import { useSettings } from "@/utils/atoms/settings";
import { getOrSetDeviceId } from "@/utils/device";
import { useLog, writeToLog } from "@/utils/log";
import {
  cancelAllJobs,
  cancelJobById,
  deleteDownloadItemInfoFromDiskTmp,
  getAllJobsByDeviceId,
  getDownloadItemInfoFromDiskTmp,
  JobStatus,
} from "@/utils/optimize-server";
import {
  BaseItemDto,
  MediaSourceInfo,
} from "@jellyfin/sdk/lib/generated-client/models";
import {
  checkForExistingDownloads,
  completeHandler,
  download,
  setConfig,
} from "@kesha-antonov/react-native-background-downloader";
import MMKV from "react-native-mmkv";
import {
  focusManager,
  QueryClient,
  QueryClientProvider,
  useQuery,
  useQueryClient,
} from "@tanstack/react-query";
import axios from "axios";
import * as FileSystem from "expo-file-system";
import { useRouter } from "expo-router";
import { atom, useAtom } from "jotai";
import React, {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useMemo,
  useState,
} from "react";
import {AppState, AppStateStatus, Platform} from "react-native";
import { toast } from "sonner-native";
import { apiAtom } from "./JellyfinProvider";
import * as Notifications from "expo-notifications";
import { getItemImage } from "@/utils/getItemImage";
import useImageStorage from "@/hooks/useImageStorage";
import { storage } from "@/utils/mmkv";
import useDownloadHelper from "@/utils/download";
import { FileInfo } from "expo-file-system";
import * as Haptics from "expo-haptics";
import * as Application from "expo-application";

export type DownloadedItem = {
  item: Partial<BaseItemDto>;
  mediaSource: MediaSourceInfo;
};

export const processesAtom = atom<JobStatus[]>([]);

function onAppStateChange(status: AppStateStatus) {
  focusManager.setFocused(status === "active");
}

const DownloadContext = createContext<ReturnType<
  typeof useDownloadProvider
> | null>(null);

function useDownloadProvider() {
  const queryClient = useQueryClient();
  const [settings] = useSettings();
  const router = useRouter();
  const [api] = useAtom(apiAtom);
  const { logs } = useLog();

  const { saveSeriesPrimaryImage } = useDownloadHelper();
  const { saveImage } = useImageStorage();

  const [processes, setProcesses] = useAtom<JobStatus[]>(processesAtom);

  const authHeader = useMemo(() => {
    return api?.accessToken;
  }, [api]);

  const { data: downloadedFiles, refetch } = useQuery({
    queryKey: ["downloadedItems"],
    queryFn: getAllDownloadedItems,
    staleTime: 0,
    refetchOnMount: true,
    refetchOnReconnect: true,
    refetchOnWindowFocus: true,
  });

  useEffect(() => {
    const subscription = AppState.addEventListener("change", onAppStateChange);

    return () => subscription.remove();
  }, []);

  useQuery({
    queryKey: ["jobs"],
    queryFn: async () => {
      const deviceId = await getOrSetDeviceId();
      const url = settings?.optimizedVersionsServerUrl;

      if (
        settings?.downloadMethod !== "optimized" ||
        !url ||
        !deviceId ||
        !authHeader
      )
        return [];

      const jobs = await getAllJobsByDeviceId({
        deviceId,
        authHeader,
        url,
      });

      const downloadingProcesses = processes
        .filter((p) => p.status === "downloading")
        .filter((p) => jobs.some((j) => j.id === p.id));

      const updatedProcesses = jobs.filter(
        (j) => !downloadingProcesses.some((p) => p.id === j.id)
      );

      setProcesses([...updatedProcesses, ...downloadingProcesses]);

      for (let job of jobs) {
        const process = processes.find((p) => p.id === job.id);
        if (
          process &&
          process.status === "optimizing" &&
          job.status === "completed"
        ) {
          if (settings.autoDownload) {
            startDownload(job);
          } else {
            toast.info(`${job.item.Name} is ready to be downloaded`, {
              action: {
                label: "Go to downloads",
                onClick: () => {
                  router.push("/downloads");
                  toast.dismiss();
                },
              },
            });
            Notifications.scheduleNotificationAsync({
              content: {
                title: job.item.Name,
                body: `${job.item.Name} is ready to be downloaded`,
                data: {
                  url: `/downloads`,
                },
              },
              trigger: null,
            });
          }
        }
      }

      return jobs;
    },
    staleTime: 0,
    refetchInterval: 2000,
    enabled: settings?.downloadMethod === "optimized",
  });

  useEffect(() => {
    const checkIfShouldStartDownload = async () => {
      if (processes.length === 0) return;
      await checkForExistingDownloads();
    };

    checkIfShouldStartDownload();
  }, [settings, processes]);

  const removeProcess = useCallback(
    async (id: string) => {
      const deviceId = await getOrSetDeviceId();
      if (!deviceId || !authHeader || !settings?.optimizedVersionsServerUrl)
        return;

      try {
        await cancelJobById({
          authHeader,
          id,
          url: settings?.optimizedVersionsServerUrl,
        });
      } catch (error) {
        console.error(error);
      }
    },
    [settings?.optimizedVersionsServerUrl, authHeader]
  );

  const APP_CACHE_DOWNLOAD_DIRECTORY = `${FileSystem.cacheDirectory}${Application.applicationId}/Downloads/`

  const startDownload = useCallback(
    async (process: JobStatus) => {
      if (!process?.item.Id || !authHeader) throw new Error("No item id");

      setProcesses((prev) =>
        prev.map((p) =>
          p.id === process.id
            ? {
                ...p,
                speed: undefined,
                status: "downloading",
                progress: 0,
              }
            : p
        )
      );

      setConfig({
        isLogsEnabled: true,
        progressInterval: 500,
        headers: {
          Authorization: authHeader,
        },
      });

      toast.info(`Download started for ${process.item.Name}`, {
        action: {
          label: "Go to downloads",
          onClick: () => {
            router.push("/downloads");
            toast.dismiss();
          },
        },
      });

      const baseDirectory = FileSystem.documentDirectory;

      download({
        id: process.id,
        url: settings?.optimizedVersionsServerUrl + "download/" + process.id,
        destination: `${baseDirectory}/${process.item.Id}.mp4`,
      })
        .begin(() => {
          setProcesses((prev) =>
            prev.map((p) =>
              p.id === process.id
                ? {
                    ...p,
                    speed: undefined,
                    status: "downloading",
                    progress: 0,
                  }
                : p
            )
          );
        })
        .progress((data) => {
          const percent = (data.bytesDownloaded / data.bytesTotal) * 100;
          setProcesses((prev) =>
            prev.map((p) =>
              p.id === process.id
                ? {
                    ...p,
                    speed: undefined,
                    status: "downloading",
                    progress: percent,
                  }
                : p
            )
          );
        })
        .done(async (doneHandler) => {
          await saveDownloadedItemInfo(
            process.item,
            doneHandler.bytesDownloaded
          );
          toast.success(`Download completed for ${process.item.Name}`, {
            duration: 3000,
            action: {
              label: "Go to downloads",
              onClick: () => {
                router.push("/downloads");
                toast.dismiss();
              },
            },
          });
          setTimeout(() => {
            completeHandler(process.id);
            removeProcess(process.id);
          }, 1000);
        })
        .error(async (error) => {
          removeProcess(process.id);
          completeHandler(process.id);
          let errorMsg = "";
          if (error.errorCode === 1000) {
            errorMsg = "No space left";
          }
          if (error.errorCode === 404) {
            errorMsg = "File not found on server";
          }
          toast.error(`Download failed for ${process.item.Name} - ${errorMsg}`);
          writeToLog("ERROR", `Download failed for ${process.item.Name}`, {
            error,
            processDetails: {
              id: process.id,
              itemName: process.item.Name,
              itemId: process.item.Id,
            },
          });
          console.error("Error details:", {
            errorCode: error.errorCode,
          });
        });
    },
    [queryClient, settings?.optimizedVersionsServerUrl, authHeader]
  );

  const startBackgroundDownload = useCallback(
    async (url: string, item: BaseItemDto, mediaSource: MediaSourceInfo) => {
      if (!api || !item.Id || !authHeader)
        throw new Error("startBackgroundDownload ~ Missing required params");

      try {
        const fileExtension = mediaSource.TranscodingContainer;
        const deviceId = await getOrSetDeviceId();

        await saveSeriesPrimaryImage(item);
        const itemImage = getItemImage({
          item,
          api,
          variant: "Primary",
          quality: 90,
          width: 500,
        });
        await saveImage(item.Id, itemImage?.uri);

        const response = await axios.post(
          settings?.optimizedVersionsServerUrl + "optimize-version",
          {
            url,
            fileExtension,
            deviceId,
            itemId: item.Id,
            item,
          },
          {
            headers: {
              "Content-Type": "application/json",
              Authorization: authHeader,
            },
          }
        );

        if (response.status !== 201) {
          throw new Error("Failed to start optimization job");
        }

        toast.success(`Queued ${item.Name} for optimization`, {
          action: {
            label: "Go to download",
            onClick: () => {
              router.push("/downloads");
              toast.dismiss();
            },
          },
        });
      } catch (error) {
        writeToLog("ERROR", "Error in startBackgroundDownload", error);
        console.error("Error in startBackgroundDownload:", error);
        if (axios.isAxiosError(error)) {
          console.error("Axios error details:", {
            message: error.message,
            response: error.response?.data,
            status: error.response?.status,
            headers: error.response?.headers,
          });
          toast.error(
            `Failed to start download for ${item.Name}: ${error.message}`
          );
          if (error.response) {
            toast.error(
              `Server responded with status ${error.response.status}`
            );
          } else if (error.request) {
            toast.error("No response received from server");
          } else {
            toast.error("Error setting up the request");
          }
        } else {
          console.error("Non-Axios error:", error);
          toast.error(
            `Failed to start download for ${item.Name}: Unexpected error`
          );
        }
      }
    },
    [settings?.optimizedVersionsServerUrl, authHeader]
  );

  const deleteAllFiles = async (): Promise<void> => {
    Promise.all([
      deleteLocalFiles(),
      removeDownloadedItemsFromStorage(),
      cancelAllServerJobs(),
      queryClient.invalidateQueries({ queryKey: ["downloadedItems"] }),
    ])
      .then(() =>
        toast.success("All files, folders, and jobs deleted successfully")
      )
      .catch((reason) => {
        console.error("Failed to delete all files, folders, and jobs:", reason);
        toast.error("An error occurred while deleting files and jobs");
      });
  };

  const forEveryDocumentDirFile = async (
    includeMMKV: boolean = true,
    ignoreList: string[] = [],
    callback: (file: FileInfo) => void
  ) => {
    const baseDirectory = FileSystem.documentDirectory;
    if (!baseDirectory) {
      throw new Error("Base directory not found");
    }

    console.log(`ignoreList length: ${ignoreList?.length}`);

    const dirContents = await FileSystem.readDirectoryAsync(baseDirectory);
    for (const item of dirContents) {
      // Exclude mmkv directory.
      // Deleting this deletes all user information as well. Logout should handle this.
      if (
        (item == "mmkv" && !includeMMKV) ||
        ignoreList.some(i => item.includes(i))
      ) {
        console.log("Skipping read for item", item)
        continue;
      }
      await FileSystem.getInfoAsync(`${baseDirectory}${item}`)
        .then((itemInfo) => {
          console.log("Loading itemInfo", itemInfo);

          if (itemInfo.exists && !itemInfo.isDirectory) {
            callback(itemInfo);
          }
        })
        .catch(e =>
          console.error(e)
        )
    }
  }

  const deleteLocalFiles = async (): Promise<void> => {
    await forEveryDocumentDirFile(false, [], (file) => {
      console.warn("Deleting file", file.uri);
      FileSystem.deleteAsync(file.uri, { idempotent: true });
    });
  };

  const removeDownloadedItemsFromStorage = async () => {
    // delete any saved images first
    Promise.all([deleteFileByType("Movie"), deleteFileByType("Episode")])
      .then(() => storage.delete("downloadedItems"))
      .catch((reason) => {
        console.error("Failed to remove downloadedItems from storage:", reason);
        throw reason;
      });
  };

  const cancelAllServerJobs = async (): Promise<void> => {
    if (!authHeader) {
      throw new Error("No auth header available");
    }
    if (!settings?.optimizedVersionsServerUrl) {
      console.error("No server URL configured");
      return;
    }

    const deviceId = await getOrSetDeviceId();
    if (!deviceId) {
      throw new Error("Failed to get device ID");
    }

    try {
      await cancelAllJobs({
        authHeader,
        url: settings.optimizedVersionsServerUrl,
        deviceId,
      });
    } catch (error) {
      console.error("Failed to cancel all server jobs:", error);
      throw error;
    }
  };

  const deleteFile = async (id: string): Promise<void> => {
    if (!id) {
      console.error("Invalid file ID");
      return;
    }

    try {
      const directory = FileSystem.documentDirectory;

      if (!directory) {
        console.error("Document directory not found");
        return;
      }
      const dirContents = await FileSystem.readDirectoryAsync(directory);

      for (const item of dirContents) {
        const itemNameWithoutExtension = item.split(".")[0];
        if (itemNameWithoutExtension === id) {
          const filePath = `${directory}${item}`;
          await FileSystem.deleteAsync(filePath, { idempotent: true });
          break;
        }
      }

      const downloadedItems = storage.getString("downloadedItems");
      if (downloadedItems) {
        let items = JSON.parse(downloadedItems) as DownloadedItem[];
        items = items.filter((item) => item.item.Id !== id);
        storage.set("downloadedItems", JSON.stringify(items));
      }

      queryClient.invalidateQueries({ queryKey: ["downloadedItems"] });
    } catch (error) {
      console.error(
        `Failed to delete file and storage entry for ID ${id}:`,
        error
      );
    }
  };

  const deleteItems = async (items: BaseItemDto[]) => {
    Promise.all(
      items.map((i) => {
        if (i.Id) return deleteFile(i.Id);
        return;
      })
    ).then(() =>
      Haptics.notificationAsync(Haptics.NotificationFeedbackType.Success)
    );
  };

  const cleanCacheDirectory = async () => {
    const cacheDir = await FileSystem.getInfoAsync(APP_CACHE_DOWNLOAD_DIRECTORY);
    if (cacheDir.exists) {
      const cachedFiles = await FileSystem.readDirectoryAsync(APP_CACHE_DOWNLOAD_DIRECTORY)
      let position = 0
      const batchSize = 3

      // batching promise.all to avoid OOM
      while (position < cachedFiles.length) {
        const itemsForBatch = cachedFiles.slice(position, position + batchSize)
        await Promise.all(itemsForBatch.map(async file => {
          const info = await FileSystem.getInfoAsync(`${APP_CACHE_DOWNLOAD_DIRECTORY}${file}`)
          if (info.exists) {
            await FileSystem.deleteAsync(info.uri, { idempotent: true })
            return Promise.resolve(file)
          }
          return Promise.reject()
        }))

        position += batchSize
      }
    }
  }

  const deleteFileByType = async (type: BaseItemDto["Type"]) => {
    await Promise.all(
      downloadedFiles
        ?.filter((file) => file.item.Type == type)
        ?.flatMap((file) => {
          const promises = [];
          if (type == "Episode" && file.item.SeriesId)
            promises.push(deleteFile(file.item.SeriesId));
          promises.push(deleteFile(file.item.Id!));
          return promises;
        }) || []
    );
  };

  const appSizeUsage = useMemo(async () => {
    const sizes: number[] = downloadedFiles?.map(d => {
      return getDownloadedItemSize(d.item.Id!!)
    }) || [];

    await forEveryDocumentDirFile(
      true,
      getAllDownloadedItems().map(d => d.item.Id!!),
      (file) => {
        if (file.exists) {
          sizes.push(file.size);
        }
      }).catch(e => {
      console.error(e)
    })

    return sizes.reduce((sum, size) => sum + size, 0);
  }, [logs, downloadedFiles, forEveryDocumentDirFile]);

  function getDownloadedItem(itemId: string): DownloadedItem | null {
    try {
      const downloadedItems = storage.getString("downloadedItems");
      if (downloadedItems) {
        const items: DownloadedItem[] = JSON.parse(downloadedItems);
        const item = items.find((i) => i.item.Id === itemId);
        return item || null;
      }
      return null;
    } catch (error) {
      console.error(`Failed to retrieve item with ID ${itemId}:`, error);
      return null;
    }
  }

  function getAllDownloadedItems(): DownloadedItem[] {
    try {
      const downloadedItems = storage.getString("downloadedItems");
      if (downloadedItems) {
        return JSON.parse(downloadedItems) as DownloadedItem[];
      } else {
        return [];
      }
    } catch (error) {
      console.error("Failed to retrieve downloaded items:", error);
      return [];
    }
  }

  function saveDownloadedItemInfo(item: BaseItemDto, size: number = 0) {
    try {
      const downloadedItems = storage.getString("downloadedItems");
      let items: DownloadedItem[] = downloadedItems
        ? JSON.parse(downloadedItems)
        : [];

      const existingItemIndex = items.findIndex((i) => i.item.Id === item.Id);

      const data = getDownloadItemInfoFromDiskTmp(item.Id!);

      if (!data?.mediaSource)
        throw new Error(
          "Media source not found in tmp storage. Did you forget to save it before starting download?"
        );

      const newItem = { item, mediaSource: data.mediaSource };

      if (existingItemIndex !== -1) {
        items[existingItemIndex] = newItem;
      } else {
        items.push(newItem);
      }

      deleteDownloadItemInfoFromDiskTmp(item.Id!);

      storage.set("downloadedItems", JSON.stringify(items));
      storage.set("downloadedItemSize-" + item.Id, size.toString());

      queryClient.invalidateQueries({ queryKey: ["downloadedItems"] });
      refetch();
    } catch (error) {
      console.error(
        "Failed to save downloaded item information with media source:",
        error
      );
    }
  }

  function getDownloadedItemSize(itemId: string): number {
    const size = storage.getString("downloadedItemSize-" + itemId);
    return size ? parseInt(size) : 0;
  }

  return {
    processes,
    startBackgroundDownload,
    downloadedFiles,
    deleteAllFiles,
    deleteFile,
    deleteItems,
    saveDownloadedItemInfo,
    removeProcess,
    setProcesses,
    startDownload,
    getDownloadedItem,
    deleteFileByType,
    appSizeUsage,
    getDownloadedItemSize,
    APP_CACHE_DOWNLOAD_DIRECTORY,
    cleanCacheDirectory
  };
}

export function DownloadProvider({ children }: { children: React.ReactNode }) {
  const downloadProviderValue = useDownloadProvider();

  return (
    <DownloadContext.Provider value={downloadProviderValue}>
      {children}
    </DownloadContext.Provider>
  );
}

export function useDownload() {
  const context = useContext(DownloadContext);
  if (context === null) {
    throw new Error("useDownload must be used within a DownloadProvider");
  }
  return context;
}