dah_installer

--theinsektAPIs/installerAPI
--a program used to install/download computercraft programs

--incomplete erroneous example
--os.loadAPI("dah_installer")
--doInstallFile(shell, {}, "")


--experimental
--only tested a little
--may stop working when testing new stuff



function loadLines(path)
 if  not fs.exists(path) then
  return nil
 end
 local h=fs.open(path, "r")
 if h==nil then
  return nil
 end
 local res={}
 while(true) do
  local line=h.readLine()
  if line==nil then break end
  res[#res+1]=line
 end
 h.close()
 return res
end



function getWords(line)
 local words={}
 --"%S+"
 --"%a+"
 for word in string.gmatch(line, "%S+") do
  words[#words+1]=word
 end
 return words
end



--do the commands and add to the installed
--table if something was installed
--installed[path]=code
--should have the same code if it's the same file
--that way the same install file can be referenced twice
commands={


 installfile=function(shellObj,installed,words)
  --get parameters
  local command=words[1]
  local code=words[2]
  local path="installfiles/"..code
  --local path=words[3]
  --download the install file, and mark it as installed
  local res=pastebin2(shellObj,installed, command, code, path)
  if res~=2 then --if res==1 or res==-1
   return res
  end
  --do installs in install file
  return doInstallFile(shellObj,installed,path)
 end,


 pastebin=function(shellObj,installed,words)
  --get parameters
  local command=words[1]
  local code=words[2]
  local path=words[3]
  --download the file and mark it as installed
  return pastebin2(shellObj,installed, command,code,path)
 end,


 ["comment"]=function(shellObj,installed,words)
  return 0
 end,


}

--returns 0 if the line is empty or should be ignored
--returns -2 if unrecognised command
--returns 1 if already installed
--returns 2 if installed
--returns -1 if two different files have the same path
--positive number are good, negative are bad

resCodeMeanings={
[-2]="unrecognised command",
[-1]="two different files have the same path",
[0]="line was empty or ignored",
[1]="skipped because already installed",
[2]="performed installation",
}

function getRescodeMeaning(resCode)
 local res=resCodeMeanings[resCode]
 if res==nil then
  return "unrecognized resCode"
 end
 return res
end



--returns 1 if already installed
--returns 2 if installed
--returns -1 if two different files have the same path
--positive number are good, negative are bad
function pastebin2(shellObj, installed, command,code,path)
  --check parameters
  if type(installed)~="table" then error("Error: the parameter called installed, should be a table.",2) end
  if type(command)~="string" then error("Error: the parameter called command, should be a string",2) end
  if type(code)~="string" then error("Error: the parameter called code, should be a string",2) end
  if type(path)~="string" then error("Error: the parameter called path, should be a string",2) end
  --check if already installed
  if installed[path]~=nil then
   if installed[path]==code then
    --return have already installed code
    return 1
   else
    --have already installed a different file
    --with the same path
    return -1
   end
  end
  --download file (install)
  pastebin(shellObj,path,code,true)
  --update installed
  installed[path]=code
  --return did install code
  return 2
end



--returns 0 if the line is empty or should be ignored
--returns -2 if unrecognised command
--returns 1 if already installed
--returns 2 if installed
--returns -1 if two different files have the same path
--positive number are good, negative are bad
function doInstallLine(shellObj,installed,line)
 --get the words on the line
  local words=getWords(line)
  --
  return doInstallWords(shellObj,installed,words)
end



--install using words from command line
function doInstallWords(shellObj,installed,words)
  --DEBUG
  --for k,v in ipairs(words) do
  -- print(k,": ",v)
  --end
  --if line has no commands return 0
  if words==nil or #words==0 then
   return 0
  end
  --get the command on the line
  local command=words[1]
  --get the command function
  local f=commands[command]
  --if that command function does not exist return -2
  if f==nil then
   return -2
  end
  --run the command function
  return f(shellObj, installed, words)
end



function doInstallFile(shellObj, installed, path)
 --check arguments
 if installed==nil then installed={} end
 if type(path)~="string" then error("Error: path should be a string",2) end
 if type(installed)~="table" then error("Error: installed should be a table or nil",2) end
 --load lines from install file
 local lines=loadLines(path)
 --for each line
 for lineNr,line in ipairs(lines) do
  local resCode = doInstallLine(shellObj, installed, line)
  --throw errors here depending on the if the resCode is an error
  if resCode < 0 then
   local resCodeString="resCode "..tostring(resCode).." ("..installerAPI.getRescodeMeaning(resCode)..")"
   error("Error: "..resCodeString.." in file "..path.." on line "..tostring(lineNr))
  end
 end
 return 2
end



function pastebin(shellObj,path,code,overwrite)
  if overwrite then
   fs.delete(path)
  end
  shellObj.run("pastebin","get", code, path)
end