#!/usr/bin/env lua

--
-- Yoink
-- This script is a predictable alternative to the system install program.
--

function show_help()
	print([[

Install files, optionally changing the mode of the installed files.
Usage:
  install.lua [-m MODE] SOURCE... DEST

If DEST is a directory, the source(s) will be copied into DEST with their
same names.
]])
end


-- Get the next argument passed to the script.
function shift()
	var = arg[1]
	table.remove(arg, 1)
	return var
end

-- Execute a command and return its output or nil if the command failed to
-- run.
function backtick_run(command)
	local fd = io.popen(command.." 2>/dev/null")
	if fd then local stdout = fd:read("*l") fd:close() return stdout end
	return nil
end

-- Return true if a filespec is a directory, false otherwise.
function is_directory(path)
	return os.execute(string.format("test -d %q", path)) == 0
end

-- Get the basename of a path.
function basename(path, ext)
	if not ext then ext = "" end
	return backtick_run(string.format("basename %q %s", path, ext))
end

-- Get the directory part of a path.
function dirname(path)
	if path:sub(-1) == "/" then path = path .. "." end
	return backtick_run(string.format("dirname %q", path))
end

-- Like mkdir -p except portable.
function mkdir(path)
	if path:sub(1,1) ~= "/" then path = os.getenv("PWD") .. "/" .. path end
	path = path:gsub("/$", "")
	path = path:gsub("/+", "/")
	path = path:gsub("/[^/]+/%.%.", "")
	path = path:gsub("%./", "")
	path = path:gsub("/%.", "")

	local compound = ""
	for component in path:gmatch("(/[^/]*)") do
		compound = compound .. component
		if not is_directory(compound) then
			local result = os.execute(string.format("mkdir %q", compound))
			if result ~= 0 then os.exit(1) end
		end
	end
end

-- Change the mode of a file or directory.
function chmod(mode, filespec)
	if not mode or mode == "" then return end
	local result = os.execute(string.format("chmod %s %q", mode, filespec))
	if result ~= 0 then os.exit(1) end
end

-- Install a file.  If destination is a directory, the source will be
-- installed into the directory with the same name.
function install(mode, source, dest)
	if is_directory(dest) then dest = dest .. "/" .. basename(source) end
	local result = os.execute(string.format("cp %q %q", source, dest))
	if result == 0 then chmod(mode, dest) else os.exit(1) end
end


files = {}

-- Consume and parse each argument.
while 0 < #arg do
	local v = shift()
	if v == "-h" or v == "--help" then show_help() os.exit(0) end
	if v == "-m" then mode = shift() else table.insert(files, v) end
end

-- Check the arguments and determine the target.
if #files < 2 then show_help() os.exit(1)
else target = table.remove(files) end

-- Perform the installation.
if 1 < #files then
	mkdir(target)
	for i,file in ipairs(files) do install(mode, file, target) end
else
	mkdir(dirname(target))
	install(mode, files[1], target)
end