import { spawn } from "node:child_process";
import fs from "node:fs/promises";
import os from "node:os";
import path from "node:path";

import YAML from "yaml";

import type { MoltbotConfig } from "../config/config.js";
import { resolveStateDir } from "../config/paths.js";
import { resolveAgentWorkspaceDir } from "../agents/agent-scope.js";
import { createSubsystemLogger } from "../logging/subsystem.js";
import {
  listSessionFilesForAgent,
  buildSessionEntry,
  type SessionFileEntry,
} from "./session-files.js";
import { requireNodeSqlite } from "./sqlite.js";
import type {
  MemoryProviderStatus,
  MemorySearchManager,
  MemorySearchResult,
  MemorySource,
  MemorySyncProgressUpdate,
} from "./types.js";
import type { ResolvedMemoryBackendConfig, ResolvedQmdConfig } from "./backend-config.js";

const log = createSubsystemLogger("memory");

const SNIPPET_HEADER_RE = /@@\s*-([0-9]+),([0-9]+)/;

type QmdQueryResult = {
  docid?: string;
  score?: number;
  file?: string;
  snippet?: string;
  body?: string;
};

type CollectionRoot = {
  path: string;
  kind: MemorySource;
};

type SessionExporterConfig = {
  dir: string;
  retentionMs?: number;
  collectionName: string;
};

export class QmdMemoryManager implements MemorySearchManager {
  static async create(params: {
    cfg: MoltbotConfig;
    agentId: string;
    resolved: ResolvedMemoryBackendConfig;
  }): Promise<QmdMemoryManager | null> {
    const resolved = params.resolved.qmd;
    if (!resolved) return null;
    const manager = new QmdMemoryManager({ cfg: params.cfg, agentId: params.agentId, resolved });
    await manager.initialize();
    return manager;
  }

  private readonly cfg: MoltbotConfig;
  private readonly agentId: string;
  private readonly qmd: ResolvedQmdConfig;
  private readonly workspaceDir: string;
  private readonly stateDir: string;
  private readonly agentStateDir: string;
  private readonly qmdDir: string;
  private readonly cacheDir: string;
  private readonly configDir: string;
  private readonly xdgConfigHome: string;
  private readonly xdgCacheHome: string;
  private readonly collectionsFile: string;
  private readonly indexPath: string;
  private readonly env: NodeJS.ProcessEnv;
  private readonly collectionRoots = new Map<string, CollectionRoot>();
  private readonly sources = new Set<MemorySource>();
  private readonly docPathCache = new Map<
    string,
    { rel: string; abs: string; source: MemorySource }
  >();
  private readonly sessionExporter: SessionExporterConfig | null;
  private updateTimer: NodeJS.Timeout | null = null;
  private pendingUpdate: Promise<void> | null = null;
  private closed = false;
  private db: import("node:sqlite").DatabaseSync | null = null;
  private lastUpdateAt: number | null = null;

  private constructor(params: {
    cfg: MoltbotConfig;
    agentId: string;
    resolved: ResolvedQmdConfig;
  }) {
    this.cfg = params.cfg;
    this.agentId = params.agentId;
    this.qmd = params.resolved;
    this.workspaceDir = resolveAgentWorkspaceDir(params.cfg, params.agentId);
    this.stateDir = resolveStateDir(process.env, os.homedir);
    this.agentStateDir = path.join(this.stateDir, "agents", this.agentId);
    this.qmdDir = path.join(this.agentStateDir, "qmd");
    this.cacheDir = path.join(this.qmdDir, "cache");
    this.configDir = path.join(this.qmdDir, "config");
    this.xdgConfigHome = path.join(this.qmdDir, "xdg-config");
    this.xdgCacheHome = path.join(this.qmdDir, "xdg-cache");
    this.collectionsFile = path.join(this.configDir, "index.yml");
    this.indexPath = path.join(this.cacheDir, "index.sqlite");
    this.env = {
      ...process.env,
      QMD_CONFIG_DIR: this.configDir,
      XDG_CONFIG_HOME: this.xdgConfigHome,
      XDG_CACHE_HOME: this.xdgCacheHome,
      INDEX_PATH: this.indexPath,
      NO_COLOR: "1",
    };
    this.sessionExporter = this.qmd.sessions.enabled
      ? {
          dir: this.qmd.sessions.exportDir ?? path.join(this.qmdDir, "sessions"),
          retentionMs: this.qmd.sessions.retentionDays
            ? this.qmd.sessions.retentionDays * 24 * 60 * 60 * 1000
            : undefined,
          collectionName: this.pickSessionCollectionName(),
        }
      : null;
    if (this.sessionExporter) {
      this.qmd.collections = [
        ...this.qmd.collections,
        {
          name: this.sessionExporter.collectionName,
          path: this.sessionExporter.dir,
          pattern: "**/*.md",
          kind: "sessions",
        },
      ];
    }
  }

  private async initialize(): Promise<void> {
    await fs.mkdir(this.cacheDir, { recursive: true });
    await fs.mkdir(this.configDir, { recursive: true });
    await fs.mkdir(this.xdgConfigHome, { recursive: true });
    await fs.mkdir(this.xdgCacheHome, { recursive: true });

    this.bootstrapCollections();
    await this.writeCollectionsConfig();

    if (this.qmd.update.onBoot) {
      await this.runUpdate("boot", true);
    }
    if (this.qmd.update.intervalMs > 0) {
      this.updateTimer = setInterval(() => {
        void this.runUpdate("interval").catch((err) => {
          log.warn(`qmd update failed (${String(err)})`);
        });
      }, this.qmd.update.intervalMs);
    }
  }

  private bootstrapCollections(): void {
    this.collectionRoots.clear();
    this.sources.clear();
    for (const collection of this.qmd.collections) {
      const kind: MemorySource = collection.kind === "sessions" ? "sessions" : "memory";
      this.collectionRoots.set(collection.name, { path: collection.path, kind });
      this.sources.add(kind);
    }
  }

  private async writeCollectionsConfig(): Promise<void> {
    const collections: Record<string, { path: string; pattern: string }> = {};
    for (const collection of this.qmd.collections) {
      collections[collection.name] = {
        path: collection.path,
        pattern: collection.pattern,
      };
    }
    const yaml = YAML.stringify({ collections }, { indent: 2, lineWidth: 0 });
    await fs.writeFile(this.collectionsFile, yaml, "utf-8");
  }

  async search(
    query: string,
    opts?: { maxResults?: number; minScore?: number; sessionKey?: string },
  ): Promise<MemorySearchResult[]> {
    if (!this.isScopeAllowed(opts?.sessionKey)) return [];
    const trimmed = query.trim();
    if (!trimmed) return [];
    await this.pendingUpdate?.catch(() => undefined);
    const limit = Math.min(
      this.qmd.limits.maxResults,
      opts?.maxResults ?? this.qmd.limits.maxResults,
    );
    const args = ["query", trimmed, "--json", "-n", String(limit)];
    let stdout: string;
    try {
      const result = await this.runQmd(args, { timeoutMs: this.qmd.limits.timeoutMs });
      stdout = result.stdout;
    } catch (err) {
      log.warn(`qmd query failed: ${String(err)}`);
      throw err instanceof Error ? err : new Error(String(err));
    }
    let parsed: QmdQueryResult[] = [];
    try {
      parsed = JSON.parse(stdout);
    } catch (err) {
      const message = err instanceof Error ? err.message : String(err);
      log.warn(`qmd query returned invalid JSON: ${message}`);
      throw new Error(`qmd query returned invalid JSON: ${message}`);
    }
    const results: MemorySearchResult[] = [];
    for (const entry of parsed) {
      const doc = await this.resolveDocLocation(entry.docid);
      if (!doc) continue;
      const snippet = entry.snippet?.slice(0, this.qmd.limits.maxSnippetChars) ?? "";
      const lines = this.extractSnippetLines(snippet);
      const score = typeof entry.score === "number" ? entry.score : 0;
      const minScore = opts?.minScore ?? 0;
      if (score < minScore) continue;
      results.push({
        path: doc.rel,
        startLine: lines.startLine,
        endLine: lines.endLine,
        score,
        snippet,
        source: doc.source,
      });
    }
    return results.slice(0, limit);
  }

  async sync(params?: {
    reason?: string;
    force?: boolean;
    progress?: (update: MemorySyncProgressUpdate) => void;
  }): Promise<void> {
    if (params?.progress) {
      params.progress({ completed: 0, total: 1, label: "Updating QMD index…" });
    }
    await this.runUpdate(params?.reason ?? "manual", params?.force);
    if (params?.progress) {
      params.progress({ completed: 1, total: 1, label: "QMD index updated" });
    }
  }

  async readFile(params: {
    relPath: string;
    from?: number;
    lines?: number;
  }): Promise<{ text: string; path: string }> {
    const relPath = params.relPath?.trim();
    if (!relPath) throw new Error("path required");
    const absPath = this.resolveReadPath(relPath);
    const content = await fs.readFile(absPath, "utf-8");
    if (!params.from && !params.lines) {
      return { text: content, path: relPath };
    }
    const lines = content.split("\n");
    const start = Math.max(1, params.from ?? 1);
    const count = Math.max(1, params.lines ?? lines.length);
    const slice = lines.slice(start - 1, start - 1 + count);
    return { text: slice.join("\n"), path: relPath };
  }

  status(): MemoryProviderStatus {
    const counts = this.readCounts();
    return {
      backend: "qmd",
      provider: "qmd",
      model: "qmd",
      requestedProvider: "qmd",
      files: counts.totalDocuments,
      chunks: counts.totalDocuments,
      dirty: false,
      workspaceDir: this.workspaceDir,
      dbPath: this.indexPath,
      sources: Array.from(this.sources),
      sourceCounts: counts.sourceCounts,
      vector: { enabled: true, available: true },
      batch: {
        enabled: false,
        failures: 0,
        limit: 0,
        wait: false,
        concurrency: 0,
        pollIntervalMs: 0,
        timeoutMs: 0,
      },
      custom: {
        qmd: {
          collections: this.qmd.collections.length,
          lastUpdateAt: this.lastUpdateAt,
        },
      },
    };
  }

  async probeVectorAvailability(): Promise<boolean> {
    return true;
  }

  async close(): Promise<void> {
    if (this.closed) return;
    this.closed = true;
    if (this.updateTimer) {
      clearInterval(this.updateTimer);
      this.updateTimer = null;
    }
    await this.pendingUpdate?.catch(() => undefined);
    if (this.db) {
      this.db.close();
      this.db = null;
    }
  }

  private async runUpdate(reason: string, force?: boolean): Promise<void> {
    if (this.pendingUpdate && !force) return this.pendingUpdate;
    const run = async () => {
      if (this.sessionExporter) {
        await this.exportSessions();
      }
      await this.runQmd(["update"], { timeoutMs: 120_000 });
      try {
        await this.runQmd(["embed"], { timeoutMs: 120_000 });
      } catch (err) {
        log.warn(`qmd embed failed (${reason}): ${String(err)}`);
      }
      this.lastUpdateAt = Date.now();
      this.docPathCache.clear();
    };
    this.pendingUpdate = run().finally(() => {
      this.pendingUpdate = null;
    });
    await this.pendingUpdate;
  }

  private async runQmd(
    args: string[],
    opts?: { timeoutMs?: number },
  ): Promise<{ stdout: string; stderr: string }> {
    return await new Promise((resolve, reject) => {
      const child = spawn(this.qmd.command, args, {
        env: this.env,
        cwd: this.workspaceDir,
      });
      let stdout = "";
      let stderr = "";
      const timer = opts?.timeoutMs
        ? setTimeout(() => {
            child.kill("SIGKILL");
            reject(new Error(`qmd ${args.join(" ")} timed out after ${opts.timeoutMs}ms`));
          }, opts.timeoutMs)
        : null;
      child.stdout.on("data", (data) => {
        stdout += data.toString();
      });
      child.stderr.on("data", (data) => {
        stderr += data.toString();
      });
      child.on("error", (err) => {
        if (timer) clearTimeout(timer);
        reject(err);
      });
      child.on("close", (code) => {
        if (timer) clearTimeout(timer);
        if (code === 0) {
          resolve({ stdout, stderr });
        } else {
          reject(new Error(`qmd ${args.join(" ")} failed (code ${code}): ${stderr || stdout}`));
        }
      });
    });
  }

  private ensureDb() {
    if (this.db) return this.db;
    const sqlite = requireNodeSqlite();
    this.db = sqlite.open(this.indexPath, { readonly: true });
    return this.db;
  }

  private async exportSessions(): Promise<void> {
    if (!this.sessionExporter) return;
    const exportDir = this.sessionExporter.dir;
    await fs.mkdir(exportDir, { recursive: true });
    const files = await listSessionFilesForAgent(this.agentId);
    const keep = new Set<string>();
    const cutoff = this.sessionExporter.retentionMs
      ? Date.now() - this.sessionExporter.retentionMs
      : null;
    for (const sessionFile of files) {
      const entry = await buildSessionEntry(sessionFile);
      if (!entry) continue;
      if (cutoff && entry.mtimeMs < cutoff) continue;
      const target = path.join(exportDir, `${path.basename(sessionFile, ".jsonl")}.md`);
      await fs.writeFile(target, this.renderSessionMarkdown(entry), "utf-8");
      keep.add(target);
    }
    const exported = await fs.readdir(exportDir).catch(() => []);
    for (const name of exported) {
      if (!name.endsWith(".md")) continue;
      const full = path.join(exportDir, name);
      if (!keep.has(full)) {
        await fs.rm(full, { force: true });
      }
    }
  }

  private renderSessionMarkdown(entry: SessionFileEntry): string {
    const header = `# Session ${path.basename(entry.absPath, path.extname(entry.absPath))}`;
    const body = entry.content?.trim().length ? entry.content.trim() : "(empty)";
    return `${header}\n\n${body}\n`;
  }

  private pickSessionCollectionName(): string {
    const existing = new Set(this.qmd.collections.map((collection) => collection.name));
    if (!existing.has("sessions")) return "sessions";
    let counter = 2;
    let candidate = `sessions-${counter}`;
    while (existing.has(candidate)) {
      counter += 1;
      candidate = `sessions-${counter}`;
    }
    return candidate;
  }

  private async resolveDocLocation(
    docid?: string,
  ): Promise<{ rel: string; abs: string; source: MemorySource } | null> {
    if (!docid) return null;
    const normalized = docid.startsWith("#") ? docid.slice(1) : docid;
    if (!normalized) return null;
    const cached = this.docPathCache.get(normalized);
    if (cached) return cached;
    const db = this.ensureDb();
    const row = db
      .prepare("SELECT collection, path FROM documents WHERE hash LIKE ? AND active = 1 LIMIT 1")
      .get(`${normalized}%`) as { collection: string; path: string } | undefined;
    if (!row) return null;
    const location = this.toDocLocation(row.collection, row.path);
    if (!location) return null;
    this.docPathCache.set(normalized, location);
    return location;
  }

  private extractSnippetLines(snippet: string): { startLine: number; endLine: number } {
    const match = SNIPPET_HEADER_RE.exec(snippet);
    if (match) {
      const start = Number(match[1]);
      const count = Number(match[2]);
      if (Number.isFinite(start) && Number.isFinite(count)) {
        return { startLine: start, endLine: start + count - 1 };
      }
    }
    const lines = snippet.split("\n").length;
    return { startLine: 1, endLine: lines };
  }

  private readCounts(): {
    totalDocuments: number;
    sourceCounts: Array<{ source: MemorySource; files: number; chunks: number }>;
  } {
    try {
      const db = this.ensureDb();
      const rows = db
        .prepare(
          "SELECT collection, COUNT(*) as c FROM documents WHERE active = 1 GROUP BY collection",
        )
        .all() as Array<{ collection: string; c: number }>;
      const bySource = new Map<MemorySource, { files: number; chunks: number }>();
      for (const source of this.sources) {
        bySource.set(source, { files: 0, chunks: 0 });
      }
      let total = 0;
      for (const row of rows) {
        const root = this.collectionRoots.get(row.collection);
        const source = root?.kind ?? "memory";
        const entry = bySource.get(source) ?? { files: 0, chunks: 0 };
        entry.files += row.c ?? 0;
        entry.chunks += row.c ?? 0;
        bySource.set(source, entry);
        total += row.c ?? 0;
      }
      return {
        totalDocuments: total,
        sourceCounts: Array.from(bySource.entries()).map(([source, value]) => ({
          source,
          files: value.files,
          chunks: value.chunks,
        })),
      };
    } catch (err) {
      log.warn(`failed to read qmd index stats: ${String(err)}`);
      return {
        totalDocuments: 0,
        sourceCounts: Array.from(this.sources).map((source) => ({ source, files: 0, chunks: 0 })),
      };
    }
  }

  private isScopeAllowed(sessionKey?: string): boolean {
    const scope = this.qmd.scope;
    if (!scope) return true;
    const channel = this.deriveChannelFromKey(sessionKey);
    const chatType = this.deriveChatTypeFromKey(sessionKey);
    const normalizedKey = sessionKey ?? "";
    for (const rule of scope.rules ?? []) {
      if (!rule) continue;
      const match = rule.match ?? {};
      if (match.channel && match.channel !== channel) continue;
      if (match.chatType && match.chatType !== chatType) continue;
      if (match.keyPrefix && !normalizedKey.startsWith(match.keyPrefix)) continue;
      return rule.action === "allow";
    }
    const fallback = scope.default ?? "allow";
    return fallback === "allow";
  }

  private deriveChannelFromKey(key?: string) {
    if (!key) return undefined;
    const parts = key.split(":").filter(Boolean);
    if (parts.length >= 3 && (parts[1] === "group" || parts[1] === "channel")) {
      return parts[0]?.toLowerCase();
    }
    return undefined;
  }

  private deriveChatTypeFromKey(key?: string) {
    if (!key) return undefined;
    if (key.includes(":group:")) return "group";
    if (key.includes(":channel:")) return "channel";
    return "direct";
  }

  private toDocLocation(
    collection: string,
    collectionRelativePath: string,
  ): { rel: string; abs: string; source: MemorySource } | null {
    const root = this.collectionRoots.get(collection);
    if (!root) return null;
    const normalizedRelative = collectionRelativePath.replace(/\\/g, "/");
    const absPath = path.normalize(path.resolve(root.path, collectionRelativePath));
    const relativeToWorkspace = path.relative(this.workspaceDir, absPath);
    const relPath = this.buildSearchPath(
      collection,
      normalizedRelative,
      relativeToWorkspace,
      absPath,
    );
    return { rel: relPath, abs: absPath, source: root.kind };
  }

  private buildSearchPath(
    collection: string,
    collectionRelativePath: string,
    relativeToWorkspace: string,
    absPath: string,
  ): string {
    const insideWorkspace = this.isInsideWorkspace(relativeToWorkspace);
    if (insideWorkspace) {
      const normalized = relativeToWorkspace.replace(/\\/g, "/");
      if (!normalized) return path.basename(absPath);
      return normalized;
    }
    const sanitized = collectionRelativePath.replace(/^\/+/, "");
    return `qmd/${collection}/${sanitized}`;
  }

  private isInsideWorkspace(relativePath: string): boolean {
    if (!relativePath) return true;
    if (relativePath.startsWith("..")) return false;
    if (relativePath.startsWith(`..${path.sep}`)) return false;
    return !path.isAbsolute(relativePath);
  }

  private resolveReadPath(relPath: string): string {
    if (relPath.startsWith("qmd/")) {
      const [, collection, ...rest] = relPath.split("/");
      if (!collection || rest.length === 0) {
        throw new Error("invalid qmd path");
      }
      const root = this.collectionRoots.get(collection);
      if (!root) throw new Error(`unknown qmd collection: ${collection}`);
      const joined = rest.join("/");
      const resolved = path.resolve(root.path, joined);
      if (!this.isWithinRoot(root.path, resolved)) {
        throw new Error("qmd path escapes collection");
      }
      return resolved;
    }
    const absPath = path.resolve(this.workspaceDir, relPath);
    if (!this.isWithinWorkspace(absPath)) {
      throw new Error("path escapes workspace");
    }
    return absPath;
  }

  private isWithinWorkspace(absPath: string): boolean {
    const normalizedWorkspace = this.workspaceDir.endsWith(path.sep)
      ? this.workspaceDir
      : `${this.workspaceDir}${path.sep}`;
    if (absPath === this.workspaceDir) return true;
    const candidate = absPath.endsWith(path.sep) ? absPath : `${absPath}${path.sep}`;
    return candidate.startsWith(normalizedWorkspace);
  }

  private isWithinRoot(root: string, candidate: string): boolean {
    const normalizedRoot = root.endsWith(path.sep) ? root : `${root}${path.sep}`;
    if (candidate === root) return true;
    const next = candidate.endsWith(path.sep) ? candidate : `${candidate}${path.sep}`;
    return next.startsWith(normalizedRoot);
  }
}