-- ReaAssist Screen Reader Mode Installer
-- https://reaassist.app
--
-- Downloads the small ReaAssist bootstrap script plus the accessible
-- Screen Reader Mode entry point, registers both as REAPER actions, sets
-- Screen Reader Mode as the default, then launches it. ReaAssist fetches
-- the rest on first run.
--
-- To run: REAPER > Actions > Show action list > Load ReaScript,
-- choose this file, then click Run.

local INSTALL_REL = "Scripts/mbriggs-reaper/ReaAssist/"
local EXT_NS = "reaassist"
local RELEASE_COMMIT = "648636a0252b7605f3106b4d5a237d6d41aa39b2"
local MAIN_URL =
  "https://raw.githubusercontent.com/michaelbriggsaudio/mbriggs-reaper/" ..
  RELEASE_COMMIT .. "/ReaAssist/ReaAssist.lua"
local SR_URL =
  "https://raw.githubusercontent.com/michaelbriggsaudio/mbriggs-reaper/" ..
  RELEASE_COMMIT .. "/ReaAssist/ReaAssist_Screen_Reader_Mode.lua"
local MAIN_SHA256 =
  "388a309ce251be4afd2876e68eca05c458fa02821b77b770542a2a3aa25a7547"
local SR_SHA256 =
  "6ab04e252061abcc68625fe1badf442e0976f0312596ccc458b6c4e9e88fa1a7"
local OSARA_URL = "https://osara.reaperaccessibility.com/snapshots/"
local TITLE = "ReaAssist Screen Reader Mode Installer"

local function die(msg)
  reaper.MB(msg, TITLE, 0)
end

local function confirm_install_start()
  local message =
    "ReaAssist Screen Reader Mode will now install and open.\n\n" ..
    "REAPER may be quiet while it downloads and verifies the files. " ..
    "This can take 20 seconds or more on some connections.\n\n" ..
    "Please wait until Screen Reader Mode opens or an error message appears.\n\n" ..
    "Choose OK to start the install, or Cancel to stop."
  local show_message = reaper.ShowMessageBox or reaper.MB
  if not show_message then return true end
  return show_message(message, TITLE, 1) == 1
end

local function safe_url(url)
  url = tostring(url or "")
  if not url:match("^https?://") then return "" end
  return url:gsub("[^%w%-%.%_%~%:%/%?%#%[%]%@%!%&%*%+%,%;%=%{%}%%]", "")
end

local function open_url(url)
  url = safe_url(url)
  if url == "" then return false end
  if reaper.CF_ShellExecute then
    local ok, result = pcall(reaper.CF_ShellExecute, url)
    return ok and result ~= false
  end
  local os_name = reaper.GetOS and tostring(reaper.GetOS() or "") or ""
  local result, _, code
  if os_name:match("^Win") then
    result, _, code = os.execute('start "" "' .. url .. '"')
  elseif os_name:match("^OSX") or os_name:match("^macOS") then
    result, _, code = os.execute("open '" .. url .. "' >/dev/null 2>&1 &")
  else
    result, _, code = os.execute("xdg-open '" .. url .. "' >/dev/null 2>&1 &")
  end
  return result == true or result == 0 or code == 0
end

local function copy_url(url)
  if not reaper.CF_SetClipboard then return false end
  return pcall(reaper.CF_SetClipboard, tostring(url or ""))
end

local function require_osara_first()
  if reaper.osara_outputMessage then return true end
  local message =
    "ReaAssist Screen Reader Mode requires the OSARA accessibility extension.\n\n" ..
    "Click OK to open the OSARA download page. Close Reaper, install OSARA and then run this installer again.\n\n" ..
    "Click Cancel if you did not intend to open the Screen Reader Mode."
  local choice = reaper.MB(message, TITLE, 1)
  if choice == 1 then
    copy_url(OSARA_URL)
    open_url(OSARA_URL)
  end
  return false
end

local function read_file(path)
  local f = io.open(path, "rb")
  if not f then return nil end
  local content = f:read("*a")
  f:close()
  return content
end

local function file_exists(path)
  local f = io.open(path, "rb")
  if not f then return false end
  f:close()
  return true
end

local function unix_quote(value)
  return "'" .. tostring(value):gsub("'", "'\\''") .. "'"
end

local function sha256_file(path)
  local os_name = reaper.GetOS() or ""
  local cmd
  if os_name:match("^Win") then
    cmd = 'certutil -hashfile "' .. path .. '" SHA256'
  elseif os_name:match("OSX") or os_name:match("macOS") then
    cmd = "/usr/bin/shasum -a 256 " .. unix_quote(path)
  else
    cmd = "sha256sum " .. unix_quote(path)
  end

  local output = reaper.ExecProcess(cmd, 30000)
  if not output then
    return nil, "the operating-system SHA-256 tool could not be launched"
  end
  local exit_code = tonumber(output:match("^(%-?%d+)"))
  if exit_code ~= 0 then
    return nil, "the operating-system SHA-256 tool failed (exit " ..
      tostring(exit_code or "unknown") .. ")"
  end
  for candidate in output:gmatch("%x+") do
    if #candidate == 64 then return candidate:lower() end
  end
  return nil, "the SHA-256 result could not be read"
end

local function verify_sha256(path, expected_sha256, label)
  local actual_sha256, err = sha256_file(path)
  if actual_sha256 == expected_sha256 then return true end
  local detail = err or
    ("expected " .. expected_sha256 .. " but received " .. tostring(actual_sha256))
  return false, "Downloaded " .. label ..
    " failed immutable release verification. Nothing was installed.\n\n" .. detail
end

local function download_to(url, tmp_path, label)
  local os_name = reaper.GetOS() or ""
  local is_mac = os_name:match("OSX") or os_name:match("macOS")
  local curl_bin = is_mac and "/usr/bin/curl" or "curl"
  local cmd = string.format(
    '%s -fsSL --connect-timeout 10 --max-time 45 -o "%s" "%s"',
    curl_bin, tmp_path, url)
  local rc = reaper.ExecProcess(cmd, 60000)
  if not rc then
    return false,
      "Could not launch curl from REAPER (ExecProcess returned nil).\n\n" ..
      "Command attempted:\n" .. cmd
  end
  if not rc:match("^0\n") then
    local code = rc:match("^(%d+)") or "?"
    return false, string.format(
      "Download failed for %s (curl exit %s).\n\n%s",
      tostring(label or "file"), code, rc:sub(1, 300))
  end
  return true
end

local function remove_if_present(path)
  if not file_exists(path) then return true end
  local ok, err = os.remove(path)
  if ok then return true end
  return false, tostring(err)
end

local function clean_transaction_files(entries)
  for _, entry in ipairs(entries) do
    remove_if_present(entry.tmp_path)
  end
end

local function restore_backups(entries, remove_installed)
  local errors = {}
  if remove_installed then
    for _, entry in ipairs(entries) do
      if entry.installed then
        local ok, err = remove_if_present(entry.final_path)
        if not ok then
          errors[#errors + 1] = "could not remove new " .. entry.label .. ": " .. err
        end
      end
    end
  end
  for index = #entries, 1, -1 do
    local entry = entries[index]
    if entry.backed_up then
      local ok, err = os.rename(entry.backup_path, entry.final_path)
      if not ok then
        errors[#errors + 1] = "could not restore " .. entry.label .. ": " ..
          tostring(err) .. " (backup retained at " .. entry.backup_path .. ")"
      end
    end
  end
  clean_transaction_files(entries)
  return table.concat(errors, "\n")
end

local function install_transaction(entries)
  for _, entry in ipairs(entries) do
    entry.had_existing = file_exists(entry.final_path)
    entry.backed_up = false
    entry.installed = false
    if file_exists(entry.backup_path) then
      local removed, remove_err = remove_if_present(entry.backup_path)
      if not removed then
        local rollback_err = restore_backups(entries, false)
        local message = "Could not remove stale backup for " .. entry.label ..
          ": " .. remove_err
        if rollback_err ~= "" then message = message .. "\n\n" .. rollback_err end
        return false, message
      end
    end
    if entry.had_existing then
      local ok, err = os.rename(entry.final_path, entry.backup_path)
      if not ok then
        local rollback_err = restore_backups(entries, false)
        local message = "Could not back up existing " .. entry.label .. ": " ..
          tostring(err)
        if rollback_err ~= "" then message = message .. "\n\n" .. rollback_err end
        return false, message
      end
      entry.backed_up = true
    end
  end

  for _, entry in ipairs(entries) do
    local ok, err = os.rename(entry.tmp_path, entry.final_path)
    if not ok then
      local rollback_err = restore_backups(entries, true)
      local message = "Could not move downloaded " .. entry.label ..
        " into place: " .. tostring(err)
      if rollback_err ~= "" then message = message .. "\n\n" .. rollback_err end
      return false, message
    end
    entry.installed = true
  end
  return true
end

local function register_action(entry)
  entry.registration_attempted = true
  local ok, action_id = pcall(reaper.AddRemoveReaScript,
    true, 0, entry.final_path, true)
  if not ok or not action_id or action_id == 0 then return nil end
  entry.action_id = action_id
  return action_id
end

local function rollback_transaction(entries)
  for _, entry in ipairs(entries) do
    if entry.registration_attempted then
      pcall(reaper.AddRemoveReaScript, false, 0, entry.final_path, true)
    end
  end

  local rollback_err = restore_backups(entries, true)
  for _, entry in ipairs(entries) do
    if entry.had_existing and file_exists(entry.final_path) then
      local ok, action_id = pcall(reaper.AddRemoveReaScript,
        true, 0, entry.final_path, true)
      if not ok or not action_id or action_id == 0 then
        local message = "could not restore the prior " .. entry.label ..
          " action registration"
        rollback_err = rollback_err == "" and message or
          (rollback_err .. "\n" .. message)
      end
    end
  end
  return rollback_err
end

local function commit_transaction(entries)
  for _, entry in ipairs(entries) do
    if entry.backed_up then remove_if_present(entry.backup_path) end
  end
end

if not require_osara_first() then return end
if not confirm_install_start() then return end

local target_dir = reaper.GetResourcePath() .. "/" .. INSTALL_REL
reaper.RecursiveCreateDirectory(target_dir, 0)

local main_path = target_dir .. "ReaAssist.lua"
local sr_path = target_dir .. "ReaAssist_Screen_Reader_Mode.lua"
local old_sr_path = target_dir .. "ReaAssist - Screen Reader Mode.lua"
local main_tmp = main_path .. ".tmp"
local sr_tmp = sr_path .. ".tmp"

local ok, err = download_to(MAIN_URL, main_tmp, "ReaAssist.lua")
if not ok then
  os.remove(main_tmp)
  die(err .. "\n\nCheck your network connection and try again.\n\n" ..
      "If the problem continues, you can install ReaAssist manually from " ..
      "https://github.com/michaelbriggsaudio/mbriggs-reaper")
  return
end

local content = read_file(main_tmp)
local has_header = content and content:match("ReaAssist %- REAPER Smart Assistant")
local has_version = content and content:match('VERSION%s*=%s*"%d+%.%d+%.%d+"')
if not (has_header and has_version) then
  os.remove(main_tmp)
  die("Downloaded ReaAssist.lua does not look like ReaAssist. Try again later.")
  return
end

ok, err = verify_sha256(main_tmp, MAIN_SHA256, "ReaAssist.lua")
if not ok then
  os.remove(main_tmp)
  die(err .. "\n\nPlease download the current installer again from https://reaassist.app")
  return
end

ok, err = download_to(SR_URL, sr_tmp, "ReaAssist_Screen_Reader_Mode.lua")
if not ok then
  os.remove(main_tmp)
  os.remove(sr_tmp)
  die(err .. "\n\nCheck your network connection and try again.\n\n" ..
      "If the problem continues, you can install ReaAssist manually from " ..
      "https://github.com/michaelbriggsaudio/mbriggs-reaper")
  return
end

content = read_file(sr_tmp)
if not (content
    and content:match("ReaAssist %- Screen Reader Mode")
    and content:find("CFG.VERSION", 1, true)) then
  os.remove(main_tmp)
  os.remove(sr_tmp)
  die("Downloaded Screen Reader Mode file does not look like ReaAssist. Try again later.")
  return
end

ok, err = verify_sha256(sr_tmp, SR_SHA256, "Screen Reader Mode")
if not ok then
  os.remove(main_tmp)
  os.remove(sr_tmp)
  die(err .. "\n\nPlease download the current installer again from https://reaassist.app")
  return
end

local entries = {
  {
    label = "ReaAssist.lua",
    tmp_path = main_tmp,
    final_path = main_path,
    backup_path = main_path .. ".bak",
  },
  {
    label = "Screen Reader Mode",
    tmp_path = sr_tmp,
    final_path = sr_path,
    backup_path = sr_path .. ".bak",
  },
}

ok, err = install_transaction(entries)
if not ok then
  die(err .. "\n\nThe previous ReaAssist installation was kept whenever it " ..
    "could be restored safely.")
  return
end

local main_action = register_action(entries[1])
if not main_action then
  local rollback_err = rollback_transaction(entries)
  local message = "ReaAssist could not be registered as a REAPER action, so " ..
    "the previous installation was restored."
  if rollback_err ~= "" then message = message .. "\n\n" .. rollback_err end
  die(message)
  return
end

local sr_action = register_action(entries[2])
if not sr_action then
  local rollback_err = rollback_transaction(entries)
  local message = "Screen Reader Mode could not be registered as a REAPER " ..
    "action, so the previous installation was restored."
  if rollback_err ~= "" then message = message .. "\n\n" .. rollback_err end
  die(message)
  return
end

commit_transaction(entries)
pcall(reaper.AddRemoveReaScript, false, 0, old_sr_path, true)
pcall(os.remove, old_sr_path)

reaper.SetExtState(EXT_NS, "prefer_screen_reader", "1", true)
reaper.Main_OnCommand(sr_action, 0)