local mp = require("mp")
local msg = require("mp.msg")

local misc = require("src.utils.misc")

---@class list.item
---@field ass string
---@field style string

---@class list
---@field open boolean is the list open
---@field header string default header
---@field default_style string default ass styling for each item
---@field osd table mpv osd overlay table
---@field items list.item[]
---@field selected number index representing which item in items is selected
---@field keybinds table[] a list of keybinds to be applied
---@field max_items number the maximum number of items which can fit on the screen
local list = {}

--- create a new list
---@return list list
function list:new()
  ---@type list
  ---@diagnostic disable-next-line: missing-fields
  local o = {}

  setmetatable(o, self)
  self.__index = self

  o.header = [[{\c&HC35CAA&}J{\c&HC66691&}e{\c&HCA7079&}l{\c&HCD7A61&}l{\c&HD18548&}y{\c&HD48F30&}f{\c&HD89918&}i{\c&HDCA400&}n]]
  o.default_style = [[{\r\fs23\fnmonospace}]]

  o.osd = mp.create_osd_overlay("ass-events")
  o.osd.data = ""
  o.selected = 1
  o.keybinds = {}
  o.max_items = 26

  return o
end

--- small wrapper around the list to set all items and redraw immediately
---@param items list.item[]?
function list:set(items)
  self.items = items or {}
  self:update()
end

--- display text fading in and out
---@param rate number time between each step
---@param text string
---@return table timer
function list:set_fade_animation(rate, text)
  self.selected = 0
  local opacity, direction = 255, -1
  local function load_animation()
    opacity = opacity + direction * 10
    if opacity >= 255 then
      opacity = 255
      direction = -1
    elseif opacity <= 0 then
      opacity = 0
      direction = 1
    end
    self:set({{
      style = string.format(
        [[{\alpha%s&}{\c&Hffffff&}]],
        string.format("&H%02X&", 255 - math.floor(opacity))
      ),
      ass = text,
    }})
  end
  return misc.mpv_timer(rate, load_animation, text)
end

--- small wrapper around list:set to log the text provided
---@param item list.item
function list:log(item)
  self.selected = 0
  msg.fatal(item.ass)
  self:set({ item })
end

--- draw the list to the screen
function list:update()
  self.open = true

  -- add all keybinds when we open the ui
  for _, v in ipairs(self.keybinds) do
    mp.add_forced_key_binding(v[1], "dynamic/"..self.osd.id.."/"..v[2], v[3], v[4])
  end

  ---@type list.item[]
  local scrolled_items = {}
  local selected = self.selected
  if self.selected > (self.max_items / 2) then
    if (#self.items - self.selected) > (self.max_items / 2) then
      scrolled_items = { table.unpack(
        self.items or {},
        self.selected - (self.max_items / 2) + 1
      ) }
      selected = (self.max_items / 2)
    else
      scrolled_items = { table.unpack(
        self.items or {},
        (#self.items - self.max_items) + 1
      ) }
      selected = (self.max_items / 2) + (((self.max_items / 2) + self.selected)
                  - #self.items)
    end
  else
    scrolled_items = self.items or {}
  end

  -- put all the items in the list
  self.osd.data = [[{\r\fnmonospace}]]..self.header..[[\N]]
  for i, item in ipairs(scrolled_items) do
    -- if self.selected <= 0 then there should be no selection indicators drawn
    if self.selected > 0 then
      if i == selected then
        self.osd.data = self.osd.data..self.default_style..[[● ]]
      else
        self.osd.data = self.osd.data..self.default_style..[[○ ]]
      end
    else
      self.osd.data = self.osd.data..self.default_style
    end
    self.osd.data = self.osd.data
                    ..(item.style or [[{\c&Hffffff&}]])
                    ..item.ass
    if self.items[i + 1] then
      self.osd.data = self.osd.data..[[{\r}\N]]
    end
  end
  self.osd:update()
end

--- close the list
function list:close()
  -- remove all the keybinds
  for _,v in ipairs(self.keybinds) do
    mp.remove_key_binding("dynamic/"..self.osd.id.."/"..v[2])
  end

  -- close the list
  self.osd:remove()
  self.open = false
end

--- go up
function list:up()
  if self.selected > 1 then
    self.selected = self.selected - 1
    self:update()
  end
end

--- go down
function list:down()
  if self.selected < #self.items then
    self.selected = self.selected + 1
    self:update()
  end
end

--- helper to addkeys to the list view
---@param keys string keybind
---@param name string action name
---@param fn function callback
---@param opts? table options
function list:addkey(keys, name, fn, opts)
  opts = opts or { repeatable = true }
  local i = 1
  for key in keys:gmatch("%S+") do
    table.insert(self.keybinds, { key, name..i, fn, opts })
    i = i + 1
  end
end

return list