import { createHash } from "node:crypto";
import {
  appendFileSync,
  chmodSync,
  existsSync,
  mkdirSync,
  readFileSync,
  renameSync,
  unlinkSync,
  writeFileSync,
} from "node:fs";
import { join } from "node:path";
import type { PromptPermissionDetails } from "../service.js";
import type { AutoReviewAnalysisConfig, AutoReviewConfig } from "./config.js";
import type { ReviewAssessment } from "./verdict.js";

const DIRECTORY_MODE = 0o700;
const FILE_MODE = 0o600;
const MAX_PATTERN_LENGTH = 240;

interface LedgerState {
  version: 1;
  completedSequence: number;
  lastAnalyzedSequence: number;
  proposalSequence: number;
  analysisPending: boolean;
}

export interface AutoReviewLedgerRecord {
  version: 1;
  sequence: number;
  timestamp: string;
  requestId: string;
  source: string;
  agentName: string;
  surface: string;
  toolName?: string;
  normalizedPattern: string;
  fingerprint: string;
  outcome: "allow" | "deny";
  riskLevel: ReviewAssessment["riskLevel"];
  userAuthorization: ReviewAssessment["userAuthorization"];
  authorizationDependent: boolean;
  policyRevision: string;
  policyHash: string;
  provider: string;
  model: string;
}

export interface AutoReviewAnalysisBatch {
  fromSequence: number;
  toSequence: number;
  records: AutoReviewLedgerRecord[];
  policyHash: string;
}

export interface StoredAnalysisProposal {
  version: 1;
  proposalId: string;
  createdAt: string;
  fromSequence: number;
  toSequence: number;
  policyHash: string;
  proposal: unknown;
}

function initialState(): LedgerState {
  return {
    version: 1,
    completedSequence: 0,
    lastAnalyzedSequence: 0,
    proposalSequence: 0,
    analysisPending: false,
  };
}

function hash(value: unknown): string {
  return createHash("sha256").update(JSON.stringify(value)).digest("hex");
}

function bounded(value: string): string {
  return value.length <= MAX_PATTERN_LENGTH
    ? value
    : `${value.slice(0, MAX_PATTERN_LENGTH - 1)}…`;
}

const SAFE_SUBCOMMAND_COMMANDS = new Set([
  "bun", "cargo", "docker", "git", "go", "kubectl", "npm", "pnpm",
  "sudo", "systemctl", "yarn",
]);
const SAFE_PATH_PREFIXES = new Set([
  "app", "apps", "config", "docs", "etc", "lib", "opt", "packages",
  "private", "src", "test", "tests", "tmp", "Users", "var", "workspace",
  "workspaces",
]);

function normalizedExecutable(value: string): string {
  const executable = value.replace(/\\/g, "/").split("/").filter(Boolean).at(-1) ?? "";
  return /^[A-Za-z0-9._+-]{1,64}$/u.test(executable) ? executable : "<command>";
}

function normalizeCommand(command: string): string {
  const words = command.trim().replace(/\s+/g, " ").split(" ").filter(Boolean);
  if (words.length === 0) return "<empty-command>";
  const executable = normalizedExecutable(words[0]!);
  const subcommand = words[1];
  if (
    subcommand !== undefined &&
    SAFE_SUBCOMMAND_COMMANDS.has(executable) &&
    /^[A-Za-z0-9._+-]{1,64}$/u.test(subcommand)
  ) {
    return bounded(`${executable} ${subcommand} *`);
  }
  return bounded(words.length === 1 ? executable : `${executable} *`);
}

function normalizePath(value: string): string {
  const normalized = value.trim().replace(/\\/g, "/");
  if (normalized.length === 0) return "<empty-path>";
  if (normalized === "~" || normalized.startsWith("~/")) return "~/*";
  const absolute = normalized.startsWith("/");
  const segments = normalized.split("/").filter(Boolean);
  const first = segments[0];
  if (first && SAFE_PATH_PREFIXES.has(first)) {
    return bounded(`${absolute ? "/" : ""}${first}/*`);
  }
  if (!absolute && segments.length === 1) {
    const extension = normalized.match(/\.[A-Za-z0-9]{1,10}$/u)?.[0];
    if (extension) return `*${extension.toLowerCase()}`;
  }
  return absolute ? "/<path>/*" : "<relative>/*";
}

function derivePattern(details: PromptPermissionDetails): string {
  if (typeof details.command === "string") return normalizeCommand(details.command);
  if (typeof details.path === "string") return normalizePath(details.path);
  const values = details.accessIntent?.matchValues;
  if (Array.isArray(values) && typeof values[0] === "string") return normalizePath(values[0]);
  if (details.toolName) return bounded(details.toolName);
  return bounded(details.surface ?? "unknown");
}

function readJson<T>(path: string): T | undefined {
  if (!existsSync(path)) return undefined;
  try {
    return JSON.parse(readFileSync(path, "utf8")) as T;
  } catch {
    return undefined;
  }
}

export class AutoReviewLedger {
  private readonly ledgerDir: string;
  private readonly proposalsDir: string;
  private readonly statePath: string;
  private readonly decisionsPath: string;
  private state: LedgerState;

  constructor(rootDir: string) {
    this.ledgerDir = join(rootDir, "ledger");
    this.proposalsDir = join(rootDir, "proposals");
    this.statePath = join(rootDir, "state.json");
    this.decisionsPath = join(this.ledgerDir, "decisions.jsonl");
    for (const dir of [rootDir, this.ledgerDir, this.proposalsDir]) {
      mkdirSync(dir, { recursive: true, mode: DIRECTORY_MODE });
      try { chmodSync(dir, DIRECTORY_MODE); } catch { /* best effort on non-POSIX */ }
    }
    this.state = readJson<LedgerState>(this.statePath) ?? initialState();
    this.persistState();
  }

  recordDecision(event: {
    details: PromptPermissionDetails;
    assessment: ReviewAssessment;
    policyRevision: string;
    config: AutoReviewConfig;
    analysis: AutoReviewAnalysisConfig;
  }): AutoReviewLedgerRecord {
    const sequence = this.state.completedSequence + 1;
    const pattern = derivePattern(event.details);
    const surface = bounded(event.details.accessIntent?.surface ?? event.details.surface ?? "unknown");
    const toolName = event.details.toolName ? bounded(event.details.toolName) : undefined;
    const record: AutoReviewLedgerRecord = {
      version: 1,
      sequence,
      timestamp: new Date().toISOString(),
      requestId: bounded(event.details.requestId),
      source: bounded(event.details.source),
      agentName: bounded(event.details.agentName ?? "main"),
      surface,
      ...(toolName ? { toolName } : {}),
      normalizedPattern: pattern,
      fingerprint: hash({ surface, toolName, pattern }),
      outcome: event.assessment.outcome,
      riskLevel: event.assessment.riskLevel,
      userAuthorization: event.assessment.userAuthorization,
      authorizationDependent: event.assessment.userAuthorization !== "unknown",
      policyRevision: bounded(event.policyRevision),
      policyHash: hash(event.config),
      provider: bounded(event.config.provider),
      model: bounded(event.config.model),
    };
    appendFileSync(this.decisionsPath, `${JSON.stringify(record)}\n`, {
      encoding: "utf8",
      mode: FILE_MODE,
    });
    try { chmodSync(this.decisionsPath, FILE_MODE); } catch { /* best effort */ }

    this.state.completedSequence = sequence;
    if (
      event.analysis.enabled &&
      sequence - this.state.lastAnalyzedSequence >= event.analysis.threshold
    ) {
      this.state.analysisPending = true;
    }
    this.persistState();
    return record;
  }

  hasPendingAnalysis(): boolean {
    return this.state.analysisPending;
  }

  prepareBatch(config: AutoReviewAnalysisConfig): AutoReviewAnalysisBatch | undefined {
    const records = this.readRecords();
    const fromSequence = this.state.lastAnalyzedSequence + 1;
    const eligible = records.filter((record) => record.sequence >= fromSequence);
    if (eligible.length < config.threshold) return undefined;
    const selected = eligible.slice(0, config.threshold);
    const policyHash = selected[0]?.policyHash ?? "";
    return {
      fromSequence,
      toSequence: selected.at(-1)!.sequence,
      records: selected,
      policyHash,
    };
  }

  saveProposal(batch: AutoReviewAnalysisBatch, proposal: unknown): StoredAnalysisProposal {
    const next = this.state.proposalSequence + 1;
    const proposalId = `proposal-${String(next).padStart(6, "0")}`;
    const stored: StoredAnalysisProposal = {
      version: 1,
      proposalId,
      createdAt: new Date().toISOString(),
      fromSequence: batch.fromSequence,
      toSequence: batch.toSequence,
      policyHash: batch.policyHash,
      proposal,
    };
    this.writeAtomic(join(this.proposalsDir, `${proposalId}.json`), stored);
    this.state.proposalSequence = next;
    this.state.lastAnalyzedSequence = batch.toSequence;
    this.state.analysisPending =
      this.state.completedSequence - this.state.lastAnalyzedSequence > 0;
    this.persistState();
    return stored;
  }

  compact(config: AutoReviewAnalysisConfig): void {
    const keep = Math.max(config.threshold, config.threshold * config.retainAnalyzedBatches);
    const records = this.readRecords();
    const retained = records.slice(-keep);
    const content = retained.map((record) => JSON.stringify(record)).join("\n");
    this.writeAtomic(this.decisionsPath, content ? `${content}\n` : "");
  }

  private readRecords(): AutoReviewLedgerRecord[] {
    if (!existsSync(this.decisionsPath)) return [];
    return readFileSync(this.decisionsPath, "utf8")
      .split("\n")
      .filter(Boolean)
      .flatMap((line) => {
        try { return [JSON.parse(line) as AutoReviewLedgerRecord]; }
        catch { return []; }
      })
      .sort((left, right) => left.sequence - right.sequence);
  }

  private persistState(): void {
    this.writeAtomic(this.statePath, this.state);
  }

  private writeAtomic(path: string, value: unknown): void {
    const temporaryPath = `${path}.${process.pid}.${Date.now()}.tmp`;
    const content = typeof value === "string" ? value : `${JSON.stringify(value, null, 2)}\n`;
    writeFileSync(temporaryPath, content, { encoding: "utf8", mode: FILE_MODE, flag: "wx" });
    try {
      renameSync(temporaryPath, path);
      try { chmodSync(path, FILE_MODE); } catch { /* best effort */ }
    } catch (error) {
      try { unlinkSync(temporaryPath); } catch { /* best effort */ }
      throw error;
    }
  }
}