// ScratchpadSummary — structured normalization of a tree-split or
// long-running scratchpad. Distinct from EvidenceRecord because a
// scratchpad accumulates across many calls; this schema captures the
// state at a checkpoint moment.
import {
  ValidationResult, requireString, requireIsoTimestamp, requireProvenance, requireStringArray,
} from "./types";

export const SCRATCHPAD_SCHEMA_VERSION = 1;

export interface ScratchpadSummary {
  schema_version: number;
  run_id: string;
  current_objective: string;
  completed_steps: string[];
  failed_steps: string[];
  pending_steps: string[];
  important_paths: string[];        // file paths the scratchpad references
  decisions: string[];              // architectural/scope decisions made
  unresolved_questions: string[];
  validation_status: "pass" | "fail" | "partial" | "pending";
  next_command?: string;            // recommendation for next action
  source_scratchpad_hash: string;   // sha256 of the full source scratchpad text — diff detection
  summarized_at: string;            // ISO 8601
  provenance: { source_file: string; line_offset?: number; sig_hash: string; recorded_at: string };
}

const STATUS = ["pass", "fail", "partial", "pending"];

export function validateScratchpadSummary(input: unknown): ValidationResult<ScratchpadSummary> {
  const errors: string[] = [];
  if (typeof input !== "object" || input === null) return { valid: false, errors: ["expected object"] };
  const r = input as Record<string, unknown>;
  let ok = true;

  if (r.schema_version !== SCRATCHPAD_SCHEMA_VERSION) {
    errors.push(`schema_version: expected ${SCRATCHPAD_SCHEMA_VERSION}, got ${JSON.stringify(r.schema_version)}`);
    ok = false;
  }
  ok = requireString(r.run_id, "run_id", errors) && ok;
  ok = requireString(r.current_objective, "current_objective", errors) && ok;
  ok = requireIsoTimestamp(r.summarized_at, "summarized_at", errors) && ok;
  if (typeof r.source_scratchpad_hash !== "string" || !/^[0-9a-f]{64}$/.test(r.source_scratchpad_hash as string)) {
    errors.push("source_scratchpad_hash: must be hex sha256");
    ok = false;
  }
  ok = requireStringArray(r.completed_steps, "completed_steps", errors) && ok;
  ok = requireStringArray(r.failed_steps, "failed_steps", errors) && ok;
  ok = requireStringArray(r.pending_steps, "pending_steps", errors) && ok;
  ok = requireStringArray(r.important_paths, "important_paths", errors) && ok;
  ok = requireStringArray(r.decisions, "decisions", errors) && ok;
  ok = requireStringArray(r.unresolved_questions, "unresolved_questions", errors) && ok;
  if (!STATUS.includes(r.validation_status as string)) {
    errors.push(`validation_status: must be one of ${STATUS.join("|")}`);
    ok = false;
  }
  if (r.next_command !== undefined && typeof r.next_command !== "string") {
    errors.push("next_command: expected string when present");
    ok = false;
  }
  ok = requireProvenance(r.provenance, "provenance", errors) && ok;

  if (!ok) return { valid: false, errors };
  return { valid: true, value: r as unknown as ScratchpadSummary };
}