import { useCallback, useEffect, useMemo, useState } from "react";
import { isAxiosError } from "axios";
import { useNavigate, useParams } from "react-router-dom";
import {
  Alert,
  Badge,
  Button,
  Group,
  Loader,
  Paper,
  Stack,
  Text,
  Title,
} from "@mantine/core";
import { useTranslation } from "react-i18next";
import DownloadIcon from "@mui/icons-material/Download";
import LoginIcon from "@mui/icons-material/Login";
import OpenInNewIcon from "@mui/icons-material/OpenInNew";

import { useFileActions } from "@app/contexts/FileContext";
import { useNavigationActions } from "@app/contexts/NavigationContext";
import { alert } from "@app/components/toast";
import {
  downloadShareLink,
  fetchShareLinkMetadata,
  importShareLinkToWorkbench,
  ShareLinkMetadata,
} from "@app/services/shareLinkImport";

type ShareLinkStatus =
  | "loading"
  | "ready"
  | "login"
  | "forbidden"
  | "notfound"
  | "error";

export default function ShareLinkPage() {
  const { token } = useParams<{ token: string }>();
  const { actions } = useFileActions();
  const { actions: navActions } = useNavigationActions();
  const navigate = useNavigate();
  const { t } = useTranslation();
  const [status, setStatus] = useState<ShareLinkStatus>("loading");
  const [metadata, setMetadata] = useState<ShareLinkMetadata | null>(null);
  const [isWorking, setIsWorking] = useState(false);

  const normalizedToken = useMemo(() => (token || "").trim(), [token]);
  const shareRole = (metadata?.accessRole ?? "viewer").toLowerCase();
  const hasReadAccess =
    shareRole === "editor" ||
    shareRole === "commenter" ||
    shareRole === "viewer";
  const canDownload = hasReadAccess;
  const canOpen = hasReadAccess;

  const loadMetadata = useCallback(async () => {
    if (!normalizedToken) {
      setStatus("notfound");
      return;
    }
    setStatus("loading");
    try {
      const data = await fetchShareLinkMetadata(normalizedToken);
      setMetadata(data);
      setStatus("ready");
    } catch (error: unknown) {
      const statusCode = isAxiosError(error)
        ? error.response?.status
        : undefined;
      if (statusCode === 401) {
        setStatus("login");
      } else if (statusCode === 403) {
        setStatus("forbidden");
      } else if (statusCode === 404 || statusCode === 410) {
        setStatus("notfound");
      } else {
        setStatus("error");
      }
    }
  }, [normalizedToken]);

  useEffect(() => {
    void loadMetadata();
  }, [loadMetadata]);

  const handleLogin = useCallback(() => {
    navigate("/login", {
      replace: true,
      state: { from: { pathname: `/share/${normalizedToken}` } },
    });
  }, [navigate, normalizedToken]);

  const handleDownload = useCallback(async () => {
    if (!normalizedToken || !canDownload) return;
    setIsWorking(true);
    try {
      const { blob, filename } = await downloadShareLink(normalizedToken);
      const url = URL.createObjectURL(blob);
      const link = document.createElement("a");
      link.href = url;
      link.download = filename || "shared-file";
      document.body.appendChild(link);
      link.click();
      link.remove();
      URL.revokeObjectURL(url);
    } catch (error: unknown) {
      const statusCode = isAxiosError(error)
        ? error.response?.status
        : undefined;
      if (statusCode === 401) {
        setStatus("login");
      } else if (statusCode === 403) {
        setStatus("forbidden");
      } else if (statusCode === 404 || statusCode === 410) {
        setStatus("notfound");
      } else {
        alert({
          alertType: "error",
          title: t(
            "storageShare.downloadFailed",
            "Unable to download this file.",
          ),
          expandable: false,
          durationMs: 3500,
        });
      }
    } finally {
      setIsWorking(false);
    }
  }, [canDownload, normalizedToken, t]);

  const handleOpen = useCallback(async () => {
    if (!normalizedToken || !canOpen) return;
    setIsWorking(true);
    try {
      const selectedIds = await importShareLinkToWorkbench(
        normalizedToken,
        actions,
        metadata,
      );
      if (selectedIds.length > 0) {
        actions.setSelectedFiles(selectedIds);
      }
      navActions.setWorkbench("viewer");
      navigate("/", { replace: true });
    } catch (error: unknown) {
      const statusCode = isAxiosError(error)
        ? error.response?.status
        : undefined;
      if (statusCode === 401) {
        setStatus("login");
      } else if (statusCode === 403) {
        setStatus("forbidden");
      } else if (statusCode === 404 || statusCode === 410) {
        setStatus("notfound");
      } else {
        alert({
          alertType: "error",
          title: t("storageShare.loadFailed", "Unable to open shared file."),
          expandable: false,
          durationMs: 3500,
        });
      }
    } finally {
      setIsWorking(false);
    }
  }, [actions, canOpen, metadata, navActions, navigate, normalizedToken, t]);

  const title =
    metadata?.fileName || t("storageShare.titleDefault", "Shared file");
  const ownerLabel =
    metadata?.owner || t("storageShare.ownerUnknown", "Unknown");

  return (
    <div style={{ minHeight: "100%", padding: "2.5rem 1.5rem" }}>
      <Paper
        radius="lg"
        p="xl"
        withBorder
        shadow="sm"
        style={{ maxWidth: 720, margin: "0 auto" }}
      >
        <Stack gap="md">
          <Group justify="space-between" align="center">
            <Title order={3}>
              {t("storageShare.shareHeading", "Shared file")}
            </Title>
            <Group gap="xs">
              {metadata?.accessRole && (
                <Badge variant="light" color="gray">
                  {shareRole === "editor"
                    ? t("storageShare.roleEditor", "Editor")
                    : shareRole === "commenter"
                      ? t("storageShare.roleCommenter", "Commenter")
                      : t("storageShare.roleViewer", "Viewer")}
                </Badge>
              )}
            </Group>
          </Group>

          {status === "loading" && (
            <Group justify="center" py="xl">
              <Loader size="sm" />
              <Text size="sm" c="dimmed">
                {t("storageShare.loading", "Loading share link...")}
              </Text>
            </Group>
          )}

          {status === "ready" && (
            <>
              <Text size="lg" fw={600}>
                {title}
              </Text>
              <Text size="sm" c="dimmed">
                {t("storageShare.ownerLabel", "Owner")}: {ownerLabel}
              </Text>
              {metadata?.createdAt && (
                <Text size="sm" c="dimmed">
                  {t("storageShare.createdAt", "Created")}{" "}
                  {new Date(metadata.createdAt).toLocaleString()}
                </Text>
              )}
              <Group justify="flex-start" gap="sm" pt="sm">
                <Button
                  leftSection={<OpenInNewIcon style={{ fontSize: 18 }} />}
                  onClick={handleOpen}
                  loading={isWorking}
                  disabled={!canOpen}
                >
                  {t("storageShare.openInApp", "Open in Stirling PDF")}
                </Button>
                <Button
                  variant="light"
                  leftSection={<DownloadIcon style={{ fontSize: 18 }} />}
                  onClick={handleDownload}
                  loading={isWorking}
                  disabled={!canDownload}
                >
                  {t("storageShare.download", "Download")}
                </Button>
              </Group>
              {!canDownload && (
                <Alert
                  mt="md"
                  color="yellow"
                  title={t("storageShare.accessLimitedTitle", "Limited access")}
                >
                  {shareRole === "commenter"
                    ? t(
                        "storageShare.accessLimitedCommenter",
                        "Comment access is coming soon. Ask the owner for editor access if you need to download.",
                      )
                    : t(
                        "storageShare.accessLimitedViewer",
                        "This link is view-only. Ask the owner for editor access if you need to download.",
                      )}
                </Alert>
              )}
            </>
          )}

          {status === "login" && (
            <Alert
              color="blue"
              title={t("storageShare.loginRequired", "Login required")}
            >
              <Text size="sm">
                {t(
                  "storageShare.loginPrompt",
                  "Sign in to access this shared file.",
                )}
              </Text>
              <Group mt="md">
                <Button
                  leftSection={<LoginIcon style={{ fontSize: 18 }} />}
                  onClick={handleLogin}
                >
                  {t("storageShare.goToLogin", "Go to login")}
                </Button>
              </Group>
            </Alert>
          )}

          {status === "forbidden" && (
            <Alert
              color="red"
              title={t("storageShare.accessDeniedTitle", "No access")}
            >
              {t(
                "storageShare.accessDeniedBody",
                "You do not have access to this file. Ask the owner to share it with you.",
              )}
            </Alert>
          )}

          {status === "notfound" && (
            <Alert
              color="red"
              title={t("storageShare.expiredTitle", "Link expired")}
            >
              {t(
                "storageShare.expiredBody",
                "This share link is invalid or has expired.",
              )}
            </Alert>
          )}

          {status === "error" && (
            <Alert
              color="red"
              title={t(
                "storageShare.loadFailed",
                "Unable to open shared file.",
              )}
            >
              {t("storageShare.tryAgain", "Please try again later.")}
            </Alert>
          )}
        </Stack>
      </Paper>
    </div>
  );
}