ?? "",
        selecionadas,
        complemento: resposta?.complemento ?? ""
      };

      return acc;
    }, {})
  };
}

type SaveStatus = "idle" | "dirty" | "saving" | "saved" | "error";

function formatTime(value: string) {
  return new Intl.DateTimeFormat("pt-BR", {
    hour: "2-digit",
    minute: "2-digit"
  }).format(new Date(value));
}

export function SecaoForm({ briefingId, secaoId, perguntas, readOnly = false }: Props) {
  const [status, setStatus] = useState<SaveStatus>("idle");
  const [savedAt, setSavedAt] = useState<string | null>(null);
  const [message, setMessage] = useState<string | null>(null);
  const [, startTransition] = useTransition();
  const debounceRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const router = useRouter();
  const form = useForm<FormValues>({
    defaultValues: getDefaultValues(perguntas)
  });
  const watchedValues = form.watch();

  async function saveNow(values: FormValues) {
    if (readOnly) {
      return true;
    }

    setStatus("saving");
    setMessage(null);

    const result = await salvarRespostas(briefingId, secaoId, values);

    startTransition(() => {
      if (!result.ok) {
        setStatus("error");
        setMessage(result.message ?? "Erro ao salvar. Tente novamente.");
        return;
      }

      form.reset(values);
      setStatus("saved");
      setSavedAt(result.savedAt ?? new Date().toISOString());
    });

    return result.ok;
  }

  useEffect(() => {
    if (readOnly || !form.formState.isDirty) {
      return;
    }

    setStatus("dirty");

    if (debounceRef.current) {
      clearTimeout(debounceRef.current);
    }

    debounceRef.current = setTimeout(() => {
      void saveNow(form.getValues());
    }, 800);

    return () => {
      if (debounceRef.current) {
        clearTimeout(debounceRef.current);
      }
    };
  }, [watchedValues, form, readOnly]);

  useEffect(() => {
    function handleBeforeUnload(event: BeforeUnloadEvent) {
      if (form.formState.isDirty && status !== "saved") {
        event.preventDefault();
      }
    }

    window.addEventListener("beforeunload", handleBeforeUnload);
    return () => window.removeEventListener("beforeunload", handleBeforeUnload);
  }, [form.formState.isDirty, status]);

  useEffect(() => {
    async function handleClick(event: MouseEvent) {
      const link = (event.target as HTMLElement).closest("a");

      if (!link || readOnly || !form.formState.isDirty) {
        return;
      }

      const href = link.getAttribute("href");

      if (!href || !href.startsWith(`/briefings/${briefingId}`)) {
        return;
      }

      event.preventDefault();

      if (debounceRef.current) {
        clearTimeout(debounceRef.current);
      }

      const saved = await saveNow(form.getValues());

      if (saved) {
        router.push(href);
      }
    }

    document.addEventListener("click", handleClick);
    return () => document.removeEventListener("click", handleClick);
  }, [briefingId, form, readOnly, router]);

  return (
    <FormProvider {...form}>
      <form className="space-y-4">
        <div className="sticky top-0 z-20 rounded-lg border bg-card p-3 text-sm shadow-sm">
          {readOnly ? (
            <span className="text-muted-foreground">Briefing enviado. Respostas em modo leitura.</span>
          ) : status === "saving" ? (
            <span className="text-muted-foreground">Salvando...</span>
          ) : status === "saved" && savedAt ? (
            <span className="text-muted-foreground">Salvo as {formatTime(savedAt)}</span>
          ) : status === "error" ? (
            <span className="text-destructive">{message ?? "Erro ao salvar — tentar de novo"}</span>
          ) : status === "dirty" ? (
            <span className="text-muted-foreground">Alteracoes pendentes...</span>
          ) : (
            <span className="text-muted-foreground">Rascunho pronto para edicao.</span>
          )}
        </div>
        {perguntas.map((pergunta, index) => (
          <fieldset key={pergunta.id} disabled={readOnly} className="disabled:opacity-75">
            <PerguntaField
              briefingId={briefingId}
              pergunta={pergunta}
              index={index}
              readOnly={readOnly}
            />
          </fieldset>
        ))}
        {!readOnly ? (
          <div className="flex flex-col gap-3 sm:flex-row">
            <Button type="button" variant="outline" onClick={() => form.reset()}>
              Descartar alteracoes locais
            </Button>
            <Button type="button" onClick={() => saveNow(form.getValues())}>
              Salvar agora
            </Button>
          </div>
        ) : null}
      </form>
    </FormProvider>
  );
}