import React, { useMemo } from "react";

import { Box, Tooltip, Typography, useTheme } from "@mui/material";

import WorkOutlineIcon from "@mui/icons-material/WorkOutline";
import ForumIcon from "@mui/icons-material/Forum";
import MarkEmailReadIcon from "@mui/icons-material/MarkEmailRead";
import EmojiEventsIcon from "@mui/icons-material/EmojiEvents";
import CloseIcon from "@mui/icons-material/Close";

import { alpha } from "@mui/material/styles";

import { JobApplication } from "../types";

function normalizeStatus(status?: string): string {
  if (!status) return "Applied";
  if (status === "Interviewing") return "Interview";
  return status;
}

function isTerminalRejected(status: string) {
  return status === "Rejected" || status === "Ghosted";
}

export default function JobFlowBar({ job }: { job: JobApplication | null }) {
  const theme = useTheme();
  const steps = useMemo(
    () =>
      [
        { key: "applied" as const, label: "Applied", color: theme.palette.info.main, icon: <WorkOutlineIcon fontSize="inherit" /> },
        { key: "interview" as const, label: "Interview", color: theme.palette.primary.main, icon: <ForumIcon fontSize="inherit" /> },
        { key: "reply" as const, label: "Reply", color: theme.palette.success.main, icon: <MarkEmailReadIcon fontSize="inherit" /> },
        { key: "offer" as const, label: "Offer", color: theme.palette.success.dark, icon: <EmojiEventsIcon fontSize="inherit" /> },
        { key: "outcome" as const, label: "Outcome", color: theme.palette.text.secondary, icon: <EmojiEventsIcon fontSize="inherit" /> },
      ] as const,
    [theme.palette.info.main, theme.palette.primary.main, theme.palette.success.main, theme.palette.success.dark, theme.palette.text.secondary],
  );

  if (!job) return null;

  const status = normalizeStatus(job.status);
  const reply = Boolean(job.responseReceived);
  const rejected = isTerminalRejected(status);

  const activeIndex = (() => {
    if (rejected) return 4;
    if (status === "Offer") return 3;
    if (reply) return 2;
    if (status === "Interview") return 1;
    return 0;
  })();

  const breakIndex = rejected ? activeIndex : null;
  const visibleSteps = breakIndex !== null ? steps.slice(0, breakIndex + 1) : steps;

  const segCount = visibleSteps.length;
  const segWidth = `${100 / segCount}%`;

  return (
    <Box sx={{ mb: 2 }}>
      <Typography variant="overline" sx={{ display: "block", mb: 0.75 }}>
        Flow
      </Typography>

      <Box
        sx={{
          display: "flex",
          borderRadius: 999,
          overflow: "hidden",
          border: `1px solid ${alpha(theme.palette.text.primary, 0.12)}`,
          height: 44,
          background: alpha("#fff", 0.65),
        }}
      >
        {visibleSteps.map((s, idx) => {
          const filled = idx <= activeIndex && breakIndex === null;
          const terminalFilled = breakIndex !== null && idx < breakIndex;
          const isBreak = breakIndex !== null && idx === breakIndex;

          const bg = filled || terminalFilled ? s.color : alpha(s.color, 0.12);
          const fg = filled || terminalFilled ? "#fff" : alpha(theme.palette.text.primary, 0.6);

          const title = (() => {
            if (isBreak) return `${status} (stopped here)`;
            if (idx === 2 && reply) return "Reply received";
            return s.label;
          })();

          return (
            <Tooltip key={s.key} title={title}>
              <Box
                sx={{
                  width: segWidth,
                  display: "flex",
                  alignItems: "center",
                  justifyContent: "center",
                  position: "relative",
                  background: isBreak ? theme.palette.error.main : bg,
                  color: "#fff",
                  borderRight: idx === visibleSteps.length - 1 ? "none" : `1px solid ${alpha("#fff", 0.35)}`,
                  userSelect: "none",
                }}
              >
                {isBreak ? (
                  <CloseIcon fontSize="inherit" />
                ) : (
                  <Box sx={{ display: "inline-flex", alignItems: "center", gap: 1, color: fg, fontWeight: 900 }}>
                    <Box sx={{ fontSize: 18, display: "inline-flex" }}>{s.icon}</Box>
                    <span style={{ fontSize: 13 }}>{s.key === "outcome" && rejected ? status : s.label}</span>
                  </Box>
                )}

                {isBreak ? (
                  <Box
                    sx={{
                      position: "absolute",
                      inset: 0,
                      display: "flex",
                      alignItems: "center",
                      justifyContent: "center",
                      fontWeight: 900,
                      letterSpacing: "0.02em",
                    }}
                  >
                    {status} <span style={{ marginLeft: 8, display: "inline-flex" }}><CloseIcon fontSize="inherit" /></span>
                  </Box>
                ) : null}
              </Box>
            </Tooltip>
          );
        })}
      </Box>
    </Box>
  );
}