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

# Fail-closed compatibility gate for an upgrade or rollback. This command does
# not deploy. It produces a machine-readable plan that a release workflow must
# verify before it changes runtime state.
#
# upgrade-compatibility.sh check --from 1.0.0 --to 1.0.1 [--matrix FILE]
# upgrade-compatibility.sh check --from 1.0.1 --to 1.0.0 --rollback [--matrix FILE]

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/casan-paths.sh"
CMD="${1:-}"; shift || true
FROM=""; TO=""; ROLLBACK=false
MATRIX="${CASAN_COMPATIBILITY_MATRIX:-$CASAN_APP_ROOT/infra/production/compatibility-matrix.json}"
while [[ "$#" -gt 0 ]]; do
  case "$1" in
    --from) FROM="${2:-}"; shift 2 ;;
    --to) TO="${2:-}"; shift 2 ;;
    --matrix) MATRIX="${2:-}"; shift 2 ;;
    --rollback) ROLLBACK=true; shift ;;
    *) echo "UPGRADE_COMPATIBILITY_FAIL reason=unknown_option option=$1" >&2; exit 64 ;;
  esac
done
[[ "$CMD" == "check" && -n "$FROM" && -n "$TO" && -f "$MATRIX" ]] || {
  echo "Usage: upgrade-compatibility.sh check --from X.Y.Z --to X.Y.Z [--rollback] [--matrix FILE]" >&2; exit 64; }

python3 - "$MATRIX" "$FROM" "$TO" "$ROLLBACK" <<'PY'
import json, re, sys
matrix, source, target, rollback = sys.argv[1:]
def parse(v):
    m = re.fullmatch(r'(\d+)\.(\d+)\.(\d+)', v)
    if not m: raise ValueError('invalid_semver')
    return tuple(map(int, m.groups()))
try:
    src, dst = parse(source), parse(target)
    data = json.load(open(matrix, encoding='utf8'))
except Exception as e:
    print(f'UPGRADE_COMPATIBILITY_FAIL reason={str(e)[:80]}', file=sys.stderr); raise SystemExit(1)
def matches(pattern, version):
    m = re.fullmatch(r'(\d+)\.(\d+)\.(x|\d+)', pattern)
    if not m: return False
    a,b,c=m.groups()
    return version[0] == int(a) and version[1] == int(b) and (c == 'x' or version[2] == int(c))
for rule in data.get('rules', []):
    if matches(str(rule.get('from','')), src) and matches(str(rule.get('to','')), dst):
        if rollback == 'true' and rule.get('rollback') != 'supported':
            continue
        print(json.dumps({'decision':'allow','from':source,'to':target,'rollback':rollback == 'true',
                          'policy_schema':rule.get('policy_schema'),'evidence_pack_schema':rule.get('evidence_pack_schema'),
                          'required_steps':['verify_release_provenance','state_backup','artifact_smoke','post_deploy_evidence_verify']}, sort_keys=True))
        raise SystemExit(0)
print(json.dumps({'decision':'deny','from':source,'to':target,'rollback':rollback == 'true',
                  'reason':'no_approved_compatibility_rule'}, sort_keys=True), file=sys.stderr)
raise SystemExit(1)
PY