// SQL for the four forum tables (TEAMS.md §5.2, §5.2a).
//
// Kept apart from teamAccess.db.js for the same reason that file is kept apart
// from teams.db.js: forum CONTENT and forum ACCESS are different questions, and a
// query here that read `team_members` to decide who may see a thread would be the
// exact collapse §2.5 forbids. Nothing in this file resolves access; callers hand
// it a decision the resolver already made.

const { query } = require('../../utils/db')

const THREAD_COLUMNS = `
  id, team_id, type, title, created_by, created_username, created_at,
  last_post_at, post_count, pinned, locked, status`

const POST_COLUMNS = `
  id, thread_id, author_user_id, author_username, body_html, created_at,
  edited_at, edited_by, status`

// ── threads ────────────────────────────────────────────────────────────────

/**
 * A Team's threads, newest activity first with pinned rows on top.
 *
 * `includeHidden` is the staff/leader view. Hidden is not deleted: a hidden
 * thread stays in the ledger and comes back with `unhide`, which is why the
 * status filter is a parameter rather than a WHERE clause everyone remembers.
 */
async function threadsByTeam(teamId, { includeHidden = false, limit = 50, offset = 0 } = {}) {
  const statuses = includeHidden ? "('visible','hidden')" : "('visible')"
  return query(
    `SELECT ${THREAD_COLUMNS} FROM team_forum_threads
      WHERE team_id = ? AND status IN ${statuses}
      ORDER BY pinned DESC, COALESCE(last_post_at, created_at) DESC, id DESC
      LIMIT ? OFFSET ?`,
    [teamId, limit, offset],
  )
}

async function threadById(id) {
  const rows = await query(`SELECT ${THREAD_COLUMNS} FROM team_forum_threads WHERE id = ? LIMIT 1`, [id])
  return rows[0] || null
}

async function insertThread({ teamId, type, title, createdBy, createdUsername }) {
  const res = await query(
    `INSERT INTO team_forum_threads (team_id, type, title, created_by, created_username, last_post_at, post_count)
     VALUES (?, ?, ?, ?, ?, NOW(), 0)`,
    [teamId, type, title, createdBy, createdUsername],
  )
  return res.insertId
}

/** Apply one moderation action's effect. The LEDGER row is written separately. */
async function setThreadFlags(id, { pinned, locked, status }) {
  const sets = []
  const args = []
  if (pinned !== undefined) { sets.push('pinned = ?'); args.push(pinned ? 1 : 0) }
  if (locked !== undefined) { sets.push('locked = ?'); args.push(locked ? 1 : 0) }
  if (status !== undefined) { sets.push('status = ?'); args.push(status) }
  if (!sets.length) return false
  args.push(id)
  const res = await query(`UPDATE team_forum_threads SET ${sets.join(', ')} WHERE id = ?`, args)
  return res.affectedRows > 0
}

// ── posts ──────────────────────────────────────────────────────────────────

async function postsByThread(threadId, { includeHidden = false } = {}) {
  const statuses = includeHidden ? "('visible','hidden')" : "('visible')"
  return query(
    `SELECT ${POST_COLUMNS} FROM team_forum_posts
      WHERE thread_id = ? AND status IN ${statuses} ORDER BY created_at, id`,
    [threadId],
  )
}

async function postById(id) {
  const rows = await query(`SELECT ${POST_COLUMNS} FROM team_forum_posts WHERE id = ? LIMIT 1`, [id])
  return rows[0] || null
}

/**
 * Append a post and move the thread's counters in the same breath.
 *
 * Two statements rather than a trigger: the counters are a denormalisation for
 * the thread list, and a trigger would put half the write in the schema where
 * nobody reading this file would find it.
 */
async function insertPost({ threadId, authorUserId, authorUsername, bodyHtml }) {
  const res = await query(
    `INSERT INTO team_forum_posts (thread_id, author_user_id, author_username, body_html)
     VALUES (?, ?, ?, ?)`,
    [threadId, authorUserId, authorUsername, bodyHtml],
  )
  await query(
    'UPDATE team_forum_threads SET post_count = post_count + 1, last_post_at = NOW() WHERE id = ?',
    [threadId],
  )
  return res.insertId
}

async function setPostStatus(id, status) {
  const res = await query('UPDATE team_forum_posts SET status = ? WHERE id = ?', [status, id])
  return res.affectedRows > 0
}

/**
 * Rewrite a post's body, stamping who edited it and when.
 *
 * `edited_at` is set unconditionally, including when a staffer edits — the column
 * answers "has this been changed since it was written", which a reader needs to
 * know regardless of whose hand did it. `edited_by` is the second half of that
 * answer and is why the two are separate columns rather than a boolean.
 */
async function updatePostBody(id, bodyHtml, editedBy) {
  const res = await query(
    'UPDATE team_forum_posts SET body_html = ?, edited_at = NOW(), edited_by = ? WHERE id = ?',
    [bodyHtml, editedBy, id],
  )
  return res.affectedRows > 0
}

/**
 * Recompute a thread's denormalised counters from the posts that are actually
 * visible.
 *
 * Called after every post moderation rather than incrementing and decrementing,
 * because hide → unhide → delete → restore is a sequence in which a counter kept
 * by deltas drifts the first time any step is retried or raced. The read is one
 * indexed aggregate over one thread; correctness is worth more than the write it
 * saves. `last_post_at` falls back to NULL for an emptied thread, which is what
 * `threadsByTeam`'s COALESCE onto `created_at` already expects.
 */
async function recountThread(threadId) {
  await query(
    `UPDATE team_forum_threads t
        SET t.post_count = (SELECT COUNT(*) FROM team_forum_posts p
                             WHERE p.thread_id = t.id AND p.status = 'visible'),
            t.last_post_at = (SELECT MAX(p.created_at) FROM team_forum_posts p
                               WHERE p.thread_id = t.id AND p.status = 'visible')
      WHERE t.id = ?`,
    [threadId],
  )
}

// ── the moderation ledger (append-only) ────────────────────────────────────

async function insertModeration({ teamId, targetType, targetId, action, actorUserId, actorUsername, actorRole, reason }) {
  await query(
    `INSERT INTO team_forum_moderation
       (team_id, target_type, target_id, action, actor_user_id, actor_username, actor_role, reason)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
    [teamId, targetType, targetId, action, actorUserId, actorUsername, actorRole, reason ?? null],
  )
}

async function moderationForTeam(teamId, { limit = 100, offset = 0 } = {}) {
  return query(
    `SELECT id, team_id, target_type, target_id, action, actor_user_id, actor_username,
            actor_role, reason, created_at
       FROM team_forum_moderation WHERE team_id = ?
      ORDER BY created_at DESC, id DESC LIMIT ? OFFSET ?`,
    [teamId, limit, offset],
  )
}

// ── uploads (§5.2a) ────────────────────────────────────────────────────────

const UPLOAD_COLUMNS = `
  id, team_id, post_id, uploader_user_id, uploader_username, filename, mimetype,
  byte_size, created_at, deleted_at, deleted_by`

async function insertUpload({ teamId, postId, uploaderUserId, uploaderUsername, filename, mimetype, byteSize }) {
  const res = await query(
    `INSERT INTO team_forum_uploads
       (team_id, post_id, uploader_user_id, uploader_username, filename, mimetype, byte_size)
     VALUES (?, ?, ?, ?, ?, ?, ?)`,
    [teamId, postId ?? null, uploaderUserId, uploaderUsername, filename, mimetype, byteSize],
  )
  return res.insertId
}

async function uploadById(id) {
  const rows = await query(`SELECT ${UPLOAD_COLUMNS} FROM team_forum_uploads WHERE id = ? LIMIT 1`, [id])
  return rows[0] || null
}

/** Bytes this account has uploaded in the trailing window — the §5.5.4 daily quota. */
async function bytesUploadedSince(userId, sinceHours) {
  const rows = await query(
    `SELECT COALESCE(SUM(byte_size), 0) AS bytes FROM team_forum_uploads
      WHERE uploader_user_id = ? AND created_at > (NOW() - INTERVAL ? HOUR)`,
    [userId, sinceHours],
  )
  return Number(rows[0]?.bytes || 0)
}

/** The admin attribution view: who uploaded what, when, how much, and where. */
async function listUploads({ limit = 100, offset = 0, includeDeleted = false } = {}) {
  return query(
    `SELECT u.id, u.team_id, u.post_id, u.uploader_user_id, u.uploader_username,
            u.filename, u.mimetype, u.byte_size, u.created_at, u.deleted_at, u.deleted_by,
            t.name AS team_name, t.slug AS team_slug
       FROM team_forum_uploads u JOIN teams t ON t.id = u.team_id
      ${includeDeleted ? '' : 'WHERE u.deleted_at IS NULL'}
      ORDER BY u.created_at DESC, u.id DESC LIMIT ? OFFSET ?`,
    [limit, offset],
  )
}

async function softDeleteUpload(id, deletedBy) {
  const res = await query(
    'UPDATE team_forum_uploads SET deleted_at = NOW(), deleted_by = ? WHERE id = ? AND deleted_at IS NULL',
    [deletedBy, id],
  )
  return res.affectedRows > 0
}

/** Soft-delete every upload attached to a post — the lifecycle half of §5.5.4. */
async function softDeleteUploadsForPost(postId, deletedBy) {
  await query(
    'UPDATE team_forum_uploads SET deleted_at = NOW(), deleted_by = ? WHERE post_id = ? AND deleted_at IS NULL',
    [deletedBy, postId],
  )
}

/**
 * The other half of the pair: a restored post gets its images back.
 *
 * Without this, `delete` then `restore` returns the words and loses the pictures —
 * and loses them SILENTLY, because the soft-deleted rows survive the retention
 * window before the sweep takes the bytes, so the post looks fine until the night
 * it does not. Beyond that window the row itself is gone and this is a no-op;
 * nothing can be done about that and nothing should pretend otherwise.
 */
async function restoreUploadsForPost(postId) {
  await query(
    'UPDATE team_forum_uploads SET deleted_at = NULL, deleted_by = NULL WHERE post_id = ? AND deleted_at IS NOT NULL',
    [postId],
  )
}

/** Rows soft-deleted longer ago than the retention window — the sweep's worklist. */
async function sweepableUploads(retentionDays) {
  return query(
    `SELECT id, filename FROM team_forum_uploads
      WHERE deleted_at IS NOT NULL AND deleted_at < (NOW() - INTERVAL ? DAY)`,
    [retentionDays],
  )
}

/** Never-referenced uploads older than the grace period — a composer opened and abandoned. */
async function orphanedUploads(graceHours) {
  return query(
    `SELECT id, filename FROM team_forum_uploads
      WHERE post_id IS NULL AND deleted_at IS NULL AND created_at < (NOW() - INTERVAL ? HOUR)`,
    [graceHours],
  )
}

async function deleteUploadRows(ids) {
  if (!ids.length) return 0
  const res = await query(
    `DELETE FROM team_forum_uploads WHERE id IN (${ids.map(() => '?').join(',')})`,
    ids,
  )
  return res.affectedRows
}


module.exports = {
  threadsByTeam,
  threadById,
  insertThread,
  setThreadFlags,
  postsByThread,
  postById,
  insertPost,
  setPostStatus,
  updatePostBody,
  recountThread,
  insertModeration,
  moderationForTeam,
  insertUpload,
  uploadById,
  bytesUploadedSince,
  listUploads,
  softDeleteUpload,
  softDeleteUploadsForPost,
  restoreUploadsForPost,
  sweepableUploads,
  orphanedUploads,
  deleteUploadRows,
}