/** Same-origin, capability-gated transport for HUX-03. */

import { ACCEPT, API_VERSION, RESPONSE_SCHEMAS } from "./contracts.ts";
import { normalizeConversation, normalizeProject, preservesConversation } from "./model.ts";
import {
  boundedLimit,
  isOpaqueId,
  isUtc,
  normalizeIdentity,
  safeCursor,
  safeTags,
  sameIdentity,
  scopedPath,
} from "./security.ts";
import type {
  Conversation,
  ConversationPatch,
  Page,
  Project,
  ProjectPatch,
  RawConversation,
  RawEnvelope,
  RawProject,
  ScopedIdentity,
  SearchFilters,
} from "./types.ts";

interface FoundationClient {
  apiVersion: string;
  identity: ScopedIdentity;
  enabled(flag: string): boolean;
  endpoint(path: string): string;
}

interface FetchResponse {
  ok: boolean;
  status: number;
  json(): Promise<unknown>;
}

interface ClientOptions {
  client: FoundationClient;
  fetcher?: (url: string, init: Record<string, unknown>) => Promise<FetchResponse>;
}

interface RawMutationEnvelope {
  schema?: unknown;
  api_version?: unknown;
  identity?: unknown;
  item?: unknown;
}

export class OrganizationContractError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "OrganizationContractError";
  }
}

function assertAvailable(client: FoundationClient): void {
  if (client.apiVersion !== API_VERSION || !client.enabled("hux.foundation") ||
      !client.enabled("hux.projects")) {
    throw new OrganizationContractError("Project organization is not enabled");
  }
}

function assertEnvelope(raw: unknown, schema: string, expected: ScopedIdentity): RawEnvelope {
  if (!raw || typeof raw !== "object" || Array.isArray(raw)) {
    throw new OrganizationContractError("Invalid organization response");
  }
  const value = raw as RawEnvelope;
  const identity = normalizeIdentity(value.identity);
  if (value.schema !== schema || value.api_version !== API_VERSION || !identity ||
      !sameIdentity(identity, expected)) {
    throw new OrganizationContractError("Organization response crossed its scope");
  }
  return value;
}

function pagination(raw: RawEnvelope): Pick<Page<never>, "nextCursor" | "total"> {
  const cursor = safeCursor(raw.next_cursor);
  if (cursor === undefined || (raw.total !== null && raw.total !== undefined &&
      (!Number.isSafeInteger(raw.total) || (raw.total as number) < 0))) {
    throw new OrganizationContractError("Invalid organization pagination");
  }
  return {nextCursor: cursor || null, total: raw.total as number | null | undefined ?? null};
}

function pageQuery(cursor: string | null | undefined, limit: number | undefined): URLSearchParams {
  const query = new URLSearchParams();
  const safe = safeCursor(cursor);
  if (safe === undefined) throw new TypeError("Invalid organization cursor");
  if (safe) query.set("cursor", safe);
  query.set("limit", String(boundedLimit(limit)));
  return query;
}

function projectPage(raw: unknown, expected: ScopedIdentity): Page<Project> {
  const value = assertEnvelope(raw, RESPONSE_SCHEMAS.projects, expected);
  if (!Array.isArray(value.items) || value.items.length > 100) {
    throw new OrganizationContractError("Project page exceeds its bound");
  }
  const items = value.items.map((item) => normalizeProject(item as RawProject, expected.userRef));
  if (items.some((item) => item === null) ||
      new Set(items.map((item) => item?.id)).size !== items.length) {
    throw new OrganizationContractError("Invalid project record");
  }
  return {...pagination(value), items: items as Project[]};
}

function conversationPage(
  raw: unknown,
  schema: string,
  expected: ScopedIdentity,
  projectIds: ReadonlySet<string>,
): Page<Conversation> {
  const value = assertEnvelope(raw, schema, expected);
  if (!Array.isArray(value.items) || value.items.length > 100) {
    throw new OrganizationContractError("Conversation page exceeds its bound");
  }
  const items = value.items.map((item) =>
    normalizeConversation(item as RawConversation, expected.userRef, projectIds));
  if (items.some((item) => item === null) ||
      new Set(items.map((item) => item?.id)).size !== items.length) {
    throw new OrganizationContractError("Invalid conversation record");
  }
  return {...pagination(value), items: items as Conversation[]};
}

function mutationItem(
  raw: unknown,
  schema: string,
  expected: ScopedIdentity,
): unknown {
  const value = assertEnvelope(raw, schema, expected) as RawMutationEnvelope;
  if (!("item" in value) || value.item === undefined) {
    throw new OrganizationContractError("Mutation response has no item");
  }
  return value.item;
}

export function createOrganizationClient(options: ClientOptions) {
  const client = options.client;
  const fetcher = options.fetcher || (typeof fetch === "function" ? fetch.bind(globalThis) : null);
  if (!client || !fetcher) throw new TypeError("Organization client requires HUX and fetch clients");
  const identity = client.identity;

  async function request(path: string, init: Record<string, unknown> = {}): Promise<unknown> {
    assertAvailable(client);
    const response = await fetcher(client.endpoint(path), {
      cache: "no-store", credentials: "same-origin",
      headers: {Accept: ACCEPT, ...(init.body ? {"Content-Type": "application/json"} : {})},
      ...init,
    });
    if (!response.ok) throw new OrganizationContractError(
      response.status === 409 ? "This item changed; refresh before trying again" :
        `Organization request failed (${response.status})`,
    );
    return response.json();
  }

  async function listProjects(cursor?: string | null, limit?: number): Promise<Page<Project>> {
    const query = pageQuery(cursor, limit);
    return projectPage(await request(`/projects?${query}`), identity);
  }

  async function listConversations(
    projectId: string,
    projectIds: ReadonlySet<string>,
    cursor?: string | null,
    limit?: number,
  ): Promise<Page<Conversation>> {
    if (!projectIds.has(projectId)) throw new TypeError("Project is outside this workspace");
    const path = `${scopedPath("/projects", projectId)}/conversations?${pageQuery(cursor, limit)}`;
    const page = conversationPage(await request(path), RESPONSE_SCHEMAS.conversations, identity, projectIds);
    if (page.items.some((item) => item.projectId !== projectId)) {
      throw new OrganizationContractError("Conversation crossed its project boundary");
    }
    return page;
  }

  async function searchConversations(
    filters: SearchFilters,
    projectIds: ReadonlySet<string>,
  ): Promise<Page<Conversation>> {
    const text = typeof filters.query === "string" ? filters.query.trim() : "";
    if (!text || text.length > 200) throw new TypeError("Search query must be 1 to 200 characters");
    const query = pageQuery(filters.cursor, filters.limit);
    query.set("q", text);
    if (filters.projectId) {
      if (!projectIds.has(filters.projectId)) throw new TypeError("Search project is outside this workspace");
      query.set("project_id", filters.projectId);
    }
    const tags = safeTags(filters.tags || []);
    if (tags === null) throw new TypeError("Search tags are invalid");
    tags.forEach((tag) => query.append("tag", tag));
    if (filters.pinned !== undefined) query.set("pinned", String(filters.pinned));
    return conversationPage(await request(`/conversations/search?${query}`),
      RESPONSE_SCHEMAS.search, identity, projectIds);
  }

  async function updateProject(before: Project, patch: ProjectPatch): Promise<Project> {
    if (before.owner !== identity.userRef || !isUtc(patch.expectedUpdatedAt)) {
      throw new TypeError("Project mutation is outside this workspace");
    }
    const tags = patch.tags === undefined ? undefined : safeTags(patch.tags);
    const name = patch.name === undefined ? undefined : patch.name.trim();
    if (tags === null || (name !== undefined && (!name || name.length > 120))) {
      throw new TypeError("Project mutation is invalid");
    }
    const body = {expected_updated_at: patch.expectedUpdatedAt,
      ...(name !== undefined ? {name} : {}), ...(tags !== undefined ? {tags} : {}),
      ...(patch.pinned !== undefined ? {pinned: patch.pinned} : {})};
    const raw = mutationItem(await request(scopedPath("/projects", before.id),
      {method: "PATCH", body: JSON.stringify(body)}), RESPONSE_SCHEMAS.projectMutation, identity);
    const item = normalizeProject(raw as RawProject, identity.userRef);
    if (!item || item.id !== before.id) throw new OrganizationContractError("Project identity changed during mutation");
    return item;
  }

  async function updateConversation(
    before: Conversation,
    patch: ConversationPatch,
    projectIds: ReadonlySet<string>,
  ): Promise<Conversation> {
    if (before.owner !== identity.userRef || !isUtc(patch.expectedUpdatedAt) ||
        (before.projectId !== null && !projectIds.has(before.projectId)) ||
        (patch.projectId !== undefined && patch.projectId !== null && !projectIds.has(patch.projectId))) {
      throw new TypeError("Conversation mutation is outside this workspace");
    }
    const tags = patch.tags === undefined ? undefined : safeTags(patch.tags);
    const title = patch.title === undefined ? undefined : patch.title.trim();
    if (tags === null || (title !== undefined && (!title || title.length > 200))) {
      throw new TypeError("Conversation mutation is invalid");
    }
    const body = {expected_updated_at: patch.expectedUpdatedAt,
      ...(title !== undefined ? {title} : {}),
      ...(patch.projectId !== undefined ? {project_id: patch.projectId} : {}),
      ...(tags !== undefined ? {tags} : {}),
      ...(patch.pinned !== undefined ? {pinned: patch.pinned} : {})};
    const raw = mutationItem(await request(scopedPath("/conversations", before.id),
      {method: "PATCH", body: JSON.stringify(body)}), RESPONSE_SCHEMAS.conversationMutation, identity);
    const item = normalizeConversation(raw as RawConversation, identity.userRef, projectIds);
    const intendedProject = patch.projectId === undefined ? before.projectId : patch.projectId;
    if (!item || item.projectId !== intendedProject || !preservesConversation(before, item)) {
      throw new OrganizationContractError("Conversation lineage or attachments changed during mutation");
    }
    return item;
  }

  return Object.freeze({listConversations, listProjects, searchConversations,
    updateConversation, updateProject});
}