module Mailmate::CLI::Discover

def parse_options(argv)
  opts = { dry_run: false, yes: false, force: false, app_support_dir: nil }
  OptionParser.new do |o|
    o.banner = "Usage: mmdiscover [--app-support-dir PATH] [--dry-run] [--yes] [--force]"
    o.on("--app-support-dir PATH", "Override the MailMate app-support location") { |p| opts[:app_support_dir] = File.expand_path(p) }
    o.on("--dry-run", "Print what would be written; don't write") { opts[:dry_run] = true }
    o.on("-y", "--yes", "Skip the y/N prompt") { opts[:yes] = true }
    o.on("--force", "Overwrite existing config even if it has identities not in Identities.plist") { opts[:force] = true }
  end.parse!(argv)
  opts
end

def read_accounts(path)
  return [] unless File.exist?(path)
  json = `plutil -convert json -o - #{shellesc(path)}`
  data = JSON.parse(json) rescue {}
  sources = data["sources"] || data["Sources"] || []
  sources.map do |s|
    name = s["name"] || s["Name"] || "(unnamed)"
    server_url = s["serverURL"] || s["ServerURL"] || ""
    host = server_url.split("@").last || "(no host)"
    { name: name, host: host }
  end
end

def read_existing_identities(path)
  return nil unless File.exist?(path)
  require "yaml"
  data = YAML.safe_load_file(path) rescue nil
  return [] unless data.is_a?(Hash)
  Array(data["identities"]).map { |a| a.to_s.downcase.strip }.reject(&:empty?)
end

def read_identities(path)
  return [] unless File.exist?(path)
  json = `plutil -convert json -o - #{shellesc(path)}`
  data = JSON.parse(json) rescue {}
  ids = data["identities"] || data["Identities"] || []
  all = ids.flat_map do |i|
    raw = i["emailAddresses"] || i["EmailAddresses"] || i["emailAddress"] || ""
    raw.to_s.split(/[\s,]+/)
  end
  all.map { |a| a.strip.downcase }.reject(&:empty?).uniq
end

def run(argv)
  opts = parse_options(argv)
  app_support_dir = opts[:app_support_dir] || File.expand_path("~/Library/Application Support/MailMate")
  unless File.directory?(app_support_dir)
    warn "mmdiscover: MailMate app-support directory not found at #{app_support_dir}"
    warn "  Pass --app-support-dir if your install is elsewhere, or check that MailMate is installed."
    return 1
  end
  sources_plist    = File.join(app_support_dir, "Sources.plist")
  identities_plist = File.join(app_support_dir, "Identities.plist")
  accounts   = read_accounts(sources_plist)
  identities = read_identities(identities_plist)
  $stdout.puts "Found #{accounts.size} account#{"s" if accounts.size != 1} in Sources.plist:"
  accounts.each { |a| $stdout.puts "  #{a[:name].ljust(35)}(#{a[:host]})" }
  $stdout.puts
  $stdout.puts "Found #{identities.size} identity address#{"es" if identities.size != 1} in Identities.plist:"
  identities.each { |addr| $stdout.puts "  #{addr}" }
  $stdout.puts
  # Compare against existing config, if any, and surface differences.
  # Without --force we won't silently overwrite manual additions
  # (e.g. aliases that aren't outgoing identities in MailMate).
  existing_identities = read_existing_identities(CONFIG_FILE)
  if existing_identities && !opts[:force] && !opts[:dry_run]
    only_in_existing = existing_identities - identities
    only_in_new      = identities - existing_identities
    if !only_in_existing.empty? || !only_in_new.empty?
      $stdout.puts "Existing #{CONFIG_FILE} has a different identity set:"
      only_in_existing.each { |a| $stdout.puts "  - #{a}  (in current config, NOT in Identities.plist)" }
      only_in_new.each      { |a| $stdout.puts "  + #{a}  (in Identities.plist, NOT in current config)" }
      $stdout.puts
      $stdout.puts "Re-run with --force to overwrite, or hand-merge if you have manual additions to preserve."
      return 0
    end
  end
  if opts[:dry_run]
    $stdout.puts "(--dry-run) Would write #{CONFIG_FILE} and #{LOADER_FILE}; skipping."
    return 0
  end
  unless opts[:yes]
    $stdout.print "Write these to #{CONFIG_FILE}? [y/N] "
    response = $stdin.gets&.strip&.downcase
    unless %w[y yes].include?(response)
      $stdout.puts "Aborted."
      return 0
    end
  end
  FileUtils.mkdir_p(CONFIG_DIR)
  write_config(identities, app_support_dir, opts[:app_support_dir])
  write_bundle_loader
  $stdout.puts "Wrote #{CONFIG_FILE}"
  $stdout.puts "Wrote #{LOADER_FILE}"
  0
end

def shellesc(s)
  "'#{s.gsub("'", "'\\\\''")}'"
end

def write_bundle_loader
  gem_lib = File.expand_path("../..", __dir__) # → ~/code/claude/mailmate/lib
  File.open(LOADER_FILE, "w") do |f|
    f.puts "# Mailmate gem bundle-loader — written by mmdiscover."
    f.puts "# MailMate bundle handlers `load` this file then `require \"mailmate\"`."
    f.puts "# Re-run mmdiscover to refresh if the gem's location changes."
    f.puts
    f.puts "$LOAD_PATH.unshift #{gem_lib.inspect} unless $LOAD_PATH.include?(#{gem_lib.inspect})"
  end
end

def write_config(identities, _app_support_dir, app_support_override)
  File.open(CONFIG_FILE, "w") do |f|
    f.puts "# Mailmate gem configuration — written by mmdiscover on #{Time.now.strftime("%Y-%m-%d %H:%M")}"
    f.puts
    if app_support_override
      f.puts "app_support_dir: #{app_support_override}"
      f.puts
    end
    f.puts "identities:"
    identities.each { |addr| f.puts "  - #{addr}" }
  end
end