import { chmodSync, copyFileSync, existsSync, mkdirSync, readFileSync, rmSync, writeFileSync } from "node:fs";
import os from "node:os";
import path from "node:path";
import { execFileSync } from "node:child_process";
import { createServer } from "node:net";
import * as p from "@clack/prompts";
import pc from "picocolors";
import {
  applyPendingMigrations,
  ensurePostgresDatabase,
  formatDatabaseBackupResult,
  runDatabaseBackup,
  runDatabaseRestore,
} from "@paperclipai/db";
import type { Command } from "commander";
import { ensureAgentJwtSecret, loadPaperclipEnvFile, mergePaperclipEnvEntries, readPaperclipEnvEntries, resolvePaperclipEnvFile } from "../config/env.js";
import { expandHomePrefix } from "../config/home.js";
import type { PaperclipConfig } from "../config/schema.js";
import { readConfig, resolveConfigPath, writeConfig } from "../config/store.js";
import { printPaperclipCliBanner } from "../utils/banner.js";
import { resolveRuntimeLikePath } from "../utils/path-resolver.js";
import {
  buildWorktreeConfig,
  buildWorktreeEnvEntries,
  DEFAULT_WORKTREE_HOME,
  formatShellExports,
  isWorktreeSeedMode,
  resolveSuggestedWorktreeName,
  resolveWorktreeSeedPlan,
  resolveWorktreeLocalPaths,
  sanitizeWorktreeInstanceId,
  type WorktreeSeedMode,
  type WorktreeLocalPaths,
} from "./worktree-lib.js";

type WorktreeInitOptions = {
  name?: string;
  instance?: string;
  home?: string;
  fromConfig?: string;
  fromDataDir?: string;
  fromInstance?: string;
  serverPort?: number;
  dbPort?: number;
  seed?: boolean;
  seedMode?: string;
  force?: boolean;
};

type WorktreeEnvOptions = {
  config?: string;
  json?: boolean;
};

type EmbeddedPostgresInstance = {
  initialise(): Promise<void>;
  start(): Promise<void>;
  stop(): Promise<void>;
};

type EmbeddedPostgresCtor = new (opts: {
  databaseDir: string;
  user: string;
  password: string;
  port: number;
  persistent: boolean;
  onLog?: (message: unknown) => void;
  onError?: (message: unknown) => void;
}) => EmbeddedPostgresInstance;

type EmbeddedPostgresHandle = {
  port: number;
  startedByThisProcess: boolean;
  stop: () => Promise<void>;
};

function nonEmpty(value: string | null | undefined): string | null {
  return typeof value === "string" && value.trim().length > 0 ? value.trim() : null;
}

function readPidFilePort(postmasterPidFile: string): number | null {
  if (!existsSync(postmasterPidFile)) return null;
  try {
    const lines = readFileSync(postmasterPidFile, "utf8").split("\n");
    const port = Number(lines[3]?.trim());
    return Number.isInteger(port) && port > 0 ? port : null;
  } catch {
    return null;
  }
}

function readRunningPostmasterPid(postmasterPidFile: string): number | null {
  if (!existsSync(postmasterPidFile)) return null;
  try {
    const pid = Number(readFileSync(postmasterPidFile, "utf8").split("\n")[0]?.trim());
    if (!Number.isInteger(pid) || pid <= 0) return null;
    process.kill(pid, 0);
    return pid;
  } catch {
    return null;
  }
}

async function isPortAvailable(port: number): Promise<boolean> {
  return await new Promise<boolean>((resolve) => {
    const server = createServer();
    server.unref();
    server.once("error", () => resolve(false));
    server.listen(port, "127.0.0.1", () => {
      server.close(() => resolve(true));
    });
  });
}

async function findAvailablePort(preferredPort: number, reserved = new Set<number>()): Promise<number> {
  let port = Math.max(1, Math.trunc(preferredPort));
  while (reserved.has(port) || !(await isPortAvailable(port))) {
    port += 1;
  }
  return port;
}

function detectGitBranchName(cwd: string): string | null {
  try {
    const value = execFileSync("git", ["branch", "--show-current"], {
      cwd,
      encoding: "utf8",
      stdio: ["ignore", "pipe", "ignore"],
    }).trim();
    return nonEmpty(value);
  } catch {
    return null;
  }
}

function resolveSourceConfigPath(opts: WorktreeInitOptions): string {
  if (opts.fromConfig) return path.resolve(opts.fromConfig);
  const sourceHome = path.resolve(expandHomePrefix(opts.fromDataDir ?? "~/.paperclip"));
  const sourceInstanceId = sanitizeWorktreeInstanceId(opts.fromInstance ?? "default");
  return path.resolve(sourceHome, "instances", sourceInstanceId, "config.json");
}

function resolveSourceConnectionString(config: PaperclipConfig, envEntries: Record<string, string>, portOverride?: number): string {
  if (config.database.mode === "postgres") {
    const connectionString = nonEmpty(envEntries.DATABASE_URL) ?? nonEmpty(config.database.connectionString);
    if (!connectionString) {
      throw new Error(
        "Source instance uses postgres mode but has no connection string in config or adjacent .env.",
      );
    }
    return connectionString;
  }

  const port = portOverride ?? config.database.embeddedPostgresPort;
  return `postgres://paperclip:paperclip@127.0.0.1:${port}/paperclip`;
}

export function copySeededSecretsKey(input: {
  sourceConfigPath: string;
  sourceConfig: PaperclipConfig;
  sourceEnvEntries: Record<string, string>;
  targetKeyFilePath: string;
}): void {
  if (input.sourceConfig.secrets.provider !== "local_encrypted") {
    return;
  }

  mkdirSync(path.dirname(input.targetKeyFilePath), { recursive: true });

  const sourceInlineMasterKey =
    nonEmpty(input.sourceEnvEntries.PAPERCLIP_SECRETS_MASTER_KEY) ??
    nonEmpty(process.env.PAPERCLIP_SECRETS_MASTER_KEY);
  if (sourceInlineMasterKey) {
    writeFileSync(input.targetKeyFilePath, sourceInlineMasterKey, {
      encoding: "utf8",
      mode: 0o600,
    });
    try {
      chmodSync(input.targetKeyFilePath, 0o600);
    } catch {
      // best effort
    }
    return;
  }

  const sourceKeyFileOverride =
    nonEmpty(input.sourceEnvEntries.PAPERCLIP_SECRETS_MASTER_KEY_FILE) ??
    nonEmpty(process.env.PAPERCLIP_SECRETS_MASTER_KEY_FILE);
  const sourceConfiguredKeyPath = sourceKeyFileOverride ?? input.sourceConfig.secrets.localEncrypted.keyFilePath;
  const sourceKeyFilePath = resolveRuntimeLikePath(sourceConfiguredKeyPath, input.sourceConfigPath);

  if (!existsSync(sourceKeyFilePath)) {
    throw new Error(
      `Cannot seed worktree database because source local_encrypted secrets key was not found at ${sourceKeyFilePath}.`,
    );
  }

  copyFileSync(sourceKeyFilePath, input.targetKeyFilePath);
  try {
    chmodSync(input.targetKeyFilePath, 0o600);
  } catch {
    // best effort
  }
}

async function ensureEmbeddedPostgres(dataDir: string, preferredPort: number): Promise<EmbeddedPostgresHandle> {
  const moduleName = "embedded-postgres";
  let EmbeddedPostgres: EmbeddedPostgresCtor;
  try {
    const mod = await import(moduleName);
    EmbeddedPostgres = mod.default as EmbeddedPostgresCtor;
  } catch {
    throw new Error(
      "Embedded PostgreSQL support requires dependency `embedded-postgres`. Reinstall dependencies and try again.",
    );
  }

  const postmasterPidFile = path.resolve(dataDir, "postmaster.pid");
  const runningPid = readRunningPostmasterPid(postmasterPidFile);
  if (runningPid) {
    return {
      port: readPidFilePort(postmasterPidFile) ?? preferredPort,
      startedByThisProcess: false,
      stop: async () => {},
    };
  }

  const port = await findAvailablePort(preferredPort);
  const instance = new EmbeddedPostgres({
    databaseDir: dataDir,
    user: "paperclip",
    password: "paperclip",
    port,
    persistent: true,
    onLog: () => {},
    onError: () => {},
  });

  if (!existsSync(path.resolve(dataDir, "PG_VERSION"))) {
    await instance.initialise();
  }
  if (existsSync(postmasterPidFile)) {
    rmSync(postmasterPidFile, { force: true });
  }
  await instance.start();

  return {
    port,
    startedByThisProcess: true,
    stop: async () => {
      await instance.stop();
    },
  };
}

async function seedWorktreeDatabase(input: {
  sourceConfigPath: string;
  sourceConfig: PaperclipConfig;
  targetConfig: PaperclipConfig;
  targetPaths: WorktreeLocalPaths;
  instanceId: string;
  seedMode: WorktreeSeedMode;
}): Promise<string> {
  const seedPlan = resolveWorktreeSeedPlan(input.seedMode);
  const sourceEnvFile = resolvePaperclipEnvFile(input.sourceConfigPath);
  const sourceEnvEntries = readPaperclipEnvEntries(sourceEnvFile);
  copySeededSecretsKey({
    sourceConfigPath: input.sourceConfigPath,
    sourceConfig: input.sourceConfig,
    sourceEnvEntries,
    targetKeyFilePath: input.targetPaths.secretsKeyFilePath,
  });
  let sourceHandle: EmbeddedPostgresHandle | null = null;
  let targetHandle: EmbeddedPostgresHandle | null = null;

  try {
    if (input.sourceConfig.database.mode === "embedded-postgres") {
      sourceHandle = await ensureEmbeddedPostgres(
        input.sourceConfig.database.embeddedPostgresDataDir,
        input.sourceConfig.database.embeddedPostgresPort,
      );
    }
    const sourceConnectionString = resolveSourceConnectionString(
      input.sourceConfig,
      sourceEnvEntries,
      sourceHandle?.port,
    );
    const backup = await runDatabaseBackup({
      connectionString: sourceConnectionString,
      backupDir: path.resolve(input.targetPaths.backupDir, "seed"),
      retentionDays: 7,
      filenamePrefix: `${input.instanceId}-seed`,
      includeMigrationJournal: true,
      excludeTables: seedPlan.excludedTables,
      nullifyColumns: seedPlan.nullifyColumns,
    });

    targetHandle = await ensureEmbeddedPostgres(
      input.targetConfig.database.embeddedPostgresDataDir,
      input.targetConfig.database.embeddedPostgresPort,
    );

    const adminConnectionString = `postgres://paperclip:paperclip@127.0.0.1:${targetHandle.port}/postgres`;
    await ensurePostgresDatabase(adminConnectionString, "paperclip");
    const targetConnectionString = `postgres://paperclip:paperclip@127.0.0.1:${targetHandle.port}/paperclip`;
    await runDatabaseRestore({
      connectionString: targetConnectionString,
      backupFile: backup.backupFile,
    });
    await applyPendingMigrations(targetConnectionString);

    return formatDatabaseBackupResult(backup);
  } finally {
    if (targetHandle?.startedByThisProcess) {
      await targetHandle.stop();
    }
    if (sourceHandle?.startedByThisProcess) {
      await sourceHandle.stop();
    }
  }
}

export async function worktreeInitCommand(opts: WorktreeInitOptions): Promise<void> {
  printPaperclipCliBanner();
  p.intro(pc.bgCyan(pc.black(" paperclipai worktree init ")));

  const cwd = process.cwd();
  const name = resolveSuggestedWorktreeName(
    cwd,
    opts.name ?? detectGitBranchName(cwd) ?? undefined,
  );
  const seedMode = opts.seedMode ?? "minimal";
  if (!isWorktreeSeedMode(seedMode)) {
    throw new Error(`Unsupported seed mode "${seedMode}". Expected one of: minimal, full.`);
  }
  const instanceId = sanitizeWorktreeInstanceId(opts.instance ?? name);
  const paths = resolveWorktreeLocalPaths({
    cwd,
    homeDir: opts.home ?? DEFAULT_WORKTREE_HOME,
    instanceId,
  });
  const sourceConfigPath = resolveSourceConfigPath(opts);
  const sourceConfig = existsSync(sourceConfigPath) ? readConfig(sourceConfigPath) : null;

  if ((existsSync(paths.configPath) || existsSync(paths.instanceRoot)) && !opts.force) {
    throw new Error(
      `Worktree config already exists at ${paths.configPath} or instance data exists at ${paths.instanceRoot}. Re-run with --force to replace it.`,
    );
  }

  if (opts.force) {
    rmSync(paths.repoConfigDir, { recursive: true, force: true });
    rmSync(paths.instanceRoot, { recursive: true, force: true });
  }

  const preferredServerPort = opts.serverPort ?? ((sourceConfig?.server.port ?? 3100) + 1);
  const serverPort = await findAvailablePort(preferredServerPort);
  const preferredDbPort = opts.dbPort ?? ((sourceConfig?.database.embeddedPostgresPort ?? 54329) + 1);
  const databasePort = await findAvailablePort(preferredDbPort, new Set([serverPort]));
  const targetConfig = buildWorktreeConfig({
    sourceConfig,
    paths,
    serverPort,
    databasePort,
  });

  writeConfig(targetConfig, paths.configPath);
  mergePaperclipEnvEntries(buildWorktreeEnvEntries(paths), paths.envPath);
  ensureAgentJwtSecret(paths.configPath);
  loadPaperclipEnvFile(paths.configPath);

  let seedSummary: string | null = null;
  if (opts.seed !== false) {
    if (!sourceConfig) {
      throw new Error(
        `Cannot seed worktree database because source config was not found at ${sourceConfigPath}. Use --no-seed or provide --from-config.`,
      );
    }
    const spinner = p.spinner();
    spinner.start(`Seeding isolated worktree database from source instance (${seedMode})...`);
    try {
      seedSummary = await seedWorktreeDatabase({
        sourceConfigPath,
        sourceConfig,
        targetConfig,
        targetPaths: paths,
        instanceId,
        seedMode,
      });
      spinner.stop(`Seeded isolated worktree database (${seedMode}).`);
    } catch (error) {
      spinner.stop(pc.red("Failed to seed worktree database."));
      throw error;
    }
  }

  p.log.message(pc.dim(`Repo config: ${paths.configPath}`));
  p.log.message(pc.dim(`Repo env: ${paths.envPath}`));
  p.log.message(pc.dim(`Isolated home: ${paths.homeDir}`));
  p.log.message(pc.dim(`Instance: ${paths.instanceId}`));
  p.log.message(pc.dim(`Server port: ${serverPort} | DB port: ${databasePort}`));
  if (seedSummary) {
    p.log.message(pc.dim(`Seed mode: ${seedMode}`));
    p.log.message(pc.dim(`Seed snapshot: ${seedSummary}`));
  }
  p.outro(
    pc.green(
      `Worktree ready. Run Paperclip inside this repo and the CLI/server will use ${paths.instanceId} automatically.`,
    ),
  );
}

export async function worktreeEnvCommand(opts: WorktreeEnvOptions): Promise<void> {
  const configPath = resolveConfigPath(opts.config);
  const envPath = resolvePaperclipEnvFile(configPath);
  const envEntries = readPaperclipEnvEntries(envPath);
  const out = {
    PAPERCLIP_CONFIG: configPath,
    ...(envEntries.PAPERCLIP_HOME ? { PAPERCLIP_HOME: envEntries.PAPERCLIP_HOME } : {}),
    ...(envEntries.PAPERCLIP_INSTANCE_ID ? { PAPERCLIP_INSTANCE_ID: envEntries.PAPERCLIP_INSTANCE_ID } : {}),
    ...(envEntries.PAPERCLIP_CONTEXT ? { PAPERCLIP_CONTEXT: envEntries.PAPERCLIP_CONTEXT } : {}),
    ...envEntries,
  };

  if (opts.json) {
    console.log(JSON.stringify(out, null, 2));
    return;
  }

  console.log(formatShellExports(out));
}

export function registerWorktreeCommands(program: Command): void {
  const worktree = program.command("worktree").description("Worktree-local Paperclip instance helpers");

  worktree
    .command("init")
    .description("Create repo-local config/env and an isolated instance for this worktree")
    .option("--name <name>", "Display name used to derive the instance id")
    .option("--instance <id>", "Explicit isolated instance id")
    .option("--home <path>", `Home root for worktree instances (default: ${DEFAULT_WORKTREE_HOME})`)
    .option("--from-config <path>", "Source config.json to seed from")
    .option("--from-data-dir <path>", "Source PAPERCLIP_HOME used when deriving the source config")
    .option("--from-instance <id>", "Source instance id when deriving the source config", "default")
    .option("--server-port <port>", "Preferred server port", (value) => Number(value))
    .option("--db-port <port>", "Preferred embedded Postgres port", (value) => Number(value))
    .option("--seed-mode <mode>", "Seed profile: minimal or full (default: minimal)", "minimal")
    .option("--no-seed", "Skip database seeding from the source instance")
    .option("--force", "Replace existing repo-local config and isolated instance data", false)
    .action(worktreeInitCommand);

  worktree
    .command("env")
    .description("Print shell exports for the current worktree-local Paperclip instance")
    .option("-c, --config <path>", "Path to config file")
    .option("--json", "Print JSON instead of shell exports")
    .action(worktreeEnvCommand);
}