local core = require "core"
local command = require "core.command"
local common = require "core.common"
local config = require "core.config"
local View = require "core.view"
local style = require "core.style"

local BORDER_WIDTH = common.round(1 * SCALE)
local UNDERLINE_WIDTH = common.round(2 * SCALE)
local UNDERLINE_MARGIN = common.round(1 * SCALE)

local noop = function() end

---@class core.nagview : core.view
---@field super core.view
local NagView = View:extend()

function NagView:new()
  NagView.super.new(self)
  self.size.y = 0
  self.show_height = 0
  self.force_focus = false
  self.queue = {}
  self.scrollable = true
  self.target_height = 0
  self.on_mouse_pressed_root = nil
  self.dim_alpha = 0
end

function NagView:get_title()
  return self.title
end

-- The two methods below are duplicated from DocView
function NagView:get_line_height()
  return math.floor(style.font:get_height() * config.line_height)
end

function NagView:get_line_text_y_offset()
  local lh = self:get_line_height()
  local th = style.font:get_height()
  return (lh - th) / 2
end

-- Buttons height without padding
function NagView:get_buttons_height()
  local lh = style.font:get_height()
  local bt_padding = lh / 2
  return lh + 2 * BORDER_WIDTH + 2 * bt_padding
end

function NagView:get_target_height()
  return self.target_height + 2 * style.padding.y
end

function NagView:get_scrollable_size()
  local w, h = system.get_window_size(core.window)
  if self.visible and self:get_target_height() > h then
    self.size.y = h
    return self:get_target_height()
  else
    self.size.y = 0
  end
  return 0
end

function NagView:dim_window_content()
  local ox, oy = self:get_content_offset()
  oy = oy + self.show_height
  local w, h = core.root_view.size.x, core.root_view.size.y - oy
  core.root_view:defer_draw(function()
    local dim_color = { table.unpack(style.nagbar_dim) }
    dim_color[4] = style.nagbar_dim[4] * self.dim_alpha
    renderer.draw_rect(ox, oy, w, h, dim_color)
  end)
end

function NagView:change_hovered(i)
  if i ~= self.hovered_item then
    self.hovered_item = i
    self.underline_progress = 0
    core.redraw = true
  end
end

function NagView:each_option()
  return coroutine.wrap(function()
    if not self.options then return end
    local opt, bw,bh,ox,oy
    bh = self:get_buttons_height()
    ox,oy = self:get_content_offset()
    ox = ox + self.size.x
    oy = oy + self.show_height - bh - style.padding.y

    for i = #self.options, 1, -1 do
      opt = self.options[i]
      bw = style.font:get_width(opt.text) + 2 * BORDER_WIDTH + style.padding.x

      ox = ox - bw - style.padding.x
      coroutine.yield(i, opt, ox,oy,bw,bh)
    end
  end)
end

function NagView:on_mouse_moved(mx, my, ...)
  if not self.visible then return end
  core.set_active_view(self)
  NagView.super.on_mouse_moved(self, mx, my, ...)
  for i, _, x,y,w,h in self:each_option() do
    if mx >= x and my >= y and mx < x + w and my < y + h then
      self:change_hovered(i)
      break
    end
  end
end

local function register_mouse_pressed(self)
  if self.on_mouse_pressed_root then return end
  -- RootView is loaded locally to avoid NagView and RootView being
  -- mutually recursive
  local RootView = require "core.rootview"
  self.on_mouse_pressed_root = RootView.on_mouse_pressed
  local this = self
  function RootView:on_mouse_pressed(button, x, y, clicks)
    if
      not this:on_mouse_pressed(button, x, y, clicks)
    then
      return this.on_mouse_pressed_root(self, button, x, y, clicks)
    else
      return true
    end
  end
  self.new_on_mouse_pressed_root = RootView.on_mouse_pressed
end

local function unregister_mouse_pressed(self)
  local RootView = require "core.rootview"
  if
    self.on_mouse_pressed_root
    and
    -- just in case prevent overwriting what something else may
    -- have overwrote after us, but after testing with various
    -- plugins this doesn't seems to happen, but just in case
    self.new_on_mouse_pressed_root == RootView.on_mouse_pressed
  then
    RootView.on_mouse_pressed = self.on_mouse_pressed_root
    self.on_mouse_pressed_root = nil
    self.new_on_mouse_pressed_root = nil
  end
end

function NagView:on_mouse_pressed(button, mx, my, clicks)
  if not self.visible then return false end
  if NagView.super.on_mouse_pressed(self, button, mx, my, clicks) then return true end
  for i, _, x,y,w,h in self:each_option() do
    if mx >= x and my >= y and mx < x + w and my < y + h then
      self:change_hovered(i)
      command.perform "dialog:select"
    end
  end
  return true
end

function NagView:on_text_input(text)
  if not self.visible then return end
  if text:lower() == "y" then
    command.perform "dialog:select-yes"
  elseif text:lower() == "n" then
    command.perform "dialog:select-no"
  end
end

function NagView:update()
  if not self.visible and self.show_height <= 0 then return end
  NagView.super.update(self)

  if self.visible and core.active_view == self and self.title then
    local target_height = self:get_target_height()
    self:move_towards(self, "show_height", target_height, nil, "nagbar")
    self:move_towards(self, "underline_progress", 1, nil, "nagbar")
    self:move_towards(self, "dim_alpha", self.show_height / target_height, nil, "nagbar")
  else
    self:move_towards(self, "show_height", 0, nil, "nagbar")
    self:move_towards(self, "dim_alpha", 0, nil, "nagbar")
    if self.show_height <= 0 then
      self.title = nil
      self.message = nil
      self.options = nil
      self.on_selected = nil
    end
  end
end

local function draw_nagview_message(self)
  self:dim_window_content()

  -- draw message's background
  local ox, oy = self:get_content_offset()
  renderer.draw_rect(ox, oy, self.size.x, self.show_height, style.nagbar)

  ox = ox + style.padding.x

  core.push_clip_rect(ox, oy, self.size.x, self.show_height)

  -- if there are other items, show it
  if #self.queue > 0 then
    local str = string.format("[%d]", #self.queue)
    ox = common.draw_text(style.font, style.nagbar_text, str, "left", ox, oy, self.size.x, self.show_height)
    ox = ox + style.padding.x
  end

  -- draw message
  local lh = style.font:get_height() * config.line_height
  oy = oy + style.padding.y + (self.target_height - self:get_message_height()) / 2
  for msg_line in self.message:gmatch("(.-)\n") do
    local ty = oy + self:get_line_text_y_offset()
    renderer.draw_text(style.font, msg_line, ox, ty, style.nagbar_text)
    oy = oy + lh
  end

  -- draw buttons
  for i, opt, bx,by,bw,bh in self:each_option() do
    local fw,fh = bw - 2 * BORDER_WIDTH, bh - 2 * BORDER_WIDTH
    local fx,fy = bx + BORDER_WIDTH, by + BORDER_WIDTH

    -- draw the button
    renderer.draw_rect(bx,by,bw,bh, style.nagbar_text)
    renderer.draw_rect(fx,fy,fw,fh, style.nagbar)

    if i == self.hovered_item then -- draw underline
      local uw = fw - 2 * UNDERLINE_MARGIN
      local halfuw = uw / 2
      local lx = fx + UNDERLINE_MARGIN + halfuw - (halfuw * self.underline_progress)
      local ly = fy + fh - UNDERLINE_MARGIN - UNDERLINE_WIDTH
      uw = uw * self.underline_progress
      renderer.draw_rect(lx,ly,uw,UNDERLINE_WIDTH, style.nagbar_text)
    end

    common.draw_text(style.font, style.nagbar_text, opt.text, "center", fx,fy,fw,fh)
  end

  self:draw_scrollbar()

  core.pop_clip_rect()
end

function NagView:draw()
  if (not self.visible and self.show_height <= 0) or not self.title then
    return
  end
  core.root_view:defer_draw(draw_nagview_message, self)
end

function NagView:on_scale_change(new_scale, old_scale)
  BORDER_WIDTH = common.round(1 * new_scale)
  UNDERLINE_WIDTH = common.round(2 * new_scale)
  UNDERLINE_MARGIN = common.round(1 * new_scale)
  self.target_height = math.max(
    self:get_message_height(),
    self:get_buttons_height()
  )
end

function NagView:get_message_height()
  local h = 0
  for str in string.gmatch(self.message, "(.-)\n") do
    h = h + style.font:get_height() * config.line_height
  end
  return h
end

function NagView:next()
  local opts = table.remove(self.queue, 1) or {}
  if opts.title and opts.message and opts.options then
    self.visible = true
    self.title = opts.title
    self.message = opts.message and opts.message .. "\n"
    self.options = opts.options
    self.on_selected = opts.on_selected

    local message_height = self:get_message_height()
    -- self.target_height is the nagview height needed to display the message and
    -- the buttons, excluding the top and bottom padding space.
    self.target_height = math.max(message_height, self:get_buttons_height())
    self:change_hovered(common.find_index(self.options, "default_yes"))

    self.force_focus = true
    core.set_active_view(self)
    -- We add a hook to manage all the mouse_pressed events.
    register_mouse_pressed(self)
  else
    self.force_focus = false
    core.set_active_view(core.next_active_view or core.last_active_view)
    self.visible = false
    unregister_mouse_pressed(self)
  end
end

function NagView:show(title, message, options, on_select)
  local opts = {}
  opts.title = assert(title, "No title")
  opts.message = assert(message, "No message")
  opts.options = assert(options, "No options")
  opts.on_selected = on_select or noop
  table.insert(self.queue, opts)
  self:next()
end

return NagView