local Menu = {}

local default_config = {
    window = {
        margin = { 1, 0, 1, 0 },
        padding = { 1, 1, 1, 1 },
        title_pos = "center",
        border = { "", "-", "", "", "", "", "", "" },
        zindex = 1000,
    },
    icons = {
        separator = "➜",
    },
}

function Menu:new(config)
    config = vim.tbl_deep_extend("force", default_config, config or {})

    local opts = {}
    opts.window = config.window
    opts.icons = config.icons

    setmetatable(opts, self)
    self.__index = self
    return opts
end

function Menu:_get_window_margins()
    local margins = {}

    for i, m in ipairs(self.window.margin) do
        local _m = m
        if m > 0 and m < 1 then
            if i % 2 == 0 then
                _m = math.floor(vim.o.columns * m)
            else
                _m = math.floor(vim.o.lines * m)
            end
        end
        margins[i] = _m
    end

    return margins
end

local function add_vertical_padding(content, size)
    for _ = 1, size do
        table.insert(content, "")
    end
end

function Menu:_process_items(items)
    local pad_top, pad_right, pad_bot, pad_left = unpack(self.window.padding)

    local content = {}
    local keys = {}

    add_vertical_padding(content, pad_top)

    for _, item in ipairs(items) do
        if item.key then
            keys[item.key] = item

            table.insert(content, string.rep(" ", pad_left) .. vim.fn.join({
                item.key,
                self.icons.separator,
                item.label,
            }) .. string.rep(" ", pad_right))
        end
    end

    add_vertical_padding(content, pad_bot)

    return keys, content
end

function Menu:_open_window(title, content)
    local margins = self:_get_window_margins()
    local wins = vim.tbl_filter(
        function(w)
            return vim.api.nvim_win_is_valid(w)
                and vim.api.nvim_win_get_config(w).relative == ""
        end,
        vim.api.nvim_list_wins()
    )

    local line_lengths = vim.tbl_map(function(s) return #s end, content)
    line_lengths[#line_lengths + 1] = #title
    local pref_width = vim.fn.max(line_lengths)

    self.buffer = vim.api.nvim_create_buf(false, true)
    vim.api.nvim_buf_set_lines(self.buffer, 0, -1, true, content)

    local window = vim.api.nvim_open_win(self.buffer, false, {
        title = title,
        title_pos = self.window.title_pos,
        relative = "editor",
        width = vim.fn.min({ vim.o.columns, pref_width })
            - margins[2]
            - margins[4],
        height = #content,
        focusable = false,
        anchor = "SW",
        border = self.window.border,
        row = vim.o.lines
            - margins[3]
            + ((vim.o.laststatus == 0 or vim.o.laststatus == 1 and #wins == 1) and 1 or 0)
            - vim.o.cmdheight,
        col = margins[4],
        style = "minimal",
        noautocmd = true,
    } --[[@as vim.api.keyset.win_config]])
    vim.api.nvim__redraw({ win = window, valid = true })
    return window
end

function Menu:_close()
    vim.api.nvim_win_close(self.window, true)
    vim.api.nvim_buf_delete(self.buffer, { force = true })
    vim.cmd.redraw()
end

function Menu:open(data)
    local keys, content = self:_process_items(data.items)
    self.window = self:_open_window(data.title, content)

    local char = vim.fn.nr2char(vim.fn.getchar())
    self:_close()

    local entry = keys[char]
    if entry and entry.action then return entry.action() end
end

return Menu