import { PathUtils } from "./PathUtils.js";

export class ChangeSetValidator {
  validate(changeset) {
    if (!Array.isArray(changeset)) throw new Error("changeset must be array");
    const normalized = [];

    for (const item of changeset) {
      if (!item || typeof item !== "object") throw new Error("invalid changeset item");
      if (!["create", "update", "delete"].includes(item.op)) throw new Error("invalid op");
      const path = PathUtils.normalizeRelative(item.path);

      if (item.op === "create") {
        if (typeof item.proposed_content !== "string") throw new Error("create needs proposed_content");
      }

      if (item.op === "update") {
        if (typeof item.base_hash !== "string") throw new Error("update needs base_hash");
        if (typeof item.proposed_content !== "string") throw new Error("update needs proposed_content");
      }

      if (item.op === "delete") {
        if (typeof item.base_hash !== "string") throw new Error("delete needs base_hash");
        if ("proposed_content" in item) throw new Error("delete forbids proposed_content");
      }

      normalized.push({
        op: item.op,
        path,
        base_hash: item.base_hash || null,
        proposed_content: item.proposed_content ?? null,
        reason: item.reason || ""
      });
    }

    return normalized;
  }
}