local util = {}
local magick = require("magick")
local db = require("lapis.db")
local html_escape = require("lapis.html").escape
local constants   = require("constants")
local string_trim = require("lapis.util").trim

local Avatars = require("models").Avatars
local Users = require("models").Users
local Posts = require("models").Posts
local PostHistory = require("models").PostHistory

local babycode = require("lib.babycode")

util.TransientUser = {
  is_admin = function (self)
    return false
  end,
  is_mod = function (self)
    return false
  end,
  is_guest = function (self)
    return true
  end,
  is_system = function (self)
    return false
  end,
  is_logged_in_guest = function (self)
    return false
  end,
  is_logged_in = function (self)
    return false
  end,
  username = "Deleted User",
}

-- PURE API

function util.get_user_avatar_url(req, user)
  return Avatars:find(user.avatar_id).file_path
end

---split a string
---@param s string subject
---@param delimiter string? string to split by, can be empty to split by character
---@param max_matches integer? the maximum number of returned elements
---@param trim boolean? whether to trim whitespace off matches
---@param allow_empty boolean? should empty matches be in the resulting table
---@return string[]
function util.s_split(s, delimiter, max_matches, trim, allow_empty)
  local result = {}
  if s == "" then
    return result
  end
  trim = trim == nil and true or trim
  local tr = function(subj)
    if trim then return string_trim(subj) else return subj end
  end
  max_matches = max_matches or -1
  allow_empty = allow_empty == nil and true or allow_empty
  
  if delimiter == "" then
    for i=1, #s do
      local c = s:sub(i, 1)
      if allow_empty or c ~= "" then
        table.insert(result, c)
        if max_matches > 0 and #result == max_matches then
          break
        end
      end
    end
    return result
  end
  
  local current_pos = 1
  local delim_len = #delimiter
  
  while true do
    if max_matches > 0 and #result >= max_matches then
      break
    end
---@diagnostic disable-next-line: param-type-mismatch
    local start_pos, end_pos = s:find(delimiter, current_pos, true)
    if not start_pos then
      break
    end
    local substr = s:sub(current_pos, start_pos - 1)
    if allow_empty or substr ~= "" then
      table.insert(result, tr(substr))
    end
    current_pos = end_pos + 1
  end
  
  local substr = s:sub(current_pos)
  if allow_empty or substr ~= "" then
    table.insert(result, tr(substr))
  end
  
  return result
end

function util.split_sentences(sentences, max_sentences)
  return util.s_split(sentences, ".", max_sentences or 2, true, false)
end

function util.infobox_message(msg)
  local sentences = util.split_sentences(msg)
  if #sentences == 1 then
    return "<b>" .. sentences[1] .. ". " .. "</b>"
  end
  return "<span><b>" .. sentences[1] .. ". " .. "</b> " .. sentences[2] .. ".</span>"
end

function util.get_logged_in_user(req)
  if req.session.session_key == nil then
    return nil
  end

  local session = db.select('* FROM "sessions" WHERE "key" = ? AND "expires_at" > "?" LIMIT 1', req.session.session_key, os.time())
  if #session > 0 then
    return Users:find({id = session[1].user_id})
  end

  return nil
end

function util.get_logged_in_user_or_transient(req)
  return util.get_logged_in_user(req) or util.TransientUser
end

function util.ntob(v)
  return v ~= 0
end

function util.bton(b)
  return 1 and b or 0
end

function util.stob(s)
  if s == "true" then
    return true
  end
  if s == "false" then
    return false
  end
end

function util.form_bool_to_sqlite(s)
  return util.bton(util.stob(s))
end

function util.is_thread_locked(thread)
  return util.ntob(thread.is_locked)
end

function util.is_topic_locked(topic)
  return util.ntob(topic.is_locked)
end

-- OTHER API

function util.validate_and_create_image(input_image, filename)
  local img = magick.load_image_from_blob(input_image)

  if not img then
    return false
  end

  img:strip()
  img:set_gravity("CenterGravity")

  local width, height = img:get_width(), img:get_height()
  local min_dim = math.min(width, height)
  if min_dim > 256 then
    local ratio = 256.0 / min_dim
    local new_w, new_h = width * ratio, height * ratio
    img:resize(new_w, new_h)
  end

  width, height = img:get_width(), img:get_height()
  local crop_size = math.min(width, height)
  local x_offset = (width - crop_size) / 2
  local y_offset = (height - crop_size) / 2
  img:crop(crop_size, crop_size, x_offset, y_offset)

  img:set_format("webp")
  img:set_quality(85)

  img:write(filename)
  img:destroy()
  return true
end

function util.destroy_avatar(avatar_id)
  if avatar_id == 1 then
    print("won't delete default avatar")
    return
  end
  
  local avatar = Avatars:find(avatar_id)
  
  if not avatar then
    return
  end
  
  local file_path = "static" .. avatar.file_path
  local f = io.open(file_path, "r")
  if not f then
    print("can't open avatar file")
  else
    f:close()
    os.remove(file_path)
    avatar:delete()
  end
end

function util.create_post(thread_id, user_id, content, markup_language)
  markup_language = markup_language or "babycode"
  db.query("BEGIN")
  local post = Posts:create({
    thread_id = thread_id,
    user_id = user_id,
    current_revision_id = db.NULL,
  })
  
  local parsed_content = ""
  if markup_language == "babycode" then
    parsed_content = babycode.to_html(content, html_escape)
  end
  
  local revision = PostHistory:create({
    post_id = post.id,
    content = parsed_content,
    is_initial_revision = true,
    original_markup = content,
    markup_language = "babycode",
  })
  
  post:update({current_revision_id = revision.id})
  
  db.query("COMMIT")
  return post
end

function util.transfer_and_delete_user(user)
  local deleted_user = Users:find({
    username = "DeletedUser",
  })
  -- this needs to be atomic
  db.query("BEGIN")
  db.query('UPDATE "threads" SET "user_id" = ? WHERE "user_id" = ?', deleted_user.id, user.id)
  db.query('UPDATE "posts" SET "user_id" = ? WHERE "user_id" = ?', deleted_user.id, user.id)
  user:delete() -- uncomment later
  db.query("COMMIT")
end

function util.pop_infobox(req)
  if not req.session.infobox then return end
  req.infobox = req.session.infobox
  req.session.infobox = nil
end

function util.inject_infobox(req, message, kind)
  kind = kind or constants.InfoboxKind.INFO
  local ib = {
    msg = message,
    kind = kind,
  }
  req.session.infobox = ib
end

function util.inject_err_infobox(req, message)
  local ib = {
    msg = message,
    kind = constants.InfoboxKind.ERROR,
  }
  req.session.infobox = ib
end

function util.inject_warn_infobox(req, message)
  local ib = {
    msg = message,
    kind = constants.InfoboxKind.WARN,
  }
  req.session.infobox = ib
end

return util