/**
 * Builtin image `tfp-builtin/json-schema-check:1` — a structural check: the
 * submitted artifact (role `document`) must parse as JSON and satisfy the
 * JSON Schema bound to the Contract's `document_schema` reference slot.
 *
 * Contract semantics: verified when the document parses and validates;
 * refuted when it is well-formed JSON that violates the schema (a wrong
 * shape is a statement about the work); inconclusive when it is not JSON
 * or not UTF-8 at all (unreadable, not wrong). The check establishes
 * structure only: nothing about whether the content is true.
 */

import type { SandboxFs } from '../sandbox.js';
import { unsupportedKeywords, validateSchema, violationLines, type JsonSchema } from '../../json-schema.js';
import type { RunManifest } from '../../contracts.js';

export const JSON_SCHEMA_IMAGE_REF = 'tfp-builtin/json-schema-check:1';
const MAX_VIOLATIONS_REPORTED = 50;

export async function jsonSchemaCheck(fs: SandboxFs): Promise<number> {
  const manifest = JSON.parse(fs.readText('/input/manifest.json')) as RunManifest;
  const finish = (result: 'verified' | 'refuted' | 'inconclusive', reason: string, violations: string[] = []) => {
    fs.writeFile('/output/evidence/summary.json', JSON.stringify({ valid: result === 'verified', violations_count: violations.length, violations: violations.slice(0, MAX_VIOLATIONS_REPORTED) }));
    fs.writeFile('/output/result.json', JSON.stringify({ result, reason, findings: violations.slice(0, MAX_VIOLATIONS_REPORTED) }));
    fs.log(`${result}: ${reason}`);
    return 0;
  };
  const schemaPath = manifest.reference.find((r) => r.key === 'document_schema')?.path;
  if (!schemaPath) return finish('inconclusive', 'no bound document_schema');
  let schema: JsonSchema;
  try { schema = JSON.parse(fs.readText(schemaPath)) as JsonSchema; } catch { return finish('inconclusive', 'the bound document_schema is not valid JSON'); }
  const unsupported = unsupportedKeywords(schema);
  if (unsupported.length) return finish('inconclusive', `the bound document_schema uses keywords this checker does not implement: ${unsupported.slice(0, 5).join(', ')}`);
  const docPath = manifest.artifacts.find((a) => a.role === 'document')?.path;
  if (!docPath) return finish('inconclusive', 'no document artifact');
  let text: string;
  try { text = fs.readText(docPath); } catch { return finish('inconclusive', 'document is not UTF-8 text'); }
  let doc: unknown;
  try { doc = JSON.parse(text); } catch (e) { return finish('inconclusive', `document is not valid JSON: ${(e as Error).message.slice(0, 120)}`); }
  fs.log(`document: ${text.length} characters of JSON`);
  const violations = violationLines(validateSchema(schema, doc));
  if (violations.length) return finish('refuted', `document violates the schema at ${violations.length} place(s); first: ${violations[0]}`, violations);
  return finish('verified', 'document parses and satisfies the bound schema');
}