-- The original author's credits for a Forge port of an existing game:  the fields of the game's own
-- games.dat entry (developer, publisher, year, platform, genre, creator, source, description), the
-- "KEY: value" lines of its main script's header comment as notes, and the licence files beside
-- the script, which a release carries.  Nothing is invented:  a field the original does not state
-- is left out.
--
--     lua5.4 util/forgeCredits.lua <description.forge> <game directory> <main script>
--
-- writes or replaces the description's credits block, just after its title, and touches nothing
-- else in it.  util/forgePortKaris.lua loads this file for creditsFor, so a converted description
-- carries its credits from the start.

local CREDIT_KEYS = {
	{ field = "developer",   key = "DEVELOPER" },
	{ field = "publisher",   key = "PUBLISHER" },
	{ field = "year",        key = "YEAR" },
	{ field = "platform",    key = "PLATFORM" },
	{ field = "genre",       key = "GENRE" },
	{ field = "creator",     key = "CREATOR" },
	{ field = "source",      key = "SOURCE" },
	{ field = "description", key = "DESCRIPTION" }
}
local LICENCE_PATTERNS = { "^copying", "^licen[cs]e", "^gpl" }
local GAMES_DAT_DEPTH  = 2    -- How many folders above the script games.dat may be.


local function readFile(path)
	local handle = io.open(path, "rb")
	local text   = nil

	if handle then
		text = handle:read("a")
		handle:close()
	end

	return text
end


-- The games.dat entry for the script:  beside it or a folder or two above, the entry whose SCRIPT
-- names this script, or the only entry there is.
local function gamesEntry(dir, main)
	local folder = dir

	for _ = 0, GAMES_DAT_DEPTH do
		local text = readFile(folder .. "/games.dat")

		if text then
			local sandbox = {}
			local chunk   = load(text, "games.dat", "t", sandbox)

			if chunk and pcall(chunk) and (type(sandbox.GAMES) == "table") then
				for _, entry in ipairs(sandbox.GAMES) do
					local script = tostring(entry.SCRIPT or "")

					if script:lower():sub(-#main) == main:lower() then
						return entry
					end
				end
				if #sandbox.GAMES == 1 then
					return sandbox.GAMES[1]
				end
			end
		end
		folder = folder:match("^(.*)[/\\][^/\\]+$") or folder
	end

	return nil
end


-- The header comment's "KEY: value" lines, as the author wrote them:  program name, author, who
-- converted it and for what.
local function headerNotes(dir, main)
	local text  = readFile(dir .. "/" .. main) or ""
	local block = text:match("%-%-%[=*%[(.-)%]=*%]")
	local notes = {}

	for line in (block or ""):gmatch("[^\r\n]+") do
		local key, value = line:match("^%s*([A-Z][A-Z0-9 /%-]*[A-Z0-9])%s*:%s*(.-)%s*$")

		if key and (value ~= "") then
			notes[#notes + 1] = key:sub(1, 1) .. key:sub(2):lower() .. ":  " .. value
		end
	end

	return notes
end


-- The licence files beside the script, by name.
local function licences(dir)
	local found  = {}
	local handle = io.popen('ls -1 "' .. dir .. '" 2>/dev/null')

	if handle then
		for name in handle:lines() do
			for _, pattern in ipairs(LICENCE_PATTERNS) do
				if name:lower():match(pattern) then
					found[#found + 1] = name
					break
				end
			end
		end
		handle:close()
	end
	table.sort(found)

	return found
end


-- The credits block as description source, one line, or nil when there is nothing to credit.
function creditsFor(dir, main)
	local entry = gamesEntry(dir, main) or {}
	local parts = {}
	local notes = headerNotes(dir, main)
	local files = licences(dir)

	for _, credit in ipairs(CREDIT_KEYS) do
		local value = entry[credit.key]

		if type(value) == "number" then
			parts[#parts + 1] = string.format("%s = %d", credit.field, value)
		elseif (type(value) == "string") and (value ~= "") then
			parts[#parts + 1] = string.format("%s = %q", credit.field, value)
		end
	end
	if #notes > 0 then
		local quoted = {}

		for _, note in ipairs(notes) do
			quoted[#quoted + 1] = string.format("%q", note)
		end
		parts[#parts + 1] = "notes = { " .. table.concat(quoted, ", ") .. " }"
	end
	if #files > 0 then
		local quoted = {}

		for _, name in ipairs(files) do
			quoted[#quoted + 1] = string.format("%q", name)
		end
		parts[#parts + 1] = "licenses = { " .. table.concat(quoted, ", ") .. " }"
	end
	if #parts == 0 then
		return nil
	end

	return "\tcredits = { " .. table.concat(parts, ", ") .. " },"
end


-- The description with its credits line put just after the title, replacing one already there.
local function withCredits(text, line)
	local out   = {}
	local after = false

	for row in (text .. "\n"):gmatch("(.-)\n") do
		if not row:match("^\tcredits = {") then
			out[#out + 1] = row
			if (not after) and line and row:match("^\ttitle%s*=") then
				out[#out + 1] = line
				after = true
			end
		end
	end
	while (#out > 0) and (out[#out] == "") do
		out[#out] = nil
	end

	return table.concat(out, "\n") .. "\n", after
end


if arg and arg[0] and arg[0]:match("forgeCredits%.lua$") then
	local description = arg[1] or error("a description")
	local dir         = arg[2] or error("the game's directory")
	local main        = arg[3] or error("its main script")
	local text        = readFile(description) or error("cannot read " .. description)
	local line        = creditsFor(dir, main)
	local result, put = withCredits(text, line)

	if line and not put then
		error("no title line in " .. description)
	end
	local handle = io.open(description, "wb")

	handle:write(result)
	handle:close()
	print(description .. ":  " .. (line and line:gsub("^\t", "") or "nothing to credit"))
end