import { useCallback, useRef } from "react";
import { Box, Button, Chip, Paper, Stack, Typography } from "@mui/material";
import { useNavigate } from "react-router-dom";
import { api } from "../api";
import { useViewResource } from "../hooks/useViewResource";
import { useI18n } from "../i18n/I18nProvider";
import ViewStateNotice from "../components/ViewStateNotice";
import { PageHeader } from "../layout/PageLayout";
import type { JobApplication } from "../types";

type PagedJobs = { items: JobApplication[]; total: number; page: number; pageSize: number };

export default function OfferComparisonPage() {
  const navigate = useNavigate();
  const { language, t } = useI18n();
  const load = useCallback(() => api.get<PagedJobs>("/jobapplications", { params: { status: "Offer", page: 1, pageSize: 25, sortBy: "dateApplied", sortDir: "asc" } }).then((r) => r.data), []);
  const resource = useViewResource(load, { initialData: { items: [], total: 0, page: 1, pageSize: 25 }, errorMessage: "" });
  const resultsRef = useRef<HTMLDivElement>(null);
  const retryPending = useRef(false);
  const loading = resource.loading || resource.refreshing;
  const locale = language === "nb" ? "nb-NO" : "en";
  const date = (value?: string | null) => value ? new Date(value).toLocaleDateString(locale) : "—";
  const periods = new Map([["year", t("salaryPeriodYear")], ["month", t("salaryPeriodMonth")], ["hour", t("salaryPeriodHour")]]);

  return (
    <Stack spacing={2} sx={{ minWidth: 0 }}>
      <PageHeader level="h2" title={t("offerComparisonTitle")} description={t("offerComparisonHelp")}
        actions={!loading && !resource.error && resource.data.items.length > 0 ? <Button variant="outlined" onClick={() => navigate("/jobs?status=Offer&sortBy=dateApplied&sortDir=asc")}>{t("offerComparisonAllOffers")}</Button> : null} />
      <Box ref={resultsRef} role="region" aria-label={t("offerComparisonTitle")} tabIndex={-1} aria-busy={loading} sx={{ minWidth: 0 }}>
      <ViewStateNotice compact loading={loading} title={t("offerComparisonLoadFailed")}
        error={resource.error ? { ...resource.error, message: resource.error.message || t("offerComparisonLoadFailed") } : null}
        onRetry={() => {
          if (loading || retryPending.current) return;
          retryPending.current = true;
          resultsRef.current?.focus();
          void resource.reload().finally(() => { retryPending.current = false; });
        }} />
      {!loading && !resource.error && resource.data.items.length === 0 ? (
        <Paper variant="outlined" sx={{ p: "var(--app-card-padding)", textAlign: "center" }}>
          <Typography component="h3" variant="sectionTitle">{t("offerComparisonEmpty")}</Typography>
          <Typography color="text.secondary" sx={{ mt: 0.5, mb: 2 }}>{t("offerComparisonEmptyHelp")}</Typography>
          <Button variant="contained" onClick={() => navigate("/jobs")}>{t("jobApplications")}</Button>
        </Paper>
      ) : null}
      {!loading && !resource.error && resource.data.items.length > 0 ? <Box sx={{ mb: 2 }}>
        <Typography variant="body2">{t("offerComparisonSampleCount", { shown: resource.data.items.length, total: resource.data.total })}</Typography>
        {resource.data.total > resource.data.items.length ? <Typography variant="body2" color="text.secondary" sx={{ mt: 0.5, overflowWrap: "anywhere" }}>{t("offerComparisonSampleHelp")}</Typography> : null}
      </Box> : null}
      <Box sx={{ display: "grid", gridTemplateColumns: { xs: "1fr", md: "repeat(2, minmax(0, 1fr))", xl: "repeat(3, minmax(0, 1fr))" }, gap: 2 }}>
        {resource.data.items.map((offer) => (
          <Paper key={offer.id} component="article" aria-label={offer.jobTitle} variant="outlined" sx={{ p: "var(--app-card-padding)", display: "flex", flexDirection: "column", minWidth: 0 }}>
            <Stack direction="row" justifyContent="space-between" spacing={1} alignItems="flex-start">
              <Box sx={{ minWidth: 0 }}><Typography component="h3" variant="sectionTitle" sx={{ overflowWrap: "anywhere" }}>{offer.jobTitle}</Typography><Typography color="text.secondary" sx={{ overflowWrap: "anywhere" }}>{offer.company?.name}</Typography></Box>
              <Chip size="small" color="success" label={t("statusOffer")} sx={{ flexShrink: 0 }} />
            </Stack>
            <Stack spacing={1.25} sx={{ my: 2 }}>
              <Fact label={t("offerComparisonCompensation")} value={formatSalary(offer, t("offerComparisonNotRecorded"), locale, periods)} />
              <Fact label={t("companiesLocation")} value={offer.location || t("offerComparisonNotRecorded")} />
              <Fact label={t("jobTableDateApplied")} value={date(offer.dateApplied)} />
              <Fact label={t("offerComparisonDecisionDeadline")} value={date(offer.deadline)} />
              <Fact label={t("companiesNextContact")} value={date(offer.followUpAt)} />
              <Fact label={t("workspaceNextAction")} value={offer.nextAction || t("offerComparisonNotRecorded")} />
              <Fact label={t("offerComparisonNotes")} value={offer.notes || t("offerComparisonNotRecorded")} multiline />
            </Stack>
            <Button variant="outlined" sx={{ mt: "auto", alignSelf: "flex-start", maxWidth: "100%", whiteSpace: "normal", overflowWrap: "anywhere" }} onClick={() => navigate(`/jobs/${offer.id}`)}>{t("workspaceOpenFull")}</Button>
          </Paper>
        ))}
      </Box>
      </Box>
    </Stack>
  );
}

function Fact({ label, value, multiline = false }: { label: string; value: string; multiline?: boolean }) {
  return <Box><Typography variant="overline" color="text.secondary">{label}</Typography><Typography variant="body2" sx={{ whiteSpace: multiline ? "pre-wrap" : "normal", overflowWrap: "anywhere" }}>{value}</Typography></Box>;
}

function formatSalary(job: JobApplication, fallback: string, locale: string, periods: Map<string, string>) {
  if (job.salaryMin != null || job.salaryMax != null) {
    const range = [job.salaryMin, job.salaryMax].filter((value) => value != null).map((value) => Number(value).toLocaleString(locale)).join(" – ");
    const period = job.salaryPeriod ? periods.get(job.salaryPeriod.toLowerCase()) ?? job.salaryPeriod : null;
    return `${range} ${job.salaryCurrency || ""}${period ? ` / ${period}` : ""}`.trim();
  }
  return job.salary || fallback;
}