local phosphor = require "assets.phosphor"
local qcolor = require "quarrel.color"
local qui = require "quarrel.ui"
local wibox = require "wibox"

local WEEKDAY_MAP = { 7, 1, 2, 3, 4, 5, 6 }

local M = {}

local l_grid =  wibox.widget {
    layout = wibox.layout.grid,
    forced_num_rows = 7,
    forced_num_cols = 7,
    border_width = {
        inner = qui.BORDER_WIDTH,
        outer = 0,
    },
    border_color = qcolor.palette.border.variant,
}

local w_month = wibox.widget {
    widget = wibox.widget.textbox,
    text = "-",
}

local w_year = wibox.widget {
    widget = wibox.widget.textbox,
    text = "-",
}

local offset = 0

M.widget = wibox.widget(qui.styled {
    widget = wibox.container.background,
    bg = qcolor.palette.bg.high,
    {
        widget = wibox.container.margin,
        margins = qui.BORDER_WIDTH,
        {
            {
                l_grid,
                {
                    widget = wibox.container.background,
                    bg = qcolor.palette.border(),
                    forced_width = qui.BORDER_WIDTH,
                },
                layout = wibox.layout.fixed.horizontal,
            },
            {
                widget = wibox.container.margin,
                margins = qui.BIG_PADDING,
                {
                    {
                        widget = wibox.container.place,
                        fill_horizontal = true,
                        {
                            {
                                widget = wibox.container.place,
                                w_month,
                            },
                            qui.separator {
                                size = qui.BORDER_WIDTH
                            },
                            w_year,
                            layout = wibox.layout.fixed.vertical,
                            spacing = qui.PADDING
                        }
                    },
                    nil,
                    qui.styled {
                        widget = wibox.container.background,
                        bg = qcolor.palette.bg.highest,
                        {
                            {
                                widget = wibox.container.margin,
                                margins = qui.PADDING,
                                {
                                    widget = wibox.container.place,
                                    qui.icon {
                                        icon = phosphor.caret_up_bold,
                                        widget = {
                                            forced_height = qui.CHAR_HEIGHT / 2,
                                            forced_width = qui.CHAR_HEIGHT / 2,
                                        },
                                    },
                                },
                            },
                            {
                                widget = wibox.container.background,
                                bg = qcolor.palette.border.variant,
                                forced_height = qui.BORDER_WIDTH,
                            },
                            {
                                widget = wibox.container.margin,
                                margins = qui.PADDING,
                                {
                                    widget = wibox.container.place,
                                    qui.icon {
                                        icon = phosphor.caret_down_bold,
                                        widget = {
                                            forced_height = qui.CHAR_HEIGHT / 2,
                                            forced_width = qui.CHAR_HEIGHT / 2,
                                        },
                                    },
                                },
                            },
                            layout = wibox.layout.fixed.vertical,
                        },
                    },
                    layout = wibox.layout.align.vertical,
                },
            },
            layout = wibox.layout.fixed.horizontal,
        },
    },
})

function M:render(grid)
    for i, row in ipairs(grid) do
        for j, col in ipairs(row) do
            local widget = l_grid:get_widgets_at(i, j)[1]
            widget.widget.widget.widget.text = col[1]
            if col[2] then
                widget.bg = qcolor.palette.yellow()
                widget.fg = qcolor.palette.bg()
            elseif j % 6 == 0 or j % 7 == 0 then
                widget.bg = col[3] and qcolor.palette.bg.highest or qcolor.palette.bg.high
            else
                widget.bg = col[3] and qcolor.palette.bg.high or qcolor.palette.bg()
            end

            if i == 1 then
                widget.fg = qcolor.palette.fg()
            elseif not col[2] then
                widget.fg = qcolor.palette.fg.low
            end
        end
    end
end

-- Logic heavily inspired by https://github.com/Sinomor/dotfiles/blob/e409f9a84bf40daf1e39c0179ec749232ed827c9/home/.config/awesome/ui/control/moment/calendar.lua#L134-L173
function M:compute(year, month)
    local grid = {
        {
            { "Mo", false, true },
            { "Tu", false, true },
            { "We", false, true },
            { "Th", false, true },
            { "Fr", false, true },
            { "Sa", false, true },
            { "Su", false, true },
        },
        {},
        {},
        {},
        {},
        {},
        {},
    }
    local current = os.date("*t", os.time())
    local first_day = os.date("*t", os.time { year = year, month = month, day = 1 })
    local last_day = os.date("*t", os.time { year = year, month = month + 1, day = 0 })

    local days = last_day.day

    local prev_days = os.date("*t", os.time { year = year, month = month, day = 0 })
    local prev_offset = WEEKDAY_MAP[first_day.wday] - 1
    local prev_month = month - 1 == -1 and 12 or month - 1
    local prev_year = prev_month == 12 and year - 1 or year

    if prev_offset ~= -1 then
        for offset = prev_offset, 1, -1 do
            local day = prev_days.day - offset + 1
            table.insert(
                grid[2],
                { day, day == current.day and prev_month == current.month and prev_year == current.year, false }
            )
        end
    end

    do
        local row = 2
        local weekday = WEEKDAY_MAP[first_day.wday]
        for day = 1, days do
            table.insert(
                grid[row],
                { day, day == current.day and month == current.month and year == current.year, true }
            )
            if weekday == 7 then
                row = row + 1
                weekday = 1
            else
                weekday = weekday + 1
            end
        end

        local next_month = month + 1 == 13 and 1 or month + 1
        local next_year = next_month == 1 and year + 1 or year
        for day = 1, 42 - prev_offset - days do
            table.insert(
                grid[row],
                { day, day == current.day and next_month + 1 == current.month and next_year == current.year, false }
            )
            if weekday == 7 then
                row = row + 1
                weekday = 1
            else
                weekday = weekday + 1
            end
        end
    end

    w_month.text = month
    w_year.text = year
    self:render(grid)
end

-- Set up the widget
for _ = 1, 49 do
    local cell = wibox.widget {
        widget = wibox.container.background,
        bg = qcolor.palette.bg.high,
        {
            widget = wibox.container.margin,
            margins = qui.PADDING * 1.5,
            {
                widget = wibox.container.place,
                forced_height = qui.CHAR_HEIGHT,
                forced_width = qui.CHAR_HEIGHT,
                {
                    widget = wibox.widget.textbox,
                    markup = "",
                },
            },
        },
    }
    l_grid:add(cell)
end
local current_time = os.date "*t"
M:compute(current_time.year, current_time.month)
l_grid:add_row_border(2, qui.BORDER_WIDTH, { color = qcolor.palette.border() })

return M