---@type Trans
local Trans = require 'Trans'
local util = Trans.util

-- FIXME :Adjust Window Size

---@class TransHover: TransFrontend
---@field ns integer @namespace for hover window
---@field buffer TransBuffer @buffer for hover window
---@field window TransWindow @hover window
---@field queue TransHover[] @hover queue for all hover instances
---@field destroy_funcs fun(hover:TransHover)[] @functions to be executed when hover window is closed
---@field opts TransHoverOpts @options for hover window
---@field pin boolean @whether hover window is pinned
local M = Trans.metatable('frontend.hover', {
    ns = vim.api.nvim_create_namespace 'TransHoverWin',
    queue = {},
})
M.__index = M


---Set up function which will be invoked when this module is loaded
function M.setup()
    local set = vim.keymap.set
    for action, key in pairs(M.opts.keymaps) do
        set('n', key, function()
            local instance = M.get_active_instance()
            if instance then
                coroutine.wrap(instance.execute)(instance, action)
            else
                vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes(key, true, true, true), 'n', false)
            end
        end)
    end
end

---Create a new hover instance
---@return TransHover new_instance
function M.new()
    local new_instance = {
        pin = false,
        buffer = Trans.buffer.new(),
        destroy_funcs = {},
    }
    M.queue[#M.queue + 1] = new_instance

    return setmetatable(new_instance, M)
end

---Get the first active instances
---@return TransHover
function M.get_active_instance()
    M.clear_dead_instance()
    return M.queue[#M.queue]
end

---Clear dead instance
function M.clear_dead_instance()
    local queue = M.queue
    for i = #queue, 1, -1 do
        if not queue[i]:is_available() then
            queue[i]:destroy()
            table.remove(queue, i)
        end
    end
end

---Destroy hover instance and execute destroy functions
function M:destroy()
    coroutine.wrap(function()
        for _, func in ipairs(self.destroy_funcs) do
            func(self)
        end

        if self.window:is_valid() then
            self.window:try_close()
        end
        if self.buffer:is_valid() then
            self.buffer:destroy()
        end
        self.pin = false
    end)()
end

---Init hover window
---@param opts?
---|{width?: integer, height?: integer, col?: integer, row?: integer, relative?: string}
---@return unknown
function M:init_window(opts)
    opts = opts or {}
    local m_opts = self.opts
    local option = {
        buffer = self.buffer,
        animation = m_opts.animation,
        win_opts = {
            relative  = opts.relative or 'cursor',
            col       = opts.col or 1,
            row       = opts.row or 1,
            width     = opts.width or m_opts.width,
            height    = opts.height or m_opts.height,
            title     = m_opts.title,
            title_pos = m_opts.title and 'center',
            zindex    = 100,
        },
    }

    self.window = Trans.window.new(option)
    return self.window
end

---Get Formatted icon text
---@param format string format string
---@return string formatted text
---@return integer _ replaced count
function M:icon_format(format)
    return format:gsub('{{(%w+)}}', self.opts.icon)
end

---Get Check function for waiting
---@return fun(backend: TransBackend): boolean
function M:wait()
    local opts     = self.opts
    local buffer   = self.buffer
    local pause    = util.pause
    local cell     = opts.icon.cell
    local spinner  = Trans.style.spinner[opts.spinner]
    local times    = opts.width - spinner[1]:width()
    local size     = #spinner
    local interval = math.floor(opts.timeout / times)

    self:init_window {
        height = 2,
        width = opts.width,
    }

    self.waitting = true
    local cur     = 0
    local pr      = util.node.prompt
    local it      = util.node.item
    return function(backend)
        cur = cur + 1
        buffer[1] = pr(backend.name_zh)
        buffer[2] = it { spinner[cur % size + 1] .. (cell):rep(cur), 'TransWaitting' }
        pause(interval)
        return cur < times
    end
end

---FallBack window for no result
function M:fallback()
    local opts = self.opts
    local fallback_msg = self:icon_format(opts.fallback_message)


    local buffer = self.buffer
    buffer:wipe()
    buffer[1] = util.center(fallback_msg, opts.width)
    buffer:add_highlight(1, 'TransFailed')
    if not self.window then
        self:init_window {
            height = buffer:line_count(),
            width = self.opts.width,
        }
    end

    self:defer()
end

---Defer function when process done
function M:defer()
    util.main_loop(function()
        self.window:set('wrap', true)
        self.buffer:set('modifiable', false)

        local auto_close_events = self.opts.auto_close_events
        if not auto_close_events then return end

        vim.api.nvim_create_autocmd(auto_close_events, {
            callback = function(opts)
                vim.defer_fn(function()
                    if not self.pin and vim.api.nvim_get_current_win() ~= self.window.winid then
                        pcall(vim.api.nvim_del_autocmd, opts.id)
                        self:destroy()
                    end
                end, 0)
            end,
        })
    end)
end

---Display Result in hover window
---@param data TransData
---@overload fun(result:TransResult)
function M:process(data)
    if not self.waitting and self.window and self.window:is_valid() then
        self:execute 'toggle_entry'
        return
    end
    self.waitting = false

    local result, name = data:get_available_result()
    if not result then
        self:fallback()
        return
    end

    local opts   = self.opts
    local buffer = self.buffer

    if opts.auto_play then
        (data.from == 'en' and data.str or result.definition[1]):play()
    end

    -- vim.pretty_print(result)
    util.main_loop(function()
        buffer[buffer:is_valid() and 'wipe' or 'init'](buffer)

        ---@cast name string
        self:load(result, name, opts.order[name])
    end)

    local window = self.window
    local lines = buffer:lines()

    local valid = window and window:is_valid()
    local width =
        valid and
        (opts.auto_resize and
            math.max(
                math.min(opts.width, util.display_width(lines) + opts.padding),
                math.min(data.str:width(), opts.split_width)
            )
            or opts.width)
        or math.min(opts.width, util.display_width(lines) + opts.padding)

    local height = math.min(opts.height, util.display_height(lines, width))

    if valid then
        window:resize { width = width, height = height }
    else
        window = self:init_window {
            height = height,
            width = width,
        }
    end

    self:defer()
end

---Check if hover window and buffer are valid
---@return boolean @whether hover window and buffer are valid
function M:is_available()
    return self.buffer:is_valid() and self.window:is_valid()
end

---@class TransFrontend
---@field hover TransHover @hover frontend
return M
