[CC] github_get

--[[[
    Attempts to retreive a given directory from github
    Retreives the directory from tobast/computercraft_softs from github.
--]]

RAW_GITHUB_BASEURL='https://raw.githubusercontent.com/tobast/computercraft_softs/master/'
TREE_GITHUB_BASEURL='https://api.github.com/repos/tobast/computercraft_softs/git/trees/'

function getFileFromGithub(githubpath, localpath)
    print('Get '..githubpath)
    local fileContents = http.get(RAW_GITHUB_BASEURL..githubpath).readAll()
    if(fileContents == nil) then
        error('Could not fetch raw file '..githubpath)
    end
    if(fs.exists(localpath)) then
        fs.delete(localpath)
    end
    local file = io.open(localpath,'w')
    file:write(fileContents)
    file:close()
end

-- Auto-get json lib if not present, to make the script work easily
if(fs.exists('/lib/json') == false) then
    fs.makeDir('/lib')
    getFileFromGithub('github_get/lib/json','/lib/json')
end
-- END auto-get json
os.loadAPI('/lib/json')

function splitStringSlash(str)
    local pos = str:find('/')
    if(pos == nil) then
        return {str,''}
    else
        return {str:sub(1,pos-1),str:sub(pos+1)}
    end
end

function retrieve(path,root,sha,github_path)
    if(sha == nil) then
        sha = 'HEAD'
    end
    if(github_path == nil) then
        github_path = ''
    end

    local jsonStr = http.get(TREE_GITHUB_BASEURL..sha)
    if(jsonStr == nil) then
        error('Could not fetch tree at '..github_path)
    end
    local jsonObject = json.decode(jsonStr.readAll())
    local tree = jsonObject.tree

    if(path == '') then
        for _,item in pairs(tree) do
            if(item.type == 'blob') then -- File, get it!
                getFileFromGithub(github_path..(item.path), root..(item.path))
            elseif(item.type == 'tree') then
                fs.makeDir(root..(item.path))
                retrieve('',root..(item.path)..'/',(item.sha),github_path..(item.path)..'/')
            end
        end
    else
        local splitted = splitStringSlash(path)
        local pathHead = splitted[1]
        local pathTail = splitted[2]

        local found = false
        for _,item in pairs(tree) do
            if(item.type == 'tree' and item.path == pathHead) then
                found = true
                retrieve(pathTail,root,item.sha,github_path..(item.path)..'/')
            end
        end
        if(found == false) then
            error(github_path..pathHead..' does not exist!')
            return
        end
    end
end

function main(argv)
    if(#argv < 1) then
        print('Missing argument: path. Exiting.')
    else
        local path = argv[1]
        local root = '/'
        if(argv[2] ~= nil) then
            root = argv[2]
        end

        if(root:sub(#root) ~= '/') then
            root = root..'/'
        end
        if(fs.isDir(root) == false) then
            fs.makeDir(root)
        end

        retrieve(path,root)
    end
end

main({...})