-- SPDX-FileCopyrightText: © 2022—2026 Vladimir Zorin <vladimir@deviant.guru>
-- SPDX-License-Identifier: LicenseRef-OWL-1.0-or-later
-- Licensed under OWL v1.0+. See LICENSE.

local testimony = require("testimony")
local std = require("std")
local git_pack = require("git.pack")
local crypto = require("crypto")

local testify = testimony.new("== git.pack ==")

-- os.execute returns a boolean with LUA52COMPAT, a number otherwise
local sh = function(cmd)
	local r = os.execute(cmd .. " >/dev/null 2>&1")
	return r == true or r == 0
end

local has_git = sh("git --version")

local sh_out = function(cmd)
	local f = io.popen(cmd)
	if not f then
		return nil
	end
	local out = f:read("*a")
	f:close()
	return out and out:match("^%s*(.-)%s*$")
end

local make_fixture = function()
	local dir = "/tmp/" .. std.nanoid()
	local g = "git -C " .. dir .. " -c user.name=test -c user.email=test@test"
	if not sh("git init -q " .. dir) then
		return nil
	end
	std.fs.write_file(dir .. "/readme.txt", "hello lilush pack writer\n")
	std.fs.mkdir(dir .. "/sub")
	std.fs.write_file(dir .. "/sub/data.bin", string.rep("\0\1\2\3", 1024))
	sh(g .. " add -A")
	sh(g .. " commit -q -m first")
	std.fs.write_file(dir .. "/readme.txt", "hello again\n")
	sh(g .. " add -A")
	sh(g .. " commit -q -m second")
	local head = sh_out("git -C " .. dir .. " rev-parse HEAD")
	if not head or #head ~= 40 then
		return nil
	end
	return { dir = dir, git_dir = dir .. "/.git", head = head }
end

local fixture = has_git and make_fixture() or nil

if fixture then
	testify:that("collect_objects: walks the full graph from HEAD", function()
		local objects = git_pack.collect_objects(fixture.git_dir, { fixture.head })
		testimony.assert_not_nil(objects)
		-- 2 commits, 3 trees (root x2 + sub), 3 blobs (readme x2 + data.bin)
		testimony.assert_equal(8, #objects)
	end)

	testify:that("collect_objects: unknown want yields an error", function()
		local objects, err = git_pack.collect_objects(fixture.git_dir, { string.rep("f", 40) })
		testimony.assert_nil(objects)
		testimony.assert_match("object not found", err)
	end)

	testify:that("build_pack: valid pack v2 structure and trailer", function()
		local objects = git_pack.collect_objects(fixture.git_dir, { fixture.head })
		local pack = git_pack.build_pack(fixture.git_dir, objects)
		testimony.assert_equal("PACK", pack:sub(1, 4))
		testimony.assert_equal("\0\0\0\2", pack:sub(5, 8))
		testimony.assert_equal(#objects, string.byte(pack, 12))
		testimony.assert_equal(crypto.sha1(pack:sub(1, -21)), pack:sub(-20))
	end)

	testify:that("build_pack: output passes git index-pack --strict", function()
		local objects = git_pack.collect_objects(fixture.git_dir, { fixture.head })
		local pack = git_pack.build_pack(fixture.git_dir, objects)
		local pack_path = fixture.dir .. "/generated.pack"
		std.fs.write_file(pack_path, pack)
		testimony.assert_true(sh("git index-pack --strict " .. pack_path))
	end)
else
	print("-- git binary not found (or fixture failed), skipping git.pack tests --")
end

if fixture then
	os.execute("rm -rf " .. fixture.dir)
end
testify:conclude()