--[[
  Opus OS Installer
  Self-contained installer that downloads from Gitea
]]

local GITEA_HOST  = 'git.spatulaa.com'
local GITEA_USER  = 'MayaTheShy'
local GITEA_REPO  = 'Opus'
local GITEA_BRANCH = 'main'

local TREE_URL = 'https://%s/api/v1/repos/%s/%s/git/trees/%s?recursive=1'
local FILE_URL = 'https://%s/%s/%s/raw/branch/%s/%s'

local colors    = _G.colors
local fs        = _G.fs
local http      = _G.http
local os        = _G.os
local parallel  = _G.parallel
local term      = _G.term
local textutils = _G.textutils

local args = { ... }
local mode = args[1] or 'install'

-- Utility functions

local function httpGet(url)
  local h, msg = http.get(url)
  if h then
    local content = h.readAll()
    h.close()
    return content
  end
  return nil, msg
end

local function download(url, path)
  local dir = fs.getDir(path)
  if dir ~= '' and not fs.exists(dir) then
    fs.makeDir(dir)
  end
  local content, msg = httpGet(url)
  if content then
    local f = fs.open(path, 'w')
    f.write(content)
    f.close()
    return true
  end
  return false, msg or 'Download failed'
end

local function formatSize(size)
  if size >= 1000000 then
    return string.format('%dM', math.floor(size / 1000000))
  elseif size >= 1000 then
    return string.format('%dK', math.floor(size / 1000))
  end
  return tostring(size)
end

local function center(text, y)
  local w = term.getSize()
  term.setCursorPos(math.floor((w - #text) / 2) + 1, y)
  term.write(text)
end

local function drawHeader(title)
  local w = term.getSize()
  term.setBackgroundColor(colors.cyan)
  term.setTextColor(colors.white)
  term.setCursorPos(1, 1)
  term.clearLine()
  center(title, 1)
  term.setBackgroundColor(colors.black)
  term.setTextColor(colors.white)
end

local function drawProgressBar(y, pct)
  local w = term.getSize()
  local barW = w - 4
  local filled = math.floor(barW * pct / 100)

  term.setCursorPos(3, y)
  term.setBackgroundColor(colors.gray)
  term.write(string.rep(' ', barW))
  term.setCursorPos(3, y)
  term.setBackgroundColor(colors.lime)
  term.write(string.rep(' ', filled))
  term.setBackgroundColor(colors.black)
end

local function waitForKey(prompt)
  local _, h = term.getSize()
  if prompt then
    term.setTextColor(colors.lightGray)
    center(prompt, h)
  end
  os.pullEvent('key')
end

-- Get file listing from Gitea API

local function getFileList(branch)
  local url = string.format(TREE_URL, GITEA_HOST, GITEA_USER, GITEA_REPO, branch)
  local content, msg = httpGet(url)
  if not content then
    return nil, 'Failed to get file list: ' .. (msg or 'unknown error')
  end

  local data = textutils.unserialiseJSON(content)
  if not data then
    return nil, 'Invalid response from server'
  end
  if data.message then
    return nil, data.message
  end

  local files = {}
  local totalSize = 0
  for _, v in pairs(data.tree) do
    if v.type == 'blob' then
      local path = v.path:gsub('%s', '%%20')
      files[path] = {
        url = string.format(FILE_URL, GITEA_HOST, GITEA_USER, GITEA_REPO, branch, path),
        size = v.size or 0,
      }
      totalSize = totalSize + math.max(500, v.size or 0)
    end
  end

  return files, nil, totalSize
end

-- Splash screen

local function showSplash()
  term.clear()
  drawHeader('Opus OS Installer')

  local _, h = term.getSize()
  local y = 3

  term.setTextColor(colors.yellow)
  center('Opus OS v1.0', y)
  y = y + 2

  term.setTextColor(colors.white)
  center('By: Kepler', y)
  y = y + 2

  term.setTextColor(colors.lightGray)
  local desc = {
    'A user friendly operating system',
    'featuring multitasking, networking,',
    'and automation.',
  }
  for _, line in ipairs(desc) do
    center(line, y)
    y = y + 1
  end

  y = y + 1
  term.setTextColor(colors.gray)
  center('Source: ' .. GITEA_HOST, y)

  waitForKey('Press any key to continue...')
end

-- License screen

local function showLicense()
  term.clear()
  drawHeader('License Review')

  local _, h = term.getSize()
  term.setCursorPos(2, 3)
  term.setTextColor(colors.yellow)
  print('  Copyright (c) 2018 Kepler')
  print()
  term.setTextColor(colors.lightGray)

  local license = [[
  Permission is hereby granted, free of
  charge, to any person obtaining a copy
  of this software to deal in the Software
  without restriction, including without
  limitation the rights to use, copy,
  modify, merge, publish, distribute,
  sublicense, and/or sell copies of the
  Software.

  THE SOFTWARE IS PROVIDED "AS IS",
  WITHOUT WARRANTY OF ANY KIND.]]

  print(license)

  waitForKey('Press any key to accept...')
end

-- Branch selection (only shown for full install)

local function selectBranch()
  local branches = {
    { branch = 'main',        description = 'Main (Stable)' },
    { branch = 'develop-1.8', description = '1.8+ Unstable' },
    { branch = 'master-1.8',  description = '1.8+ Stable'   },
  }

  local selected = 1

  while true do
    term.clear()
    drawHeader('Select Branch')

    local _, h = term.getSize()
    term.setCursorPos(2, 3)
    term.setTextColor(colors.yellow)
    print('  Choose which branch to install:')
    print()

    for i, b in ipairs(branches) do
      term.setCursorPos(3, 4 + i)
      if i == selected then
        term.setTextColor(colors.yellow)
        term.write('> ')
      else
        term.setTextColor(colors.white)
        term.write('  ')
      end
      term.write(b.branch)
      term.setTextColor(colors.gray)
      term.write(' - ' .. b.description)
    end

    term.setTextColor(colors.lightGray)
    center('Up/Down to select, Enter to confirm', h)

    local event, key = os.pullEvent('key')
    if key == keys.up then
      selected = selected > 1 and selected - 1 or #branches
    elseif key == keys.down then
      selected = selected < #branches and selected + 1 or 1
    elseif key == keys.enter then
      return branches[selected].branch
    end
  end
end

-- File list review

local function showFileReview(files, totalSize)
  term.clear()
  drawHeader('Review Files')

  local _, h = term.getSize()
  local count = 0
  for _ in pairs(files) do count = count + 1 end

  term.setCursorPos(2, 3)
  term.setTextColor(colors.yellow)
  print(string.format('  %d files to install', count))
  print()
  term.setTextColor(colors.white)
  print(string.format('  Space required: %s', formatSize(totalSize)))

  local diskFree = fs.getFreeSpace('/')
  if totalSize > diskFree then
    term.setTextColor(colors.red)
    print(string.format('  Free space:     %s  (NOT ENOUGH!)', formatSize(diskFree)))
  else
    term.setTextColor(colors.lime)
    print(string.format('  Free space:     %s', formatSize(diskFree)))
  end

  print()
  term.setTextColor(colors.lightGray)

  -- Show first few files
  local shown = 0
  for path in pairs(files) do
    if shown < (h - 11) then
      term.setCursorPos(3, 9 + shown)
      local display = path
      local w = term.getSize()
      if #display > w - 4 then
        display = '...' .. display:sub(-(w - 7))
      end
      term.write(display)
      shown = shown + 1
    end
  end
  if count > shown then
    term.setCursorPos(3, 9 + shown)
    term.setTextColor(colors.gray)
    term.write(string.format('... and %d more files', count - shown))
  end

  waitForKey('Press any key to begin install...')
end

-- Install files with progress

local function installFiles(files)
  if mode == 'update' then
    fs.delete('sys')
  end

  term.clear()
  drawHeader('Installing...')

  local _, h = term.getSize()
  local total = 0
  for _ in pairs(files) do total = total + 1 end

  local fileList = {}
  for path, entry in pairs(files) do
    table.insert(fileList, { path = path, url = entry.url })
  end

  local completed = 0
  local failed = 0
  local lastFile = ''

  -- Download with 5 parallel workers
  local workers = {}
  for _ = 1, 5 do
    table.insert(workers, function()
      while true do
        local entry = table.remove(fileList)
        if not entry then break end

        lastFile = entry.path
        local s, m = download(entry.url, entry.path)
        if not s then
          failed = failed + 1
        end
        completed = completed + 1
      end
    end)
  end

  -- Progress display alongside downloads
  table.insert(workers, function()
    while completed < total do
      local pct = math.floor(completed / total * 100)

      term.setCursorPos(2, 4)
      term.setTextColor(colors.white)
      term.clearLine()
      term.write(string.format(' Progress: %d/%d (%d%%)', completed, total, pct))

      term.setCursorPos(2, 6)
      term.setTextColor(colors.lightGray)
      term.clearLine()
      local w = term.getSize()
      local display = lastFile
      if #display > w - 4 then
        display = '...' .. display:sub(-(w - 7))
      end
      term.write(' ' .. display)

      drawProgressBar(h - 3, pct)

      if failed > 0 then
        term.setCursorPos(2, 8)
        term.setTextColor(colors.red)
        term.write(string.format(' Failed: %d', failed))
      end

      os.sleep(0.1)
    end
  end)

  parallel.waitForAll(table.unpack(workers))

  -- Final progress update
  drawProgressBar(h - 3, 100)
  term.setCursorPos(2, 4)
  term.setTextColor(colors.lime)
  term.clearLine()
  term.write(string.format(' Complete: %d/%d files', completed, total))

  term.setCursorPos(2, 6)
  term.clearLine()

  if failed > 0 then
    term.setCursorPos(2, 8)
    term.setTextColor(colors.red)
    term.write(string.format(' %d files failed to download', failed))
  end

  return failed == 0
end

-- Done screen

local function showDone(success)
  local _, h = term.getSize()

  term.setCursorPos(2, h - 1)
  if success then
    term.setTextColor(colors.yellow)
    center('Install complete! Rebooting...', h - 1)
    os.sleep(2)
    os.reboot()
  else
    term.setTextColor(colors.red)
    center('Install finished with errors.', h - 1)
    waitForKey('Press any key to exit...')
  end
end

-- Main installer flow

local function main()
  local branch = GITEA_BRANCH

  if mode == 'install' then
    showSplash()
    showLicense()
    branch = selectBranch()
  end

  -- Get file list
  term.clear()
  drawHeader('Opus OS Installer')
  term.setCursorPos(2, 4)
  term.setTextColor(colors.white)
  term.write(' Fetching file list...')

  local files, err, totalSize = getFileList(branch)
  if not files then
    term.setCursorPos(2, 6)
    term.setTextColor(colors.red)
    print(' Error: ' .. (err or 'unknown'))
    waitForKey('Press any key to exit...')
    return
  end

  if mode == 'install' then
    showFileReview(files, totalSize)
  end

  local success = installFiles(files)
  showDone(success)
end

main()