local nvim = require 'nvim'

local function highlight(group, guifg, guibg, ctermfg, ctermbg, attr, guisp)
	local parts = {group}
	if guifg then table.insert(parts, "guifg=#"..guifg) end
	if guibg then table.insert(parts, "guibg=#"..guibg) end
	if ctermfg then table.insert(parts, "ctermfg="..ctermfg) end
	if ctermbg then table.insert(parts, "ctermbg="..ctermbg) end
	if attr then
		table.insert(parts, "gui="..attr)
		table.insert(parts, "cterm="..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, use_256_colorspace)
	-- Terminal color definitions
	local cterm00        = "00"
	local cterm03        = "08"
	local cterm05        = "07"
	local cterm07        = "15"
	local cterm08        = "01"
	local cterm0A        = "03"
	local cterm0B        = "02"
	local cterm0C        = "06"
	local cterm0D        = "04"
	local cterm0E        = "05"

	local cterm01, cterm02, cterm04, cterm06, cterm09, cterm0F

	if use_256_colorspace then
		cterm01 = "18"
		cterm02 = "19"
		cterm04 = "20"
		cterm06 = "21"
		cterm09 = "16"
		cterm0F = "17"
	else
		cterm01 = "10"
		cterm02 = "11"
		cterm04 = "12"
		cterm06 = "13"
		cterm09 = "09"
		cterm0F = "14"
	end

	-- Neovim terminal colours
	if nvim.fn.has("nvim") then
		nvim.g.terminal_color_0 =  "#"..theme.base00
		nvim.g.terminal_color_1 =  "#"..theme.base08
		nvim.g.terminal_color_2 =  "#"..theme.base0B
		nvim.g.terminal_color_3 =  "#"..theme.base0A
		nvim.g.terminal_color_4 =  "#"..theme.base0D
		nvim.g.terminal_color_5 =  "#"..theme.base0E
		nvim.g.terminal_color_6 =  "#"..theme.base0C
		nvim.g.terminal_color_7 =  "#"..theme.base05
		nvim.g.terminal_color_8 =  "#"..theme.base03
		nvim.g.terminal_color_9 =  "#"..theme.base08
		nvim.g.terminal_color_10 = "#"..theme.base0B
		nvim.g.terminal_color_11 = "#"..theme.base0A
		nvim.g.terminal_color_12 = "#"..theme.base0D
		nvim.g.terminal_color_13 = "#"..theme.base0E
		nvim.g.terminal_color_14 = "#"..theme.base0C
		nvim.g.terminal_color_15 = "#"..theme.base07
		if nvim.o.background == "light" then
			nvim.g.terminal_color_background = "#"..theme.base05
			nvim.g.terminal_color_foreground = "#"..theme.base0B
		else
			nvim.g.terminal_color_background = "#"..theme.base00
			nvim.g.terminal_color_foreground = "#"..theme.base0E
		end
	-- VIM, not NVIM settings
	-- elseif nvim.fn.has("terminal") then
	-- 	nvim.g.terminal_ansi_colors = {
	-- 		theme.base00,
	-- 		theme.base08,
	-- 		theme.base0B,
	-- 		theme.base0A,
	-- 		theme.base0D,
	-- 		theme.base0E,
	-- 		theme.base0C,
	-- 		theme.base05,
	-- 		theme.base03,
	-- 		theme.base08,
	-- 		theme.base0B,
	-- 		theme.base0A,
	-- 		theme.base0D,
	-- 		theme.base0E,
	-- 		theme.base0C,
	-- 		theme.base07,
	-- 	}
	end

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

	-- Vim editor colors
	highlight("Normal",        theme.base05, theme.base00, cterm05, theme.base00 , nil, nil)
	highlight("Bold",          nil, nil, nil, nil, "bold", nil)
	highlight("Debug",         theme.base08, nil, cterm08, nil, nil, nil)
	highlight("Directory",     theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("Error",         theme.base00, theme.base08, cterm00, cterm08, nil, nil)
	highlight("ErrorMsg",      theme.base08, theme.base00, cterm08, cterm00, nil, nil)
	highlight("Exception",     theme.base08, nil, cterm08, nil, nil, nil)
	highlight("FoldColumn",    theme.base0C, theme.base01, cterm0C, cterm01, nil, nil)
	highlight("Folded",        theme.base03, theme.base01, cterm03, cterm01, nil, nil)
	highlight("IncSearch",     theme.base01, theme.base09, cterm01, cterm09, "none", nil)
	highlight("Italic",        nil, nil, nil, nil, "none", nil)
	highlight("Macro",         theme.base08, nil, cterm08, nil, nil, nil)
	highlight("MatchParen",    nil, theme.base03, nil, cterm03,  nil, nil)
	highlight("ModeMsg",       theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("MoreMsg",       theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("Question",      theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("Search",        theme.base01, theme.base0A, cterm01, cterm0A,  nil, nil)
	highlight("Substitute",    theme.base01, theme.base0A, cterm01, cterm0A, "none", nil)
	highlight("SpecialKey",    theme.base03, nil, cterm03, nil, nil, nil)
	highlight("TooLong",       theme.base08, nil, cterm08, nil, nil, nil)
	highlight("Underlined",    theme.base08, nil, cterm08, nil, nil, nil)
	highlight("Visual",        nil, theme.base02, nil, cterm02, nil, nil)
	highlight("VisualNOS",     theme.base08, nil, cterm08, nil, nil, nil)
	highlight("WarningMsg",    theme.base08, nil, cterm08, nil, nil, nil)
	highlight("WildMenu",      theme.base08, theme.base0A, cterm08, nil, nil, nil)
	highlight("Title",         theme.base0D, nil, cterm0D, nil, "none", nil)
	highlight("Conceal",       theme.base0D, theme.base00, cterm0D, cterm00, nil, nil)
	highlight("Cursor",        theme.base00, theme.base05, cterm00, cterm05, nil, nil)
	highlight("NonText",       theme.base03, nil, cterm03, nil, nil, nil)
	highlight("LineNr",        theme.base03, "NONE", cterm03, "NONE", nil, nil)
	highlight("SignColumn",    theme.base03, "NONE", cterm03, "NONE", nil, nil)
	highlight("StatusLine",    theme.base04, theme.base02, cterm04, cterm02, "none", nil)
	highlight("StatusLineNC",  theme.base03, "NONE", cterm03, "NONE", "none", nil)
	highlight("VertSplit",     theme.base02, "NONE", cterm02, "NONE", "none", nil)
	highlight("ColorColumn",   nil, theme.base01, nil, cterm01, "none", nil)
	highlight("CursorColumn",  nil, theme.base01, nil, cterm01, "none", nil)
	highlight("CursorLine",    nil, theme.base01, nil, cterm01, "none", nil)
	highlight("CursorLineNr",  theme.base04, "NONE", cterm04, "NONE", nil, nil)
	highlight("QuickFixLine",  nil, theme.base01, nil, cterm01, "none", nil)
	highlight("PMenu",         theme.base05, theme.base01, cterm05, cterm01, "none", nil)
	highlight("PMenuSel",      theme.base01, theme.base05, cterm01, cterm05, nil, nil)
	highlight("TabLine",       theme.base03, theme.base01, cterm03, cterm01, "none", nil)
	highlight("TabLineFill",   theme.base03, theme.base01, cterm03, cterm01, "none", nil)
	highlight("TabLineSel",    theme.base0B, theme.base01, cterm0B, cterm01, "none", nil)

	-- Standard syntax highlighting
	highlight("Boolean",      theme.base09, nil, cterm09, nil, nil, nil)
	highlight("Character",    theme.base08, nil, cterm08, nil, nil, nil)
	highlight("Comment",      theme.base03, nil, cterm03, nil, nil, nil)
	highlight("Conditional",  theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("Constant",     theme.base09, nil, cterm09, nil, nil, nil)
	highlight("Define",       theme.base0E, nil, cterm0E, nil, "none", nil)
	highlight("Delimiter",    theme.base0F, nil, cterm0F, nil, nil, nil)
	highlight("Float",        theme.base09, nil, cterm09, nil, nil, nil)
	highlight("Function",     theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("Identifier",   theme.base08, nil, cterm08, nil, "none", nil)
	highlight("Include",      theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("Keyword",      theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("Label",        theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("Number",       theme.base09, nil, cterm09, nil, nil, nil)
	highlight("Operator",     theme.base05, nil, cterm05, nil, "none", nil)
	highlight("PreProc",      theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("Repeat",       theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("Special",      theme.base0C, nil, cterm0C, nil, nil, nil)
	highlight("SpecialChar",  theme.base0F, nil, cterm0F, nil, nil, nil)
	highlight("Statement",    theme.base08, nil, cterm08, nil, nil, nil)
	highlight("StorageClass", theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("String",       theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("Structure",    theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("Tag",          theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("Todo",         theme.base0A, theme.base01, cterm0A, cterm01, nil, nil)
	highlight("Type",         theme.base0A, nil, cterm0A, nil, "none", nil)
	highlight("Typedef",      theme.base0A, nil, cterm0A, nil, nil, nil)

	---
	-- Extra definitions
	---

	-- C highlighting
	highlight("cOperator",   theme.base0C, nil, cterm0C, nil, nil, nil)
	highlight("cPreCondit",  theme.base0E, nil, cterm0E, nil, nil, nil)

	-- C# highlighting
	highlight("csClass",                 theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("csAttribute",             theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("csModifier",              theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("csType",                  theme.base08, nil, cterm08, nil, nil, nil)
	highlight("csUnspecifiedStatement",  theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("csContextualStatement",   theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("csNewDecleration",        theme.base08, nil, cterm08, nil, nil, nil)

	-- CSS highlighting
	highlight("cssBraces",      theme.base05, nil, cterm05, nil, nil, nil)
	highlight("cssClassName",   theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("cssColor",       theme.base0C, nil, cterm0C, nil, nil, nil)

	-- Diff highlighting
	highlight("DiffAdd",      theme.base0B, theme.base01,  cterm0B, cterm01, nil, nil)
	highlight("DiffChange",   theme.base03, theme.base01,  cterm03, cterm01, nil, nil)
	highlight("DiffDelete",   theme.base08, theme.base01,  cterm08, cterm01, nil, nil)
	highlight("DiffText",     theme.base0D, theme.base01,  cterm0D, cterm01, nil, nil)
	highlight("DiffAdded",    theme.base0B, theme.base00,  cterm0B, cterm00, nil, nil)
	highlight("DiffFile",     theme.base08, theme.base00,  cterm08, cterm00, nil, nil)
	highlight("DiffNewFile",  theme.base0B, theme.base00,  cterm0B, cterm00, nil, nil)
	highlight("DiffLine",     theme.base0D, theme.base00,  cterm0D, cterm00, nil, nil)
	highlight("DiffRemoved",  theme.base08, theme.base00,  cterm08, cterm00, nil, nil)

	-- Git highlighting
	highlight("gitcommitOverflow",       theme.base08, nil, cterm08, nil, nil, nil)
	highlight("gitcommitSummary",        theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("gitcommitComment",        theme.base03, nil, cterm03, nil, nil, nil)
	highlight("gitcommitUntracked",      theme.base03, nil, cterm03, nil, nil, nil)
	highlight("gitcommitDiscarded",      theme.base03, nil, cterm03, nil, nil, nil)
	highlight("gitcommitSelected",       theme.base03, nil, cterm03, nil, nil, nil)
	highlight("gitcommitHeader",         theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("gitcommitSelectedType",   theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("gitcommitUnmergedType",   theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("gitcommitDiscardedType",  theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("gitcommitBranch",         theme.base09, nil, cterm09, nil, "bold", nil)
	highlight("gitcommitUntrackedFile",  theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("gitcommitUnmergedFile",   theme.base08, nil, cterm08, nil, "bold", nil)
	highlight("gitcommitDiscardedFile",  theme.base08, nil, cterm08, nil, "bold", nil)
	highlight("gitcommitSelectedFile",   theme.base0B, nil, cterm0B, nil, "bold", nil)

	-- GitGutter highlighting
	highlight("GitGutterAdd",     theme.base0B, theme.base01, cterm0B, cterm01, nil, nil)
	highlight("GitGutterChange",  theme.base0D, theme.base01, cterm0D, cterm01, nil, nil)
	highlight("GitGutterDelete",  theme.base08, theme.base01, cterm08, cterm01, nil, nil)
	highlight("GitGutterChangeDelete",  theme.base0E, theme.base01, cterm0E, cterm01, nil, nil)

	-- HTML highlighting
	highlight("htmlBold",    theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("htmlItalic",  theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("htmlEndTag",  theme.base05, nil, cterm05, nil, nil, nil)
	highlight("htmlTag",     theme.base05, nil, cterm05, nil, nil, nil)

	-- JavaScript highlighting
	highlight("javaScript",        theme.base05, nil, cterm05, nil, nil, nil)
	highlight("javaScriptBraces",  theme.base05, nil, cterm05, nil, nil, nil)
	highlight("javaScriptNumber",  theme.base09, nil, cterm09, nil, nil, nil)
	-- pangloss/vim-javascript highlighting
	highlight("jsOperator",          theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("jsStatement",         theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("jsReturn",            theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("jsThis",              theme.base08, nil, cterm08, nil, nil, nil)
	highlight("jsClassDefinition",   theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("jsFunction",          theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("jsFuncName",          theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("jsFuncCall",          theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("jsClassFuncName",     theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("jsClassMethodType",   theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("jsRegexpString",      theme.base0C, nil, cterm0C, nil, nil, nil)
	highlight("jsGlobalObjects",     theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("jsGlobalNodeObjects", theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("jsExceptions",        theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("jsBuiltins",          theme.base0A, nil, cterm0A, nil, nil, nil)

	-- Mail highlighting
	highlight("mailQuoted1",  theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("mailQuoted2",  theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("mailQuoted3",  theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("mailQuoted4",  theme.base0C, nil, cterm0C, nil, nil, nil)
	highlight("mailQuoted5",  theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("mailQuoted6",  theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("mailURL",      theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("mailEmail",    theme.base0D, nil, cterm0D, nil, nil, nil)

	-- Markdown highlighting
	highlight("markdownCode",              theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("markdownError",             theme.base05, theme.base00, cterm05, cterm00, nil, nil)
	highlight("markdownCodeBlock",         theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("markdownHeadingDelimiter",  theme.base0D, nil, cterm0D, nil, nil, nil)

	-- NERDTree highlighting
	highlight("NERDTreeDirSlash",  theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("NERDTreeExecFile",  theme.base05, nil, cterm05, nil, nil, nil)

	-- PHP highlighting
	highlight("phpMemberSelector",  theme.base05, nil, cterm05, nil, nil, nil)
	highlight("phpComparison",      theme.base05, nil, cterm05, nil, nil, nil)
	highlight("phpParent",          theme.base05, nil, cterm05, nil, nil, nil)
	highlight("phpMethodsVar",      theme.base0C, nil, cterm0C, nil, nil, nil)

	-- Python highlighting
	highlight("pythonOperator",  theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("pythonRepeat",    theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("pythonInclude",   theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("pythonStatement", theme.base0E, nil, cterm0E, nil, nil, nil)

	-- Ruby highlighting
	highlight("rubyAttribute",               theme.base0D, nil, cterm0D, nil, nil, nil)
	highlight("rubyConstant",                theme.base0A, nil, cterm0A, nil, nil, nil)
	highlight("rubyInterpolationDelimiter",  theme.base0F, nil, cterm0F, nil, nil, nil)
	highlight("rubyRegexp",                  theme.base0C, nil, cterm0C, nil, nil, nil)
	highlight("rubySymbol",                  theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("rubyStringDelimiter",         theme.base0B, nil, cterm0B, nil, nil, nil)

	-- SASS highlighting
	highlight("sassidChar",     theme.base08, nil, cterm08, nil, nil, nil)
	highlight("sassClassChar",  theme.base09, nil, cterm09, nil, nil, nil)
	highlight("sassInclude",    theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("sassMixing",     theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("sassMixinName",  theme.base0D, nil, cterm0D, nil, nil, nil)

	-- Signify highlighting
	highlight("SignifySignAdd",     theme.base0B, theme.base01, cterm0B, cterm01, nil, nil)
	highlight("SignifySignChange",  theme.base0D, theme.base01, cterm0D, cterm01, nil, nil)
	highlight("SignifySignDelete",  theme.base08, theme.base01, cterm08, cterm01, nil, nil)

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

	-- Startify highlighting
	highlight("StartifyBracket",  theme.base03, nil, cterm03, nil, nil, nil)
	highlight("StartifyFile",     theme.base07, nil, cterm07, nil, nil, nil)
	highlight("StartifyFooter",   theme.base03, nil, cterm03, nil, nil, nil)
	highlight("StartifyHeader",   theme.base0B, nil, cterm0B, nil, nil, nil)
	highlight("StartifyNumber",   theme.base09, nil, cterm09, nil, nil, nil)
	highlight("StartifyPath",     theme.base03, nil, cterm03, nil, nil, nil)
	highlight("StartifySection",  theme.base0E, nil, cterm0E, nil, nil, nil)
	highlight("StartifySelect",   theme.base0C, nil, cterm0C, nil, nil, nil)
	highlight("StartifySlash",    theme.base03, nil, cterm03, nil, nil, nil)
	highlight("StartifySpecial",  theme.base03, nil, cterm03, nil, nil, nil)

	-- Java highlighting
	highlight("javaOperator",     theme.base0D, nil, cterm0D, nil, nil, nil)
 
  -- LspDiagnostic base highlight group
	highlight("LspDiagnosticsDefaultError",       theme.base08, nil, cterm00, cterm08, nil, nil)
	highlight("LspDiagnosticsDefaultWarning",     theme.base0A, nil, cterm08, cterm00, nil, nil)
	highlight("LspDiagnosticsDefaultInformation", theme.base0D, nil, cterm08, cterm00, nil, nil)
	highlight("LspDiagnosticsDefaultHint",        theme.base0C, nil, cterm08, cterm00, 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,
})