import * as React from "react";
import { useLocation, matchPath, useNavigate } from "react-router-dom";
import {
  AppBar,
  Toolbar,
  Typography,
  IconButton,
  Tooltip,
  Button,
  Box,
  Drawer,
  List,
  ListItemButton,
  ListItemText,
  Divider,
  useMediaQuery,
  useTheme,
} from "@mui/material";
import MenuIcon from "@mui/icons-material/Menu";
import LogoutIcon from "@mui/icons-material/Logout";
import DarkModeIcon from "@mui/icons-material/DarkMode";
import LightModeIcon from "@mui/icons-material/LightMode";
import { useAuth } from "../react-auth";
import { ColorModeContext } from "./shared-theme/AppTheme";

interface HeaderProps {
  routerMapping: {
    path: string;
    headerTitle: string;
  }[];
  onDrawerToggle?: () => void;
}

const NAV_LINKS = [
  { label: "Home", path: "/" },
  { label: "Expenses", path: "/expenses" },
  { label: "Reports", path: "/reports" },
  { label: "Fetch Requests", path: "/fetch-requests" },
];

function isActive(path: string, locationPath: string): boolean {
  if (path === "/") return locationPath === "/" || locationPath === "/home";
  return matchPath({ path, end: false }, locationPath) !== null;
}

export default function Header({ routerMapping, onDrawerToggle }: HeaderProps) {
  const location = useLocation();
  const navigate = useNavigate();
  const { currentUser, logout } = useAuth();
  const { mode, toggleColorMode } = React.useContext(ColorModeContext);

  const theme = useTheme();
  const isMobile = useMediaQuery(theme.breakpoints.down("md"));
  const [mobileOpen, setMobileOpen] = React.useState(false);

  const isAuthenticated = !!currentUser;

  const navContent = (
    <Box
      sx={{
        display: { xs: "none", md: "flex" },
        alignItems: "center",
        gap: 0.5,
        ml: 3,
      }}
    >
      {NAV_LINKS.map((link) => {
        const active = isActive(link.path, location.pathname);
        return (
          <Button
            key={link.path}
            color="inherit"
            onClick={() => navigate(link.path)}
            sx={{
              textTransform: "none",
              fontWeight: active ? 600 : 500,
              color: active ? "text.primary" : "text.secondary",
              px: 1.5,
              borderRadius: "6px",
              position: "relative",
              "&::after":
                active
                  ? {
                      content: '""',
                      position: "absolute",
                      left: 12,
                      right: 12,
                      bottom: 4,
                      height: 2,
                      borderRadius: 1,
                      backgroundColor: "primary.main",
                    }
                  : {},
              "&:hover": { backgroundColor: "action.hover", color: "text.primary" },
            }}
          >
            {link.label}
          </Button>
        );
      })}
    </Box>
  );

  const authSection = (
    <Box sx={{ display: "flex", alignItems: "center", gap: 1 }}>
      {isAuthenticated ? (
        <>
          <Button
            color="inherit"
            onClick={() => navigate("/admin")}
            sx={{
              textTransform: "none",
              fontWeight: isActive("/admin", location.pathname) ? 600 : 500,
              color: isActive("/admin", location.pathname) ? "text.primary" : "text.secondary",
              display: { xs: "none", sm: "inline-flex" },
            }}
          >
            Admin
          </Button>
          <Button
            color="inherit"
            onClick={() => navigate("/profile/me")}
            sx={{ textTransform: "none", fontWeight: 500 }}
          >
            {currentUser.username}
          </Button>
          <Tooltip title="Logout">
            <IconButton color="inherit" onClick={logout} aria-label="Logout">
              <LogoutIcon />
            </IconButton>
          </Tooltip>
        </>
      ) : (
        <Button
          color="inherit"
          variant="outlined"
          onClick={() => navigate("/login")}
          sx={{ textTransform: "none" }}
        >
          Login
        </Button>
      )}
    </Box>
  );

  const drawerContent = (
    <Box sx={{ width: 260 }} role="presentation">
      <Box sx={{ p: 2 }}>
        <Brand />
      </Box>
      <Divider />
      <List>
        {routerMapping
          .filter((r) => !r.path.startsWith("/login") && !r.path.startsWith("/register") && !r.path.startsWith("/profile"))
          .map((route) => {
            const active = isActive(route.path, location.pathname);
            return (
              <ListItemButton
                key={route.path}
                selected={active}
                onClick={() => {
                  navigate(route.path);
                  setMobileOpen(false);
                }}
                sx={{
                  borderRadius: "6px",
                  mx: 1,
                  mb: 0.5,
                  "&.Mui-selected": {
                    backgroundColor: "action.selected",
                  },
                }}
              >
                <ListItemText
                  primary={route.headerTitle}
                  primaryTypographyProps={{ fontWeight: active ? 600 : 500, fontSize: 14 }}
                />
              </ListItemButton>
            );
          })}
        <Divider sx={{ my: 1 }} />
        {isAuthenticated ? (
          <>
            <ListItemButton onClick={() => navigate("/profile/me")} sx={{ borderRadius: "6px", mx: 1 }}>
              <ListItemText primary="Profile" primaryTypographyProps={{ fontSize: 14 }} />
            </ListItemButton>
            <ListItemButton onClick={logout} sx={{ borderRadius: "6px", mx: 1 }}>
              <ListItemText primary="Logout" primaryTypographyProps={{ fontSize: 14 }} />
            </ListItemButton>
          </>
        ) : (
          <ListItemButton onClick={() => navigate("/login")} sx={{ borderRadius: "6px", mx: 1 }}>
            <ListItemText primary="Login" primaryTypographyProps={{ fontSize: 14 }} />
          </ListItemButton>
        )}
      </List>
    </Box>
  );

  return (
    <>
      <AppBar
        position="sticky"
        color="default"
        sx={{
          zIndex: (theme) => theme.zIndex.drawer + 1,
          backdropFilter: "blur(8px)",
          boxShadow: "none",
          borderBottom: "1px solid",
          borderColor: "divider",
          backgroundColor: "background.default",
        }}
      >
        <Toolbar>
          {/* MOBILE MENU */}
          {isMobile && (
            <IconButton
              color="inherit"
              edge="start"
              onClick={() => setMobileOpen(true)}
              aria-label="Open navigation"
              sx={{ mr: 1 }}
            >
              <MenuIcon />
            </IconButton>
          )}

          {/* BRAND — always leftmost */}
          <Brand onClick={() => navigate("/")} />

          {navContent}

          <Box sx={{ flexGrow: 1 }} />

          {/* THEME TOGGLE — right side */}
          <IconButton onClick={toggleColorMode} color="inherit" aria-label="Toggle color mode" sx={{ mr: 1 }}>
            {mode === "dark" ? <LightModeIcon /> : <DarkModeIcon />}
          </IconButton>

          {authSection}
        </Toolbar>
      </AppBar>

      <Drawer
        open={mobileOpen}
        onClose={() => setMobileOpen(false)}
        ModalProps={{ keepMounted: true }}
      >
        {drawerContent}
      </Drawer>
    </>
  );
}

function Brand({ onClick }: { onClick?: () => void }) {
  return (
    <Box
      onClick={onClick}
      sx={{
        display: "flex",
        alignItems: "center",
        gap: 1,
        cursor: onClick ? "pointer" : "default",
        userSelect: "none",
      }}
    >
      <Box
        sx={{
          width: 28,
          height: 28,
          borderRadius: "8px",
          display: "flex",
          alignItems: "center",
          justifyContent: "center",
          background: "linear-gradient(135deg, #635BFF 0%, #8B5CF6 100%)",
          color: "#fff",
          fontWeight: 700,
          fontSize: 15,
        }}
      >
        K
      </Box>
      <Typography
        variant="h6"
        sx={{ fontWeight: 700, letterSpacing: "-0.02em", color: "text.primary" }}
      >
        Khata
      </Typography>
    </Box>
  );
}