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

import {
  Box,
  Card,
  CardContent,
  Chip,
  IconButton,
  Menu,
  MenuItem,
  Paper,
  Typography,
} from "@mui/material";
import { alpha, useTheme } from "@mui/material/styles";
import MoreHorizIcon from "@mui/icons-material/MoreHoriz";

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

const STATUSES = ["Applied", "Waiting", "Interview", "Offer", "Rejected", "Ghosted"] as const;
type Status = (typeof STATUSES)[number];

function normalizeStatus(status: string): Status | "Other" {
  if (status === "Interviewing") return "Interview";
  if ((STATUSES as readonly string[]).includes(status)) return status as Status;
  return "Other";
}

function toneColor(theme: any, status: Status | "Other"): string {
  if (status === "Rejected") return theme.palette.error.main;
  if (status === "Waiting" || status === "Ghosted") return theme.palette.warning.main;
  if (status === "Offer") return theme.palette.success.main;
  if (status === "Interview") return alpha(theme.palette.primary.main, 0.95);
  return theme.palette.primary.main;
}

export default function KanbanBoard() {
  const theme = useTheme();
  const { t } = useI18n();
  const [jobs, setJobs] = useState<JobApplication[]>([]);
  const [dragJobId, setDragJobId] = useState<number | null>(null);
  const [menuAnchor, setMenuAnchor] = useState<null | HTMLElement>(null);
  const [menuJobId, setMenuJobId] = useState<number | null>(null);

  useEffect(() => {
    api.get<JobApplication[]>("/jobapplications/board").then((r) => setJobs(r.data));
  }, []);

  const groups = useMemo(() => {
    const map = new Map<string, JobApplication[]>();
    STATUSES.forEach((s) => map.set(s, []));
    map.set("Other", []);
    for (const j of jobs) {
      const key = normalizeStatus(j.status);
      map.get(key)!.push(j);
    }
    map.forEach((arr, k) => {
      arr.sort((a, b) => +new Date(b.dateApplied) - +new Date(a.dateApplied));
      map.set(k, arr);
    });
    return map;
  }, [jobs]);

  const onDropTo = async (status: Status) => {
    if (!dragJobId) return;
    setDragJobId(null);
    await api.patch(`/jobapplications/${dragJobId}/status`, { status });
    setJobs((prev) => prev.map((j) => (j.id === dragJobId ? { ...j, status } : j)));
  };

  const setStatus = async (id: number, status: Status) => {
    await api.patch(`/jobapplications/${id}/status`, { status });
    setJobs((prev) => prev.map((j) => (j.id === id ? { ...j, status } : j)));
  };

  const currentMenuStatus = menuJobId == null ? null : normalizeStatus(jobs.find((j) => j.id === menuJobId)?.status ?? "");

  return (
    <Box sx={{ mt: 2 }}>
      <Typography variant="body2" sx={{ color: "text.secondary", mb: 1 }}>
        Drag cards between columns to update status.
      </Typography>

      <Box sx={{ display: "grid", gridTemplateColumns: { xs: "1fr", md: "repeat(3, 1fr)", xl: "repeat(6, 1fr)" }, gap: 2, alignItems: "start" }}>
        {STATUSES.map((status) => {
          const c = toneColor(theme, status);
          const list = groups.get(status) ?? [];
          return (
            <Paper
              key={status}
              onDragOver={(e) => e.preventDefault()}
              onDrop={() => void onDropTo(status)}
              sx={{
                p: 1.5,
                borderRadius: 3,
                minHeight: 220,
                border: `1px solid ${alpha(c, theme.palette.mode === "dark" ? 0.25 : 0.18)}`,
                background: alpha(c, theme.palette.mode === "dark" ? 0.10 : 0.06),
              }}
            >
              <Box sx={{ display: "flex", justifyContent: "space-between", alignItems: "center", mb: 1 }}>
                <Typography variant="subtitle1" sx={{ fontWeight: 800, color: theme.palette.mode === "dark" ? "#f8fafc" : "inherit" }}>
                  {status}
                </Typography>
                <Chip
                  size="small"
                  label={list.length}
                  sx={{
                    fontWeight: 800,
                    color: alpha(c, theme.palette.mode === "dark" ? 0.95 : 0.9),
                    backgroundColor: alpha(c, theme.palette.mode === "dark" ? 0.18 : 0.12),
                    border: `1px solid ${alpha(c, theme.palette.mode === "dark" ? 0.35 : 0.22)}`,
                  }}
                />
              </Box>

              <Box sx={{ display: "flex", flexDirection: "column", gap: 1 }}>
                {list.map((j) => (
                  <Card
                    key={j.id}
                    draggable
                    onDragStart={() => setDragJobId(j.id)}
                    onDragEnd={() => setDragJobId(null)}
                    sx={{
                      cursor: "grab",
                      borderRadius: 3,
                      border: `1px solid ${alpha(c, theme.palette.mode === "dark" ? 0.22 : 0.14)}`,
                      background: theme.palette.mode === "dark" ? "rgba(15,23,42,0.82)" : "rgba(255,255,255,0.96)",
                      backdropFilter: "blur(8px)",
                      color: theme.palette.mode === "dark" ? "#e5eefc" : "#0f172a",
                    }}
                  >
                    <CardContent sx={{ p: 1.25, "&:last-child": { pb: 1.25 } }}>
                      <Box sx={{ display: "flex", justifyContent: "space-between", gap: 1 }}>
                        <Typography sx={{ fontWeight: 800, lineHeight: 1.25, color: theme.palette.mode === "dark" ? "#f8fafc" : "#0f172a" }}>
                          {j.company?.name ?? ""}
                        </Typography>
                        <IconButton
                          size="small"
                          sx={{ color: theme.palette.mode === "dark" ? "#e2e8f0" : "#0f172a" }}
                          onClick={(e) => {
                            e.stopPropagation();
                            setMenuJobId(j.id);
                            setMenuAnchor(e.currentTarget);
                          }}
                        >
                          <MoreHorizIcon fontSize="small" />
                        </IconButton>
                      </Box>
                      <Typography variant="body2" sx={{ color: theme.palette.mode === "dark" ? "#cbd5e1" : "#475569" }}>
                        {j.jobTitle}
                      </Typography>
                      <Box sx={{ display: "flex", gap: 1, mt: 1, flexWrap: "wrap" }}>
                        <Chip size="small" label={`${j.daysSince}d`} sx={{ color: theme.palette.mode === "dark" ? "#e2e8f0" : "#0f172a", backgroundColor: theme.palette.mode === "dark" ? "rgba(148,163,184,0.18)" : "rgba(148,163,184,0.18)" }} />
                        {j.location ? <Chip size="small" label={j.location} sx={{ color: theme.palette.mode === "dark" ? "#e2e8f0" : "#0f172a", backgroundColor: theme.palette.mode === "dark" ? "rgba(148,163,184,0.18)" : "rgba(148,163,184,0.18)" }} /> : null}
                      </Box>
                    </CardContent>
                  </Card>
                ))}
                {list.length === 0 && (
                  <Typography variant="body2" sx={{ color: "text.secondary", py: 1 }}>
                    Drop here
                  </Typography>
                )}
              </Box>
            </Paper>
          );
        })}
      </Box>

      <Menu anchorEl={menuAnchor} open={Boolean(menuAnchor)} onClose={() => { setMenuAnchor(null); setMenuJobId(null); }}>
        {(["Applied", "Waiting", "Interview", "Offer", "Rejected", "Ghosted"] as const)
          .filter((s) => s !== currentMenuStatus)
          .map((s) => (
            <MenuItem key={s} onClick={() => { if (menuJobId) void setStatus(menuJobId, s); setMenuAnchor(null); setMenuJobId(null); }}>
              {t("jobTableSetStatus", { status: s })}
            </MenuItem>
          ))}
      </Menu>
    </Box>
  );
}