local fs=require("filesystem")
local serialization=require("serialization")
local B={}
B.CFG="/etc/yaru-backup.cfg"

function B.config()
local cfg={src="/home",dst=nil,keep=3}
local f=io.open(B.CFG)
if f then
local ok,t=pcall(serialization.unserialize,f:read("*a"))
f:close()
if ok and type(t)=="table"then for k,v in pairs(t)do cfg[k]=v end end
end
return cfg
end
function B.save(cfg)
local f=io.open(B.CFG,"w")
if f then f:write(serialization.serialize(cfg));f:close()end
end

function B.snapshots(dst)
local r={}
local dir=fs.concat(dst or"","Backups")
if dst and fs.isDirectory(dir)then
for n in fs.list(dir)do if n:sub(-1)=="/"then r[#r+1]=n:sub(1,-2)end end
end
table.sort(r,function(a,b)return a>b end)
return r
end

local function walk(src,fn)
for name in fs.list(src)do
local p=fs.concat(src,name)
if name:sub(-1)=="/"then
if not fs.isLink(p)then walk(p,fn)end
else fn(p)end
end
end


function B.run(cfg,progress,stamp)
if not cfg.dst or not fs.isDirectory(cfg.dst)then return nil,"no destination drive"end
local dst=fs.canonical(cfg.dst)
local src=fs.canonical(cfg.src)
if(dst.."/"):sub(1,#src+1)==src.."/"then return nil,"destination is inside the source folder"end
local files={}
walk(src,function(p)files[#files+1]=p end)
local snap=fs.concat(dst,"Backups",stamp)
fs.makeDirectory(snap)
local bytes=0
for i,p in ipairs(files)do
local rel=p:sub(#src+2)
local target=fs.concat(snap,rel)
fs.makeDirectory(fs.path(target))
local ok,err=fs.copy(p,target)
if not ok then return nil,rel..": "..tostring(err)end
bytes=bytes+(fs.size(p)or 0)
if progress and i%5==0 then progress(i,#files,rel)end
end
local f=io.open(fs.concat(snap,".backup-info"),"w")
if f then f:write(serialization.serialize({src=src,files=#files,bytes=bytes}));f:close()end

local snaps=B.snapshots(dst)
for i=(cfg.keep or 3)+1,#snaps do fs.remove(fs.concat(dst,"Backups",snaps[i]))end
return#files,bytes
end

function B.info(dst,name)
local f=io.open(fs.concat(dst,"Backups",name,".backup-info"))
if not f then return{}end
local ok,t=pcall(serialization.unserialize,f:read("*a"))
f:close()
return ok and t or{}
end


function B.restore(dst,name,into,progress)
local snap=fs.concat(dst,"Backups",name)
local n=0
local files={}
walk(snap,function(p)if fs.name(p)~=".backup-info"then files[#files+1]=p end end)
for i,p in ipairs(files)do
local target=fs.concat(into,p:sub(#snap+2))
fs.makeDirectory(fs.path(target))
fs.copy(p,target)
n=n+1
if progress and i%5==0 then progress(i,#files,p)end
end
return n
end

return B