import { normalizeAuthorityBaseUrl } from "./authority-capabilities.js";

export const AUTHORITY_PROTOCOL_AUTO = "auto";
export const AUTHORITY_PROTOCOL_SERVER_PLUGIN_V06 = "server-plugin-v06";
export const AUTHORITY_SESSION_HEADER = "x-authority-session-token";

function normalizeProtocol(value = AUTHORITY_PROTOCOL_AUTO) {
  const normalized = String(value || AUTHORITY_PROTOCOL_AUTO).trim().toLowerCase();
  if (["v06", "v0.6", "server-plugin", AUTHORITY_PROTOCOL_SERVER_PLUGIN_V06].includes(normalized)) {
    return AUTHORITY_PROTOCOL_SERVER_PLUGIN_V06;
  }
  return AUTHORITY_PROTOCOL_SERVER_PLUGIN_V06;
}

function clonePlain(value, fallbackValue = null) {
  if (value == null) return fallbackValue;
  if (typeof globalThis.structuredClone === "function") {
    try {
      return globalThis.structuredClone(value);
    } catch {
    }
  }
  try {
    return JSON.parse(JSON.stringify(value));
  } catch {
    return fallbackValue;
  }
}

function normalizeHeaderName(name = "") {
  return String(name || "").trim().toLowerCase();
}

function hasSessionHeader(headers = {}) {
  return Object.keys(headers || {}).some((name) => normalizeHeaderName(name) === AUTHORITY_SESSION_HEADER);
}

function buildDefaultSessionInitConfig(source = {}) {
  const config = source && typeof source === "object" && !Array.isArray(source) ? source : {};
  return {
    extensionId: String(config.extensionId || "third-party/st-bme"),
    displayName: String(config.displayName || "ST-BME"),
    version: String(config.version || "0.0.0"),
    installType: String(config.installType || "local"),
    declaredPermissions: clonePlain(config.declaredPermissions, null) || {
      storage: { kv: true, blob: true },
      fs: { private: true },
      sql: { private: true },
      trivium: { private: true },
      jobs: { background: true },
      events: { channels: true },
    },
    ...(config.uiLabel ? { uiLabel: String(config.uiLabel) } : {}),
  };
}

function readPayloadErrorMessage(payload = null, fallback = "") {
  if (!payload || typeof payload !== "object" || Array.isArray(payload)) return fallback;
  return String(payload.error || payload.message || payload.reason || fallback || "");
}

async function readResponsePayload(response = null) {
  if (!response) return {};
  const contentType = String(response.headers?.get?.("content-type") || "").toLowerCase();
  if (contentType.includes("application/json") && typeof response.json === "function") {
    try {
      return await response.json();
    } catch {
      return {};
    }
  }
  if (typeof response.json === "function") {
    try {
      return await response.json();
    } catch {
    }
  }
  if (typeof response.text === "function") {
    try {
      return { error: await response.text() };
    } catch {
      return {};
    }
  }
  return {};
}

export class AuthorityHttpError extends Error {
  constructor(message, options = {}) {
    super(message);
    this.name = "AuthorityHttpError";
    this.status = Number(options.status || 0);
    this.code = String(options.code || "");
    this.category = String(options.category || "");
    this.payload = clonePlain(options.payload, null);
    this.path = String(options.path || "");
    this.protocol = String(options.protocol || "");
  }
}

export class AuthorityHttpClient {
  constructor(options = {}) {
    this.baseUrl = normalizeAuthorityBaseUrl(options.baseUrl);
    this.fetchImpl = options.fetchImpl || (typeof fetch === "function" ? fetch.bind(globalThis) : null);
    this.headerProvider = typeof options.headerProvider === "function" ? options.headerProvider : null;
    this.protocol = normalizeProtocol(options.protocol || options.authorityProtocol);
    this.sessionToken = String(options.sessionToken || options.authoritySessionToken || "");
    this.sessionInitConfig = buildDefaultSessionInitConfig(options.sessionInitConfig || options.initConfig || options);
    this.sessionPromise = null;
  }

  async buildHeaders({ session = false } = {}) {
    let provided = {};
    if (this.headerProvider) {
      provided = await this.headerProvider() || {};
    }
    const headers = {
      Accept: "application/json",
      "Content-Type": "application/json",
      ...provided,
    };
    if (session && this.sessionToken && !hasSessionHeader(headers)) {
      headers[AUTHORITY_SESSION_HEADER] = this.sessionToken;
    }
    return headers;
  }

  async ensureSession() {
    if (this.sessionToken) return this.sessionToken;
    if (!this.sessionPromise) {
      this.sessionPromise = this.requestJson("/session/init", {
        method: "POST",
        body: this.sessionInitConfig,
        session: false,
        protocol: AUTHORITY_PROTOCOL_SERVER_PLUGIN_V06,
      }).then((payload) => {
        const token = String(payload?.sessionToken || payload?.token || "");
        if (!token) {
          throw new AuthorityHttpError("Authority session init did not return a session token", {
            status: 0,
            path: "/session/init",
            protocol: AUTHORITY_PROTOCOL_SERVER_PLUGIN_V06,
            payload,
          });
        }
        this.sessionToken = token;
        return token;
      }).catch((error) => {
        this.sessionPromise = null;
        throw error;
      });
    }
    return await this.sessionPromise;
  }

  async requestJson(path, options = {}) {
    if (typeof this.fetchImpl !== "function") {
      throw new AuthorityHttpError("Authority fetch unavailable", {
        path,
        protocol: options.protocol || this.protocol,
      });
    }
    const method = String(options.method || "POST").toUpperCase();
    const session = Boolean(options.session);
    if (session && !this.sessionToken) {
      await this.ensureSession();
    }
    const headers = await this.buildHeaders({ session });
    const response = await this.fetchImpl(`${this.baseUrl}${path}`, {
      method,
      headers,
      ...(method === "GET" || options.body === undefined ? {} : { body: JSON.stringify(options.body) }),
      ...(options.signal ? { signal: options.signal } : {}),
    });
    const status = Number(response?.status || 0);
    const payload = await readResponsePayload(response);
    if (!response?.ok) {
      const message = readPayloadErrorMessage(payload, `Authority HTTP ${status || "unknown"}`);
      throw new AuthorityHttpError(message || `Authority HTTP ${status || "unknown"}`, {
        status,
        code: payload?.code,
        category: payload?.category,
        payload,
        path,
        protocol: options.protocol || this.protocol,
      });
    }
    return payload;
  }
}

export function createAuthorityHttpClient(options = {}) {
  return new AuthorityHttpClient(options);
}