local args = {...}
local internet=require("internet")
local filesystem=require("filesystem")
local unicode=require("unicode")

YES = {"y","yes","Y","Yes","YES"}
NO = {"n","no","N","No","NO"}

SupportedRemotes = {
    Github = {
        BaseUrl = "https://github.com/",
        RawApiUrl = "https://raw.githubusercontent.com/",
        Implemented = true
    },
    Gitea = {
        BaseUrl = "https://git.realrobin.io",
        Implemented = false
    }
}

EmptyRepository = {
    Owner = nil,
    Name = nil,
    ShortName = nil,
    RepoIdentifier = nil,
    Remote = nil,
    CurrentBranch = nil,
    CurrentLocalPath = nil
}

---default repo to update
DefaultRepository = {
    Owner = "seesberger",
    Name = "PowerManager",
    ShortName = "powerman",
    RepoIdentifier = "seesberger/PowerManager",
    Remote = SupportedRemotes.Github,
    CurrentBranch = "master",
    CurrentLocalPath = ""
}

DefaultTemporaryDownloadPath = "/home/.tmp/git/"
DefaultInstallationPath = "/usr/"

local function askYesOrNoQuestion(question, expectedTrue, expectedFalse, defaultYesOnEnter)
    local function checkContains(array,value)
        for idx, val in pairs(array) do
            if value == val then return true end
        end
        return false
    end

    if defaultYesOnEnter==true then print(question.." [Y/n]") else print(question.." [y/N]") end
    while true do
        local userInput = io.read("l")
        if checkContains({""}, userInput) then return defaultYesOnEnter end
        if checkContains(expectedTrue, userInput) then return true end
        if checkContains(expectedFalse, userInput) then return false end
        print("Please answer with yes or no. You can also press ENTER to choose the default option.")
    end
end

local function askTextQuestion(question, defaultAnswerOnEnter, allowOnly)
    local allowedInputsString = ""
    for idx, entry in pairs(allowOnly) do allowedInputsString = allowedInputsString..entry end
    if allowOnly then print(question.." ["..allowedInputsString.."]")
    else print(question) end
    local userInput = nil
    local found = false
    repeat
        userInput = io.read("l")
        if allowOnly then
            for idx, entry in pairs(allowOnly) do if entry == userInput then found = true end end
        else break end
    until found
    if userInput == "" then return defaultAnswerOnEnter else return userInput end
end

local function makeDirIfNotExists(target)
    if filesystem.exists(target) then
        if not filesystem.isDirectory(target) then error("target directory already exists and is not a directory.") end
        if filesystem.get(target).isReadOnly() then error("target directory is read-only.") end
    else
        if not filesystem.makeDirectory(target) then error("directory creation failed") end
    end
end

--- todo: pcall and catch errors
local function downloadRepo(repository, remote, autoOverride)

    local function validateRepositoryIdentifier(repository)
        if not repository.RepoIdentifier:match("^[%w-.]*/[%w-.]*$") then
            print('"'..repository.RepoIdentifier..'" does not look like a valid repo identifier.\nShould be <owner>/<reponame>')
            return
        end
    end

    validateRepositoryIdentifier(repository)

    --- FIXME: If download only mode is enabled, set this to /home. still todo
    local targetDownloadPath = DefaultTemporaryDownloadPath..repository.RepoIdentifier
    repository.CurrentLocalPath = targetDownloadPath.."/"
    local success, res = pcall(makeDirIfNotExists, targetDownloadPath)
    if not success then error("the download failed because of filesystem errors.") end

    local function fetchFilesAndSubdirs(repository, remote, dir)
        dir = dir or "" -- default value, start at root dir
        if remote == SupportedRemotes.Github then
            print("fetching contents for "..repository.RepoIdentifier..dir)
            local githubApiUrl="https://api.github.com/repos/"..repository.RepoIdentifier.."/contents"..dir
            local success,chunks=pcall(internet.request,githubApiUrl)
            local raw=""
            local files={}
            local directories={}

            if success then for chunk in chunks do raw=raw..chunk end
            else error("you've been cut off. Serves you right.") end

            --- do not question the magic of the outer gods
            --- turns raw response into t, which has usable fields.
            raw=raw:gsub("%[","{"):gsub("%]","}"):gsub("(\".-\"):(.-[,{}])",function(a,b) return "["..a.."]="..b end)
            local t=load("return "..raw)()

            for i=1,#t do
                if t[i].type=="dir" then
                table.insert(directories,dir.."/"..t[i].name)

                local subfiles,subdirs=fetchFilesAndSubdirs(repository,remote,dir.."/"..t[i].name)
                for i=1,#subfiles do
                    table.insert(files,subfiles[i])
                end
                for i=1,#subdirs do
                    table.insert(directories,subdirs[i])
                end
                else
                files[#files+1]=dir.."/"..t[i].name
                end
            end

            return files, directories
        else error("not Implemented") end
    end

    --- fetch and make dirs in the target download path recursively
    local files,dirs=fetchFilesAndSubdirs(repository, repository.Remote, "")
    for i=1,#dirs do
        local success, err = pcall(makeDirIfNotExists, targetDownloadPath..dirs[i])
        if not success then error(("the download failed because of filesystem errors. %x"):format(err)) end
    end

    local replaceMode="ask"
    if autoOverride == true then replaceMode = "always" end

    local function downloadFiles(files, targetDownloadPath, replaceMode)
        local replace=nil
        local downloadedFileTargets = {}
        for i=1,#files do
            if replaceMode == "always" then replace = true end
            local fileExists = filesystem.exists(targetDownloadPath..files[i])
            if fileExists then
                --- FIXME dir löschen statt error
                if filesystem.isDirectory(targetDownloadPath..files[i]) then error("file "..targetDownloadPath..files[i].." blocked by directory with same name!") end
                
                if replace == nil then
                    local userInput = askTextQuestion("\nFile "..targetDownloadPath..files[i].." already exists.\nReplace with new version?","n",{"y","n","A","S"})

                    --- FIXME: replaceMode ist broken. A wird immer wieder gefragt.
                    if userInput=="A" then
                    replaceMode="always"
                    userInput="y"
                    elseif userInput=="S" then
                    replaceMode="never"
                    userInput="n"
                    end
                    if userInput == "y" then replace=true end
                    if userInput == "n" then replace=false end
                end
            end
            if fileExists and replace then filesystem.remove(targetDownloadPath..files[i]) end
            if replace or (replace == nil) then
                --- TODO @Freddy: Coole Animation hinzufügen
                print("downloading file "..files[i])
                --- HACK: RawApiUrl is for using Github Raw API. may have to be patched for Gitea Support
                local url=repository.Remote.RawApiUrl..repository.RepoIdentifier.."/"..repository.CurrentBranch..files[i]
                local success,response=pcall(internet.request,url)
                if success then
                    local raw=""
                    for chunk in response do
                        raw=raw..chunk
                    end
                    local absoluteDownloadFileTargetPath = targetDownloadPath..files[i]
                    print("writing to "..absoluteDownloadFileTargetPath)
                    local file=io.open(absoluteDownloadFileTargetPath,"w")
                    if file then -- might be nil under wierd circumstances
                        file:write(raw)
                        file:close()
                    end
                    table.insert(downloadedFileTargets, files[i])
                else error("a file did not download correctly. aborting") end
            else error("file not removed, but installation was cancelled - This might result in a broken install.") end
        end
        --- return list of all abolute paths the files were downloaded to
        return downloadedFileTargets
    end

    success, res = pcall(downloadFiles, files, targetDownloadPath, replaceMode)
    if success then print("All files downloaded successfully.") return res else error(res) end

end

local function installFiles(downloadedFiles, downloadTargetDir, installTargetDir)
    local installedFiles = {}
    
    --- FIXME: ask user about replacing files.
    local replace = true
    makeDirIfNotExists(installTargetDir)
    for idx, file in pairs(downloadedFiles) do
        print(idx..": Installing File "..downloadTargetDir..file:sub(2,-1).." to target directory "..installTargetDir..file)
        local fileExists = filesystem.exists(installTargetDir..file)
        if fileExists and replace then filesystem.remove(installTargetDir..file) end
        if replace or (replace == nil) then
            --- TODO @Freddy: Coole Animation hinzufügen
            os.execute("cp "..downloadTargetDir..file:sub(2,-1).." "..installTargetDir..file)
            table.insert(installedFiles, installTargetDir..file)
        else error("file not removed, but installation was cancelled - This might result in a broken install.") end
    end
    return installedFiles
end

local function installShortcut(currentRepoPath, shortcutName, targetDir)
    print("installing shortcut...")
    makeDirIfNotExists(targetDir)
    os.execute("mv "..currentRepoPath.."shortcut.lua "..targetDir..shortcutName..".lua")
end

--- todo: automatic read of dependency list (txt file containing lines with <link> <dst> or somethink like it)
--- removeme
local function legacyInstallDependencies()
    print("Legacy Mode: Installing hardcoded dependencies...")
    os.execute("wget -f https://github.com/kevinkk525/OC-GUI-API/raw/master/shapes_default.lua /lib/shapes_default.lua")
    os.execute("wget -f https://github.com/kevinkk525/OC-GUI-API/raw/master/GUI.lua /lib/GUI.lua")
    os.execute("wget -f https://github.com/kevinkk525/OC-GUI-API/raw/master/term_mod.lua /lib/term_mod.lua")
    os.execute("wget -f https://github.com/kevinkk525/OC-GUI-API/raw/master/tech_demo.lua /home/GUI_tech_demo.lua")
end

local function removeDownloads(downloadTargetDir, downloadedFiles)
    for idx, file in pairs(downloadedFiles) do
        file = file:sub(2,-1) --- get "file" from previous string "/file"
        print(idx..": Removing temporary file "..downloadTargetDir..file)
        local fileExists = filesystem.exists(downloadTargetDir..file)
        if fileExists then filesystem.remove(downloadTargetDir..file) end
    end
    print("cleaned temporary files.")
end

local function createManifest(installedFiles, installedShortcuts, manifestTarget, repoName)
    makeDirIfNotExists(manifestTarget)
    local manifest = ""
    for idx, file in pairs(installedFiles) do
        manifest = manifest..file.."\n"
    end
    for idy, shortcut in pairs(installedShortcuts) do
        manifest = manifest..shortcut.."\n"
    end
    print("writing manifest to "..manifestTarget.."/"..repoName)
    local file=io.open(manifestTarget.."/"..repoName,"w")
    if file then -- might be nil under wierd circumstances
        file:write(manifest)
        file:close()
    end
end

--- fix legacy shit
local function runFullInstallTask(repository, shortcutName)
    --- first, download the actual repo.
    --- then, find dependencies - if then exist, download and install them
    --- then, install the actual program
    local installTargetDir  = "/usr/"..repository.Name
    local shortcutTargetDir = "/usr/bin/"
    local downloadTargetDir = DefaultTemporaryDownloadPath
    local manifestTarget = "/etc/manifest/"

    legacyInstallDependencies() --only for testing while new version not implemented yet
    print("downloading "..repository.RepoIdentifier)
    local downloadedFiles = downloadRepo(repository, repository.Remote, false) --enable auto-overwrite in other situations still todo
    local installedFiles = installFiles(downloadedFiles, downloadTargetDir, installTargetDir)
    local installedShortcuts = installShortcut(repository.CurrentLocalPath, shortcutName, shortcutTargetDir)
    removeDownloads(downloadTargetDir, downloadedFiles)
    createManifest(installedFiles, installedShortcuts, manifestTarget, repository.Name)
end

local function printHelpText()
    local helpText =        "This updater pulls the git files for installation and application updates.\n"..
    "Usage:\n" ..
    "updater <option>  - no args: manual update and install\n"..
    "  '' -h or        - this help text\n"..
    "  '' -d or        - install default config"
    print(helpText)
end

local function run(cliArgs)
    local repo = EmptyRepository
    local shortcutName = nil

    if #cliArgs<1 then
        print("No Arguments given. For help, please check -h or --help")
        return
    end
    if cliArgs[1] == "-h" then
        printHelpText()
        return
    elseif cliArgs[1] == "-d" then
        --- ask user about repo
        if askYesOrNoQuestion("Use default config? (github::seesberger/PowerManager)?",YES,NO,true) == true then
            repo = DefaultRepository
            --- ask user about shortcutname
            if askYesOrNoQuestion("Use default shortcut name \"powerman\"?",YES,NO,true) then shortcutName = "powerman" end
            runFullInstallTask(repo, shortcutName)
        --- TODO non-default config
        else print("other things not implemented yet") end
    else
        print('"'..cliArgs[1]..'" - Bad argument. Try --help')
    print("Program exited.")
    end
end

run(args)