import React, { useEffect, useRef, useState } from "react";
import { useNavigate } from "react-router-dom";

import { Alert, Box, Button, IconButton, LinearProgress, Typography } from "@mui/material";
import CheckCircleIcon from "@mui/icons-material/CheckCircle";
import CloseIcon from "@mui/icons-material/Close";
import RadioButtonUncheckedIcon from "@mui/icons-material/RadioButtonUnchecked";

import { api, getApiErrorMessage } from "../api";
import { useI18n } from "../i18n/I18nProvider";
import { getUserKeyFromToken } from "../themePrefs";
import { PageSection } from "../layout/PageLayout";

type MeResponse = {
  email?: string | null;
  firstName?: string | null;
  lastName?: string | null;
  displayName?: string | null;
};
type CareerProfileResponse = {
  cvText?: string | null;
  profile?: {
    summary?: string[];
    jobs?: unknown[];
    education?: unknown[];
    projects?: unknown[];
    certifications?: unknown[];
    languages?: unknown[];
    otherSections?: unknown[];
    skills?: string[];
    interests?: string[];
  };
};
type ConnectionStatus = { connected?: boolean };

export default function OnboardingChecklist({ hasJobs }: { hasJobs: boolean | null }) {
  const navigate = useNavigate();
  const { t } = useI18n();
  // The session boundary disposes this owner before another account is adopted.
  const [dismissalKey] = useState(() => `onboardingDismissed:${getUserKeyFromToken()}`);
  const [dismissed, setDismissed] = useState(() => {
    try { return window.localStorage.getItem(dismissalKey) === "true"; }
    catch { return false; }
  });
  const [status, setStatus] = useState<{ profile: boolean; cv: boolean; email: boolean } | null>(null);
  const [loading, setLoading] = useState(true);
  const [loadError, setLoadError] = useState<{ cause: unknown } | null>(null);
  const [readAttempt, setReadAttempt] = useState(0);
  const dismissRef = useRef<HTMLButtonElement>(null);

  useEffect(() => {
    if (dismissed) return;
    let active = true;
    setLoading(true);
    setLoadError(null);
    setStatus(null);
    Promise.all([
      api.get<MeResponse>("/auth/me"),
      api.get<CareerProfileResponse>("/career/profile"),
      Promise.all(["/gmail/status", "/microsoft-graph/status", "/imap/status"].map((url) =>
        api.get<ConnectionStatus>(url).then((r) => Boolean(r.data?.connected)),
      )),
    ]).then(([me, career, connections]) => {
      if (!active) return;
      const profile = career.data?.profile;
      const structuredCount = [
        ...(profile?.summary ?? []),
        ...(profile?.jobs ?? []),
        ...(profile?.education ?? []),
        ...(profile?.projects ?? []),
        ...(profile?.certifications ?? []),
        ...(profile?.languages ?? []),
        ...(profile?.otherSections ?? []),
        ...(profile?.skills ?? []),
        ...(profile?.interests ?? []),
      ].length;
      setStatus({
        profile: Boolean(me.data?.displayName?.trim() || me.data?.firstName?.trim() || me.data?.lastName?.trim()),
        cv: structuredCount > 0 || Boolean(career.data?.cvText?.trim()),
        email: connections.some(Boolean),
      });
    }).catch((cause: unknown) => {
      if (active) setLoadError({ cause });
    }).finally(() => {
      if (active) setLoading(false);
    });
    return () => { active = false; };
  }, [dismissed, readAttempt]);

  if (dismissed) return null;

  // These four recorded steps are guidance, not a completeness score or proof of
  // verified email, an imported CV, a rendered PDF, or a live mailbox grant.
  const steps = [
    { done: status?.profile ?? null, label: t("onboardingStepProfile"), path: "/profile", actionLabel: t("onboardingStepProfileAction") },
    { done: status?.cv ?? null, label: t("onboardingStepCv"), path: "/career", actionLabel: t("onboardingStepCvAction") },
    { done: status?.email ?? null, label: t("onboardingStepEmail"), path: "/settings/connected-accounts", actionLabel: t("onboardingStepEmailAction") },
    { done: hasJobs, label: t("onboardingStepJob"), path: "/jobs", actionLabel: t("onboardingStepJobAction") },
  ];
  const completed = steps.filter((step) => step.done === true).length;
  if (status && hasJobs !== null && completed === steps.length) return null;

  return (
    <PageSection surface title={t("onboardingTitle")} description={t("onboardingBody")} actions={
        <IconButton
          ref={dismissRef}
          size="small"
          aria-label={t("onboardingDismiss")}
          onClick={() => {
            try { window.localStorage.setItem(dismissalKey, "true"); }
            catch { /* This dismissal still applies while the page remains open. */ }
            setDismissed(true);
          }}
        >
          <CloseIcon fontSize="small" />
        </IconButton>
    }>
      {loading ? <>
        <Typography role="status" variant="body2" color="text.secondary">{t("loading")}</Typography>
        <LinearProgress aria-label={t("loading")} sx={{ mt: 1.5 }} />
      </> : loadError ? (
        <Alert severity="error" sx={{ overflowWrap: "anywhere" }} action={
          <Button color="inherit" onClick={() => {
            // Retry is replaced by loading feedback; keep focus inside this setup section.
            dismissRef.current?.focus();
            setReadAttempt((attempt) => attempt + 1);
          }}>{t("retry")}</Button>
        }>{getApiErrorMessage(loadError.cause, t("onboardingLoadFailed"))}</Alert>
      ) : status ? <>
      {hasJobs === null ? (
        <Typography role="status" variant="body2" color="text.secondary">{t("onboardingJobStatusUnknown")}</Typography>
      ) : <Typography variant="caption" color="text.secondary">{completed} / {steps.length}</Typography>}
      <LinearProgress
        variant={hasJobs === null ? "indeterminate" : "determinate"}
        value={hasJobs === null ? undefined : (completed / steps.length) * 100}
        aria-label={hasJobs === null ? t("onboardingJobStatusUnknown") : t("checklistProgress", { completed, total: steps.length })}
        sx={{ my: 1.5 }}
      />
      <Box component="ul" sx={{ display: "grid", gap: 1, listStyle: "none", m: 0, p: 0, minWidth: 0 }}>
        {steps.map((step) => (
          <Box component="li" key={step.path} sx={{ display: "flex", alignItems: "center", justifyContent: "space-between", gap: 1.5, flexWrap: "wrap", minWidth: 0 }}>
            <Box sx={{ display: "flex", alignItems: "center", gap: 1, minWidth: 0, flex: "1 1 12rem" }}>
              {step.done === null ? null : step.done ? <CheckCircleIcon fontSize="small" color="success" titleAccess={t("checklistProgress", { completed: 1, total: 1 })} sx={{ flexShrink: 0 }} /> : <RadioButtonUncheckedIcon fontSize="small" titleAccess={t("checklistProgress", { completed: 0, total: 1 })} sx={{ color: "text.secondary", flexShrink: 0 }} />}
              <Typography variant="body2" sx={{ fontWeight: step.done ? 400 : 700, color: step.done ? "text.secondary" : "text.primary", textDecoration: step.done ? "line-through" : "none", overflowWrap: "anywhere" }}>
                {step.label}
              </Typography>
            </Box>
            {step.done === false ? <Button size="small" variant="text" sx={{ maxWidth: "100%", whiteSpace: "normal", overflowWrap: "anywhere" }} onClick={() => navigate(step.path)}>{step.actionLabel}</Button> : null}
          </Box>
        ))}
      </Box>
      </> : null}
    </PageSection>
  );
}