// ── Block and "Hide for me" (USER_SAFETY.md §1, §4.1) ──────────────────────
//
// A block lives on the blocker's ACCOUNT (S2), so it applies on the website and
// in the app, on every device. The rules that shape this file, each decided by
// the org lead:
//
//   S12  A block names the author's WEBSITE ACCOUNT whenever there is one. A
//        forum author always has one; a chat speaker has one when their game
//        identity is linked. Only an unlinked game identity — most people in a
//        Rust chat feed — is blocked as itself, a Steam id.
//   S14  When that identity is later linked, the game block becomes an account
//        block, the next time the member's blocks are read. From then on it hides
//        the account's forum posts too.
//   S8   Staff (admin, editor, moderator) cannot be blocked. Blocking one is
//        refused. A block whose target LATER became staff — promoted, or a game
//        block whose identity linked to a staff account — is kept but stops
//        applying, and the Blocked page says why.
//   S9   A block does nothing to the blocked person. They are not told.
//
// "Hide for me" is one item gone from one member's view; it files no report and
// changes nothing about the item (§1).
//
// Filtering happens on the server for every reader-specific read: core's forum
// here, and a module's per-viewer feeds through `ctx.safety.forViewer` (S11).

const db = require('./userSafety.db')
const targets = require('./targets')
const registries = require('../../modules/registries')
const { STAFF_ROLES } = require('../../utils/displayAuthor')
const log = require('../../utils/logger')('safety')

const isStaffRole = (role) => STAFF_ROLES.includes(role)

const refuse = (status, code, error) => ({ ok: false, status, code, error })

/**
 * This member's blocks, as they stand NOW.
 *
 * S14 runs here: every game block is checked against its module's links, and
 * one whose identity is linked is rewritten as an account block before the list
 * is answered. Reading is where it happens because a link is made in a module,
 * which has no reason to tell core, and a block that waited for a notification
 * would be a block that silently missed one.
 *
 * A module that does not answer leaves its game blocks as they are: they still
 * apply to the Steam id, which is the block the member made.
 */
async function currentBlocks(userId) {
  let rows = await db.blocksFor(userId)
  const game = rows.filter((r) => r.blocked_user_id == null && r.module_id)

  if (game.length) {
    const groups = new Map()
    for (const r of game) {
      const key = `${r.module_id}:${r.identity_kind}`
      if (!groups.has(key)) groups.set(key, [])
      groups.get(key).push(r)
    }

    let changed = false
    for (const group of groups.values()) {
      const ident = registries.gameIdentity(group[0].module_id, group[0].identity_kind)
      if (!ident) continue
      let owners = {}
      try {
        owners = (await targets.withTimeout(
          () => ident.ownersOf(group.map((r) => r.external_id)),
          targets.MODULE_TIMEOUT_MS,
        )) || {}
      } catch (err) {
        log.warn('game identity lookup failed; game blocks left as they are', {
          module: ident.owner, kind: ident.kind, message: err.message,
        })
        continue
      }
      for (const r of group) {
        const owner = Number(owners[r.external_id])
        if (!Number.isInteger(owner) || owner <= 0) continue
        // The member blocked a Steam id that turned out to be their own. A block
        // on yourself hides nothing worth hiding, so it is simply removed.
        if (owner === Number(userId)) await db.deleteBlock(userId, r.id)
        else await db.convertToAccountBlock(r.id, owner)
        changed = true
      }
    }
    if (changed) rows = await db.blocksFor(userId)
  }

  return rows.map((r) => ({
    ...r,
    applies: r.blocked_user_id == null ? true : !isStaffRole(r.blocked_role),
  }))
}

/** One block as the member sees it on Account → Blocked. */
function publicBlock(row) {
  const account = row.blocked_user_id != null
  const ident = account ? null : registries.gameIdentity(row.module_id, row.identity_kind)
  return {
    id: row.id,
    kind: account ? 'account' : 'game',
    name: account ? (row.blocked_username || row.display_name) : row.display_name,
    identity: account
      ? null
      : {
        module: row.module_id,
        kind: row.identity_kind,
        label: ident ? ident.label : row.identity_kind,
        id: row.external_id,
      },
    applies: row.applies,
    reason: row.applies ? null : 'staff',
    createdAt: row.created_at,
  }
}

async function listBlocks(actor) {
  return (await currentBlocks(actor.id)).map(publicBlock)
}

/** Block an account, after S8's check. */
async function blockAccount(actor, userId) {
  if (Number(userId) === Number(actor.id)) return refuse(400, 'self', 'You can’t block yourself.')
  const target = await db.userById(userId)
  if (!target) return refuse(404, 'not_found', 'Not found')
  if (isStaffRole(target.role)) return refuse(403, 'staff', 'You can’t block a staff member.')
  const id = await db.insertAccountBlock({
    blockerUserId: actor.id,
    blockedUserId: target.id,
    displayName: target.username,
  })
  if (id == null) return refuse(409, 'already_blocked', `You have already blocked ${target.username}.`)
  return { ok: true, block: { id, kind: 'account', name: target.username, identity: null, applies: true, reason: null } }
}

/**
 * Block the author of one item (S12).
 *
 * The client names the item, never the person: the server reads who wrote it,
 * through the same resolver a report uses, so a member can only block someone
 * whose words they could see, and the block lands on the account when there is
 * one.
 */
async function blockAuthorOf({ actor, targetType, targetId }) {
  if (!targets.isHideable(targetType)) return refuse(400, 'unknown_target', 'Unknown target')
  const item = await targets.resolve({ targetType, targetId, viewer: actor })
  if (!item) return refuse(404, 'not_found', 'Not found')

  const { author } = item
  if (author.userId != null) return blockAccount(actor, author.userId)

  // No account on the item. A forum item with no account is a deleted one, and
  // there is nobody left to block.
  if (!item.module || !author.identity) {
    return refuse(400, 'no_author', 'That account no longer exists.')
  }

  // A game identity. S12: its account first, when it has one.
  const ident = registries.gameIdentity(item.module, author.identity.kind)
  if (!ident) return refuse(400, 'no_author', 'This player can’t be blocked.')
  let owners
  try {
    owners = (await targets.withTimeout(() => ident.ownersOf([author.identity.id]), targets.MODULE_TIMEOUT_MS)) || {}
  } catch (err) {
    log.error('game identity lookup failed', { module: ident.owner, kind: ident.kind, message: err.message })
    return refuse(503, 'module_unavailable', 'The game module did not answer. Try again in a moment.')
  }
  const owner = Number(owners[author.identity.id])
  if (Number.isInteger(owner) && owner > 0) return blockAccount(actor, owner)

  const id = await db.insertGameBlock({
    blockerUserId: actor.id,
    moduleId: item.module,
    kind: author.identity.kind,
    externalId: author.identity.id,
    displayName: author.name,
  })
  if (id == null) return refuse(409, 'already_blocked', `You have already blocked ${author.name || 'this player'}.`)
  return {
    ok: true,
    block: {
      id,
      kind: 'game',
      name: author.name,
      identity: { module: item.module, kind: ident.kind, label: ident.label, id: author.identity.id },
      applies: true,
      reason: null,
    },
  }
}

async function unblock(actor, id) {
  return (await db.deleteBlock(actor.id, id)) ? { ok: true } : refuse(404, 'not_found', 'Not found')
}

// ── hide for me ────────────────────────────────────────────────────────────

/**
 * Hide one item for this member. The type must be one a member can hide; the
 * item is not looked up — see `user_hidden_items` in schema.sql for why a row for
 * an id that does not exist is harmless and an existence check is not.
 */
async function hide(actor, targetType, targetId) {
  if (!targets.isHideable(targetType)) return refuse(400, 'unknown_target', 'Unknown target')
  await db.insertHidden(actor.id, targetType, targetId)
  return { ok: true }
}

async function unhide(actor, targetType, targetId) {
  if (!targets.isHideable(targetType)) return refuse(400, 'unknown_target', 'Unknown target')
  await db.deleteHidden(actor.id, targetType, targetId)
  return { ok: true }
}

/** Account → Blocked's "Show them all again". */
async function clearHidden(actor) {
  return db.clearHidden(actor.id)
}

async function listHidden(actor) {
  return (await db.hiddenFor(actor.id)).map((r) => ({
    targetType: r.target_type,
    targetId: Number(r.target_id),
    createdAt: r.created_at,
  }))
}

// ── what one reader's reads leave out ──────────────────────────────────────

const EMPTY_FILTER = Object.freeze({
  blockedUserIds: new Set(),
  hidden: Object.freeze({ team_forum_thread: new Set(), team_forum_post: new Set() }),
})

/**
 * What core's forum leaves out for this reader: the accounts they block (that
 * still apply) and the threads and posts they hid.
 */
async function forumFilter(userId) {
  if (!userId) return EMPTY_FILTER
  const [blocks, hidden] = await Promise.all([
    currentBlocks(userId),
    db.hiddenFor(userId, targets.FORUM_HIDEABLE),
  ])
  const filter = {
    blockedUserIds: new Set(blocks.filter((b) => b.applies && b.blocked_user_id != null).map((b) => Number(b.blocked_user_id))),
    hidden: { team_forum_thread: new Set(), team_forum_post: new Set() },
  }
  for (const h of hidden) filter.hidden[h.target_type].add(Number(h.target_id))
  return filter
}

/**
 * `ctx.safety.forViewer` (API 1.21.0, S11): what one reader has blocked and
 * hidden, for the calling module.
 *
 * `blockedUserIds` — accounts, every module's concern: a speaker linked to one
 * is hidden whichever module's feed they speak in. `blockedIdentities` — this
 * module's own unlinked game blocks, by kind. `hidden` — this reader's hides on
 * this module's report targets, by type. Ids are answered as arrays of the type
 * the module gave them (numbers for target ids, strings for identities).
 */
async function forModuleViewer(moduleId, userId) {
  const empty = { blockedUserIds: [], blockedIdentities: {}, hidden: {} }
  if (!userId) return empty
  const types = registries.allReportTargets().filter((t) => t.owner === moduleId).map((t) => t.id)
  const [blocks, hidden] = await Promise.all([currentBlocks(userId), db.hiddenFor(userId, types)])

  const out = { blockedUserIds: [], blockedIdentities: {}, hidden: {} }
  for (const b of blocks) {
    if (!b.applies) continue
    if (b.blocked_user_id != null) out.blockedUserIds.push(Number(b.blocked_user_id))
    else if (b.module_id === moduleId) {
      if (!out.blockedIdentities[b.identity_kind]) out.blockedIdentities[b.identity_kind] = []
      out.blockedIdentities[b.identity_kind].push(String(b.external_id))
    }
  }
  for (const t of types) out.hidden[t] = []
  for (const h of hidden) out.hidden[h.target_type].push(Number(h.target_id))
  return out
}

/**
 * The members whose blocks cover this author, for a notification about something
 * the author wrote: a forum post is pushed, mailed and put in the inbox of every
 * member of its Team, and a member who blocks the author must not be told about it
 * (the forum itself already leaves the post out for them).
 *
 * S8 applies here too: a staff author is blocked by nobody, so this answers empty
 * and the post reaches everyone. Answers account blocks only. A game block on the
 * author's Steam id that S14 has not yet rewritten counts from the next time its
 * owner reads the forum or their blocks, which is when the rewrite happens.
 */
async function blockersOf(authorUserId) {
  const id = Number(authorUserId)
  if (!Number.isInteger(id) || id <= 0) return []
  const author = await db.userById(id)
  if (!author || isStaffRole(author.role)) return []
  return db.blockersOf(id)
}

/** `ctx.safety.staffAmong` (S13): which of these accounts are staff. */
async function staffAmong(userIds) {
  const ids = [...new Set((Array.isArray(userIds) ? userIds : [])
    .map(Number)
    .filter((n) => Number.isInteger(n) && n > 0))]
    .slice(0, 500)
  return db.staffAmong(ids, STAFF_ROLES)
}

module.exports = {
  currentBlocks,
  listBlocks,
  blockAuthorOf,
  blockAccount,
  unblock,
  hide,
  unhide,
  listHidden,
  clearHidden,
  forumFilter,
  forModuleViewer,
  blockersOf,
  staffAmong,
  publicBlock,
}