#!/usr/bin/env bash
set -euo pipefail

root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
base="${1:-origin/main}"

if ! git -C "$root" cat-file -e "$base^{commit}" 2>/dev/null; then
  echo "Compatibility base does not exist; this is valid only for the initial version baseline: $base"
  exit 0
fi
if [[ "$(git -C "$root" rev-parse "$base")" == "$(git -C "$root" rev-parse HEAD)" ]]; then
  base="HEAD^"
fi
if ! git -C "$root" cat-file -e "$base:eng/Versions.props" 2>/dev/null; then
  echo "Base has no release version manifest; accepting the initial compatibility baseline."
  exit 0
fi

current_property() {
  sed -n "s:.*<$1>\(.*\)</$1>.*:\1:p" "$root/eng/Versions.props"
}
base_property() {
  git -C "$root" show "$base:eng/Versions.props" \
    | sed -n "s:.*<$1>\(.*\)</$1>.*:\1:p"
}
changed() {
  git -C "$root" diff --name-only "$base"...HEAD -- "$@" | grep -q .
}
require_increase() {
  local property="$1"
  local description="$2"
  shift 2
  if changed "$@"; then
    local before after
    before="$(base_property "$property")"
    after="$(current_property "$property")"
    if [[ ! "$before" =~ ^[0-9]+$ || ! "$after" =~ ^[0-9]+$ || "$after" -le "$before" ]]; then
      echo "$description changed without increasing $property ($before -> $after)." >&2
      exit 1
    fi
  fi
}

require_increase RendezvousMajorVersion "Published .NET API snapshot" \
  'tests/FinalFactory.Rendezvous.Tests/TestData/Contracts/v*/client-public-api.txt' \
  'tests/FinalFactory.Rendezvous.Tests/TestData/Contracts/v*/contracts-public-api.txt'
require_increase HttpContractVersion "HTTP/OpenAPI contract evidence" \
  'docs/api/*.json' \
  'tests/FinalFactory.Rendezvous.Tests/TestData/Contracts/v*/*.json' \
  ':(exclude)tests/FinalFactory.Rendezvous.Tests/TestData/Contracts/v*/connection-ticket.json'
require_increase UdpContractVersion "UDP contract evidence" \
  'tests/FinalFactory.Rendezvous.Tests/TestData/Contracts/v*/*.hex'
require_increase ConnectionTicketFormatVersion "Connection-ticket format evidence" \
  'tests/FinalFactory.Rendezvous.Tests/TestData/Contracts/v*/connection-ticket.json'

echo "Compatibility changes are paired with the required version increase."