#!/usr/bin/env ruby
# encoding: UTF-8
# frozen_string_literal: true

# roadmap-next - thin CLI over RoadmapQueue (intent 148).
#
# The auto loop and plastic-roadmap-continuing both call this instead of ranking roadmap
# liveness in prose. Queue mode (default) is for the auto loop: it breaks a tie
# deterministically and reports the winner's frontier state. Which mode (--which) is for
# plastic-roadmap-continuing: it returns tie_candidates so the skill's single ask can resolve
# a genuine tie.
#
# Usage:
#   roadmap-next --roadmaps-dir <dir> [--index <path>] [--which]
#
# Exits 0 on any successful analysis, including state "none" and "exhausted" (valid answers,
# not errors). Exits 2 on a missing required flag. Exits 3 when a roadmap has neither
# '## Batches' (canonical) nor '## Waves' (legacy) as its grouping heading (intent 196): a
# malformed roadmap fails loudly, never silently parses as zero entries.

require_relative "lib/roadmap_queue"
require "json"

def opt(args, name)
  (i = args.index(name)) && args[i + 1]
end

def usage
  warn "Usage: roadmap-next --roadmaps-dir <dir> [--index <path>] [--which]"
  warn "       default mode is the auto-loop queue; --which returns tie_candidates for continuing."
end

which = !!ARGV.delete("--which")
roadmaps_dir = opt(ARGV, "--roadmaps-dir")
index = opt(ARGV, "--index")

if roadmaps_dir.nil?
  warn "roadmap-next: pass --roadmaps-dir <dir>"
  usage
  exit 2
end

reader = RoadmapQueue.new(roadmaps_dir: roadmaps_dir, index_path: index)
begin
  payload = which ? reader.which : reader.queue
rescue RoadmapSavepoint::MissingGroupingHeading => e
  warn "roadmap-next: #{e.message}"
  exit 3
end
puts JSON.generate(payload)
exit 0