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

# CASAN H2 tool-input validation.
# Validates a tool-call input JSON against a JSON-Schema-style spec
# (required fields + property types + additionalProperties:false).
# Stdlib-only — supports type, required, properties, additionalProperties,
# enum. NOT a full JSON Schema engine (no $ref, no nested object recursion
# beyond one level); scoped deliberately and labeled as such.
#
# Usage: validate-tool-input.sh <schema.json> <input.json>
# Exit: 0 valid, 2 invalid, 64 usage error.

SCHEMA="${1:-}"
INPUT="${2:-}"
if [[ -z "$SCHEMA" || -z "$INPUT" || ! -f "$SCHEMA" || ! -f "$INPUT" ]]; then
  echo "Usage: validate-tool-input.sh <schema.json> <input.json>" >&2
  exit 64
fi

python3 - "$SCHEMA" "$INPUT" <<'PY'
import json, sys

schema = json.load(open(sys.argv[1], encoding="utf-8"))
data = json.load(open(sys.argv[2], encoding="utf-8"))

TYPES = {
    "string": str, "integer": int, "number": (int, float),
    "boolean": bool, "object": dict, "array": list,
}
errors = []

if schema.get("type") == "object" and not isinstance(data, dict):
    errors.append("root: expected object")
else:
    props = schema.get("properties", {})
    for field in schema.get("required", []):
        if field not in data:
            errors.append(f"missing required field: {field}")
    if schema.get("additionalProperties") is False:
        for key in data:
            if key not in props:
                errors.append(f"unexpected field: {key}")
    for key, spec in props.items():
        if key not in data:
            continue
        expected = spec.get("type")
        py = TYPES.get(expected)
        # bool is a subclass of int — guard so a boolean isn't accepted as integer
        if py and (not isinstance(data[key], py)
                   or (expected in ("integer", "number") and isinstance(data[key], bool))):
            errors.append(f"field {key}: expected {expected}")
        if "enum" in spec and data[key] not in spec["enum"]:
            errors.append(f"field {key}: not in enum {spec['enum']}")

if errors:
    sys.stderr.write("TOOL_INPUT_INVALID " + "; ".join(errors) + "\n")
    raise SystemExit(2)
print("TOOL_INPUT_VALID")
PY