import { existsSync, mkdirSync, readFileSync, writeFileSync, unlinkSync, copyFileSync, renameSync } from "fs";
import { basename, dirname } from "path";
import {
  toRepoRelativePath, TICKET_SUBDIR, TICKET_LIST_FILENAME,
  parseFrontMatter, findFileRecursively, detectConsumerTicketDir, makePath
 , CliOpts } from "./cli-utils.js";
import { readTicketIndexJson, syncActiveTicketId, writeTicketIndexJson } from "./cli-ticket-index.js";
import { collectTicketMarkdownFiles, rebuildTicketIndexFromTopicFilesIfNeeded } from "./cli-ticket-parser.js";
import { splitTicketDocMetaSection } from "./cli-ticket-docmeta.js";
import { writeTicketDocument } from "./cli-ticket-document.js";

// ─── Summary Extraction ─────────────────────────────────────────────────────

/**
 * Extracts a concise summary from ticket body content for legacy tickets.
 * Strategy: combine title + scope/background + top tasks into 1-2 lines.
 * Handles 3 legacy formats:
 *   - Old format: 🎯 Scope Bounds, 📁 Files to Modify
 *   - Mid format: ## Background, ## Analysis, ## Tasks
 *   - New format: ## Target Module, ## APC (already has summary usually)
 */
export function extractSummary(meta, content) {
  const title = meta.title || "";
  const lines = content.split("\n");

  // Collect section contents by known header patterns
  const sections: Record<string, any> = {};
  let currentSection = null;
  for (const line of lines) {
    const trimmed = line.trim();
    // Match ## headers (with or without emoji prefix)
    const headerMatch = trimmed.match(/^##\s+(?:[\u{1F3AF}\u{1F4C1}\u{1F3D7}\u{1F6D1}\u{1F504}\u{2705}\s]*)?(.+)$/u);
    if (headerMatch) {
      currentSection = headerMatch[1].trim().toLowerCase();
      sections[currentSection] = [];
      continue;
    }
    // Match # title
    if (trimmed.startsWith("# ") && !currentSection) {
      continue; // skip title line
    }
    if (currentSection && trimmed && !trimmed.startsWith(">") && !trimmed.startsWith("<!--")) {
      sections[currentSection].push(trimmed);
    }
  }

  // Priority: scope/background > analysis > tasks
  let contextLine = "";

  // Try scope bounds (old format)
  const scopeKeys = Object.keys(sections).filter(k =>
    k.includes("scope") || k.includes("target") || k.includes("background")
  );
  for (const key of scopeKeys) {
    const scopeLines = (sections[key] || [])
      .filter(l => !l.startsWith("- **Context") && !l.startsWith("["))
      .map(l => l.replace(/^[-*]\s*\*\*[^*]+:\*\*\s*/, "").replace(/`/g, ""))
      .filter(l => l.length > 5 && l.length < 200);
    if (scopeLines.length > 0) {
      contextLine = scopeLines[0];
      break;
    }
  }

  // Try analysis section if no scope found
  if (!contextLine) {
    const analysisKeys = Object.keys(sections).filter(k =>
      k.includes("analysis") || k.includes("design") || k.includes("decisions")
    );
    for (const key of analysisKeys) {
      const analysisLines = (sections[key] || [])
        .filter(l => l.length > 10 && l.length < 200 && !l.startsWith("|"))
        .map(l => l.replace(/^[-*]\s*/, ""));
      if (analysisLines.length > 0) {
        contextLine = analysisLines[0];
        break;
      }
    }
  }

  // Collect task summary (first 3 task items)
  const taskKeys = Object.keys(sections).filter(k =>
    k.includes("task") || k.includes("phased") || k.includes("execution steps")
  );
  let taskItems = [];
  for (const key of taskKeys) {
    taskItems = (sections[key] || [])
      .filter(l => /^-\s*\[[ x]\]/.test(l) || /^\d+\.\s*\[/.test(l))
      .map(l => l.replace(/^[-*\d.]+\s*\[[ x]\]\s*/, "").replace(/\[Phase\s*\d+[>]\s*/i, "").replace(/]/g, "").trim())
      .filter(l => l.length > 3)
      .slice(0, 3);
    if (taskItems.length > 0) break;
  }

  // Build summary
  const parts = [];
  if (contextLine) {
    parts.push(contextLine.length > 120 ? contextLine.substring(0, 117) + "..." : contextLine);
  }
  if (taskItems.length > 0) {
    parts.push(`주요 작업: ${taskItems.join(", ")}`);
  }

  if (parts.length === 0) {
    // Fallback: use title itself as summary
    return title || null;
  }

  const summary = parts.join(". ").substring(0, 300);
  return summary || null;
}

// ─── CAUTION Block / Target Module Injection ─────────────────────────────────

const CAUTION_BLOCK = `> **[CAUTION FOR AI AGENTS]**
> 1. Restrict all analysis, file creation, and modifications to the declared **Target Module** below.
> 2. Read the files listed in **Context Files** before doing ANY code generation.
> 3. DO NOT leak configuration, logic, or dependencies from other modules.

## Target Module
- **Target:** [Fill in the target module/submodule path]
- **Context Files:** [List architecture docs or key files to read first]`;

/**
 * Ensures the CAUTION block and Target Module section exist after the title.
 * Returns modified content or null if no change needed.
 */
export function ensureCautionBlock(content) {
  // Already has Target Module or the new-format CAUTION
  if (content.includes("## Target Module")) return null;

  // Also skip if it already has the old-format scope bounds (don't duplicate)
  const hasOldScope = /## [\u{1F3AF}]?\s*Scope Bounds/u.test(content);
  if (hasOldScope) return null;

  // Find the # title line and insert after it
  const titleMatch = content.match(/^(# .+)\n/m);
  if (!titleMatch) return null;

  const titleEnd = content.indexOf(titleMatch[0]) + titleMatch[0].length;
  const before = content.substring(0, titleEnd);
  let after = content.substring(titleEnd);

  // Skip if CAUTION already exists (old variant)
  if (after.includes("[CAUTION FOR AI AGENTS]")) return null;

  return before + "\n" + CAUTION_BLOCK + "\n" + after;
}

// ─── Main Migration ─────────────────────────────────────────────────────────

export function performUpgradeMigration(cwd, opts: CliOpts = {}) {
  const root = detectConsumerTicketDir(cwd, { createIfMissing: true });
  
  const files = collectTicketMarkdownFiles(root).filter(p => {
    const base = basename(p);
    return base !== "LATEST.md" && base !== TICKET_LIST_FILENAME && base !== "ACTIVE_TICKET.md";
  });

  console.log(`[UPGRADE] Scanning ${files.length} tickets for V2 migration...`);

  let upgraded = 0;
  let summaryAdded = 0;
  let cautionAdded = 0;

  for (const abs of files) {
    const rel = toRepoRelativePath(cwd, abs);
    const body = readFileSync(abs, "utf8");
    const { meta, content } = parseFrontMatter(body);
    let dirty = false;
    let modifiedContent = content;

    const isAlreadyInArchive = rel.includes("/archive/");

    // 1. Summary enrichment for legacy tickets
    if (!meta.summary) {
      const generated = extractSummary(meta, content);
      if (generated) {
        meta.summary = generated;
        dirty = true;
        summaryAdded++;
      }
    }

    // 2. CAUTION / Target Module injection
    const cautionResult = ensureCautionBlock(modifiedContent);
    if (cautionResult !== null) {
      modifiedContent = cautionResult;
      dirty = true;
      cautionAdded++;
    }

    // 3. Archive placement fix (existing logic)
    if (meta.status === "archived" && !isAlreadyInArchive && !opts.dryRun) {
      const finalAbs = moveFileToArchive(cwd, abs, meta.group || basename(dirname(abs)));
      const ticketDocMeta = splitTicketDocMetaSection(modifiedContent);
      writeTicketDocument(finalAbs, { meta, content: ticketDocMeta.body, docmeta: ticketDocMeta.docmeta });
      upgraded++;
      console.log(`[OK] Upgraded + archived: ${toRepoRelativePath(cwd, finalAbs)}`);
      continue;
    }

    if (dirty) {
      if (opts.dryRun) {
        const changes = [];
        if (!parseFrontMatter(body).meta.summary && meta.summary) changes.push("summary");
        if (cautionResult !== null) changes.push("caution+targetModule");
        console.log(`[DRY-RUN] Would upgrade: ${rel} (+${changes.join(", ")})`);
      } else {
        const ticketDocMeta = splitTicketDocMetaSection(modifiedContent);
        writeTicketDocument(abs, { meta, content: ticketDocMeta.body, docmeta: ticketDocMeta.docmeta });
        upgraded++;
      }
    }
  }

  console.log(`[UPGRADE] Results: ${upgraded} upgraded, ${summaryAdded} summaries added, ${cautionAdded} caution blocks added`);

  if (!opts.dryRun) {
    rebuildTicketIndexFromTopicFilesIfNeeded(cwd, { ...opts, force: true });
    syncActiveTicketId(cwd);
  }

  return upgraded;
}

// #727: performDefragmentation 제거 — 홈 uuid 스토어의 티켓을 meta.submodule 기준으로
// 서브모듈 .deuk/tickets 로 역이동(cwd write)시켜 홈 일원화(#622)를 되돌리던 코드였다.
// normalizeTicketPaths 주석('티켓은 홈에 산다, cwd로 끌어내면 안 됨')과 정면 모순이라
// 함수와 호출(upgrade 흐름)을 통째로 제거. 티켓은 홈에만 산다.

// ─── Utilities ──────────────────────────────────────────────────────────────

export function moveFileToArchive(cwd, abs, group) {
  const ticketDir = detectConsumerTicketDir(cwd);
  const archiveBase = makePath(ticketDir, "archive");
  const targetSubDir = (basename(ticketDir) === TICKET_SUBDIR || !group) ? "sub" : group;
  const targetDir = makePath(archiveBase, targetSubDir);
  mkdirSync(targetDir, { recursive: true });
  const finalAbs = makePath(targetDir, basename(abs));
  if (finalAbs !== abs) {
    if (existsSync(finalAbs)) {
      unlinkSync(abs);
    } else {
      writeFileSync(finalAbs, readFileSync(abs, "utf8"), "utf8");
      unlinkSync(abs);
    }
  }
  return finalAbs;
}

export function normalizeTicketPaths(cwd, opts: CliOpts = {}) {
  const index = readTicketIndexJson(cwd);
  const ticketDir = detectConsumerTicketDir(cwd);
  const entries = index.entries || [];
  let modified = false;

  for (const entry of entries) {
    if (!entry.path) continue;

    // #622/#623: 티켓 .md는 cwd(워크스페이스 git 트리)가 아니라 홈 ticketDir에 산다.
    // 정상 위치는 makePath(ticketDir, entry.path)이다. entry.path를 cwd 기준으로 해석해
    // 그쪽으로 옮기면, 홈에 멀쩡히 있던 .md를 워크스페이스로 끌어내 홈 디렉토리를 비우고
    // (그 순간 rebuild 스캔이 entries=0을 보고 active claim을 고아로 오인해 삭제한다).
    // 따라서 파일이 이미 ticketDir 하위에 있으면 그게 올바른 위치이므로 이동하지 않는다.
    const canonicalAbs = makePath(ticketDir, entry.path);
    if (existsSync(canonicalAbs)) continue;

    const currentAbs = makePath(cwd, entry.path);
    if (!existsSync(currentAbs)) {
      const fileName = basename(entry.path);
      const found = findFileRecursively(ticketDir, fileName);
      if (found) {
        // 발견된 파일이 이미 홈 ticketDir 하위면 정상 위치 — 워크스페이스로 옮기지 않는다.
        const destAbs = canonicalAbs;
        if (found !== destAbs) {
          mkdirSync(dirname(destAbs), { recursive: true });
          try {
            renameSync(found, destAbs);
          } catch {
            copyFileSync(found, destAbs);
            unlinkSync(found);
          }
          modified = true;
        }
      }
    }
  }

  if (modified) {
    index.updatedAt = new Date().toISOString();
    writeTicketIndexJson(cwd, index);
    if (!opts.silent) console.log(`[NORMALIZE] Corrected stale paths in ${basename(cwd)}/INDEX.json`);
  }
  return modified;
}