#!/opt/Lua51/bin/lua

local cjson = require "cjson"
local invoker = require "invoker"
local gfmt = string.format

local function goodstr(s)
	if type(s) ~= "string" then return false end
	if string.len(s) == 0 then return false end
	return true
end

local function tagman_load(cfgfile)
	local cfgd = invoker.readfile(cfgfile, TAGMAN_MAXSIZE)
	if not cfgd then
		io.stderr:write(gfmt("Error, failed to read file: %s\n", cfgfile))
		io.stderr:flush()
		return false
	end

	local okay, jdat = pcall(cjson.decode, cfgd)
	cfgd = nil -- free memory early
	if not okay or type(jdat) ~= "table" then
		io.stderr:write(gfmt("Error, failed to decode as JSON: %s\n", cfgfile))
		io.stderr:flush()
		return false
	end

	local repos = jdat["repolist"]
	if type(repos) ~= "table" then
		io.stderr:write(gfmt("Error, repolist not found in %s\n", cfgfile))
		io.stderr:flush()
		return false
	end

	local pathidx = {}
	local repidx, repoinfo = 0, {}
	while true do
		repidx = repidx + 1
		local rinfo = repos[repidx]
		if type(rinfo) ~= "table" then break end

		-- extract Git repo information
		local path_g, branch, tagv = rinfo['path'], rinfo['branch'], rinfo['tag']
		if not goodstr(path_g) then
			io.stderr:write(gfmt("Error, invalid git repository information at index: %d\n", repidx))
			io.stderr:flush()
			return false
		end

		local dotgit = gfmt("%s/.git", path_g)
		if invoker.statfile(path_g) ~= "directory" or
			invoker.statfile(dotgit) ~= "directory" then
			io.stderr:write(gfmt("Error, invalid git repository path: %s\n", path_g))
			io.stderr:flush()
			return false
		end

		if pathidx[path_g] then -- check for git duplication
			io.stderr:write(gfmt("Error, duplicated git repository: %s\n", path_g))
			io.stderr:flush()
			return false
		end

		if not goodstr(branch) then
			io.stderr:write(gfmt("Error, branch not specified for %s\n", path_g))
			io.stderr:flush()
			return false
		end
		if not goodstr(tagv) then tagv = nil end

		pathidx[path_g]  = repidx
		repoinfo[path_g]   = {
			["branch"]     = branch,
			["tag"]        = tagv,
		}
	end

	if repidx <= 0 then return nil end
	return repoinfo
end

local function mainfunc(arg1, arg2)
	if not invoker.statfile(arg1) then
		if type(arg1) ~= "string" then arg1 = "nil" end
		io.stderr:write(gfmt("Error, first json file not found: %s\n", arg1))
		io.stderr:flush()
		return false
	end
	if not invoker.statfile(arg2) then
		if type(arg2) ~= "string" then arg2 = "nil" end
		io.stderr:write(gfmt("Error, second json file not found: %s\n", arg2))
		io.stderr:flush()
		return false
	end

	local r1info = tagman_load(arg1)
	if not r1info then
		io.stderr:write(gfmt("Error, failed to load branch/tag file: %s\n", arg1))
		io.stderr:flush()
		return false
	end

	local r2info = tagman_load(arg2)
	if not r1info then
		io.stderr:write(gfmt("Error, failed to load branch/tag file: %s\n", arg2))
		io.stderr:flush()
		return false
	end

	local sep0 = "============================================================\n"
	local sep1 = "************************************************************\n"

	for path_i, info_2 in pairs(r2info) do
		local info_1 = r1info[path_i]
		if type(info_1) == "table" then
			local tag1, tag2 = info_1["tag"], info_2["tag"]
			if goodstr(tag1) and goodstr(tag2) then
				if tag1 ~= tag2 then
					io.stdout:write(sep0)
					io.stdout:write(gfmt("ChangeLog for %s\n", path_i))
					io.stdout:flush()
					if not invoker.statfile(gfmt("%s/ChangeLog", path_i)) then
						io.stderr:write(gfmt("Error, ChangeLog file not found: %s\n", path_i))
						io.stderr:flush()
					else
						invoker.invoke(0, "bash", "-c", gfmt("cd \"%s\" && (git diff \"%s\" \"%s\" -- ChangeLog | cat)",
							path_i, tag1, tag2))
					end
					io.stdout:write(sep1)
					io.stdout:flush()
				end
			else
				io.stderr:write(gfmt("Error, Git repository \"%s\" tag missing\n", path_i))
				io.stderr:flush()
			end
		else
			io.stderr:write(gfmt("Error, Git repository \"%s\" not found in \"%s\"\n", path_i, arg1))
			io.stderr:flush()
		end
		r1info[path_i] = nil
	end
	return true
end

os.exit(mainfunc(arg[1], arg[2]) and 0 or 1)