local function highlight(group, guifg, guibg, attr, guisp)
	local parts = {group}
	if guifg then table.insert(parts, "guifg=#"..guifg) end
	if guibg then table.insert(parts, "guibg=#"..guibg) end
	if attr then
		table.insert(parts, "gui="..attr)
	end
	if guisp then table.insert(parts, "guisp=#"..guisp) end

	-- nvim.ex.highlight(parts)
	vim.api.nvim_command('highlight '..table.concat(parts, ' '))
end

-- Modified from https://github.com/chriskempson/base16-vim
local function apply_base16_theme(theme)

	-- Neovim terminal colours
	if vim.fn.has("nvim") then
		vim.g.terminal_color_0 =  "#"..theme.base00
		vim.g.terminal_color_1 =  "#"..theme.base08
		vim.g.terminal_color_2 =  "#"..theme.base0B
		vim.g.terminal_color_3 =  "#"..theme.base0A
		vim.g.terminal_color_4 =  "#"..theme.base0D
		vim.g.terminal_color_5 =  "#"..theme.base0E
		vim.g.terminal_color_6 =  "#"..theme.base0C
		vim.g.terminal_color_7 =  "#"..theme.base05
		vim.g.terminal_color_8 =  "#"..theme.base03
		vim.g.terminal_color_9 =  "#"..theme.base08
		vim.g.terminal_color_10 = "#"..theme.base0B
		vim.g.terminal_color_11 = "#"..theme.base0A
		vim.g.terminal_color_12 = "#"..theme.base0D
		vim.g.terminal_color_13 = "#"..theme.base0E
		vim.g.terminal_color_14 = "#"..theme.base0C
		vim.g.terminal_color_15 = "#"..theme.base07
		if vim.o.background == "light" then
			vim.g.terminal_color_background = "#"..theme.base05
			vim.g.terminal_color_foreground = "#"..theme.base0B
		else
			vim.g.terminal_color_background = "#"..theme.base00
			vim.g.terminal_color_foreground = "#"..theme.base0E
		end
	end

	-- TODO
	-- nvim.command "hi clear"
	-- nvim.command "syntax reset"

	-- Vim editor colors
	highlight("Normal",        theme.base05, theme.base00,  nil, nil)
	highlight("Bold",          nil, nil, "bold", nil)
	highlight("Debug",         theme.base08, nil, nil, nil)
	highlight("Directory",     theme.base0D, nil, nil, nil)
	highlight("Error",         theme.base00, theme.base08, nil, nil)
	highlight("ErrorMsg",      theme.base08, theme.base00, nil, nil)
	highlight("Exception",     theme.base08, nil, nil, nil)
	highlight("FoldColumn",    theme.base0C, theme.base01, nil, nil)
	highlight("Folded",        theme.base03, theme.base01, nil, nil)
	highlight("IncSearch",     theme.base01, theme.base09, "none", nil)
	highlight("Italic",        nil, nil, "none", nil)
	highlight("Macro",         theme.base08, nil, nil, nil)
	highlight("MatchParen",    nil, theme.base03, nil,  nil)
	highlight("ModeMsg",       theme.base0B, nil, nil, nil)
	highlight("MoreMsg",       theme.base0B, nil, nil, nil)
	highlight("Question",      theme.base0D, nil, nil, nil)
	highlight("Search",        theme.base01, theme.base0A, nil, nil)
	highlight("Substitute",    theme.base01, theme.base0A, "none", nil)
	highlight("SpecialKey",    theme.base03, nil, nil, nil)
	highlight("TooLong",       theme.base08, nil, nil, nil)
	highlight("Underlined",    theme.base08, nil, nil, nil)
	highlight("Visual",        nil, theme.base02, nil, nil)
	highlight("VisualNOS",     theme.base08, nil, nil, nil)
	highlight("WarningMsg",    theme.base08, nil, nil, nil)
	highlight("WildMenu",      theme.base08, theme.base0A,  nil, nil)
	highlight("Title",         theme.base0D, nil,  "none", nil)
	highlight("Conceal",       theme.base0D, theme.base00, nil, nil)
	highlight("Cursor",        theme.base00, theme.base05, nil, nil)
	highlight("NonText",       theme.base03, nil,nil, nil)
	highlight("LineNr",        theme.base03, "NONE", nil, nil)
	highlight("SignColumn",    theme.base03, "NONE", nil, nil)
	highlight("StatusLine",    theme.base04, theme.base02, "none", nil)
	highlight("StatusLineNC",  theme.base03, "NONE", "none", nil)
	highlight("VertSplit",     theme.base02, "NONE", "none", nil)
	highlight("ColorColumn",   nil, theme.base01,  "none", nil)
	highlight("CursorColumn",  nil, theme.base01,  "none", nil)
	highlight("CursorLine",    nil, theme.base01,  "none", nil)
	highlight("CursorLineNr",  theme.base04, "NONE",  nil, nil)
	highlight("QuickFixLine",  nil, theme.base01, "none", nil)
	highlight("PMenu",         theme.base05, theme.base01, "none", nil)
	highlight("PMenuSel",      theme.base01, theme.base05, nil, nil)
	highlight("TabLine",       theme.base03, theme.base01, "none", nil)
	highlight("TabLineFill",   theme.base03, theme.base01, "none", nil)
	highlight("TabLineSel",    theme.base0B, theme.base01, "none", nil)

	-- Standard syntax highlighting
	highlight("Boolean",      theme.base09, nil, nil, nil)
	highlight("Character",    theme.base08, nil, nil, nil)
	highlight("Comment",      theme.base03, nil, nil, nil)
	highlight("Conditional",  theme.base0E, nil, nil, nil)
	highlight("Constant",     theme.base09, nil, nil, nil)
	highlight("Define",       theme.base0E, nil, "none", nil)
	highlight("Delimiter",    theme.base0F, nil, nil, nil)
	highlight("Float",        theme.base09, nil, nil, nil)
	highlight("Function",     theme.base0D, nil, nil, nil)
	highlight("Identifier",   theme.base08, nil, "none", nil)
	highlight("Include",      theme.base0D, nil, nil, nil)
	highlight("Keyword",      theme.base0E, nil, nil, nil)
	highlight("Label",        theme.base0A, nil, nil, nil)
	highlight("Number",       theme.base09, nil, nil, nil)
	highlight("Operator",     theme.base05, nil, "none", nil)
	highlight("PreProc",      theme.base0A, nil, nil, nil)
	highlight("Repeat",       theme.base0A, nil, nil, nil)
	highlight("Special",      theme.base0C, nil, nil, nil)
	highlight("SpecialChar",  theme.base0F, nil, nil, nil)
	highlight("Statement",    theme.base08, nil, nil, nil)
	highlight("StorageClass", theme.base0A, nil, nil, nil)
	highlight("String",       theme.base0B, nil, nil, nil)
	highlight("Structure",    theme.base0E, nil, nil, nil)
	highlight("Tag",          theme.base0A, nil, nil, nil)
	highlight("Todo",         theme.base0A, theme.base01,  nil, nil)
	highlight("Type",         theme.base0A, nil, "none", nil)
	highlight("Typedef",      theme.base0A, nil, nil, nil)

	---
	-- Extra definitions
	---

	-- C highlighting
	highlight("cOperator",   theme.base0C, nil, nil, nil)
	highlight("cPreCondit",  theme.base0E, nil, nil, nil)

	-- C# highlighting
	highlight("csClass",                 theme.base0A, nil, nil, nil)
	highlight("csAttribute",             theme.base0A, nil, nil, nil)
	highlight("csModifier",              theme.base0E, nil, nil, nil)
	highlight("csType",                  theme.base08, nil, nil, nil)
	highlight("csUnspecifiedStatement",  theme.base0D, nil, nil, nil)
	highlight("csContextualStatement",   theme.base0E, nil, nil, nil)
	highlight("csNewDecleration",        theme.base08, nil, nil, nil)

	-- CSS highlighting
	highlight("cssBraces",      theme.base05, nil,  nil, nil)
	highlight("cssClassName",   theme.base0E, nil,  nil, nil)
	highlight("cssColor",       theme.base0C, nil,  nil, nil)

	-- Diff highlighting
	highlight("DiffAdd",      theme.base0B, theme.base01,  nil, nil)
	highlight("DiffChange",   theme.base03, theme.base01,  nil, nil)
	highlight("DiffDelete",   theme.base08, theme.base01,  nil, nil)
	highlight("DiffText",     theme.base0D, theme.base01,  nil, nil)
	highlight("DiffAdded",    theme.base0B, theme.base00,  nil, nil)
	highlight("DiffFile",     theme.base08, theme.base00,  nil, nil)
	highlight("DiffNewFile",  theme.base0B, theme.base00,  nil, nil)
	highlight("DiffLine",     theme.base0D, theme.base00,  nil, nil)
	highlight("DiffRemoved",  theme.base08, theme.base00,  nil, nil)

	-- Git highlighting
	highlight("gitcommitOverflow",       theme.base08, nil, nil, nil)
	highlight("gitcommitSummary",        theme.base0B, nil, nil, nil)
	highlight("gitcommitComment",        theme.base03, nil, nil, nil)
	highlight("gitcommitUntracked",      theme.base03, nil, nil, nil)
	highlight("gitcommitDiscarded",      theme.base03, nil, nil, nil)
	highlight("gitcommitSelected",       theme.base03, nil, nil, nil)
	highlight("gitcommitHeader",         theme.base0E, nil, nil, nil)
	highlight("gitcommitSelectedType",   theme.base0D, nil, nil, nil)
	highlight("gitcommitUnmergedType",   theme.base0D, nil, nil, nil)
	highlight("gitcommitDiscardedType",  theme.base0D, nil, nil, nil)
	highlight("gitcommitBranch",         theme.base09, nil, "bold", nil)
	highlight("gitcommitUntrackedFile",  theme.base0A, nil, nil, nil)
	highlight("gitcommitUnmergedFile",   theme.base08, nil, "bold", nil)
	highlight("gitcommitDiscardedFile",  theme.base08, nil, "bold", nil)
	highlight("gitcommitSelectedFile",   theme.base0B, nil, "bold", nil)

	-- HTML highlighting
	highlight("htmlBold",    theme.base0A, nil, nil, nil)
	highlight("htmlItalic",  theme.base0E, nil, nil, nil)
	highlight("htmlEndTag",  theme.base05, nil, nil, nil)
	highlight("htmlTag",     theme.base05, nil, nil, nil)

	-- JavaScript highlighting
	highlight("javaScript",        theme.base05, nil, nil, nil)
	highlight("javaScriptBraces",  theme.base05, nil, nil, nil)
	highlight("javaScriptNumber",  theme.base09, nil, nil, nil)
	-- pangloss/vim-javascript highlighting
	highlight("jsOperator",          theme.base0D, nil, nil, nil)
	highlight("jsStatement",         theme.base0E, nil, nil, nil)
	highlight("jsReturn",            theme.base0E, nil, nil, nil)
	highlight("jsThis",              theme.base08, nil, nil, nil)
	highlight("jsClassDefinition",   theme.base0A, nil, nil, nil)
	highlight("jsFunction",          theme.base0E, nil, nil, nil)
	highlight("jsFuncName",          theme.base0D, nil, nil, nil)
	highlight("jsFuncCall",          theme.base0D, nil, nil, nil)
	highlight("jsClassFuncName",     theme.base0D, nil, nil, nil)
	highlight("jsClassMethodType",   theme.base0E, nil, nil, nil)
	highlight("jsRegexpString",      theme.base0C, nil, nil, nil)
	highlight("jsGlobalObjects",     theme.base0A, nil, nil, nil)
	highlight("jsGlobalNodeObjects", theme.base0A, nil, nil, nil)
	highlight("jsExceptions",        theme.base0A, nil, nil, nil)
	highlight("jsBuiltins",          theme.base0A, nil, nil, nil)

	-- Mail highlighting
	highlight("mailQuoted1",  theme.base0A, nil, nil, nil)
	highlight("mailQuoted2",  theme.base0B, nil, nil, nil)
	highlight("mailQuoted3",  theme.base0E, nil, nil, nil)
	highlight("mailQuoted4",  theme.base0C, nil, nil, nil)
	highlight("mailQuoted5",  theme.base0D, nil, nil, nil)
	highlight("mailQuoted6",  theme.base0A, nil, nil, nil)
	highlight("mailURL",      theme.base0D, nil, nil, nil)
	highlight("mailEmail",    theme.base0D, nil, nil, nil)

	-- Markdown highlighting
	highlight("markdownCode",              theme.base0B, nil, nil, nil)
	highlight("markdownError",             theme.base05, theme.base00, nil, nil)
	highlight("markdownCodeBlock",         theme.base0B, nil, nil, nil)
	highlight("markdownHeadingDelimiter",  theme.base0D, nil, nil, nil)

	-- PHP highlighting
	highlight("phpMemberSelector",  theme.base05, nil, nil, nil)
	highlight("phpComparison",      theme.base05, nil, nil, nil)
	highlight("phpParent",          theme.base05, nil, nil, nil)
	highlight("phpMethodsVar",      theme.base0C, nil, nil, nil)

	-- Python highlighting
	highlight("pythonOperator",  theme.base0E, nil, nil, nil)
	highlight("pythonRepeat",    theme.base0E, nil, nil, nil)
	highlight("pythonInclude",   theme.base0E, nil, nil, nil)
	highlight("pythonStatement", theme.base0E, nil, nil, nil)

	-- Ruby highlighting
	highlight("rubyAttribute",               theme.base0D, nil,  nil, nil)
	highlight("rubyConstant",                theme.base0A, nil,  nil, nil)
	highlight("rubyInterpolationDelimiter",  theme.base0F, nil,  nil, nil)
	highlight("rubyRegexp",                  theme.base0C, nil,  nil, nil)
	highlight("rubySymbol",                  theme.base0B, nil,  nil, nil)
	highlight("rubyStringDelimiter",         theme.base0B, nil,  nil, nil)

	-- SASS highlighting
	highlight("sassidChar",     theme.base08, nil,  nil, nil)
	highlight("sassClassChar",  theme.base09, nil,  nil, nil)
	highlight("sassInclude",    theme.base0E, nil,  nil, nil)
	highlight("sassMixing",     theme.base0E, nil,  nil, nil)
	highlight("sassMixinName",  theme.base0D, nil,  nil, nil)

	-- Spelling highlighting
	highlight("SpellBad",     nil, nil, "undercurl", theme.base08)
	highlight("SpellLocal",   nil, nil, "undercurl", theme.base0C)
	highlight("SpellCap",     nil, nil, "undercurl", theme.base0D)
	highlight("SpellRare",    nil, nil, "undercurl", theme.base0E)

	-- Java highlighting
	highlight("javaOperator",     theme.base0D, nil, nil, nil)

        -- LspDiagnostic base highlight group
	highlight("LspDiagnosticsDefaultError",       theme.base08, nil, nil, nil)
	highlight("LspDiagnosticsDefaultWarning",     theme.base0A, nil, nil, nil)
	highlight("LspDiagnosticsDefaultInformation", theme.base0D, nil, nil, nil)
	highlight("LspDiagnosticsDefaultHint",        theme.base0C, nil, nil, nil)

	-- TODO
	-- nvim.command 'syntax on'
end

return setmetatable({
	themes = function(name)
            name = "themes/" .. name .. "-base16"
            local present, theme_array = pcall(require, name)
            if present then
                return theme_array
            else
                error("No such base16 theme: " .. name)
            end
        end,
	apply_theme = apply_base16_theme,
	theme_from_array = function(array)
		assert(#array == 16, "base16.theme_from_array: The array length must be 16")
		local result = {}
		for i, value in ipairs(array) do
			assert(#value == 6, "base16.theme_from_array: array values must be in 6 digit hex format, e.g. 'ffffff'")
			local key = ("base%02X"):format(i - 1)
			result[key] = value
		end
		return result
	end
}, {
	__call = function (_, ...)
		apply_base16_theme(...)
	end,
})