import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { useSearchParams } from "react-router-dom";
import { useDeltaWatermarks } from "@govoplan/core-webui";
import type { ApiSettings } from "../../../types";
import {
  getCampaignWorkspaceDelta,
  type CampaignWorkspaceDeltaResponse
} from "../../../api/campaigns";
import type { CampaignWorkspaceData } from "../utils/campaignView";

const initialData: CampaignWorkspaceData = {
  campaign: null,
  versions: [],
  currentVersion: null,
  summary: null
};

type UseCampaignWorkspaceDataOptions = {
  includeCurrentVersion?: boolean;
  includeSummary?: boolean;
  includeVersions?: boolean;
};

export function useCampaignWorkspaceData(
  settings: ApiSettings,
  campaignId: string,
  options: UseCampaignWorkspaceDataOptions = {}
) {
  const {
    includeCurrentVersion = true,
    includeSummary = false,
    includeVersions = false
  } = options;
  const [searchParams] = useSearchParams();
  const selectedVersionId = searchParams.get("version");
  const [data, setData] = useState<CampaignWorkspaceData>(initialData);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState("");
  const dataRef = useRef<CampaignWorkspaceData>(initialData);
  const { getDeltaWatermark, setDeltaWatermark, resetDeltaWatermark } = useDeltaWatermarks();
  const queryKey = useMemo(
    () => JSON.stringify({
      campaignId,
      selectedVersionId,
      includeCurrentVersion,
      includeSummary,
      includeVersions,
      apiBaseUrl: settings.apiBaseUrl,
      apiKey: settings.apiKey,
      accessToken: settings.accessToken
    }),
    [campaignId, selectedVersionId, includeCurrentVersion, includeSummary, includeVersions, settings.apiBaseUrl, settings.apiKey, settings.accessToken]
  );

  const reload = useCallback(async () => {
    if (!campaignId) return;
    setLoading(true);
    setError("");
    try {
      const shouldLoadVersions = includeCurrentVersion || includeVersions;
      let nextWatermark = getDeltaWatermark(queryKey);
      let merged: CampaignWorkspaceData = dataRef.current;
      let hasMore = false;
      do {
        const response = await getCampaignWorkspaceDelta(settings, campaignId, {
          versionId: selectedVersionId,
          includeCurrentVersion,
          includeSummary,
          includeVersions: shouldLoadVersions,
          since: nextWatermark,
        });
        merged = mergeWorkspaceDelta(merged, response);
        nextWatermark = response.watermark ?? null;
        hasMore = response.has_more;
      } while (hasMore);
      setDeltaWatermark(queryKey, nextWatermark);
      dataRef.current = merged;
      setData(merged);
    } catch (err) {
      dataRef.current = initialData;
      setData(initialData);
      resetDeltaWatermark(queryKey);
      setError(err instanceof Error ? err.message : String(err));
    } finally {
      setLoading(false);
    }
  }, [settings, campaignId, includeCurrentVersion, includeSummary, includeVersions, selectedVersionId, queryKey, getDeltaWatermark, setDeltaWatermark, resetDeltaWatermark]);

  useEffect(() => {
    resetDeltaWatermark(queryKey);
    dataRef.current = initialData;
    setData(initialData);
  }, [queryKey, resetDeltaWatermark]);

  useEffect(() => {
    reload();
  }, [reload]);

  return { data, loading, error, reload, setError };
}

function mergeWorkspaceDelta(current: CampaignWorkspaceData, response: CampaignWorkspaceDeltaResponse): CampaignWorkspaceData {
  if (response.full) {
    return {
      campaign: response.campaign,
      versions: response.versions,
      currentVersion: response.current_version,
      summary: response.summary
    };
  }

  const deletedVersionIds = new Set(
    response.deleted
      .filter((item) => item.resource_type === "campaign_version")
      .map((item) => item.id)
  );
  const versionMap = new Map(current.versions.map((version) => [version.id, version]));
  for (const version of response.versions) {
    versionMap.set(version.id, version);
  }
  for (const versionId of deletedVersionIds) {
    versionMap.delete(versionId);
  }
  const currentVersionDeleted = current.currentVersion ? deletedVersionIds.has(current.currentVersion.id) : false;
  return {
    campaign: response.campaign ?? current.campaign,
    versions: Array.from(versionMap.values()).sort((left, right) => (right.version_number ?? 0) - (left.version_number ?? 0)),
    currentVersion: response.current_version ?? (currentVersionDeleted ? null : current.currentVersion),
    summary: response.summary ?? current.summary
  };
}