local M = {}

function M.map(mode, shortcut, command, description, buffer)
    local opts = { noremap = true, silent = true }
    opts.desc = description or nil
    opts.buffer = buffer or nil
    vim.keymap.set(mode, shortcut, command, opts)
end

function M.remove_trailing_whitespace()
    local curpos = vim.api.nvim_win_get_cursor(0)
    vim.cmd([[keeppatterns %s/\s\+$//e]])
    vim.api.nvim_win_set_cursor(0, curpos)
end

vim.api.nvim_create_augroup('config_functions', { clear = true })
vim.api.nvim_create_autocmd({ 'BufWritePre' }, {
    group = 'config_functions',
    pattern = {
        '*.lua', '*.cpp', '*.hpp',
        '*.conf', '*.cfg', '*.ini', '*.adoc'
    },
    callback = M.remove_trailing_whitespace
})

-- Insert or update a modeline at the bottom of the buffer
function M.insert_modeline()
    local comment_string = vim.o.commentstring
    local space_maybe = ''
    if string.match(comment_string, '%%s(.*)') ~= '' then
        space_maybe = ' '
    end

    local fenc = vim.o.fileencoding
    if fenc == '' then
        fenc = 'utf-8'
    end

    local modeline_elements = {
        ' vim: set',
        ' ts=' .. vim.o.tabstop,
        ' sw=' .. vim.o.shiftwidth,
        (vim.o.expandtab and ' et' or ' noet'),
        ' tw=' .. vim.o.textwidth,
        ' ft=' .. vim.o.filetype,
        ':',
        space_maybe
    }
    local modeline = comment_string:gsub('%%s', table.concat(modeline_elements))
    modeline = modeline:gsub('  ', ' ')

    local buffer = vim.api.nvim_win_get_buf(0)
    local current = vim.api.nvim_buf_get_lines(buffer, -2, -1, true)[1]
    if current == modeline then
        print('modeline already exists')
    elseif string.match(current, 'vim:') then
        vim.api.nvim_buf_set_lines(buffer, -2, -1, true, { modeline })
        print('modeline updated')
    else
        vim.api.nvim_buf_set_lines(buffer, -1, -1, true, { '', modeline })
        print('modeline inserted')
    end
end

vim.api.nvim_create_user_command('ModelineInsert', M.insert_modeline, {})

-- Files that could indicate the project's root directory
M.project_root_markers = {
    '.git', '.hg', '.svn', '.bzr', '_darcs',
    '.projectile', '.clang-format', '.luarc.json', '.editorconfig'
}

function M.get_project_root()
    local path = vim.api.nvim_buf_get_name(0)
    local sep = '/'

    repeat
        path = path:gsub(string.format('%s[^%s]*$', sep, sep), '')
        for _, marker in ipairs(M.project_root_markers) do
            if io.open(path .. sep .. marker) then
                return path
            end
        end
    until path == ''
    return nil
end

function M.shell_capture(command)
    local handle = io.popen(command)
    if not handle then return nil end
    local result = handle:read() or nil
    handle:close()
    return result
end

-- return colours from highlight groups in web notation (#rrggbb)
function M.get_hl_hex(hl_group)
    local hl = vim.api.nvim_get_hl_by_name(hl_group, true)
    local hl_hex = {}
    if hl.foreground then
        hl_hex.foreground = string.format('#%.6x', hl.foreground)
    end
    if hl.background then
        hl_hex.background = string.format('#%.6x', hl.background)
    end
    return hl_hex
end

-- return true if 'Symbols Nerd Font' is known to fontconfig
function M.nerdfont_installed()
    if os.execute([[fc-list -q 'Symbols Nerd Font']]) == 0 then
        return true
    end
    return false
end

return M