import React, { useEffect, useMemo, useRef, useState } from "react";

import {
  Box,
  Alert,
  Button,
  Dialog,
  DialogContent,
  List,
  ListItem,
  ListItemButton,
  ListItemText,
  TextField,
  Typography,
} from "@mui/material";

import SearchIcon from "@mui/icons-material/Search";

import { api } from "../api";
import { useI18n } from "../i18n/I18nProvider";

type CommandItem = {
  id: string;
  label: string;
  hint?: string;
  action: () => void;
};

type JobSearchItem = {
  id: number;
  jobTitle: string;
  company: { name: string };
};

type CompanySearchItem = {
  id: number;
  name: string;
};

interface Props {
  open: boolean;
  onClose: () => void;
  onNavigate: (to: string) => void;
  onOpenAddJob: () => void;
}

export default function QuickCommandDialog({ open, onClose, onNavigate, onOpenAddJob }: Props) {
  const { t } = useI18n();
  const [query, setQuery] = useState("");
  const [jobs, setJobs] = useState<JobSearchItem[]>([]);
  const [companies, setCompanies] = useState<CompanySearchItem[]>([]);
  const [searchState, setSearchState] = useState<"idle" | "loading" | "ready" | "error">("idle");
  const [searchAttempt, setSearchAttempt] = useState(0);
  const [activeIndex, setActiveIndex] = useState(-1);
  const searchInputRef = useRef<HTMLInputElement>(null);
  const resultRefs = useRef<Array<HTMLElement | null>>([]);

  useEffect(() => {
    if (!open) {
      setQuery("");
      setJobs([]);
      setCompanies([]);
      setSearchState("idle");
      setActiveIndex(-1);
      return;
    }
  }, [open]);

  useEffect(() => {
    if (!open) return;
    const q = query.trim();
    if (!q) {
      setJobs([]);
      setCompanies([]);
      setSearchState("idle");
      return;
    }
    const controller = new AbortController();
    setJobs([]);
    setCompanies([]);
    setSearchState("loading");
    const timeout = window.setTimeout(() => {
      Promise.all([
        api.get<{ items: JobSearchItem[] }>("/jobapplications", { params: { q, page: 1, pageSize: 15 }, signal: controller.signal }),
        api.get<CompanySearchItem[]>("/companies", { signal: controller.signal }),
      ])
        .then(([jobResponse, companyResponse]) => {
          if (controller.signal.aborted) return;
          setJobs(jobResponse.data?.items ?? []);
          setCompanies((companyResponse.data ?? []).filter((c) => c.name.toLowerCase().includes(q.toLowerCase())).slice(0, 8));
          setSearchState("ready");
        })
        .catch(() => { if (!controller.signal.aborted) setSearchState("error"); });
    }, 250);
    return () => { window.clearTimeout(timeout); controller.abort(); };
  }, [open, query, searchAttempt]);

  const commands = useMemo<CommandItem[]>(() => {
    const base: CommandItem[] = [
      { id: "go-dashboard", label: t("goToDashboard"), hint: t("analyticsOverview"), action: () => onNavigate("/dashboard") },
      { id: "go-jobs", label: t("goToJobs"), hint: t("mainApplicationsTable"), action: () => onNavigate("/jobs") },
      { id: "go-reminders", label: t("goToReminders"), hint: t("followUpQueue"), action: () => onNavigate("/reminders") },
      { id: "go-companies", label: t("goToCompanies"), hint: t("crmAndSourceTracking"), action: () => onNavigate("/companies") },
      { id: "go-settings", label: t("goToSettings"), hint: t("preferencesAndAdminTools"), action: () => onNavigate("/settings") },
      { id: "add-job", label: t("addNewJob"), hint: t("openAddJobModal"), action: onOpenAddJob },
    ];

    const q = query.trim().toLowerCase();
    if (!q) return base;
    return base.filter((item) => item.label.toLowerCase().includes(q) || item.hint?.toLowerCase().includes(q));
  }, [onNavigate, onOpenAddJob, query, t]);

  const jobItems: CommandItem[] = jobs.slice(0, 6).map((job) => ({
      id: `job-${job.id}`,
      label: `${job.company?.name ?? t("company")} - ${job.jobTitle}`,
      hint: t("openJobListAndSearchResult"),
      action: () => onNavigate(`/jobs/${job.id}`),
    }));
  const companyItems: CommandItem[] = companies.slice(0, 6).map((company) => ({
      id: `company-${company.id}`,
      label: company.name,
      hint: t("openCompanies"),
      action: () => onNavigate(`/companies?edit=${company.id}`),
    }));
  const groups = [
    { label: t("commandActions"), items: commands },
    { label: t("commandJobs"), items: jobItems },
    { label: t("commandCompanies"), items: companyItems },
  ];
  const allItems = groups.flatMap((group) => group.items);
  const activate = (item: CommandItem) => { item.action(); onClose(); };
  const onKeys = (event: React.KeyboardEvent) => {
    if (event.nativeEvent.isComposing || event.keyCode === 229 || !allItems.length) return;
    if (["ArrowDown", "ArrowUp", "Home", "End"].includes(event.key)) {
      event.preventDefault();
      const current = event.target === searchInputRef.current ? activeIndex : resultRefs.current.indexOf(event.target as HTMLElement);
      const next = event.key === "Home" ? 0 : event.key === "End" ? allItems.length - 1
        : event.key === "ArrowDown" ? (current + 1) % allItems.length
          : (current < 0 ? allItems.length - 1 : (current - 1 + allItems.length) % allItems.length);
      setActiveIndex(next);
      if (event.target !== searchInputRef.current) resultRefs.current[next]?.focus();
    } else if (event.key === "Enter" && event.target === searchInputRef.current) {
      event.preventDefault();
      activate(allItems[activeIndex < 0 ? 0 : activeIndex]);
    }
  };

  return (
    <Dialog open={open} onClose={onClose} slotProps={{ paper: { "aria-label": t("quickSearch") }, transition: { onEntered: () => searchInputRef.current?.focus() } }} fullWidth maxWidth="sm">
      <DialogContent onKeyDown={onKeys} sx={{ p: 1.5, maxHeight: "min(70vh, 620px)" }}>
        <Box sx={{ display: "flex", alignItems: "center", gap: 1, px: 1, pt: 0.5 }}>
          <SearchIcon fontSize="small" />
          <TextField
            autoFocus
            inputRef={searchInputRef}
            variant="standard"
            fullWidth
            placeholder={t("searchPlaceholder")}
            slotProps={{ htmlInput: { "aria-label": t("quickSearch") } }}
            value={query}
            onChange={(e) => { setQuery(e.target.value); setActiveIndex(-1); }}
            InputProps={{ disableUnderline: true }}
          />
          <Typography variant="caption" sx={{ color: "text.secondary", whiteSpace: "nowrap" }}>
            Ctrl/Cmd + K
          </Typography>
        </Box>

        <Box aria-live="polite" sx={{ position: "absolute", width: 1, height: 1, overflow: "hidden", clipPath: "inset(50%)" }}>
          {searchState === "loading" ? t("loading") : searchState === "ready" ? t("searchResultsCount", { count: allItems.length }) : ""}
          {activeIndex >= 0 ? ` ${allItems[activeIndex]?.label ?? ""}` : ""}
        </Box>
        {searchState === "error" ? <Alert severity="error" sx={{ mt: 1 }} action={<Button color="inherit" size="small" onClick={() => setSearchAttempt((value) => value + 1)}>{t("retry")}</Button>}>{t("searchLoadFailed")}</Alert> : null}
        {groups.map((group) => group.items.length ? <Box component="section" key={group.label} sx={{ mt: 1 }}>
          <Typography component="h2" variant="caption" color="text.secondary" sx={{ px: 2, fontWeight: 700 }}>{group.label}</Typography>
          <List dense aria-label={group.label}>
            {group.items.map((item) => <ListItem key={item.id} disablePadding>
              <ListItemButton ref={(node) => { resultRefs.current[allItems.indexOf(item)] = node; }} selected={activeIndex === allItems.indexOf(item)} onFocus={() => setActiveIndex(allItems.indexOf(item))} onClick={() => activate(item)} sx={{ borderRadius: 2 }}>
                <ListItemText primary={item.label} secondary={item.hint} />
              </ListItemButton>
            </ListItem>)}
          </List>
        </Box> : null)}
        {allItems.length === 0 && searchState !== "loading" && searchState !== "error" ? <Typography color="text.secondary" sx={{ px: 2, py: 3 }}>{t("noMatchingCommands")}</Typography> : null}
      </DialogContent>
    </Dialog>
  );
}