import { unstable_cache } from 'next/cache';
import { db } from '@/lib/db';
import { r2Client, R2_BUCKET_NAME } from '@/lib/r2';
import { ListObjectsV2Command, type ListObjectsV2CommandInput } from '@aws-sdk/client-s3';
import { isBunnyUploadsEnabled, isStripeBillingEnabled } from '@/lib/feature-flags';
import { getStripe, getStripePriceId } from '@/lib/stripe';
import { logError } from '@/lib/logger';

const BUNNY_API_BASE = 'https://video.bunnycdn.com';
const STORAGE_CACHE_SECONDS = 120;

interface R2StorageSnapshot {
  fileSizes: Map<string, number>;
  totalBytes: number;
  refreshedAt: string;
}

const globalForAdminStats = globalThis as unknown as {
  adminR2StorageSnapshot?: R2StorageSnapshot;
  adminR2StorageSnapshotPromise?: Promise<R2StorageSnapshot>;
};

interface BunnyStorageStats {
  totalBytes: number;
  byVideoId: Record<string, number>;
}

function bigintToNumber(value: bigint): number {
  return value > BigInt(Number.MAX_SAFE_INTEGER) ? Number.MAX_SAFE_INTEGER : Number(value);
}

function getBunnyConfig(): { apiKey: string; libraryId: string } {
  const apiKey = process.env.BUNNY_STREAM_API_KEY;
  const libraryId =
    process.env.BUNNY_STREAM_LIBRARY_ID || process.env.NEXT_PUBLIC_BUNNY_STREAM_LIBRARY_ID;
  if (!apiKey || !libraryId) {
    throw new Error('Missing Bunny Stream credentials.');
  }
  return { apiKey, libraryId };
}

function toRecord(value: unknown): Record<string, unknown> | null {
  if (!value || typeof value !== 'object') return null;
  return value as Record<string, unknown>;
}

function parseBunnyVideoStorageBytes(item: unknown): number {
  const record = toRecord(item);
  if (!record) return 0;

  const candidates = ['storageSize', 'storage', 'size'];
  for (const key of candidates) {
    const value = record[key];
    if (typeof value === 'number' && Number.isFinite(value) && value > 0) {
      return value;
    }
  }

  return 0;
}

function parseBunnyVideoGuid(item: unknown): string | null {
  const record = toRecord(item);
  if (!record) return null;
  const value = record.guid;
  return typeof value === 'string' && value.length > 0 ? value : null;
}

async function listAllR2FileSizes(): Promise<Map<string, number>> {
  const fileSizes = new Map<string, number>();
  let isTruncated = true;
  let continuationToken: string | undefined;

  while (isTruncated) {
    const commandParams: ListObjectsV2CommandInput = { Bucket: R2_BUCKET_NAME };
    if (continuationToken) {
      commandParams.ContinuationToken = continuationToken;
    }

    const data = await r2Client.send(new ListObjectsV2Command(commandParams));
    if (data.Contents) {
      for (const item of data.Contents) {
        if (item.Key) fileSizes.set(item.Key, item.Size || 0);
      }
    }
    isTruncated = data.IsTruncated ?? false;
    continuationToken = data.NextContinuationToken;
  }

  return fileSizes;
}

async function buildR2StorageSnapshot(): Promise<R2StorageSnapshot> {
  const fileSizes = await listAllR2FileSizes();
  let totalBytes = 0;
  for (const size of fileSizes.values()) {
    totalBytes += size;
  }

  return {
    fileSizes,
    totalBytes,
    refreshedAt: new Date().toISOString(),
  };
}

async function getR2StorageSnapshot(): Promise<R2StorageSnapshot> {
  if (globalForAdminStats.adminR2StorageSnapshot) {
    return globalForAdminStats.adminR2StorageSnapshot;
  }

  return Promise.reject(
    new Error(
      'R2 storage snapshot is not available. Trigger a manual refresh from admin dashboard.'
    )
  );
}

export async function refreshR2StorageSnapshot(): Promise<string> {
  // Single-flight. The promise slot was declared and cleared but never read, so two
  // concurrent admin refreshes each walked the whole bucket. A second caller now joins
  // the walk already in progress.
  const inFlight = globalForAdminStats.adminR2StorageSnapshotPromise;
  if (inFlight) {
    return (await inFlight).refreshedAt;
  }

  const pending = buildR2StorageSnapshot();
  globalForAdminStats.adminR2StorageSnapshotPromise = pending;
  try {
    const snapshot = await pending;
    globalForAdminStats.adminR2StorageSnapshot = snapshot;
    return snapshot.refreshedAt;
  } finally {
    globalForAdminStats.adminR2StorageSnapshotPromise = undefined;
  }
}

async function fetchBunnyStorageStats(): Promise<BunnyStorageStats> {
  // isBunnyUploadsEnabled(), not isBunnyUploadsFeatureEnabled(): the flag alone defaults
  // to on, so a self-hosted install that never configured Bunny threw
  // "Missing Bunny Stream credentials." out of getBunnyConfig() below and the dashboard
  // reported -1 instead of zero.
  if (!isBunnyUploadsEnabled()) {
    return { totalBytes: 0, byVideoId: {} };
  }

  const { apiKey, libraryId } = getBunnyConfig();
  const byVideoId: Record<string, number> = {};
  let totalBytes = 0;
  let page = 1;
  const itemsPerPage = 100;

  while (page <= 200) {
    const response = await fetch(
      `${BUNNY_API_BASE}/library/${libraryId}/videos?page=${page}&itemsPerPage=${itemsPerPage}`,
      { headers: { AccessKey: apiKey }, cache: 'no-store' }
    );

    if (!response.ok) {
      throw new Error(`Bunny API failed (${response.status})`);
    }

    const json = await response.json();
    const record = toRecord(json);
    if (!record) break;

    const rawItems = Array.isArray(record.items)
      ? record.items
      : Array.isArray(record.Items)
        ? record.Items
        : [];

    if (rawItems.length === 0) break;

    for (const rawItem of rawItems) {
      const guid = parseBunnyVideoGuid(rawItem);
      if (!guid) continue;
      const storageBytes = parseBunnyVideoStorageBytes(rawItem);
      byVideoId[guid] = storageBytes;
      totalBytes += storageBytes;
    }

    const totalItems =
      typeof record.totalItems === 'number'
        ? record.totalItems
        : typeof record.TotalItems === 'number'
          ? record.TotalItems
          : null;

    if (totalItems !== null && page * itemsPerPage >= totalItems) {
      break;
    }

    page += 1;
  }

  return { totalBytes, byVideoId };
}

export async function getCachedTotalStorage(): Promise<number> {
  try {
    const snapshot = await getR2StorageSnapshot();
    return snapshot.totalBytes;
  } catch (err) {
    logError('Failed to fetch total storage stats:', err);
    return -1;
  }
}

export const getCachedBunnyStorageStats = unstable_cache(
  async () => {
    try {
      return await fetchBunnyStorageStats();
    } catch (err) {
      logError('Failed to fetch Bunny storage stats:', err);
      return { totalBytes: -1, byVideoId: {} } as BunnyStorageStats;
    }
  },
  ['admin-bunny-storage'],
  { revalidate: STORAGE_CACHE_SECONDS }
);

export const getCachedUserBunnyStorage = unstable_cache(
  async () => {
    const perUserStorage: Record<string, number> = {};
    try {
      const bunnyStats = await getCachedBunnyStorageStats();
      if (bunnyStats.totalBytes < 0) return perUserStorage;

      const [bunnyVersions, bunnyAssets] = await Promise.all([
        db.videoVersion.findMany({
          where: { providerId: 'bunny' },
          select: {
            videoId: true,
            // What the uploader declared, used as a floor below.
            sizeBytes: true,
            video: {
              select: {
                project: {
                  // The workspace owner, not the project owner. lib/storage-quota.ts bills
                  // R2 versions to the workspace owner and comment media below does the
                  // same, and getCachedUserBunnyStorage feeds getUserTotalStorageBytes, so
                  // the moment project and workspace ownership can differ one workspace's
                  // Bunny bytes and its R2 bytes would count against two different quotas.
                  select: { workspace: { select: { ownerId: true } } },
                },
              },
            },
          },
        }),
        db.videoAsset.findMany({
          where: {
            provider: 'BUNNY',
            providerVideoId: { not: null },
          },
          select: {
            providerVideoId: true,
            billedUserId: true,
            sizeBytes: true,
          },
        }),
      ]);

      /**
       * What this video costs us, as the larger of the two numbers we have.
       *
       * Bunny reports nothing for a video until it has finished encoding it,
       * which on a half-hour source is most of an hour, and reading that zero
       * literally meant an upload was free for as long as it was being
       * processed: it did not show on the uploader's storage page and it did not
       * count against the next upload's quota check. The size declared when the
       * upload was admitted stands in until Bunny has a figure of its own, and
       * Bunny's wins once it arrives, because the renditions it makes are the
       * real bill and they are larger than the source.
       */
      const chargeableSize = (reported: number, declared: bigint | null): number => {
        const declaredBytes = declared === null ? 0 : Number(declared);
        return reported > declaredBytes ? reported : declaredBytes;
      };

      const seenVideoIds = new Set<string>();
      for (const version of bunnyVersions) {
        const ownerId = version.video.project.workspace.ownerId;
        const dedupeKey = `${ownerId}:${version.videoId}`;
        if (seenVideoIds.has(dedupeKey)) continue;
        seenVideoIds.add(dedupeKey);

        const size = chargeableSize(bunnyStats.byVideoId[version.videoId] || 0, version.sizeBytes);
        perUserStorage[ownerId] = (perUserStorage[ownerId] || 0) + size;
      }

      for (const asset of bunnyAssets) {
        if (!asset.providerVideoId) continue;
        const billedUserId = asset.billedUserId;
        const dedupeKey = `${billedUserId}:${asset.providerVideoId}`;
        if (seenVideoIds.has(dedupeKey)) continue;
        seenVideoIds.add(dedupeKey);

        const size = chargeableSize(
          bunnyStats.byVideoId[asset.providerVideoId] || 0,
          asset.sizeBytes
        );
        perUserStorage[billedUserId] = (perUserStorage[billedUserId] || 0) + size;
      }
    } catch (err) {
      logError('Failed to calculate per-user Bunny storage:', err);
    }
    return perUserStorage;
  },
  ['admin-user-bunny-storage'],
  { revalidate: STORAGE_CACHE_SECONDS }
);

export async function getCachedUserMediaStorage(): Promise<
  Record<string, { total: number; voice: number; image: number }>
> {
  // Return a plain object so it maps cleanly out of server component boundaries
  const userStorage: Record<string, { total: number; voice: number; image: number }> = {};
  try {
    const snapshot = await getR2StorageSnapshot();
    const seenKeys = new Set<string>();

    const [mediaComments, imageAssets, audioAssets] = await Promise.all([
      db.comment.findMany({
        where: { OR: [{ voiceUrl: { not: null } }, { imageUrl: { not: null } }] },
        select: {
          voiceUrl: true,
          imageUrl: true,
          version: {
            select: {
              video: {
                select: {
                  project: {
                    select: {
                      workspace: {
                        select: { ownerId: true },
                      },
                    },
                  },
                },
              },
            },
          },
        },
      }),
      db.videoAsset.findMany({
        where: { provider: 'R2_IMAGE' },
        select: {
          sourceUrl: true,
          billedUserId: true,
        },
      }),
      db.videoAsset.findMany({
        where: { provider: 'R2_AUDIO' },
        select: {
          sourceUrl: true,
          billedUserId: true,
        },
      }),
    ]);

    for (const comment of mediaComments) {
      const billedUserId = comment.version.video.project.workspace.ownerId;
      if (!billedUserId) continue;

      if (!userStorage[billedUserId]) {
        userStorage[billedUserId] = { total: 0, voice: 0, image: 0 };
      }

      if (comment.voiceUrl) {
        const keyParts = comment.voiceUrl.split('/');
        const filename = keyParts[keyParts.length - 1];
        const r2Key = `voice/${filename}`;
        const dedupeKey = `${billedUserId}:${r2Key}`;
        if (!seenKeys.has(dedupeKey)) {
          seenKeys.add(dedupeKey);
          const size = snapshot.fileSizes.get(r2Key) || 0;
          userStorage[billedUserId].voice += size;
          userStorage[billedUserId].total += size;
        }
      }

      if (comment.imageUrl) {
        const keyParts = comment.imageUrl.split('/');
        const filename = keyParts[keyParts.length - 1];
        const r2Key = `images/${filename}`;
        const dedupeKey = `${billedUserId}:${r2Key}`;
        if (!seenKeys.has(dedupeKey)) {
          seenKeys.add(dedupeKey);
          const size = snapshot.fileSizes.get(r2Key) || 0;
          userStorage[billedUserId].image += size;
          userStorage[billedUserId].total += size;
        }
      }
    }

    for (const asset of imageAssets) {
      const billedUserId = asset.billedUserId;
      if (!billedUserId) continue;
      if (!userStorage[billedUserId]) {
        userStorage[billedUserId] = { total: 0, voice: 0, image: 0 };
      }

      const keyParts = asset.sourceUrl.split('/');
      const filename = keyParts[keyParts.length - 1];
      if (!filename) continue;
      const r2Key = `images/${filename}`;
      const dedupeKey = `${billedUserId}:${r2Key}`;
      if (seenKeys.has(dedupeKey)) continue;
      seenKeys.add(dedupeKey);

      const size = snapshot.fileSizes.get(r2Key) || 0;
      userStorage[billedUserId].image += size;
      userStorage[billedUserId].total += size;
    }

    for (const asset of audioAssets) {
      const billedUserId = asset.billedUserId;
      if (!billedUserId) continue;
      if (!userStorage[billedUserId]) {
        userStorage[billedUserId] = { total: 0, voice: 0, image: 0 };
      }

      const keyParts = asset.sourceUrl.split('/');
      const filename = keyParts[keyParts.length - 1];
      if (!filename) continue;
      const r2Key = `voice/${filename}`;
      const dedupeKey = `${billedUserId}:${r2Key}`;
      if (seenKeys.has(dedupeKey)) continue;
      seenKeys.add(dedupeKey);

      const size = snapshot.fileSizes.get(r2Key) || 0;
      userStorage[billedUserId].voice += size;
      userStorage[billedUserId].total += size;
    }
  } catch (err) {
    logError('Failed to parse user storage:', err);
  }
  return userStorage;
}

export const getCachedUserDownloadEgress = unstable_cache(
  async () => {
    const perUserDownloadEgress: Record<string, number> = {};
    try {
      const grouped = await db.downloadEgressEvent.groupBy({
        by: ['billedUserId'],
        _sum: {
          estimatedBytes: true,
        },
      });

      for (const row of grouped) {
        perUserDownloadEgress[row.billedUserId] = row._sum.estimatedBytes
          ? bigintToNumber(row._sum.estimatedBytes)
          : 0;
      }
    } catch (err) {
      logError('Failed to calculate per-user download egress:', err);
    }

    return perUserDownloadEgress;
  },
  ['admin-user-download-egress'],
  { revalidate: STORAGE_CACHE_SECONDS }
);

export interface StripeStats {
  activeSubscribers: number;
  trialingUsers: number;
  pastDueUsers: number;
  canceledUsers: number;
  freeUsers: number;
  /** UNPAID, INCOMPLETE and INCOMPLETE_EXPIRED, which belong to none of the buckets above. */
  otherStatusUsers: number;
  mrrCents: number;
  currency: string;
}

const STRIPE_STATS_CACHE_SECONDS = 300;

export const getCachedStripeStats = unstable_cache(
  async (): Promise<StripeStats | null> => {
    if (!isStripeBillingEnabled()) return null;

    try {
      const statusCounts = await db.user.groupBy({
        by: ['subscriptionStatus'],
        _count: { id: true },
      });

      const counts: Record<string, number> = {};
      for (const row of statusCounts) {
        counts[row.subscriptionStatus] = row._count.id;
      }

      const activeSubscribers = counts['ACTIVE'] ?? 0;
      const trialingUsers = counts['TRIALING'] ?? 0;
      const pastDueUsers = counts['PAST_DUE'] ?? 0;
      const canceledUsers = counts['CANCELED'] ?? 0;
      const freeUsers = counts['FREE'] ?? 0;
      // UNPAID, INCOMPLETE and INCOMPLETE_EXPIRED belonged to none of the five buckets
      // above, so those users were counted nowhere and the totals silently did not add
      // up to the user table.
      const otherStatusUsers =
        (counts['UNPAID'] ?? 0) + (counts['INCOMPLETE'] ?? 0) + (counts['INCOMPLETE_EXPIRED'] ?? 0);

      let mrrCents = 0;
      let currency = 'usd';

      try {
        const stripe = getStripe();
        const priceId = getStripePriceId();
        const price = await stripe.prices.retrieve(priceId);
        const unitAmount = price.unit_amount ?? 0;
        currency = price.currency ?? 'usd';
        mrrCents = activeSubscribers * unitAmount;
      } catch (err) {
        logError('Failed to fetch Stripe price for MRR calculation:', err);
      }

      return {
        activeSubscribers,
        trialingUsers,
        pastDueUsers,
        canceledUsers,
        freeUsers,
        otherStatusUsers,
        mrrCents,
        currency,
      };
    } catch (err) {
      logError('Failed to fetch Stripe stats:', err);
      return null;
    }
  },
  ['admin-stripe-stats'],
  { revalidate: STRIPE_STATS_CACHE_SECONDS }
);