/**
 * Codex-related helper functions and state.
 *
 * Manages Codex login sessions, auth validation cache, binary resolution,
 * integration state normalization, and error / fingerprint utilities.
 */
"use strict";

const { createHash } = require("node:crypto");
const { existsSync, readFileSync } = require("node:fs");
const os = require("node:os");
const path = require("node:path");
const { StringDecoder } = require("node:string_decoder");

const { stripAnsi, extractFirstNonLocalhostUrl, toUnpackedAsarPath } = require("./shellUtils.cjs");

// ── Module-level state ──

const codexLoginSessions = new Map();
let codexValidationCache = null;
const MAX_CODEX_LOGIN_OUTPUT_BYTES = 64 * 1024;
const MAX_CODEX_LOGIN_OUTPUT_CHARS = MAX_CODEX_LOGIN_OUTPUT_BYTES;
const MAX_CODEX_LOGIN_TERMINAL_SESSIONS = 8;
const CODEX_LOGIN_KILL_GRACE_MS = 750;

const CODEX_AUTH_HINTS = [
  "not logged in",
  "authentication required",
  "auth required",
  "login required",
  "missing credentials",
  "no credentials",
  "unauthorized",
  "forbidden",
  "codex login",
  "401",
  "403",
  "invalid_grant",
  "invalid_token",
  "credentials",
];

// ── Login session helpers ──

function appendCodexLoginOutput(session, chunk) {
  const cleanChunk = stripAnsi(chunk);
  if (!cleanChunk) return;

  const combined = `${session.output || ""}${cleanChunk}`;
  if (!session.url) {
    session.url = extractFirstNonLocalhostUrl(combined);
  }
  session.output = retainUtf8Tail(combined, MAX_CODEX_LOGIN_OUTPUT_BYTES);
}

function retainUtf8Tail(value, maxBytes) {
  const buffer = Buffer.from(String(value || ""), "utf8");
  if (buffer.length <= maxBytes) return String(value || "");
  let start = buffer.length - maxBytes;
  // Never begin inside a UTF-8 continuation sequence.
  while (start < buffer.length && (buffer[start] & 0xc0) === 0x80) start += 1;
  return buffer.subarray(start).toString("utf8");
}

function createCodexLoginOutputDecoder(session) {
  const decoder = new StringDecoder("utf8");
  let ended = false;
  return {
    write(chunk) {
      if (ended) return;
      const buffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(String(chunk));
      appendCodexLoginOutput(session, decoder.write(buffer));
    },
    end() {
      if (ended) return;
      ended = true;
      appendCodexLoginOutput(session, decoder.end());
    },
  };
}

function pruneCodexLoginSessions() {
  const terminalSessionIds = [];
  for (const [sessionId, session] of codexLoginSessions) {
    if (session?.state !== "running" && !session?.process) terminalSessionIds.push(sessionId);
  }
  const excess = terminalSessionIds.length - MAX_CODEX_LOGIN_TERMINAL_SESSIONS;
  for (let index = 0; index < excess; index += 1) {
    codexLoginSessions.delete(terminalSessionIds[index]);
  }
}

function clearCodexLoginKillTimer(session, clearTimeoutFn = clearTimeout) {
  if (!session?.killTimer) return;
  clearTimeoutFn(session.killTimer);
  session.killTimer = null;
}

function stopCodexLoginProcess(session, {
  setTimeoutFn = setTimeout,
  clearTimeoutFn = clearTimeout,
} = {}) {
  const child = session?.process;
  if (!child) return false;
  clearCodexLoginKillTimer(session, clearTimeoutFn);
  session.killTimer = setTimeoutFn(() => {
    session.killTimer = null;
    if (session.process !== child) return;
    try { child.kill("SIGKILL"); } catch {}
  }, CODEX_LOGIN_KILL_GRACE_MS);
  session.killTimer?.unref?.();
  try { child.kill("SIGTERM"); } catch {}
  return true;
}

function recordCodexLoginSession(session) {
  if (!session?.id) return;
  codexLoginSessions.delete(session.id);
  codexLoginSessions.set(session.id, session);
  pruneCodexLoginSessions();
}

function toCodexLoginSessionResponse(session) {
  return {
    sessionId: session.id,
    state: session.state,
    url: session.url,
    output: session.output,
    error: session.error,
    exitCode: session.exitCode,
    codexPath: session.codexPath || null,
  };
}

function getActiveCodexLoginSession() {
  for (const session of codexLoginSessions.values()) {
    if (session.state === "running" && session.process && !session.process.killed) {
      return session;
    }
  }
  return null;
}

// ── Codex config.toml probing ──
//
// Users who hand-configure `~/.codex/config.toml` with a custom
// `model_provider` + matching `[model_providers.<name>]` entry are fully
// functional from the Codex CLI, but `codex login status` doesn't see them
// because it only reports on `~/.codex/auth.json` (populated by `codex login`).
// We read and minimally parse the config file so we can surface this as a
// valid "ready" state and skip the ChatGPT login prompt in the UI.

/** Find `#` outside quoted regions. Tracks escape state via a flag rather
 *  than peeking at the previous character, so even runs of backslashes like
 *  `"C:\\path\\"` close the string correctly. Literal (single-quoted) TOML
 *  strings don't recognize `\` as an escape, so only honor escapes inside
 *  basic (double-quoted) strings. */
function findUnquotedHash(value) {
  let inStr = false;
  let quote = "";
  let escaped = false;
  for (let i = 0; i < value.length; i++) {
    const ch = value[i];
    if (inStr) {
      if (escaped) {
        escaped = false;
        continue;
      }
      if (quote === '"' && ch === "\\") {
        escaped = true;
        continue;
      }
      if (ch === quote) {
        inStr = false;
        quote = "";
      }
      continue;
    }
    if (ch === '"' || ch === "'") {
      inStr = true;
      quote = ch;
      continue;
    }
    if (ch === "#") return i;
  }
  return -1;
}

/**
 * Parse the narrow subset of TOML we need from Codex's config.toml:
 *   - top-level string keys (e.g. `model_provider = "my_provider"`)
 *   - `[model_providers.<name>]` tables with string-valued keys
 * Unsupported TOML features (arrays, inline tables, multi-line strings, etc.)
 * are ignored — Codex's config.toml doesn't use them for provider definitions.
 */
function parseCodexConfigToml(text) {
  const result = { model_providers: {} };
  let currentProvider = null;
  let atTopLevel = true;

  // Strip UTF-8 BOM so the first key still matches the regex on Windows-edited files.
  const normalized = String(text || "").replace(/^\uFEFF/, "");
  const lines = normalized.split(/\r?\n/);
  for (const rawLine of lines) {
    let line = rawLine;
    const hashIdx = findUnquotedHash(line);
    if (hashIdx >= 0) line = line.slice(0, hashIdx);
    line = line.trim();
    if (!line) continue;

    const sectionMatch = line.match(/^\[([^\]]+)\]$/);
    if (sectionMatch) {
      const section = sectionMatch[1].trim();
      if (section.startsWith("model_providers.")) {
        currentProvider = section.slice("model_providers.".length);
        if (!result.model_providers[currentProvider]) {
          result.model_providers[currentProvider] = {};
        }
        atTopLevel = false;
      } else {
        currentProvider = null;
        atTopLevel = false;
      }
      continue;
    }

    const kvMatch = line.match(/^([A-Za-z_][\w.-]*)\s*=\s*(.+)$/);
    if (!kvMatch) continue;
    const key = kvMatch[1];
    let raw = kvMatch[2].trim();
    let value;
    if ((raw.startsWith('"') && raw.endsWith('"')) || (raw.startsWith("'") && raw.endsWith("'"))) {
      value = raw.slice(1, -1);
    } else {
      value = raw;
    }

    if (atTopLevel) {
      result[key] = value;
    } else if (currentProvider) {
      result.model_providers[currentProvider][key] = value;
    }
  }

  return result;
}

/**
 * Inspect `~/.codex/config.toml` to determine whether the user has
 * configured a custom `model_provider` that isn't the built-in OpenAI/ChatGPT
 * path.
 *
 * Returns null when:
 *   - the config file doesn't exist or can't be read
 *   - no `model_provider` is set, or it points to the default `openai` preset
 *   - the referenced provider entry is missing (config is malformed)
 *
 * Returns a summary object otherwise — even if the env_key isn't currently
 * exported in the shell environment. That case is surfaced via
 * `envKeyPresent: false` so the UI can warn the user; we don't want the
 * absence of an env var to silently fall back to the ChatGPT login flow,
 * because the config.toml is a strong signal the user doesn't want that.
 */
function readCodexCustomProviderConfig(shellEnv) {
  const home = shellEnv?.HOME || shellEnv?.USERPROFILE || os.homedir();
  if (!home) return null;
  const configPath = path.join(home, ".codex", "config.toml");
  if (!existsSync(configPath)) return null;

  let text;
  try {
    text = readFileSync(configPath, "utf8");
  } catch {
    return null;
  }

  let parsed;
  try {
    parsed = parseCodexConfigToml(text);
  } catch {
    return null;
  }

  const activeName = typeof parsed.model_provider === "string"
    ? parsed.model_provider.trim()
    : "";
  if (!activeName) return null;
  // The built-in "openai" provider still goes through ChatGPT/API-key auth
  // managed by `codex login`, so treating it as "custom" would be wrong.
  if (activeName === "openai") return null;

  const providerEntry = parsed.model_providers?.[activeName];
  if (!providerEntry) return null;

  const envKeyName = typeof providerEntry.env_key === "string" ? providerEntry.env_key.trim() : "";
  const envKeyValue = envKeyName && shellEnv ? String(shellEnv[envKeyName] || "").trim() : "";
  const hardcodedApiKey = typeof providerEntry.api_key === "string" ? providerEntry.api_key.trim() : "";
  const activeModel = typeof parsed.model === "string" ? parsed.model.trim() : "";

  // Hash the actual auth material (either the hardcoded api_key or the
  // resolved env_key value) so the SDK backend fingerprint changes when
  // the user rotates their key — without ever returning the raw value
  // across the IPC boundary.
  const authMaterial = hardcodedApiKey || envKeyValue;
  const authHash = authMaterial
    ? createHash("sha256").update(authMaterial).digest("hex")
    : null;

  return {
    providerName: activeName,
    displayName: providerEntry.name || activeName,
    baseUrl: providerEntry.base_url || null,
    envKey: envKeyName || null,
    envKeyPresent: Boolean(envKeyValue),
    hasHardcodedApiKey: Boolean(hardcodedApiKey),
    model: activeModel || null,
    authHash,
  };
}

/**
 * Returns a user-facing error message when a Codex config.toml custom
 * provider references an env_key that isn't exported in the shell env and
 * doesn't have a hardcoded api_key either — otherwise returns null. Shared
 * by every spawn path (stream handler, list-models handler) so users get
 * the same actionable message regardless of which one hits first.
 */
function getCodexCustomConfigPreflightError(customConfig) {
  if (!customConfig) return null;
  if (!customConfig.envKey) return null;
  if (customConfig.envKeyPresent || customConfig.hasHardcodedApiKey) return null;
  return `Codex is configured to use the "${customConfig.displayName}" provider from ~/.codex/config.toml, but the environment variable ${customConfig.envKey} is not set. Export it in your shell (e.g. add to ~/.zshrc) and click "Refresh Status" in Settings.`;
}

// ── Integration state ──

function normalizeCodexIntegrationState(rawOutput) {
  const normalizedOutput = String(rawOutput || "").toLowerCase();

  if (normalizedOutput.includes("logged in using chatgpt")) {
    return "connected_chatgpt";
  }
  if (
    normalizedOutput.includes("logged in using an api key") ||
    normalizedOutput.includes("logged in using api key")
  ) {
    return "connected_api_key";
  }
  if (normalizedOutput.includes("not logged in")) {
    return "not_logged_in";
  }
  return "unknown";
}

function appendCodexChatGptValidationFailure(rawOutput, validationError) {
  return [
    String(rawOutput || "").trim(),
    "",
    "ChatGPT auth validation failed:",
    validationError || "Unknown validation error",
  ].join("\n").trim();
}

// ── Error helpers ──

function safeJsonStringify(value) {
  const seen = new WeakSet();
  try {
    return JSON.stringify(value, (_key, nestedValue) => {
      if (typeof nestedValue !== "object" || nestedValue === null) {
        return nestedValue;
      }
      if (seen.has(nestedValue)) {
        return "[Circular]";
      }
      seen.add(nestedValue);
      return nestedValue;
    });
  } catch {
    return null;
  }
}

function stringifyErrorValue(value, seen = new WeakSet()) {
  if (value == null) return "";
  if (typeof value === "string") return value;
  if (typeof value === "number" || typeof value === "boolean") return String(value);
  if (value instanceof Error) return value.message || value.name || String(value);
  if (typeof value !== "object") return String(value);
  if (seen.has(value)) return "[Circular error]";
  seen.add(value);

  const candidates = [
    value?.data?.message,
    value?.data?.error,
    value?.errorText,
    value?.message,
    value?.error,
    value?.cause,
    value?.data,
  ];
  for (const candidate of candidates) {
    const message = stringifyErrorValue(candidate, seen).trim();
    if (message && message !== "{}") {
      return message;
    }
  }

  return safeJsonStringify(value) || String(value);
}

function extractCodexError(error) {
  const message = stringifyErrorValue(error) || "Unknown Codex error";
  const code = error?.data?.code || error?.code || error?.error?.code || error?.data?.error?.code;
  return {
    message,
    code: typeof code === "string" ? code : undefined,
  };
}

function isCodexAuthError(params) {
  const searchableText = `${params?.code || ""} ${params?.message || ""} ${params?.error || ""}`.toLowerCase();
  return CODEX_AUTH_HINTS.some((hint) => searchableText.includes(hint));
}

// ── Fingerprints ──

function getCodexAuthFingerprint(apiKey) {
  const normalized = String(apiKey || "").trim();
  if (!normalized) return null;
  return createHash("sha256").update(normalized).digest("hex");
}

function getCodexMcpFingerprint(mcpServers) {
  return createHash("sha256").update(JSON.stringify(mcpServers || [])).digest("hex");
}

// ── Validation cache ──

function invalidateCodexValidationCache() {
  codexValidationCache = null;
}

function getCodexValidationCache() {
  return codexValidationCache;
}

function setCodexValidationCache(value) {
  codexValidationCache = value;
}

module.exports = {
  MAX_CODEX_LOGIN_OUTPUT_BYTES,
  MAX_CODEX_LOGIN_OUTPUT_CHARS,
  MAX_CODEX_LOGIN_TERMINAL_SESSIONS,
  CODEX_LOGIN_KILL_GRACE_MS,
  codexLoginSessions,
  appendCodexLoginOutput,
  createCodexLoginOutputDecoder,
  pruneCodexLoginSessions,
  recordCodexLoginSession,
  clearCodexLoginKillTimer,
  stopCodexLoginProcess,
  toCodexLoginSessionResponse,
  getActiveCodexLoginSession,
  normalizeCodexIntegrationState,
  appendCodexChatGptValidationFailure,
  readCodexCustomProviderConfig,
  getCodexCustomConfigPreflightError,
  extractCodexError,
  isCodexAuthError,
  getCodexAuthFingerprint,
  getCodexMcpFingerprint,
  invalidateCodexValidationCache,
  getCodexValidationCache,
  setCodexValidationCache,
};