--[[--
A customizable number picker.

Example:
    local NumberPickerWidget = require("ui/widget/numberpickerwidget")
    local numberpicker = NumberPickerWidget:new{
        -- for floating point (decimals), use something like "%.2f"
        precision = "%02d",
        value = 0,
        value_min = 0,
        value_max = 23,
        value_step = 1,
        value_hold_step = 4,
        wrap = true,
    }
--]]

local Button = require("ui/widget/button")
local CenterContainer = require("ui/widget/container/centercontainer")
local Device = require("device")
local FocusManager = require("ui/widget/focusmanager")
local FrameContainer = require("ui/widget/container/framecontainer")
local Geom = require("ui/geometry")
local Font = require("ui/font")
local InfoMessage = require("ui/widget/infomessage")
local InputDialog = require("ui/widget/inputdialog")
local Size = require("ui/size")
local UIManager = require("ui/uimanager")
local VerticalGroup = require("ui/widget/verticalgroup")
local VerticalSpan = require("ui/widget/verticalspan")
local _ = require("gettext")
local T = require("ffi/util").template
local Screen = Device.screen

local NumberPickerWidget = FocusManager:extend{
    spinner_face = Font:getFace("smalltfont"),
    precision = "%02d",
    width = nil,
    height = nil,
    value = 0,
    value_min = 0,
    value_max = 23,
    value_step = 1,
    value_hold_step = 4,
    value_table = nil,
    value_index = nil,
    wrap = true,
    -- in case we need calculate number of days in a given month and year
    date_month = nil,
    date_year = nil,
    -- on update signal to the caller and pass updated value
    picker_updated_callback = nil,
    unit = "",
}

function NumberPickerWidget:init()
    self.screen_width = Screen:getWidth()
    self.screen_height = Screen:getHeight()
    self.width = self.width or math.floor(math.min(self.screen_width, self.screen_height) * 0.2)
    if self.value_table then
        self.value_index = self.value_index or 1
        self.value = self.value_table[self.value_index]
    end
    self.layout = {}

    -- Widget layout
    local bordersize = Size.border.default
    local margin = Size.margin.default
    local button_up = Button:new{
        text = "▲",
        bordersize = bordersize,
        margin = margin,
        radius = 0,
        text_font_size = 24,
        width = self.width,
        show_parent = self.show_parent,
        callback = function()
            if self.date_month and self.date_year then
                self.value_max = self:getDaysInMonth(self.date_month:getValue(), self.date_year:getValue())
            end
            self.value = self:changeValue(self.value_step)
            self:update()
        end,
        hold_callback = function()
            if self.date_month and self.date_year then
                self.value_max = self:getDaysInMonth(self.date_month:getValue(), self.date_year:getValue())
            end
            self.value = self:changeValue(self.value_hold_step)
            self:update()
        end
    }
    table.insert(self.layout, {button_up})
    local button_down = Button:new{
        text = "▼",
        bordersize = bordersize,
        margin = margin,
        radius = 0,
        text_font_size = 24,
        width = self.width,
        show_parent = self.show_parent,
        callback = function()
            if self.date_month and self.date_year then
                self.value_max = self:getDaysInMonth(self.date_month:getValue(), self.date_year:getValue())
            end
            self.value = self:changeValue(-self.value_step)
            self:update()
        end,
        hold_callback = function()
            if self.date_month and self.date_year then
                self.value_max = self:getDaysInMonth(self.date_month:getValue(), self.date_year:getValue())
            end
            self.value = self:changeValue(-self.value_hold_step)
            self:update()
        end
    }
    table.insert(self.layout, {button_down})

    local empty_space = VerticalSpan:new{ width = Size.padding.large }

    self.formatted_value = self.value
    if not self.value_table then
        self.formatted_value = string.format(self.precision, self.formatted_value)
    end

    local input_dialog
    local callback_input = nil
    if self.value_table == nil then
        callback_input = function()
            if self.date_month and self.date_year then
                self.value_max = self:getDaysInMonth(self.date_month:getValue(), self.date_year:getValue())
            end
            input_dialog = InputDialog:new{
                title = _("Enter number"),
                input_hint = T("%1 (%2 - %3)", self.formatted_value, self.value_min, self.value_max),
                input_type = "number",
                buttons = {
                    {
                        {
                            text = _("Cancel"),
                            id = "close",
                            callback = function()
                                UIManager:close(input_dialog)
                            end,
                        },
                        {
                            text = _("OK"),
                            is_enter_default = true,
                            callback = function()
                                local input_text = input_dialog:getInputText()
                                local input_value = tonumber(input_text)
                                local turn_off_checks = false

                                -- if the first character of the input string is ":" turn off min-max checks
                                if input_text:match("^:") and G_reader_settings:isTrue("debug_verbose") then
                                    turn_off_checks = true -- turn off checks
                                    input_text = input_text:gsub("^:", "") -- shorten input
                                    input_value = tonumber(input_text) -- try to get value
                                end

                                -- if the input text starts with `=`, try to evaluate the expression
                                -- only allow `math.*` and no other functions to be safe here.
                                if input_text:match("^=") then
                                    local function evaluate_string(code)
                                        -- only execute if there are no chars (except math.xxx) and no {[]} in the user input
                                        local check_code = code:gsub("math%.%a*", "")
                                        if check_code:find("[%a%[%]%{%}]") then
                                            return nil
                                        end
                                        code = code:gsub("^=", "return ")
                                        local env = {math = math} -- restrict to only math functions
                                        local func, dummy = load(code, "user_sandbox", nil, env)
                                        if func then
                                            return pcall(func)
                                        end
                                    end
                                    local dummy
                                    dummy, input_value = evaluate_string(input_text)
                                    input_value = dummy and tonumber(input_value)
                                end

                                if turn_off_checks then
                                    if not input_value then return end
                                    if input_value < self.value_min or input_value > self.value_max then
                                        UIManager:show(InfoMessage:new{
                                            text = T(_("ATTENTION:\nPrefixing the input with ':' disables sanity checks!\nThis value should be in the range of %1 - %2.\nUndefined behavior may occur."), self.value_min, self.value_max),
                                        })
                                    end
                                    self.value = input_value
                                    self:update()
                                    UIManager:close(input_dialog)
                                    return
                                end

                                if input_value and input_value >= self.value_min and input_value <= self.value_max then
                                    self.value = input_value
                                    self:update()
                                    UIManager:close(input_dialog)
                                elseif input_value and input_value < self.value_min then
                                    UIManager:show(InfoMessage:new{
                                        text = T(_("This value should be %1 or more."), self.value_min),
                                        timeout = 2,
                                    })
                                elseif input_value and input_value > self.value_max then
                                    UIManager:show(InfoMessage:new{
                                        text = T(_("This value should be %1 or less."), self.value_max),
                                        timeout = 2,
                                    })
                                else
                                    UIManager:show(InfoMessage:new{
                                        text = _("Invalid value. Please enter a valid value."),
                                        timeout = 2
                                    })
                                end
                            end,
                        },
                    },
                },
            }
            UIManager:show(input_dialog)
            input_dialog:onShowKeyboard()
        end
    end

    local unit = ""
    if self.unit then
        if self.unit == "°" then
            unit = self.unit
        elseif self.unit ~= "" then
            unit = "\u{202F}" .. self.unit -- use Narrow No-Break Space (NNBSP) here
        end
    end
    self.text_value = Button:new{
        text = tostring(self.formatted_value) .. unit,
        bordersize = 0,
        padding = 0,
        text_font_face = self.spinner_face.font,
        text_font_size = self.spinner_face.orig_size,
        width = self.width,
        show_parent = self.show_parent,
        callback = callback_input,
    }
    if callback_input then
        table.insert(self.layout, 2, {self.text_value})
    end

    local widget_spinner = VerticalGroup:new{
        align = "center",
        button_up,
        empty_space,
        self.text_value,
        empty_space,
        button_down,
    }

    self.frame = FrameContainer:new{
        bordersize = 0,
        padding = Size.padding.default,
        CenterContainer:new{
            align = "center",
            dimen = Geom:new{
                w = widget_spinner:getSize().w,
                h = widget_spinner:getSize().h
            },
            widget_spinner
        }
    }
    self.dimen = self.frame:getSize()
    self[1] = self.frame
    self:refocusWidget()
    UIManager:setDirty(self.show_parent, function()
        return "ui", self.dimen
    end)
end

--[[--
Update.
--]]
function NumberPickerWidget:update()
    self.formatted_value = self.value
    if not self.value_table then
        self.formatted_value = string.format(self.precision, self.formatted_value)
    end

    self.text_value:setText(tostring(self.formatted_value), self.width)

    self:refocusWidget()
    UIManager:setDirty(self.show_parent, function()
        return "ui", self.dimen
    end)
    if self.picker_updated_callback then
        self.picker_updated_callback(self.value, self.value_index)
    end
end

--[[--
Change value.
--]]
function NumberPickerWidget:changeValue(step)
    local value
    if self.value_index then
        self.value_index = self.value_index + step
        if self.value_index > #self.value_table then
            self.value_index = self.wrap and 1 or #self.value_table
        elseif self.value_index < 1 then
            self.value_index = self.wrap and #self.value_table or 1
        end
        value = self.value_table[self.value_index]
    else
        value = self.value + step
        if value > self.value_max then
            value = self.wrap and self.value_min or self.value_max
        elseif value < self.value_min then
            value = self.wrap and self.value_max or self.value_min
        end
    end
    return value
end

--[[--
Get days in month.
--]]
function NumberPickerWidget:getDaysInMonth(month, year)
    local days_in_month = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
    local days = days_in_month[month]
    -- check for leap year
    if (month == 2) then
        if year % 4 == 0 then
            if year % 100 == 0 then
                if year % 400 == 0 then
                    days = 29
                end
            else
                days = 29
            end
        end
    end
    return days
end

--[[--
Get value.
--]]
function NumberPickerWidget:getValue()
    return self.value, self.value_index
end

return NumberPickerWidget
