#!/usr/bin/env node
// adam-rollback.mjs — auto-reverts proposals that regressed after apply.
//
// Implements MOSS §3.5: "rollback is mandatory because... a candidate that
// passes trial can still regress live."
//
// For each regressed proposal (detected by adam-ab-measure.mjs):
//   1. Reads the applied proposal from applied/
//   2. Parses the `# Rollback` section for undo commands
//   3. Moves proposal from applied/ to proposals/ with `rolled_back: true`
//   4. Creates a regression nudge for next SessionStart
//   5. Removes the ab-tracking entry (so it doesn't re-trigger)
//
// CLI:
//   adam-rollback.mjs --proposal-id <id> [--home <path>] [--dry-run]
//   adam-rollback.mjs --auto [--home <path>] [--dry-run]
//
//   --auto mode: reads ab-measure output, rolls back all regressed proposals.
//
// Output: JSON object with rollback results per proposal.
// Does NOT execute the undo commands itself — outputs them for the skill to
// execute in-context (safety: undo commands may reference files the script
// can't safely modify).

import { readFileSync, writeFileSync, renameSync, readdirSync, existsSync, mkdirSync } from "node:fs";
import { join, basename } from "node:path";
import { homedir } from "node:os";
import { parseFrontmatter, readJsonlSafe, listJsonlFiles } from "./adam-utils.mjs";

function parseArgs(argv) {
  const args = { home: null, proposalId: null, auto: false, dryRun: false, help: false };
  for (let i = 0; i < argv.length; i++) {
    const a = argv[i];
    if (a === "--home" && i + 1 < argv.length) args.home = argv[++i];
    else if (a === "--proposal-id" && i + 1 < argv.length) args.proposalId = argv[++i];
    else if (a === "--auto") args.auto = true;
    else if (a === "--dry-run") args.dryRun = true;
    else if (a === "--help" || a === "-h") args.help = true;
  }
  return args;
}

function findAppliedProposal(appliedDir, proposalId) {
  if (!existsSync(appliedDir)) return null;
  try {
    const files = readdirSync(appliedDir).filter(n => n.endsWith(".md"));
    for (const f of files) {
      if (f.includes(proposalId)) return join(appliedDir, f);
    }
  } catch { /* skip */ }
  return null;
}

function extractRollbackSection(content) {
  const idx = content.indexOf("\n# Rollback\n");
  if (idx === -1) return null;
  let body = content.slice(idx + "\n# Rollback\n".length);
  const nextSection = body.search(/\n# |\n---/);
  if (nextSection !== -1) body = body.slice(0, nextSection);
  return body.trim() || null;
}

function extractUndoCommands(rollbackSection) {
  if (!rollbackSection) return [];
  const commands = [];
  const lines = rollbackSection.split("\n");
  let inCodeBlock = false;
  let blockLines = [];
  for (const line of lines) {
    if (line.startsWith("```")) {
      if (inCodeBlock) {
        if (blockLines.length) commands.push(blockLines.join("\n"));
        blockLines = [];
      }
      inCodeBlock = !inCodeBlock;
      continue;
    }
    if (inCodeBlock) {
      blockLines.push(line);
    }
  }
  return commands;
}

export function planRollback(appliedDir, proposalId) {
  const path = findAppliedProposal(appliedDir, proposalId);
  if (!path) return { status: "not_found", proposal_id: proposalId };

  const content = readFileSync(path, "utf8");
  const fm = parseFrontmatter(content);
  const rollbackSection = extractRollbackSection(content);
  const undoCommands = extractUndoCommands(rollbackSection);

  return {
    status: "planned",
    proposal_id: proposalId,
    applied_path: path,
    type: fm.type || "unknown",
    target: fm.target || null,
    target_skill: fm.target_skill || null,
    undo_commands: undoCommands,
    has_rollback_section: !!rollbackSection,
  };
}

export function executeRollback(plan, adamRoot, opts = {}) {
  const dryRun = opts.dryRun || false;
  const proposalsDir = join(adamRoot, "proposals");
  const nudgesPath = join(adamRoot, "active-nudges.json");
  const now = Date.now();

  if (plan.status !== "planned") return { ...plan, action: "skipped" };

  const result = {
    proposal_id: plan.proposal_id,
    type: plan.type,
    target: plan.target,
    undo_commands: plan.undo_commands,
    actions: [],
  };

  if (dryRun) {
    result.actions.push("dry_run: would move applied → proposals");
    if (plan.undo_commands.length) {
      result.actions.push(`dry_run: would output ${plan.undo_commands.length} undo command(s)`);
    }
    result.actions.push("dry_run: would create regression nudge");
    result.status = "dry_run";
    return result;
  }

  mkdirSync(proposalsDir, { recursive: true });
  const destName = `${basename(plan.applied_path).replace(/\.md$/, "")}-rollback.md`;
  const destPath = join(proposalsDir, destName);

  let content = readFileSync(plan.applied_path, "utf8");
  const rollbackMeta = `\nrolled_back: true\nrolled_back_at: "${new Date(now).toISOString()}"`;
  content = content.replace(/^(---\n[\s\S]*?)(---)/m, `$1${rollbackMeta}\n$2`);

  try {
    writeFileSync(destPath, content);
    renameSync(plan.applied_path, plan.applied_path + ".rolled-back");
    result.actions.push(`moved ${plan.applied_path} → ${destPath}`);
  } catch (e) {
    result.status = "move_failed";
    result.error = e.message;
    return result;
  }

  try {
    let nudges = [];
    if (existsSync(nudgesPath)) {
      try { nudges = JSON.parse(readFileSync(nudgesPath, "utf8")); } catch { nudges = []; }
    }
    nudges.push({
      kind: "regression_rollback",
      message: `adam: rolled back "${plan.proposal_id}" (type: ${plan.type}) — regression detected in A/B measurement. Review with /reflect.`,
      created_at: now,
      expires_at_ts: now + 7 * 86400000,
      max_displays: 3,
      displays_used: 0,
      source_proposal: plan.proposal_id,
    });
    writeFileSync(nudgesPath, JSON.stringify(nudges, null, 2));
    result.actions.push("regression nudge created");
  } catch (e) {
    result.actions.push(`nudge failed: ${e.message}`);
  }

  result.status = "rolled_back";
  return result;
}

async function main() {
  const args = parseArgs(process.argv.slice(2));
  if (args.help) {
    process.stdout.write(
      "usage: adam-rollback.mjs --proposal-id <id> [--home <path>] [--dry-run]\n" +
      "       adam-rollback.mjs --auto [--home <path>] [--dry-run]\n"
    );
    process.exit(0);
  }

  const claudeHome = args.home || join(homedir(), ".claude");
  const adamRoot = join(claudeHome, "adam");
  const appliedDir = join(adamRoot, "applied");

  try {
    const results = [];

    if (args.auto) {
      const abPath = join(adamRoot, "ab-tracking.jsonl");
      const entries = readJsonlSafe(abPath);
      const { computeDeltas } = await import("./adam-ab-measure.mjs");
      const sources = [join(adamRoot, "journal.jsonl"), ...listJsonlFiles(join(adamRoot, "journal"))];
      const journalAll = [];
      for (const p of sources) for (const e of readJsonlSafe(p)) journalAll.push(e);
      const deltas = computeDeltas(entries, journalAll);
      const regressed = deltas.filter(d => d.status === "regressed");

      for (const d of regressed) {
        const plan = planRollback(appliedDir, d.proposal_id);
        const result = executeRollback(plan, adamRoot, { dryRun: args.dryRun });
        results.push(result);
      }
    } else if (args.proposalId) {
      const plan = planRollback(appliedDir, args.proposalId);
      const result = executeRollback(plan, adamRoot, { dryRun: args.dryRun });
      results.push(result);
    } else {
      process.stderr.write("adam-rollback: specify --proposal-id or --auto\n");
      process.exit(1);
    }

    process.stdout.write(JSON.stringify({ rollbacks: results }) + "\n");
    process.exit(0);
  } catch (e) {
    process.stderr.write(`adam-rollback error: ${e.message}\n`);
    process.exit(1);
  }
}

if (import.meta.url === `file://${process.argv[1]}`) {
  main();
}