local BD = require("ui/bidi")
local CenterContainer = require("ui/widget/container/centercontainer")
local ConfirmBox = require("ui/widget/confirmbox")
local Device = require("device")
local Event = require("ui/event")
local Font = require("ui/font")
local FontList = require("fontlist")
local Input = Device.input
local InputContainer = require("ui/widget/container/inputcontainer")
local Menu = require("ui/widget/menu")
local MultiConfirmBox = require("ui/widget/multiconfirmbox")
local Notification = require("ui/widget/notification")
local Screen = require("device").screen
local UIManager = require("ui/uimanager")
local T = require("ffi/util").template
local _ = require("gettext")
local C_ = _.pgettext
local optionsutil = require("ui/data/optionsutil")

local ReaderFont = InputContainer:new{
    font_face = nil,
    font_size = nil,
    line_space_percent = nil,
    font_menu_title = _("Font"),
    face_table = nil,
    -- default gamma from crengine's lvfntman.cpp
    gamma_index = nil,
    steps = {0,1,1,1,1,1,2,2,2,3,3,3,4,4,5},
}

function ReaderFont:init()
    if Device:hasKeyboard() then
        -- add shortcut for keyboard
        self.key_events = {
            ShowFontMenu = { {"F"}, doc = "show font menu" },
            IncreaseSize = {
                { "Shift", Input.group.PgFwd },
                doc = "increase font size",
                event = "ChangeSize", args = 0.5 },
            DecreaseSize = {
                { "Shift", Input.group.PgBack },
                doc = "decrease font size",
                event = "ChangeSize", args = -0.5 },
        }
    end
    -- Build face_table for menu
    self.face_table = {}
    -- Font settings
    table.insert(self.face_table, {
        text = _("Font settings"),
        sub_item_table = self:getFontSettingsTable(),
        separator = true,
    })
    -- Font list
    local face_list = cre.getFontFaces()
    for k,v in ipairs(face_list) do
        local font_filename, font_faceindex, is_monospace = cre.getFontFaceFilenameAndFaceIndex(v)
        table.insert(self.face_table, {
            text_func = function()
                -- defaults are hardcoded in credocument.lua
                local default_font = G_reader_settings:readSetting("cre_font") or self.ui.document.default_font
                local fallback_font = G_reader_settings:readSetting("fallback_font") or self.ui.document.fallback_fonts[1]
                local monospace_font = G_reader_settings:readSetting("monospace_font") or self.ui.document.monospace_font
                local text = v
                if font_filename and font_faceindex then
                    text = FontList:getLocalizedFontName(font_filename, font_faceindex) or text
                end

                if v == monospace_font then
                    text = text .. " \u{1F13C}" -- Squared Latin Capital Letter M
                elseif is_monospace then
                    text = text .. " \u{1D39}" -- Modified Letter Capital M
                end
                if v == default_font then
                    text = text .. "   ★"
                end
                if v == fallback_font then
                    text = text .. "   �"
                end
                return text
            end,
            font_func = function(size)
                if G_reader_settings:nilOrTrue("font_menu_use_font_face") then
                    if font_filename and font_faceindex then
                        return Font:getFace(font_filename, size, font_faceindex)
                    end
                end
            end,
            callback = function()
                self:onSetFont(v)
            end,
            hold_callback = function(touchmenu_instance)
                self:makeDefault(v, is_monospace, touchmenu_instance)
            end,
            checked_func = function()
                return v == self.font_face
            end,
            menu_item_id = v,
        })
    end
    self.face_table.open_on_menu_item_id_func = function()
        return self.font_face
    end
    self.ui.menu:registerToMainMenu(self)
end

function ReaderFont:onSetDimensions(dimen)
    self.dimen = dimen
end

function ReaderFont:onReadSettings(config)
    self.font_face = config:readSetting("font_face")
                  or G_reader_settings:readSetting("cre_font")
                  or self.ui.document.default_font
    self.ui.document:setFontFace(self.font_face)

    self.header_font_face = config:readSetting("header_font_face")
                         or G_reader_settings:readSetting("header_font")
                         or self.ui.document.header_font
    self.ui.document:setHeaderFont(self.header_font_face)

    self.font_size = config:readSetting("font_size")
                  or G_reader_settings:readSetting("copt_font_size")
                  or DCREREADER_CONFIG_DEFAULT_FONT_SIZE
                  or 22
    self.ui.document:setFontSize(Screen:scaleBySize(self.font_size))

    self.font_base_weight = config:readSetting("font_base_weight")
                      or G_reader_settings:readSetting("copt_font_base_weight")
                      or 0
    self.ui.document:setFontBaseWeight(self.font_base_weight)

    self.font_hinting = config:readSetting("font_hinting")
                     or G_reader_settings:readSetting("copt_font_hinting")
                     or 2 -- auto (default in cre.cpp)
    self.ui.document:setFontHinting(self.font_hinting)

    self.font_kerning = config:readSetting("font_kerning")
                     or G_reader_settings:readSetting("copt_font_kerning")
                     or 3 -- harfbuzz (slower, but needed for proper arabic)
    self.ui.document:setFontKerning(self.font_kerning)

    self.word_spacing = config:readSetting("word_spacing")
                     or G_reader_settings:readSetting("copt_word_spacing")
                     or {95, 75}
    self.ui.document:setWordSpacing(self.word_spacing)

    self.word_expansion = config:readSetting("word_expansion")
                       or G_reader_settings:readSetting("copt_word_expansion")
                       or 0
    self.ui.document:setWordExpansion(self.word_expansion)

    self.cjk_width_scaling = config:readSetting("cjk_width_scaling")
                       or G_reader_settings:readSetting("copt_cjk_width_scaling")
                       or 100
    self.ui.document:setCJKWidthScaling(self.cjk_width_scaling)

    self.line_space_percent = config:readSetting("line_space_percent")
                           or G_reader_settings:readSetting("copt_line_spacing")
                           or DCREREADER_CONFIG_LINE_SPACE_PERCENT_MEDIUM
    self.ui.document:setInterlineSpacePercent(self.line_space_percent)

    self.gamma_index = config:readSetting("gamma_index")
                    or G_reader_settings:readSetting("copt_font_gamma")
                    or DCREREADER_CONFIG_DEFAULT_FONT_GAMMA
                    or 15 -- gamma = 1.0
    self.ui.document:setGammaIndex(self.gamma_index)

    -- Dirty hack: we have to add following call in order to set
    -- m_is_rendered(member of LVDocView) to true. Otherwise position inside
    -- document will be reset to 0 on first view render.
    -- So far, I don't know why this call will alter the value of m_is_rendered.
    table.insert(self.ui.postInitCallback, function()
        self.ui:handleEvent(Event:new("UpdatePos"))
    end)
end

function ReaderFont:onShowFontMenu()
    -- build menu widget
    local main_menu = Menu:new{
        title = self.font_menu_title,
        item_table = self.face_table,
        width = Screen:getWidth() - 100,
        height = math.floor(Screen:getHeight() * 0.5),
        single_line = true,
        items_per_page = 8,
        items_font_size = Menu.getItemFontSize(8),
    }
    -- build container
    local menu_container = CenterContainer:new{
        dimen = Screen:getSize(),
        main_menu,
    }
    main_menu.close_callback = function()
        UIManager:close(menu_container)
    end
    -- show menu

    main_menu.show_parent = menu_container

    UIManager:show(menu_container)

    return true
end

--[[
    UpdatePos event is used to tell ReaderRolling to update pos.
--]]
function ReaderFont:onChangeSize(delta)
    self.font_size = self.font_size + delta
    self.ui:handleEvent(Event:new("SetFontSize", self.font_size))
    return true
end

function ReaderFont:onSetFontSize(new_size)
    if new_size > 255 then new_size = 255 end
    if new_size < 12 then new_size = 12 end

    self.font_size = new_size
    self.ui.document:setFontSize(Screen:scaleBySize(new_size))
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("Font size set to: %1."), self.font_size))
    return true
end

function ReaderFont:onSetLineSpace(space)
    self.line_space_percent = math.min(200, math.max(50, space))
    self.ui.document:setInterlineSpacePercent(self.line_space_percent)
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("Line spacing set to: %1%."), self.line_space_percent))
    return true
end

function ReaderFont:onSetFontBaseWeight(weight)
    self.font_base_weight = weight
    self.ui.document:setFontBaseWeight(weight)
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("Font weight set to: %1."), optionsutil:getOptionText("SetFontBaseWeight", weight)))
    return true
end

function ReaderFont:onSetFontHinting(mode)
    self.font_hinting = mode
    self.ui.document:setFontHinting(mode)
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("Font hinting set to: %1"), optionsutil:getOptionText("SetFontHinting", mode)))
    return true
end

function ReaderFont:onSetFontKerning(mode)
    self.font_kerning = mode
    self.ui.document:setFontKerning(mode)
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("Font kerning set to: %1"), optionsutil:getOptionText("SetFontKerning", mode)))
    return true
end

function ReaderFont:onSetWordSpacing(values)
    self.word_spacing = values
    self.ui.document:setWordSpacing(values)
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("Word spacing set to: %1%, %2%"), values[1], values[2]))
    return true
end

function ReaderFont:onSetWordExpansion(value)
    self.word_expansion = value
    self.ui.document:setWordExpansion(value)
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("Word expansion set to: %1%."), value))
    return true
end

function ReaderFont:onSetCJKWidthScaling(value)
    self.cjk_width_scaling = value
    self.ui.document:setCJKWidthScaling(value)
    self.ui:handleEvent(Event:new("UpdatePos"))
    Notification:notify(T(_("CJK width scaling set to: %1%."), value))
    return true
end

function ReaderFont:onSetFontGamma(gamma)
    self.gamma_index = gamma
    self.ui.document:setGammaIndex(self.gamma_index)
    local gamma_level = self.ui.document:getGammaLevel()
    self.ui:handleEvent(Event:new("RedrawCurrentView"))
    Notification:notify(T(_("Font gamma set to: %1."), gamma_level))
    return true
end

function ReaderFont:onSaveSettings()
    self.ui.doc_settings:saveSetting("font_face", self.font_face)
    self.ui.doc_settings:saveSetting("header_font_face", self.header_font_face)
    self.ui.doc_settings:saveSetting("font_size", self.font_size)
    self.ui.doc_settings:saveSetting("font_base_weight", self.font_base_weight)
    self.ui.doc_settings:saveSetting("font_hinting", self.font_hinting)
    self.ui.doc_settings:saveSetting("font_kerning", self.font_kerning)
    self.ui.doc_settings:saveSetting("word_spacing", self.word_spacing)
    self.ui.doc_settings:saveSetting("word_expansion", self.word_expansion)
    self.ui.doc_settings:saveSetting("cjk_width_scaling", self.cjk_width_scaling)
    self.ui.doc_settings:saveSetting("line_space_percent", self.line_space_percent)
    self.ui.doc_settings:saveSetting("gamma_index", self.gamma_index)
end

function ReaderFont:onSetFont(face)
    if face and self.font_face ~= face then
        self.font_face = face
        self.ui.document:setFontFace(face)
        -- signal readerrolling to update pos in new height
        self.ui:handleEvent(Event:new("UpdatePos"))
    end
end

function ReaderFont:makeDefault(face, is_monospace, touchmenu_instance)
    if face then
        if is_monospace then
            -- If the font is monospace, assume it wouldn't be a candidate
            -- to be set as a fallback font, and allow it to be set as the
            -- default monospace font.
            UIManager:show(MultiConfirmBox:new{
                text = T(_("Would you like %1 to be used as the default font (★), or the monospace font (\u{1F13C})?"), face),
                choice1_text = _("Default"),
                choice1_callback = function()
                    G_reader_settings:saveSetting("cre_font", face)
                    if touchmenu_instance then touchmenu_instance:updateItems() end
                end,
                choice2_text = C_("Font", "Monospace"),
                choice2_callback = function()
                    G_reader_settings:saveSetting("monospace_font", face)
                    -- We need to reset the main font for the biases to be re-set correctly
                    local current_face = self.font_face
                    self.font_face = nil
                    self:onSetFont(current_face)
                    if touchmenu_instance then touchmenu_instance:updateItems() end
                end,
            })
            return
        end
        UIManager:show(MultiConfirmBox:new{
            text = T(_("Would you like %1 to be used as the default font (★), or the fallback font (�)?\n\nCharacters not found in the active font are shown in the fallback font instead."), face),
            choice1_text = _("Default"),
            choice1_callback = function()
                G_reader_settings:saveSetting("cre_font", face)
                if touchmenu_instance then touchmenu_instance:updateItems() end
            end,
            choice2_text = C_("Font", "Fallback"),
            choice2_callback = function()
                G_reader_settings:saveSetting("fallback_font", face)
                self.ui.document:setupFallbackFontFaces()
                self.ui:handleEvent(Event:new("UpdatePos"))
                if touchmenu_instance then touchmenu_instance:updateItems() end
            end,
        })
    end
end

function ReaderFont:addToMainMenu(menu_items)
    -- Have TouchMenu show half of the usual nb of items, so we
    -- have more room to see how the text looks with that font
    self.face_table.max_per_page = 5
    -- insert table to main reader menu
    menu_items.change_font = {
        text_func = function()
            return T(_("Font: %1"), BD.wrap(self.font_face))
        end,
        sub_item_table = self.face_table,
    }
end

function ReaderFont:gesToFontSize(ges)
    -- Dispatcher feeds us a number, not a gesture
    if type(ges) ~= "table" then return ges end

    if ges.distance == nil then
        ges.distance = 1
    end
    -- Compute the scaling based on the gesture's direction (for pinch/spread)
    local step
    if ges.direction and ges.direction == "vertical" then
        step = math.ceil(2 * #self.steps * ges.distance / Screen:getHeight())
    elseif ges.direction and ges.direction == "horizontal" then
        step = math.ceil(2 * #self.steps * ges.distance / Screen:getWidth())
    elseif ges.direction and ges.direction == "diagonal" then
        local screen_diagonal = math.sqrt(Screen:getWidth()^2 + Screen:getHeight()^2)
        step = math.ceil(2 * #self.steps * ges.distance / screen_diagonal)
    else
        step = math.ceil(2 * #self.steps * ges.distance / math.min(Screen:getWidth(), Screen:getHeight()))
    end
    local delta_int = self.steps[step] or self.steps[#self.steps]
    return delta_int
end

function ReaderFont:onIncreaseFontSize(ges)
    local delta_int = self:gesToFontSize(ges)
    Notification:notify(_("Increasing font size…"), true)
    self:onChangeSize(delta_int)
    return true
end

function ReaderFont:onDecreaseFontSize(ges)
    local delta_int = self:gesToFontSize(ges)
    Notification:notify(_("Decreasing font size…"), true)
    self:onChangeSize(-delta_int)
    return true
end

function ReaderFont:getFontSettingsTable()
    local settings_table = {}

    if Device:isAndroid() or Device:isDesktop() or Device:isEmulator() or Device:isPocketBook() then
        for _, item in ipairs(require("ui/elements/font_settings"):getSystemFontMenuItems()) do
            table.insert(settings_table, item)
        end
        settings_table[#settings_table].separator = true
    end

    table.insert(settings_table, {
        text = _("Display font names with their own font"),
        checked_func = function()
            return G_reader_settings:nilOrTrue("font_menu_use_font_face")
        end,
        callback = function()
            G_reader_settings:flipNilOrTrue("font_menu_use_font_face")
        end,
        help_text = _([[In the font menu, display each font name with its own font face.]]),
        separator = true,
    })

    table.insert(settings_table, {
        text = _("Use additional fallback fonts"),
        checked_func = function()
            return G_reader_settings:nilOrTrue("additional_fallback_fonts")
        end,
        callback = function()
            G_reader_settings:flipNilOrTrue("additional_fallback_fonts")
            self.ui.document:setupFallbackFontFaces()
            self.ui:handleEvent(Event:new("UpdatePos"))
        end,
        help_text = T(_([[
Enable additional fallback fonts, for the most complete script and language coverage.
These fonts will be used in this order:

%1

You can set a preferred fallback font with a long-press on a font name, and it will be used before these.
If that font happens to be part of this list already, it will be used first.]]),
            table.concat(self.ui.document.fallback_fonts, "\n")),
    })
    table.insert(settings_table, {
        text = _("Adjust fallback font sizes"),
        checked_func = function()
            return G_reader_settings:nilOrTrue("cre_adjusted_fallback_font_sizes")
        end,
        callback = function()
            G_reader_settings:flipNilOrTrue("cre_adjusted_fallback_font_sizes")
            self.ui.document:setAdjustedFallbackFontSizes(G_reader_settings:nilOrTrue("cre_adjusted_fallback_font_sizes"))
            self.ui:handleEvent(Event:new("UpdatePos"))
        end,
        help_text = _([[
Adjust the size of each fallback font so they all get the same x-height, and lowercase characters picked in them look similarly sized as those from the defaut font.
This may help with Greek words among Latin text (as Latin fonts often do not have all the Greek characters), but may make Chinese or Indic characters smaller when picked from fallback fonts.]]),
        separator = true,
    })

    table.insert(settings_table, {
        text_func = function()
            local scale = G_reader_settings:readSetting("cre_monospace_scaling") or 100
            return T(_("Monospace fonts scaling: %1 %"), scale)
        end,
        callback = function()
            local SpinWidget = require("ui/widget/spinwidget")
            UIManager:show(SpinWidget:new{
                value = G_reader_settings:readSetting("cre_monospace_scaling") or 100,
                value_min = 30,
                value_step = 1,
                value_hold_step = 5,
                value_max = 150,
                unit = "%",
                title_text = _("Monospace font scaling"),
                -- no info_text: we want this widget to stay small, so we can move it
                -- around to see the effect of the scaling
                keep_shown_on_apply = true,
                callback = function(spin)
                    local scale = spin.value
                    G_reader_settings:saveSetting("cre_monospace_scaling", scale)
                    self.ui.document:setMonospaceFontScaling(scale)
                    self.ui:handleEvent(Event:new("UpdatePos"))
                end,
            })
        end,
        help_text = _([[
Monospace fonts may look big when inline with your main font if it has a small x-height.
This setting allows scaling all monospace fonts by this percentage so they can fit your preferred font height, or you can make them be a bit smaller to distinguish them more easily.]]),
        separator = true,
    })

    table.insert(settings_table, {
        text = _("Generate font test document"),
        callback = function()
            UIManager:show(ConfirmBox:new{
                text = _("Would you like to generate an HTML document showing some sample text rendered with each available font?"),
                ok_callback = function()
                    self:buildFontsTestDocument()
                end,
            })
        end,
    })
    return settings_table
end

-- Default sample file
local FONT_TEST_DEFAULT_SAMPLE_PATH = "frontend/ui/elements/font-test-sample-default.template"
-- Users can set their own sample file, that will be used if found
local FONT_TEST_USER_SAMPLE_PATH = require("datastorage"):getSettingsDir() .. "/font-test-sample.html"
-- This document will be generated in the home or default directory
local FONT_TEST_FINAL_FILENAME = "font-test.html"

function ReaderFont:buildFontsTestDocument()
    local html_sample
    local f = io.open(FONT_TEST_USER_SAMPLE_PATH, "r")
    if f then
        html_sample = f:read("*all")
        f:close()
    end
    if not html_sample then
        f = io.open(FONT_TEST_DEFAULT_SAMPLE_PATH, "r")
        if not f then return nil end
        html_sample = f:read("*all")
        f:close()
    end
    local dir = G_reader_settings:readSetting("home_dir")
             or require("apps/filemanager/filemanagerutil").getDefaultDir()
             or "."
    local font_test_final_path = dir .. "/" .. FONT_TEST_FINAL_FILENAME
    f = io.open(font_test_final_path, "w")
    if not f then return end
    -- Using <section><title>...</title></section> allows for a TOC to be built by crengine
    f:write(string.format([[
<?xml version="1.0" encoding="UTF-8"?>
<html>
<head>
<title>%s</title>
<style>
h1 {
  font-size: large;
  font-weight: bold;
  text-align: center;
  page-break-before: always;
  margin-top: 0;
  margin-bottom: 0.5em;
}
a { color: black; }
</style>
</head>
<body>
<h1>%s</h1>
]], _("Available fonts test document"), _("AVAILABLE FONTS")))
    local face_list = cre.getFontFaces()
    f:write("<div style='margin: 2em'>\n")
    for _, font_name in ipairs(face_list) do
        local font_id = font_name:gsub(" ", "_"):gsub("'", "_")
        f:write(string.format("  <div><a href='#%s'>%s</a></div>\n", font_id, font_name))
    end
    f:write("</div>\n\n")
    for _, font_name in ipairs(face_list) do
        local font_id = font_name:gsub(" ", "_"):gsub("'", "_")
        f:write(string.format("<h1 id='%s'>%s</h1>\n", font_id, font_name))
        f:write(string.format("<div style='font-family: %s'>\n", font_name))
        f:write(html_sample)
        f:write("\n</div>\n\n")
    end
    f:write("</body></html>\n")
    f:close()
    UIManager:show(ConfirmBox:new{
        text = T(_("Document created as:\n%1\n\nWould you like to read it now?"), BD.filepath(font_test_final_path)),
        ok_callback = function()
            UIManager:scheduleIn(1.0, function()
                self.ui:switchDocument(font_test_final_path)
            end)
        end,
    })
end

return ReaderFont