/** Schema-aligned normalization and lineage invariants for HUX-03. */

import { isOpaqueId, isUtc, safeTags, safeText } from "./security.ts";
import type {
  ArtifactSummary,
  AttachmentView,
  Conversation,
  LineageNode,
  OrganizationSnapshot,
  Project,
  RawConversation,
  RawProject,
} from "./types.ts";

export const FOUNDATION_FLAG = "hux.foundation";
export const PROJECTS_FLAG = "hux.projects";
const MODES = new Set(["fast", "thoughtful", "research", "create", "private"]);

export function projectsEnabled(flags?: Iterable<string>): boolean {
  const enabled = new Set(flags || []);
  return enabled.has(FOUNDATION_FLAG) && enabled.has(PROJECTS_FLAG);
}

export function normalizeProject(raw: RawProject, owner: string): Project | null {
  const tags = safeTags(raw.tags);
  if (raw.schema !== "hux.project.v1" || !isOpaqueId(raw.id, "prj") ||
      raw.owner !== owner || tags === null || typeof raw.pinned !== "boolean" ||
      typeof raw.archived !== "boolean" || !isUtc(raw.created_at) ||
      !isUtc(raw.updated_at) || (raw.default_mode !== undefined &&
      (typeof raw.default_mode !== "string" || !MODES.has(raw.default_mode)))) return null;
  const name = safeText(raw.name, "", 120);
  if (!name) return null;
  return {
    id: raw.id, owner, name,
    description: safeText(raw.description, "", 2000), tags,
    pinned: raw.pinned, archived: raw.archived, updatedAt: raw.updated_at,
  };
}

function normalizeBranch(raw: unknown): Conversation["branch"] | undefined {
  if (raw === undefined) return null;
  if (!raw || typeof raw !== "object" || Array.isArray(raw)) return undefined;
  const value = raw as Record<string, unknown>;
  if (!isOpaqueId(value.parent_conversation_id, "conv") ||
      typeof value.branch_point_message_id !== "string") return undefined;
  const messageId = safeText(value.branch_point_message_id, "", 120);
  return messageId ? {
    parentConversationId: value.parent_conversation_id,
    branchPointMessageId: messageId,
  } : undefined;
}

export function normalizeConversation(
  raw: RawConversation,
  owner: string,
  projectIds: ReadonlySet<string>,
): Conversation | null {
  const tags = safeTags(raw.tags);
  const branch = normalizeBranch(raw.branch);
  const artifacts = Array.isArray(raw.artifact_ids) ? raw.artifact_ids : null;
  const projectId = raw.project_id === undefined ? null : raw.project_id;
  if (raw.schema !== "hux.conversation.v1" || !isOpaqueId(raw.id, "conv") ||
      raw.owner !== owner || tags === null || branch === undefined ||
      typeof raw.pinned !== "boolean" || typeof raw.archived !== "boolean" ||
      !artifacts || artifacts.length > 500 || new Set(artifacts).size !== artifacts.length ||
      artifacts.some((id) => !isOpaqueId(id, "art")) || !isUtc(raw.created_at) ||
      !isUtc(raw.updated_at) || (raw.last_message_at !== undefined &&
      !isUtc(raw.last_message_at)) || (raw.mode !== undefined &&
      (typeof raw.mode !== "string" || !MODES.has(raw.mode))) ||
      (projectId !== null && (!isOpaqueId(projectId, "prj") || !projectIds.has(projectId)))) return null;
  const title = safeText(raw.title, "", 200);
  if (!title || branch?.parentConversationId === raw.id) return null;
  return {
    id: raw.id, owner, projectId, title, tags, pinned: raw.pinned,
    archived: raw.archived, artifactIds: [...artifacts] as string[], branch,
    lastMessageAt: raw.last_message_at as string | undefined || null,
    updatedAt: raw.updated_at,
  };
}

/** Reject cross-owner/project records instead of silently re-homing them. */
export function normalizeSnapshot(
  rawProjects: readonly RawProject[],
  rawConversations: readonly RawConversation[],
  owner: string,
): OrganizationSnapshot {
  const seenProjects = new Set<string>();
  const projects = rawProjects.slice(0, 100).map((item) => normalizeProject(item, owner))
    .filter((item): item is Project => {
      if (!item || seenProjects.has(item.id)) return false;
      seenProjects.add(item.id);
      return true;
    });
  const projectIds = new Set(projects.map((item) => item.id));
  const seenConversations = new Set<string>();
  const conversations = rawConversations.slice(0, 500)
    .map((item) => normalizeConversation(item, owner, projectIds))
    .filter((item): item is Conversation => {
      if (!item || seenConversations.has(item.id)) return false;
      seenConversations.add(item.id);
      return true;
    });
  return {
    projects, conversations,
    rejected: Math.max(0, rawProjects.length - projects.length) +
      Math.max(0, rawConversations.length - conversations.length),
  };
}

/** Missing metadata stays visible as an attachment placeholder. */
export function attachmentViews(
  conversation: Conversation,
  summaries: readonly ArtifactSummary[],
): AttachmentView[] {
  const byId = new Map(summaries.filter((item) =>
    isOpaqueId(item.id, "art")).slice(0, 500).map((item) => [item.id, item]));
  return conversation.artifactIds.map((id) => {
    const found = byId.get(id);
    return found ? {
      id, title: safeText(found.title, "Untitled artifact", 200),
      kind: safeText(found.kind, "artifact", 40), missing: false,
    } : {id, title: "Attachment details unavailable", kind: "artifact", missing: true};
  });
}

/** Build bounded ancestry with explicit missing/cycle nodes, never a fake root. */
export function branchLineage(
  selectedId: string,
  conversations: readonly Conversation[],
): LineageNode[] {
  if (!isOpaqueId(selectedId, "conv")) return [];
  const byId = new Map(conversations.slice(0, 500).map((item) => [item.id, item]));
  const result: LineageNode[] = [];
  const visited = new Set<string>();
  let currentId: string | null = selectedId;
  while (currentId && result.length < 64) {
    if (visited.has(currentId)) {
      result.push({conversationId: currentId, title: "Circular branch reference", parentConversationId: null,
        branchPointMessageId: null, depth: result.length, missing: false, cycle: true});
      break;
    }
    visited.add(currentId);
    const item = byId.get(currentId);
    if (!item) {
      result.push({conversationId: currentId, title: "Earlier conversation unavailable",
        parentConversationId: null, branchPointMessageId: null, depth: result.length,
        missing: true, cycle: false});
      break;
    }
    result.push({conversationId: item.id, title: item.title,
      parentConversationId: item.branch?.parentConversationId || null,
      branchPointMessageId: item.branch?.branchPointMessageId || null,
      depth: result.length, missing: false, cycle: false});
    currentId = item.branch?.parentConversationId || null;
  }
  return result.reverse().map((item, depth) => ({...item, depth}));
}

/** A move/rename may not change stable lineage or orphan any attachment. */
export function preservesConversation(before: Conversation, after: Conversation): boolean {
  return before.id === after.id && before.owner === after.owner &&
    JSON.stringify(before.branch) === JSON.stringify(after.branch) &&
    before.artifactIds.length === after.artifactIds.length &&
    before.artifactIds.every((id, index) => after.artifactIds[index] === id);
}