import fs from "node:fs";
import path from "node:path";
import os from "node:os";
import crypto from "node:crypto";

import type { CommandSample } from "./discover.ts";

export type RtkRawOutputRetention = "never" | "failures" | "always";

export interface RtkRawOutputPointer {
  id: string;
  path: string;
  bytes: number;
  sha256: string;
  redacted: boolean;
}

const SECRET_PATTERNS: Array<[RegExp, string]> = [
  [/\b(sk-[A-Za-z0-9_-]{16,})\b/g, "[REDACTED_OPENAI_KEY]"],
  [/\b(xox[baprs]-[A-Za-z0-9-]{16,})\b/g, "[REDACTED_SLACK_TOKEN]"],
  [/\b(AKIA[0-9A-Z]{16})\b/g, "[REDACTED_AWS_KEY]"],
  // key=value / key: value for common credential field names (flat alternation — no nesting,
  // so no ReDoS). Covers names the bare token/secret/password set misses (private_key, etc).
  [
    /((?:api[_-]?key|api[_-]?token|access[_-]?key|access[_-]?token|client[_-]?secret|auth[_-]?token|private[_-]?key|secret[_-]?key|credentials?|token|secret|password)\s*[:=]\s*)("[^"]+"|'[^']+'|[^\s]+)/gi,
    "$1[REDACTED]",
  ],
  // Authorization / Proxy-Authorization with Bearer OR Basic (curl -v emits Basic <base64>).
  [/((?:Proxy-)?Authorization:\s*(?:Bearer|Basic)\s+)[A-Za-z0-9._~+/-]+=*/gi, "$1[REDACTED]"],
];

function dataDir(): string {
  return process.env.DATA_DIR || path.join(os.homedir(), ".omniroute");
}

function safeId(seed: string): string {
  return crypto.createHash("sha256").update(seed).digest("hex").slice(0, 24);
}

function safeUtf8Slice(value: string, maxBytes: number): string {
  if (maxBytes <= 0 || Buffer.byteLength(value, "utf8") <= maxBytes) return value;
  let bytes = 0;
  let output = "";
  for (const char of value) {
    const len = Buffer.byteLength(char, "utf8");
    if (bytes + len > maxBytes) break;
    output += char;
    bytes += len;
  }
  return `${output}\n\n--- truncated at ${maxBytes} bytes ---`;
}

export function redactRtkRawOutput(value: string): { text: string; redacted: boolean } {
  let redacted = false;
  let text = value;
  for (const [pattern, replacement] of SECRET_PATTERNS) {
    const next = text.replace(pattern, (...args: string[]) => {
      redacted = true;
      return typeof replacement === "string"
        ? replacement.replace("$1", args[1] ?? "")
        : replacement;
    });
    text = next;
  }
  return { text, redacted };
}

export function isLikelyFailureOutput(value: string): boolean {
  return /\b(error|failed|failure|exception|traceback|panic|fatal|critical|TS\d{4}|FAIL)\b/i.test(
    value
  );
}

export function maybePersistRtkRawOutput(
  raw: string,
  options: {
    retention: RtkRawOutputRetention;
    command?: string | null;
    maxBytes?: number;
    failure?: boolean;
  }
): RtkRawOutputPointer | null {
  if (options.retention === "never") return null;
  const failure = options.failure ?? isLikelyFailureOutput(raw);
  if (options.retention === "failures" && !failure) return null;
  if (raw.trim().length === 0) return null;

  const maxBytes = Math.max(1024, Math.floor(options.maxBytes ?? 1_048_576));
  const redaction = redactRtkRawOutput(safeUtf8Slice(raw, maxBytes));
  const now = Date.now();
  const commandSlug = (options.command || "tool-output")
    .replace(/[^A-Za-z0-9_-]+/g, "_")
    .replace(/^_+|_+$/g, "")
    .slice(0, 48);
  const id = safeId(`${now}:${commandSlug}:${raw.length}:${redaction.text}`);
  const dir = path.join(dataDir(), "rtk", "raw-output");
  const filePath = path.join(dir, `${now}-${commandSlug || "tool-output"}-${id}.log`);
  try {
    fs.mkdirSync(dir, { recursive: true });
    fs.writeFileSync(filePath, redaction.text);
  } catch {
    // Best-effort capture: a disk error (ENOSPC / EACCES / read-only DATA_DIR) must NEVER
    // fail the compression pipeline. Skip the capture, exactly like retention "never".
    return null;
  }

  // Sidecar metadata: the .log filename only carries a lossy command SLUG, so persist
  // the FULL command (and timestamp/flags) next to it. Keeps the .log pure output (the
  // raw-output recovery route still returns it verbatim) while letting the RTK
  // learn/discover sample source recover the exact command. Best-effort: a sidecar
  // write failure never fails the capture.
  try {
    const metaPath = filePath.replace(/\.log$/, ".meta.json");
    fs.writeFileSync(
      metaPath,
      JSON.stringify({
        command: options.command ?? null,
        timestamp: now,
        failure,
        redacted: redaction.redacted,
        bytes: Buffer.byteLength(redaction.text, "utf8"),
      })
    );
  } catch {
    // Sidecar is an optimisation for learn/discover; the .log (with slug) still works.
  }

  return {
    id,
    path: filePath,
    bytes: Buffer.byteLength(redaction.text, "utf8"),
    sha256: crypto.createHash("sha256").update(redaction.text).digest("hex"),
    redacted: redaction.redacted,
  };
}

export function readRtkRawOutput(pointerId: string): string | null {
  const dir = path.join(dataDir(), "rtk", "raw-output");
  if (!fs.existsSync(dir)) return null;
  const entry = fs
    .readdirSync(dir)
    .find((file) => file.endsWith(".log") && file.includes(pointerId));
  if (!entry) return null;
  const fullPath = path.join(dir, entry);
  if (!fullPath.startsWith(dir)) return null;
  return fs.readFileSync(fullPath, "utf8");
}

/** Recover the command for a `.log` from its filename slug (legacy, sidecar-less captures). */
function commandFromSlug(fileName: string): string {
  // `<timestamp>-<slug>-<id>.log` → strip the leading timestamp and the trailing id.
  const slug = fileName
    .replace(/^\d+-/, "")
    .replace(/-[0-9a-f]{24}\.log$/i, "")
    .replace(/\.log$/i, "");
  return slug.replace(/_+/g, " ").trim();
}

/**
 * Read the opt-in RTK raw-output store (`DATA_DIR/rtk/raw-output/*.log`) into
 * `CommandSample[]` for the pure miners `discoverRepeatedNoise()` / `suggestFilter()`.
 *
 * The command comes from the `.meta.json` sidecar when present (exact), else from the
 * filename slug (lossy, for legacy captures). Empty/unreadable entries are skipped.
 * Returns the most-recent-first samples, capped at `opts.limit` (default 500) to bound
 * memory. No throw: a corrupt entry is dropped, not propagated.
 */
export function listRtkCommandSamples(opts: { limit?: number } = {}): CommandSample[] {
  const dir = path.join(dataDir(), "rtk", "raw-output");
  if (!fs.existsSync(dir)) return [];
  const limit = Math.max(1, Math.floor(opts.limit ?? 500));

  let logs: string[];
  try {
    logs = fs.readdirSync(dir).filter((f) => f.endsWith(".log"));
  } catch {
    return [];
  }
  // Newest first: the filename is timestamp-prefixed, so a reverse lexical sort works.
  logs.sort((a, b) => (a < b ? 1 : a > b ? -1 : 0));

  const samples: CommandSample[] = [];
  for (const fileName of logs) {
    if (samples.length >= limit) break;
    const fullPath = path.join(dir, fileName);
    if (!fullPath.startsWith(dir)) continue;
    let output: string;
    try {
      output = fs.readFileSync(fullPath, "utf8");
    } catch {
      continue;
    }
    if (output.trim().length === 0) continue;

    let command = "";
    try {
      const metaRaw = fs.readFileSync(fullPath.replace(/\.log$/, ".meta.json"), "utf8");
      const meta = JSON.parse(metaRaw) as { command?: unknown };
      if (typeof meta.command === "string" && meta.command.trim()) command = meta.command.trim();
    } catch {
      // No/!invalid sidecar → fall back to the filename slug below.
    }
    if (!command) command = commandFromSlug(fileName) || "tool-output";

    samples.push({ command, output });
  }
  return samples;
}