local _VERSION = '3.0.0';

local REPO_BASE = 'https://raw.githubusercontent.com/guillaumearm/cc-libs/';
local LOCAL_STATE_DIR = '/trapos';
local LOCAL_MANIFEST_PATH = '/trapos/manifest.json';

local function printUsage()
  print('install usage:');
  print();
  print('\t\twget run <install-url>');
  print('\t\twget run <install-url> --beta');
  print('\t\twget run <install-url> --stable');
end

local function readLocalManifest()
  if not fs.exists(LOCAL_MANIFEST_PATH) then return nil end
  local f = fs.open(LOCAL_MANIFEST_PATH, 'r');
  if not f then return nil end
  local data = f.readAll();
  f.close();
  if not data or data == '' then return nil end
  return textutils.unserializeJSON(data);
end

local function writeLocalManifest(manifest)
  fs.makeDir(LOCAL_STATE_DIR);
  local f = fs.open(LOCAL_MANIFEST_PATH, 'w');
  if not f then return false end
  f.write(textutils.serializeJSON(manifest));
  f.close();
  return true;
end

local function confirmBeta()
  print();
  print('You are about to install the BETA branch (next).');
  print('Beta builds may be unstable. Continue? (y/N)');
  write('> ');
  local answer = read();
  if not answer then return false end
  answer = answer:lower();
  return answer == 'y' or answer == 'yes';
end

local function fetchManifest(branch)
  local url = REPO_BASE .. branch .. '/manifest.json';
  local response = http.get(url);
  if not response then return nil end
  local body = response.readAll();
  response.close();
  if not body or body == '' then return nil end
  return textutils.unserializeJSON(body);
end

local command = ...;
local forceBeta = false;
local forceStable = false;

if command == 'version' or command == '-version' or command == '--version' then
  print('install v' .. _VERSION);
  return;
end

if command == 'help' or command == '-help' or command == '--help' then
  printUsage();
  return;
end

if command == '--beta' or command == '-beta' then
  forceBeta = true;
elseif command == '--stable' or command == '-stable' then
  forceStable = true;
elseif command ~= nil and command ~= '' then
  printUsage();
  return;
end

local localManifest = readLocalManifest();
local localBranch = localManifest and localManifest.branch or nil;
local branch;

if forceBeta then
  branch = 'next';
  if localBranch ~= 'next' then
    if not confirmBeta() then
      print('Aborted.');
      return;
    end
  end
elseif forceStable then
  branch = 'master';
else
  branch = localBranch or 'master';
end

print('Fetching manifest from branch: ' .. branch);
local manifest = fetchManifest(branch);
if not manifest or type(manifest.files) ~= 'table' then
  print('Failed to fetch or parse manifest.json from ' .. branch);
  return;
end

-- The persisted branch reflects the actually-used branch, not the manifest default.
manifest.branch = branch;

local REPO_PREFIX = REPO_BASE .. branch .. '/';

-- Legacy file cleanup (pre-manifest installs).
fs.delete('ping-server.lua');
fs.delete('ping.lua');
fs.delete('cube.lua');
fs.delete('router.lua');
fs.delete('servers/cube-startup.lua');
fs.delete('programs/cube.lua');
fs.delete('programs/goo.lua');
fs.delete('servers/cube-server.lua');
fs.delete('servers/cube-boot.lua');

local previousDir = shell.dir();
shell.setDir('/');

fs.makeDir('/programs');
fs.makeDir('/apis');
fs.makeDir('/startup');
fs.makeDir('/servers');
fs.makeDir(LOCAL_STATE_DIR);

for _, filePath in ipairs(manifest.files) do
  fs.delete(filePath);
  shell.execute('wget', REPO_PREFIX .. filePath, filePath);
end

if not writeLocalManifest(manifest) then
  print('Warning: failed to write local manifest');
end

print();
print('=> TrapOS v' .. (manifest.version or '?') .. ' installed (branch: ' .. branch .. ')');
print('=> Execute startup/servers.lua');
shell.execute('/startup/servers.lua');

shell.setDir(previousDir);