-- ─────────────────────────────────────────────────────────────────────────────
--  Database layer – all MySQL calls live here
-- ─────────────────────────────────────────────────────────────────────────────

DB = {}

-- ── Users ──────────────────────────────────────────────────────────────────

---@param identifier string
---@param displayName string
---@return table?
function DB.GetOrCreateUser(identifier, displayName)
    local row = MySQL.single.await(
        'SELECT * FROM pc_live_users WHERE identifier = ?',
        { identifier }
    )
    if row then return row end

    MySQL.insert.await(
        'INSERT INTO pc_live_users (identifier, display_name, settings_json) VALUES (?, ?, ?)',
        { identifier, displayName, '{}' }
    )

    return MySQL.single.await(
        'SELECT * FROM pc_live_users WHERE identifier = ?',
        { identifier }
    )
end

---@param identifier string
---@param settings table
function DB.SaveSettings(identifier, settings)
    MySQL.update.await(
        'UPDATE pc_live_users SET settings_json = ? WHERE identifier = ?',
        { json.encode(settings), identifier }
    )
end

-- ── Installs ───────────────────────────────────────────────────────────────

---@param userId number
---@return table[]
function DB.GetInstalls(userId)
    return MySQL.query.await(
        'SELECT * FROM pc_live_installs WHERE user_id = ?',
        { userId }
    )
end

---@param userId number
---@param appId string
---@param version string
function DB.InstallApp(userId, appId, version)
    local existing = MySQL.single.await(
        'SELECT id FROM pc_live_installs WHERE user_id = ? AND app_id = ?',
        { userId, appId }
    )
    if existing then
        MySQL.update.await(
            'UPDATE pc_live_installs SET version = ?, installed_at = NOW() WHERE id = ?',
            { version, existing.id }
        )
    else
        MySQL.insert.await(
            'INSERT INTO pc_live_installs (user_id, app_id, version, installed_at) VALUES (?, ?, ?, NOW())',
            { userId, appId, version }
        )
    end
end

---@param userId number
---@param appId string
function DB.UninstallApp(userId, appId)
    MySQL.update.await(
        'DELETE FROM pc_live_installs WHERE user_id = ? AND app_id = ?',
        { userId, appId }
    )
end

-- ── Mail ───────────────────────────────────────────────────────────────────

---@param toId string
---@return table[]
function DB.GetInbox(toId)
    return MySQL.query.await(
        'SELECT * FROM pc_live_mail WHERE to_identifier = ? ORDER BY sent_at DESC LIMIT 100',
        { toId }
    )
end

---@param id number
---@param toId string
---@return table?
function DB.GetMail(id, toId)
    return MySQL.single.await(
        'SELECT * FROM pc_live_mail WHERE id = ? AND to_identifier = ?',
        { id, toId }
    )
end

---@param toId string
---@param fromId string
---@param subject string
---@param body string
---@return number  inserted id
function DB.SendMail(toId, fromId, subject, body)
    return MySQL.insert.await(
        'INSERT INTO pc_live_mail (to_identifier, from_identifier, subject, body, is_read, sent_at) VALUES (?, ?, ?, ?, 0, NOW())',
        { toId, fromId, subject, body }
    )
end

---@param toId       string  Empfänger-Identifier (aufgelöst)
---@param fromDisplay string  Absender-Anzeige (E-Mail oder Identifier)
---@param senderId   string  Roher Identifier des Absenders (für Gesendet-Abfrage)
---@param toAddress  string  Originale Empfängeradresse
---@param subject    string
---@param body       string
---@return number
--- deliveryId klammert die Kopien einer Zustellung zusammen: eine Mail an ein
--- geteiltes Postfach wird je Empfaenger einmal gespeichert, soll aber fuer
--- alle im selben Ordner landen.
function DB.SendMailExtended(toId, fromDisplay, senderId, toAddress, subject, body, deliveryId)
    return MySQL.insert.await(
        'INSERT INTO pc_live_mail'
        .. ' (to_identifier, from_identifier, sender_id, to_address, subject, body,'
        .. '  delivery_id, is_read, sent_at)'
        .. ' VALUES (?, ?, ?, ?, ?, ?, ?, 0, NOW())',
        { toId, fromDisplay, senderId, toAddress, subject, body, deliveryId }
    )
end

---@param id number
---@param toId string
function DB.MarkRead(id, toId)
    MySQL.update.await(
        'UPDATE pc_live_mail SET is_read = 1 WHERE id = ? AND to_identifier = ?',
        { id, toId }
    )
end

---@param id number
---@param toId string
function DB.DeleteMail(id, toId)
    MySQL.update.await(
        'DELETE FROM pc_live_mail WHERE id = ? AND to_identifier = ?',
        { id, toId }
    )
end

---@param toId string
---@return number
function DB.CountUnread(toId)
    local row = MySQL.single.await(
        'SELECT COUNT(*) as cnt FROM pc_live_mail WHERE to_identifier = ? AND is_read = 0',
        { toId }
    )
    return row and row.cnt or 0
end

---@param fromId string  Spieler-Identifier
---@return table[]
function DB.GetSent(fromId)
    return MySQL.query.await(
        'SELECT * FROM pc_live_mail'
        .. ' WHERE from_identifier = ? OR sender_id = ?'
        .. ' ORDER BY sent_at DESC LIMIT 100',
        { fromId, fromId }
    )
end

-- ── Mail Folders ───────────────────────────────────────────────────────────
--
-- Ordner gehoeren zum Postfach, nicht zur Person: ein geteiltes Postfach wird
-- von mehreren bedient und braucht dieselbe Struktur fuer alle.
--
--   address = ''  → persoenliche Ordner (Spalte address IS NULL)
--   address ~= '' → Ordner dieses Postfachs
--
-- Der Aufrufer muss vorher pruefen, ob die Person das Postfach benutzen darf.

---@param identifier string
---@param address string|nil
---@return table[]
function DB.GetFolders(identifier, address)
    if address and address ~= '' then
        return MySQL.query.await(
            'SELECT * FROM pc_live_mail_folders WHERE address = ? ORDER BY name ASC',
            { address }
        ) or {}
    end
    return MySQL.query.await(
        'SELECT * FROM pc_live_mail_folders WHERE identifier = ? AND address IS NULL ORDER BY name ASC',
        { identifier }
    ) or {}
end

---@param identifier string
---@param address string|nil
---@param name string
---@return number
function DB.CreateFolder(identifier, address, name)
    return MySQL.insert.await(
        'INSERT INTO pc_live_mail_folders (identifier, address, name) VALUES (?, ?, ?)',
        { identifier, (address ~= '' and address or nil), name }
    )
end

--- Gibt den Ordner zurueck, wenn er zu diesem Postfach gehoert – sonst nil.
--- Damit haengt jede Ordneraktion an einer Besitzpruefung statt an der Id
--- allein, die der Client frei mitschicken kann.
---@param folderId number
---@param identifier string
---@param address string|nil
---@return table|nil
function DB.GetFolder(folderId, identifier, address)
    if address and address ~= '' then
        return MySQL.single.await(
            'SELECT * FROM pc_live_mail_folders WHERE id = ? AND address = ?',
            { folderId, address }
        )
    end
    return MySQL.single.await(
        'SELECT * FROM pc_live_mail_folders WHERE id = ? AND identifier = ? AND address IS NULL',
        { folderId, identifier }
    )
end

---@param folderId number
---@param identifier string
---@param address string|nil
function DB.DeleteFolder(folderId, identifier, address)
    -- Mails zurueck in den Posteingang. Bei einem geteilten Postfach betrifft
    -- das die Kopien aller Beteiligten, sonst blieben deren Mails in einem
    -- Ordner haengen, den es nicht mehr gibt.
    if address and address ~= '' then
        MySQL.update.await(
            'UPDATE pc_live_mail SET folder_id = NULL WHERE folder_id = ? AND to_address = ?',
            { folderId, address }
        )
    else
        MySQL.update.await(
            'UPDATE pc_live_mail SET folder_id = NULL WHERE folder_id = ? AND to_identifier = ?',
            { folderId, identifier }
        )
    end

    MySQL.update.await('DELETE FROM pc_live_mail_folders WHERE id = ?', { folderId })
end

--- Mail einsortieren.
--- Im geteilten Postfach wandern alle Kopien derselben Zustellung mit, damit
--- die Ablage fuer alle gleich aussieht.
---@param mailId number
---@param folderId number|nil  nil = Posteingang
---@param identifier string
---@param address string|nil
function DB.MoveMailToFolder(mailId, folderId, identifier, address)
    local mail = MySQL.single.await(
        'SELECT id, delivery_id, to_address FROM pc_live_mail WHERE id = ? AND to_identifier = ?',
        { mailId, identifier }
    )
    if not mail then return end

    local shared = address and address ~= '' and mail.to_address == address

    if shared and mail.delivery_id then
        MySQL.update.await(
            'UPDATE pc_live_mail SET folder_id = ? WHERE delivery_id = ? AND to_address = ?',
            { folderId, mail.delivery_id, address }
        )
        return
    end

    -- Aeltere Mails haben keine delivery_id – dann bleibt es bei der Kopie.
    MySQL.update.await(
        'UPDATE pc_live_mail SET folder_id = ? WHERE id = ? AND to_identifier = ?',
        { folderId, mailId, identifier }
    )
end

---@param folderId number
---@param identifier string
---@return table[]
function DB.GetFolderMails(folderId, identifier)
    return MySQL.query.await(
        'SELECT * FROM pc_live_mail WHERE folder_id = ? AND to_identifier = ? ORDER BY sent_at DESC',
        { folderId, identifier }
    ) or {}
end

---@param identifier string
---@return table[]
function DB.GetInboxOnly(identifier)
    return MySQL.query.await(
        'SELECT * FROM pc_live_mail WHERE to_identifier = ? AND folder_id IS NULL ORDER BY sent_at DESC LIMIT 100',
        { identifier }
    )
end

-- ── Calendar ───────────────────────────────────────────────────────────────
--
-- Ein Termin ist entweder privat (address IS NULL) oder gehoert einem Postfach.
-- Postfachtermine sind entweder nur fuer dessen Leute sichtbar ('shared') oder
-- fuer alle ('public') – bearbeiten darf sie in beiden Faellen nur, wer das
-- Postfach bedienen darf.

--- Alle Termine, die diese Person sehen darf.
---@param identifier string
---@param addresses string[]  Postfaecher, auf die sie Zugriff hat
---@return table[]
function DB.GetCalendar(identifier, addresses)
    addresses = addresses or {}

    local params = { identifier }
    local clauses = { '(c.identifier = ? AND c.address IS NULL)' }

    if #addresses > 0 then
        local marks = {}
        for _, addr in ipairs(addresses) do
            marks[#marks + 1] = '?'
            params[#params + 1] = addr
        end
        clauses[#clauses + 1] = ('(c.address IN (%s))'):format(table.concat(marks, ','))
    end

    -- Oeffentliche Termine sieht jeder, auch ohne Zugriff auf das Postfach.
    clauses[#clauses + 1] = "(c.visibility = 'public')"

    return MySQL.query.await(
        'SELECT c.* FROM pc_live_calendar c WHERE '
        .. table.concat(clauses, ' OR ') .. ' ORDER BY c.start_at ASC',
        params
    ) or {}
end

---@param id number
---@return table|nil
function DB.GetCalendarEvent(id)
    return MySQL.single.await('SELECT * FROM pc_live_calendar WHERE id = ?', { id })
end

---@param identifier string
---@param address string|nil  '' oder nil = privat
---@param visibility string   'private' | 'shared' | 'public'
---@param data table
---@return number
function DB.AddCalendarEvent(identifier, address, visibility, data)
    return MySQL.insert.await(
        'INSERT INTO pc_live_calendar'
        .. ' (identifier, address, visibility, title, description, start_at, end_at, color)'
        .. ' VALUES (?, ?, ?, ?, ?, ?, ?, ?)',
        { identifier, (address ~= '' and address or nil), visibility,
          data.title, data.description or '', data.start_at,
          data.end_at or nil, data.color or '#00aaff' }
    )
end

--- Aendern. Die Berechtigung prueft der Aufrufer (server/calendar.lua) –
--- hier steht keine Bedingung mehr, weil ein Postfachtermin auch von jemandem
--- geaendert werden darf, der ihn nicht angelegt hat.
---@param id number
---@param address string|nil
---@param visibility string
---@param data table
function DB.UpdateCalendarEvent(id, address, visibility, data)
    MySQL.update.await(
        'UPDATE pc_live_calendar SET address=?, visibility=?, title=?, description=?,'
        .. ' start_at=?, end_at=?, color=? WHERE id=?',
        { (address ~= '' and address or nil), visibility,
          data.title, data.description or '', data.start_at,
          data.end_at or nil, data.color or '#00aaff', id }
    )
end

---@param id number
function DB.DeleteCalendarEvent(id)
    MySQL.update.await('DELETE FROM pc_live_calendar WHERE id = ?', { id })
end

-- ── Contacts ───────────────────────────────────────────────────────────────

---@param identifier string
---@return table[]
function DB.GetContacts(identifier)
    return MySQL.query.await(
        'SELECT * FROM pc_live_contacts WHERE identifier = ? ORDER BY name ASC',
        { identifier }
    )
end

---@param identifier string
---@param data table
---@return number
function DB.AddContact(identifier, data)
    return MySQL.insert.await(
        'INSERT INTO pc_live_contacts (identifier, name, email, phone, notes) VALUES (?, ?, ?, ?, ?)',
        { identifier, data.name, data.email or '', data.phone or '', data.notes or '' }
    )
end

---@param id number
---@param identifier string
---@param data table
function DB.UpdateContact(id, identifier, data)
    MySQL.update.await(
        'UPDATE pc_live_contacts SET name=?, email=?, phone=?, notes=? WHERE id=? AND identifier=?',
        { data.name, data.email or '', data.phone or '', data.notes or '', id, identifier }
    )
end

---@param id number
---@param identifier string
function DB.DeleteContact(id, identifier)
    MySQL.update.await(
        'DELETE FROM pc_live_contacts WHERE id = ? AND identifier = ?',
        { id, identifier }
    )
end