--
-- Copyright (c) 2023 Kyle Evans <kevans@FreeBSD.org>
--
-- SPDX-License-Identifier: BSD-2-Clause
--

local libgen = require('posix.libgen')
local lfs = require('lfs')
local stdlib = require('posix.stdlib')
local unistd = require('posix.unistd')
local sys_wait = require('posix.sys.wait')

local curdate = os.date("%B %e, %Y")

local output_head <const> = ".\\\" DO NOT EDIT-- this file is @" .. [[generated by tools/build/options/makeman.
.Dd ]] .. curdate .. [[

.Dt SRC.CONF 5
.Os
.Sh NAME
.Nm src.conf
.Nd "source build options"
.Sh DESCRIPTION
The
.Nm
file contains variables that control what components will be generated during
the build process of the
.Fx
source tree; see
.Xr build 7 .
.Pp
The
.Nm
file uses the standard makefile syntax.
However,
.Nm
should not specify any dependencies to
.Xr make 1 .
Instead,
.Nm
is to set
.Xr make 1
variables that control the aspects of how the system builds.
.Pp
The default location of
.Nm
is
.Pa /etc/src.conf ,
though an alternative location can be specified in the
.Xr make 1
variable
.Va SRCCONF .
Overriding the location of
.Nm
may be necessary if the system-wide settings are not suitable
for a particular build.
For instance, setting
.Va SRCCONF
to
.Pa /dev/null
effectively resets all build controls to their defaults.
.Pp
The only purpose of
.Nm
is to control the compilation of the
.Fx
source code, which is usually located in
.Pa /usr/src .
As a rule, the system administrator creates
.Nm
when the values of certain control variables need to be changed
from their defaults.
.Pp
In addition, control variables can be specified
for a particular build via the
.Fl D
option of
.Xr make 1
or in its environment; see
.Xr environ 7 .
.Pp
The environment of
.Xr make 1
for the build can be controlled via the
.Va SRC_ENV_CONF
variable, which defaults to
.Pa /etc/src-env.conf .
Some examples that may only be set in this file are
.Va WITH_DIRDEPS_BUILD ,
and
.Va WITH_META_MODE ,
and
.Va MAKEOBJDIRPREFIX
as they are environment-only variables.
.Pp
The values of
.Va WITH_
and
.Va WITHOUT_
variables are ignored regardless of their setting;
even if they would be set to
.Dq Li FALSE
or
.Dq Li NO .
The presence of an option causes
it to be honored by
.Xr make 1 .
.Pp
This list provides a name and short description for variables
that can be used for source builds.
.Bl -tag -width indent
]]

local output_tail <const> = [[.El
.Sh FILES
.Bl -tag -compact -width Pa
.It Pa /etc/src.conf
.It Pa /etc/src-env.conf
.It Pa /usr/share/mk/bsd.own.mk
.El
.Sh SEE ALSO
.Xr make 1 ,
.Xr make.conf 5 ,
.Xr build 7 ,
.Xr ports 7
.Sh HISTORY
The
.Nm
file appeared in
.Fx 7.0 .
.Sh AUTHORS
This manual page was autogenerated by
.An tools/build/options/makeman .
]]

local scriptdir <const> = libgen.dirname(stdlib.realpath(arg[0]))
local srcdir <const> = stdlib.realpath(scriptdir .. "/../../../")
local makesysdir <const> = srcdir .. "/share/mk"

local make_envvar = os.getenv("MAKE")
local make_cmd_override = {}
if make_envvar then
	for word in make_envvar:gmatch("[^%s]+") do
		make_cmd_override[#make_cmd_override + 1] = word
	end
end

-- Lifted from bsdinstall/scripts/pkgbase.in (read_all)
local function read_pipe(pipe)
	local ret = ""
	repeat
		local buffer = assert(unistd.read(pipe, 1024))
		ret = ret .. buffer
	until buffer == ""
	return ret
end
local function run_make(args)
	local cmd_args = {"env", "-i", "make", "-C", srcdir, "-m", makesysdir,
	    "__MAKE_CONF=/dev/null", "SRCCONF=/dev/null"}

	if #make_cmd_override > 0 then
		cmd_args[3] = make_cmd_override[1]
		for k = 2, #make_cmd_override do
			local val = make_cmd_override[k]

			table.insert(cmd_args, 3 + (k - 1), val)
		end
	end
	for k, v in ipairs(args) do
		cmd_args[#cmd_args + 1] = v
	end

	local r, w = assert(unistd.pipe())
	local pid = assert(unistd.fork())
	if pid == 0 then
		-- Child
		assert(unistd.close(r))
		assert(unistd.dup2(w, 1))
		assert(unistd.dup2(w, 2))
		assert(unistd.execp("env", cmd_args))
		unistd._exit()
	end

	-- Parent
	assert(unistd.close(w))

	local output = read_pipe(r)
	assert(unistd.close(r))

	local _, exit_type, exit_code = assert(sys_wait.wait(pid))
	assert(exit_type == "exited", "make exited with wrong status")
	assert(exit_code == 0, "make exited unsuccessfully")
	return output
end

local function native_target()
	local output = run_make({"MK_AUTO_OBJ=NO", "-V", "MACHINE",
	    "-V", "MACHINE_ARCH"})

	local arch, machine_arch
	for x in output:gmatch("[^\n]+") do
		if not arch then
			arch = x
		elseif not machine_arch then
			machine_arch = x
		end
	end

	return arch .. "/" .. machine_arch
end

local function src_targets()
	local targets = {}
	targets[native_target()] = true

	local output = run_make({"MK_AUTO_OBJ=no", "targets"})
	local curline = 0

	for line in output:gmatch("[^\n]+") do
		curline = curline + 1
		if curline ~= 1 then
			local arch = line:match("[^%s]+/[^%s]+")

			-- Make sure we don't roll over our default arch
			if arch and not targets[arch] then
				targets[arch] = false
			end
		end
	end

	return targets
end

local function config_options(srcconf, env, take_dupes, linting)
	srcconf = srcconf or "/dev/null"
	env = env or {}

	local option_args = {".MAKE.MODE=normal", "showconfig",
	    "SRC_ENV_CONF=" .. srcconf}

	for _, val in ipairs(env) do
		option_args[#option_args + 1] = val
	end

	local output = run_make(option_args)

	local options = {}
	local known_dupes = {}

	local function warn_on_dupe(option, val)
		if not linting or known_dupes[option] then
			return false
		end
		if not option:match("^OPT_") then
			val = val == "yes"
		end

		known_dupes[option] = true
		return val ~= options[val]
	end

	for opt in output:gmatch("[^\n]+") do
		if opt:match("^MK_[%a%d_]+%s+=%s+.+") then
			local name = opt:match("MK_[%a%d_]+")
			local val = opt:match("= .+"):sub(3)

			-- Some settings, e.g., MK_INIT_ALL_ZERO, may end up
			-- output twice for some reason that I haven't dug into;
			-- take the first value.  In some circumstances, though,
			-- we do make an exception and actually want to take the
			-- latest.
			if take_dupes or options[name] == nil then
				options[name] = val == "yes"
			elseif warn_on_dupe(name, val) then
				io.stderr:write("ignoring duplicate option " ..
				    name .. "\n")
			end
		elseif opt:match("^OPT_[%a%d_]+%s+=%s+.+") then
			local name = opt:match("OPT_[%a%d_]+")
			local val = opt:match("= .+"):sub(3)

			-- Multi-value options will arbitrarily use a table here
			-- to indicate the difference.
			if take_dupes or options[name] == nil then
				options[name] = val
			elseif warn_on_dupe(name, val) then
				io.stderr:write("ignoring duplicate option " ..
				    name .. "\n")
			end
		end
	end

	return options
end

local function env_only_options()
	local output = run_make({"MK_AUTO_OBJ=no", "-V", "__ENV_ONLY_OPTIONS"})
	local options = {}

	for opt in output:gmatch("[^%s]+") do
		options["MK_" .. opt] = true
	end

	return options
end

local function required_options()
	local output = run_make({"-f", "share/mk/src.opts.mk", "-V",
	    "__REQUIRED_OPTIONS"})
	local options = {}

	for opt in output:gmatch("[^%s]+") do
		options["MK_" .. opt] = true
	end

	return options
end

local function config_description(option_name)
	local fh = io.open(scriptdir .. "/" .. option_name)
	local desc

	if fh then
		desc = ""
		for line in fh:lines() do
			if not line:match("%$FreeBSD%$") then
				desc = desc .. line .. "\n"
			end
		end

		assert(fh:close())
	end

	return desc
end

local function config_descriptions(options)
	local desc = {}
	for name, _ in pairs(options) do
		if name:match("^MK_") then
			local basename = name:gsub("^MK_", "")
			local with_name = "WITH_" .. basename
			local without_name = "WITHOUT_" .. basename

			desc[with_name] = config_description(with_name)
			desc[without_name] = config_description(without_name)
		elseif name:match("^OPT_") then
			local basename = name:gsub("^OPT_", "")

			desc[name] = config_description(basename)
		end
	end
	return desc
end

local function dependent_options(tmpdir, option_name, all_opts, omit_others)
	local opt_sense = not not option_name:match("^WITH_")
	local base_option_name = option_name:gsub("^[^_]+_", "")
	local prefix = (opt_sense and "WITHOUT_") or "WITH_"

	local srcconf = tmpdir .. "/src-" ..prefix .. "ALL_" ..
	    option_name .. ".conf"
	local fh = assert(io.open(srcconf, "w+"))

	fh:write(option_name .. "=\"YES\"\n")
	if not omit_others then
		for opt, value in pairs(all_opts) do
			local base_opt = opt:gsub("^MK_", "")

			if base_opt ~= base_option_name then
				local opt_prefix = (value and "WITH_") or "WITHOUT_"
				fh:write(opt_prefix .. base_opt .. "=\"YES\"\n")
			end
		end
	end
	assert(fh:close())

	local option_name_key = "MK_" .. base_option_name
	local options = config_options(srcconf, nil, omit_others)
	for name, value in pairs(options) do
		if name == option_name_key or value == all_opts[name] then
			options[name] = nil
		elseif name:match("^OPT_") then
			-- Strip out multi-option values at the moment, they do
			-- not really make sense.
			options[name] = nil
		end
	end

	return options
end

local function export_option_table(fd, name, options)
	unistd.write(fd, name .. " = {")
	for k, v in pairs(options) do
		v = (v and "true") or "false"
		unistd.write(fd, "['" .. k .. "'] = " .. v .. ",")
	end
	unistd.write(fd, "}")
end

local function all_dependent_options(tmpdir, options, default_opts,
    with_all_opts, without_all_opts)
	local all_enforced_options = {}
	local all_effect_options = {}
	local children = {}

	for _, name in ipairs(options) do
		local rfd, wfd = assert(unistd.pipe())
		local pid = assert(unistd.fork())

		if pid == 0 then
			-- We need to pcall() this so that errors bubble up to
			-- our _exit() call rather than the main exit.
			local ret, errobj = pcall(function()
				unistd.close(rfd)

				local compare_table
				if name:match("^WITHOUT") then
					compare_table = with_all_opts
				else
					compare_table = without_all_opts
				end

				-- List of knobs forced on by this one
				local enforced_options = dependent_options(tmpdir, name,
				    compare_table)
				-- List of knobs implied by this by one (once additionally
				-- filtered based on enforced_options values)
				local effect_options = dependent_options(tmpdir, name,
				    default_opts, true)

				export_option_table(wfd, "enforced_options",
				    enforced_options)
				export_option_table(wfd, "effect_options",
				    effect_options)
			end)

			io.stderr:write(".")

			if ret then
				unistd._exit(0)
			else
				unistd.write(wfd, errobj)
				unistd._exit(1)
			end
		end

		unistd.close(wfd)
		children[pid] = {name, rfd}
	end

	while next(children) ~= nil do
::again::
		local pid, status, exitcode = sys_wait.wait(-1)

		if status ~= "exited" then
			goto again
		end

		local info = children[pid]
		children[pid] = nil

		local name = info[1]
		local rfd = info[2]
		local buf = ''
		local rbuf, sz

		-- Drain the pipe
		rbuf = unistd.read(rfd, 512)
		while #rbuf ~= 0 do
			buf = buf .. rbuf
			rbuf = unistd.read(rfd, 512)
		end

		unistd.close(rfd)

		if exitcode ~= 0 then
			error("Child " .. pid .. " failed, buf: " .. buf)
		end

		-- The child has written a pair of tables named enforced_options
		-- and effect_options to the pipe.  We'll load the pipe buffer
		-- as a string and then yank these out of the clean environment
		-- that we execute the chunk in.
		local child_env = {}
		local res, err = pcall(load(buf, "child", "t", child_env))

		all_enforced_options[name] = child_env["enforced_options"]
		all_effect_options[name] = child_env["effect_options"]
	end

	io.stderr:write("\n")
	return all_enforced_options, all_effect_options
end

local function get_defaults(target_archs, native_default_opts)
	local target_defaults = {}
	-- Set of options with differing defaults in some archs
	local different_defaults = {}

	for tgt, dflt in pairs(target_archs) do
		if dflt then
			local native_copy = {}
			for opt, val in pairs(native_default_opts) do
				native_copy[opt] = val
			end
			target_defaults[tgt] = native_copy
			goto skip
		end

		local target = tgt:gsub("/.+$", "")
		local target_arch = tgt:gsub("^.+/", "")

		local target_opts = config_options(nil, {"TARGET=" .. target,
		    "TARGET_ARCH=" .. target_arch})

		for opt, val in pairs(target_opts) do
			if val ~= native_default_opts[opt] then
				different_defaults[opt] = true
			end
		end

		target_defaults[tgt] = target_opts
::skip::
	end

	for opt in pairs(native_default_opts) do
		if different_defaults[opt] == nil then
			for _, opts in pairs(target_defaults) do
				opts[opt] = nil
			end
		end
	end

	for tgt, opts in pairs(target_defaults) do
		local val = opts["MK_ACPI"]

		if val ~= nil then
			print(" - " .. tgt .. ": " .. ((val and "yes") or "no"))
		end
	end

	return target_defaults, different_defaults
end

local function option_comparator(lhs, rhs)
	-- Convert both options to the base name, compare that instead unless
	-- they're the same option.  For the same option, we just want to get
	-- ordering between WITH_/WITHOUT_ correct.
	local base_lhs = lhs:gsub("^[^_]+_", "")
	local base_rhs = rhs:gsub("^[^_]+_", "")

	if base_lhs == base_rhs then
		return lhs < rhs
	else
		return base_lhs < base_rhs
	end
end

local function main(tmpdir)
	io.stderr:write("building src.conf.5 man page from files in " ..
	    scriptdir .. "\n")

	local env_only_opts <const> = env_only_options()
	local default_opts = config_options(nil, nil, nil, true)
	local opt_descriptions = config_descriptions(default_opts)
	local srcconf_all <const> = tmpdir .. "/src-all-enabled.conf"
	local fh = io.open(srcconf_all, "w+")
	local all_targets = src_targets()
	local target_defaults, different_defaults = get_defaults(all_targets,
	    default_opts)
	local options = {}
	local without_all_opts = {}

	for name, value in pairs(default_opts) do
		if name:match("^MK_") then
			local base_name = name:gsub("^MK_", "")
			local with_name = "WITH_" .. base_name
			local without_name = "WITHOUT_" .. base_name
			-- If it's differently defaulted on some architectures,
			-- we'll split it into WITH_/WITHOUT_ just to simplify
			-- some later bits.
			if different_defaults[name] ~= nil then
				options[#options + 1] = with_name
				options[#options + 1] = without_name
			elseif value then
				options[#options + 1] = without_name
			else
				options[#options + 1] = with_name
			end

			without_all_opts[name] = false
			assert(fh:write(with_name .. '="YES"\n'))
		else
			options[#options + 1] = name
		end
	end

	assert(fh:close())

	local with_all_opts = config_options(srcconf_all)
	local all_enforced_options, all_effect_options
	local all_required_options = required_options()

	all_enforced_options, all_effect_options = all_dependent_options(tmpdir,
	    options, default_opts, with_all_opts, without_all_opts)

	table.sort(options, option_comparator)
	io.stdout:write(output_head)
	for _, name in ipairs(options) do
		local value

		if name:match("^OPT_") then
			goto skip
		end
		assert(name:match("^WITH"), "Name looks wrong: " .. name)
		local describe_option = name

		value = not not name:match("^WITHOUT")

		-- Normalize name to MK_ for indexing into various other
		-- arrays
		name = "MK_" .. name:gsub("^[^_]+_", "")

		print(".It Va " .. describe_option:gsub("^OPT_", ""))
		if opt_descriptions[describe_option] then
			io.stdout:write(opt_descriptions[describe_option])
		else
			io.stderr:write("Missing description for " ..
			    describe_option .. "\n")
		end

		local enforced_options = all_enforced_options[describe_option]
		local effect_options = all_effect_options[describe_option]

		if different_defaults[name] ~= nil then
			print([[.Pp
This is a default setting on]])

			local which_targets = {}
			for tgt, tgt_options in pairs(target_defaults) do
				if tgt_options[name] ~= value then
					which_targets[#which_targets + 1] = tgt
				end
			end

			table.sort(which_targets)
			for idx, tgt in ipairs(which_targets) do
				io.stdout:write(tgt)
				if idx < #which_targets - 1 then
					io.stdout:write(", ")
				elseif idx == #which_targets - 1 then
					io.stdout:write(" and ")
				end
			end
			print(".")
		end

		-- Unset any implied options that are actually required.
		for dep_opt in pairs(enforced_options) do
			if all_required_options[dep_opt] then
				enforced_options[dep_opt] = nil
			end
		end
		if next(enforced_options) ~= nil then
			print([[When set, it enforces these options:
.Pp
.Bl -item -compact]])

			local sorted_dep_opt = {}
			for dep_opt in pairs(enforced_options) do
				sorted_dep_opt[#sorted_dep_opt + 1] = dep_opt
			end

			table.sort(sorted_dep_opt)
			for _, dep_opt in ipairs(sorted_dep_opt) do
				local dep_val = enforced_options[dep_opt]
				local dep_prefix = (dep_val and "WITH_") or
				    "WITHOUT_"
				local dep_name = dep_opt:gsub("^MK_",
				    dep_prefix)
				print(".It")
				print(".Va " .. dep_name)
			end

			print(".El")
		end

		if next(effect_options) ~= nil then
			if next(enforced_options) ~= nil then
				-- Remove any options that were previously
				-- noted as enforced...
				for opt, val in pairs(effect_options) do
					if enforced_options[opt] == val then
						effect_options[opt] = nil
					end
				end

				-- ... and this could leave us with an empty
				-- set.
				if next(effect_options) == nil then
					goto noenforce
				end

				print(".Pp")
			end

			print([[When set, these options are also in effect:
.Pp
.Bl -inset -compact]])

			local sorted_dep_opt = {}
			for dep_opt in pairs(effect_options) do
				sorted_dep_opt[#sorted_dep_opt + 1] = dep_opt
			end

			table.sort(sorted_dep_opt)
			for _, dep_opt in ipairs(sorted_dep_opt) do
				local dep_val = effect_options[dep_opt]
				local dep_prefix = (dep_val and "WITH_") or
				    "WITHOUT_"
				local not_dep_prefix = ((not dep_val) and "WITH_") or
				    "WITHOUT_"
				local dep_name = dep_opt:gsub("^MK_",
				    dep_prefix)
				local not_dep_name = dep_opt:gsub("^MK_",
				    not_dep_prefix)

				print(".It Va " .. dep_name)
				print("(unless")
				print(".Va " .. not_dep_name)
				print("is set explicitly)")
			end

			print(".El")
::noenforce::
		end

		if env_only_opts[name] ~= nil then
			print([[.Pp
This must be set in the environment, make command line, or
.Pa /etc/src-env.conf ,
not
.Pa /etc/src.conf .]])
		end
		::skip::
	end
	print([[.El
.Pp
The following options accept a single value from a list of valid values.
.Bl -tag -width indent]])
	for _, name in ipairs(options) do
		if name:match("^OPT_") then
			local desc = opt_descriptions[name]

			print(".It Va " .. name:gsub("^OPT_", ""))
			if desc then
				io.stdout:write(desc)
			else
				io.stderr:write("Missing description for " ..
				    name .. "\n")
			end
		end
	end
	io.stdout:write(output_tail)
end

local tmpdir = "/tmp/makeman." .. unistd.getpid()

if not lfs.mkdir(tmpdir) then
	error("Failed to create tempdir " .. tmpdir)
end

-- Catch any errors so that we can properly clean up, then re-throw it.
local ret, errobj = pcall(main, tmpdir)

for fname in lfs.dir(tmpdir) do
	if fname ~= "." and fname ~= ".." then
		assert(os.remove(tmpdir .. "/" .. fname))
	end
end

if not lfs.rmdir(tmpdir) then
	assert(io.stderr:write("Failed to clean up tmpdir: " .. tmpdir .. "\n"))
end

if not ret then
	io.stderr:write(errobj .. "\n")
	os.exit(1)
end