import { spawn } from "node:child_process";
import { createHash } from "node:crypto";
import { chmod, cp, mkdir, readdir, readFile, rm, stat } from "node:fs/promises";
import path from "node:path";
import { AgentRunError } from "../common/errors.js";
import { redactText } from "../common/redaction.js";
import type { InitialPromptAssembly, JsonRecord, ResourceBundleRef } from "../common/types.js";
import { stableHash } from "../common/validation.js";

const maxPromptRefBytes = 16 * 1024;
const maxInitialPromptBytes = 64 * 1024;
const skillSummaryChars = 600;

export interface MaterializedResourceBundle {
  workspacePath: string;
  binPath?: string;
  skillsDir?: string;
  initialPrompt?: InitialPromptAssembly;
  event: JsonRecord;
}

interface MaterializedPromptRef {
  name: string;
  path: string;
  inject: "thread-start";
  required: boolean;
  text: string;
  bytes: number;
  sha256: string;
}

interface MaterializedSkillRef {
  name: string;
  path: string;
  aggregateAs: string;
  required: boolean;
  registryPath: string;
  manifestBytes: number;
  manifestSha256: string;
  summary: string;
}

interface GitCheckout {
  repoUrl: string;
  commitId: string;
  requestedCommitId?: string;
  requestedRef?: string;
  checkoutPath: string;
  treeId: string;
}

interface GitBundleSource {
  repoUrl: string;
  commitId?: string;
  ref?: string;
}

interface MaterializedGitBundle {
  name: string | null;
  repoUrl: string;
  commitId: string;
  requestedCommitId: string | null;
  requestedRef: string | null;
  subpath: string;
  targetPath: string;
  sourceKind: "file" | "directory";
  sourceBytes: number | null;
}

export async function materializeResourceBundle(resourceBundleRef: ResourceBundleRef | null | undefined, env: NodeJS.ProcessEnv = process.env): Promise<MaterializedResourceBundle | null> {
  if (!resourceBundleRef) return null;
  const workspaceRoot = path.resolve(env.AGENTRUN_WORKSPACE_ROOT ?? "/home/agentrun/workspaces");
  const runScope = env.AGENTRUN_RUN_ID ?? env.AGENTRUN_ATTEMPT_ID ?? "standalone";
  const assemblyRoot = path.join(workspaceRoot, `gitbundle-${stableHash({ runScope, resourceBundleRef }).slice(0, 16)}`);
  const checkoutRoot = path.join(assemblyRoot, "checkouts");
  const workspacePath = path.join(assemblyRoot, "workspace");
  await rm(assemblyRoot, { recursive: true, force: true });
  await mkdir(checkoutRoot, { recursive: true });
  await mkdir(workspacePath, { recursive: true });
  const defaultSource = defaultGitBundleSource(resourceBundleRef, env);
  const checkoutCache = new Map<string, Promise<GitCheckout>>();
  const checkoutFor = (source: GitBundleSource) => {
    const key = stableHash(gitSourceIdentity(source));
    let checkout = checkoutCache.get(key);
    if (!checkout) {
      checkout = checkoutGitSource(checkoutRoot, source);
      checkoutCache.set(key, checkout);
    }
    return checkout;
  };
  const defaultCheckout = await checkoutFor(defaultSource);
  const materializedBundles = await materializeGitBundles(workspacePath, resourceBundleRef, defaultSource, defaultCheckout, checkoutFor);
  const tools = await prepareGitBundleTools(workspacePath, env);
  const skills = await discoverGitBundleSkills(workspacePath);
  const prompts = await materializePromptRefs(defaultCheckout.checkoutPath, resourceBundleRef.promptRefs ?? []);
  const initialPrompt = assembleInitialPrompt(prompts.items, skills.items);
  return {
    workspacePath,
    ...(tools.binPath ? { binPath: tools.binPath } : {}),
    ...(skills.skillsDir ? { skillsDir: skills.skillsDir } : {}),
    ...(initialPrompt ? { initialPrompt } : {}),
    event: {
      phase: "resource-bundle-materialized",
      kind: "gitbundle",
      repoUrl: resourceBundleRef.repoUrl,
      commitId: defaultCheckout.commitId,
      requestedCommitId: resourceBundleRef.commitId ?? null,
      requestedRef: defaultCheckout.requestedRef ?? null,
      treeId: defaultCheckout.treeId,
      checkoutPath: pathSummary(defaultCheckout.checkoutPath),
      workspacePath: pathSummary(workspacePath),
      bundles: {
        count: materializedBundles.length,
        items: materializedBundles.map((item) => ({ ...item, valuesPrinted: false })),
        valuesPrinted: false,
      },
      tools: tools.event,
      skillDirs: skills.event,
      promptRefs: prompts.event,
      initialPrompt: initialPrompt?.summary ?? { available: false, bytes: 0, sha256: null, promptRefCount: prompts.items.length, skillCount: skills.items.length, valuesPrinted: false },
      valuesPrinted: false,
    },
  };
}

function defaultGitBundleSource(resourceBundleRef: ResourceBundleRef, env: NodeJS.ProcessEnv): GitBundleSource {
  const ref = optionalNonEmpty(resourceBundleRef.ref) ?? optionalNonEmpty(env.AGENTRUN_RESOURCE_BUNDLE_REF) ?? optionalNonEmpty(env.AGENTRUN_WORKSPACE_REF) ?? optionalNonEmpty(env.AGENTRUN_WORKSPACE_BRANCH);
  if (ref) return { repoUrl: resourceBundleRef.repoUrl, ref };
  const commitId = optionalNonEmpty(resourceBundleRef.commitId);
  if (commitId) return { repoUrl: resourceBundleRef.repoUrl, commitId };
  return { repoUrl: resourceBundleRef.repoUrl, ref: "HEAD" };
}

function bundleGitSource(bundle: ResourceBundleRef["bundles"][number], resourceBundleRef: ResourceBundleRef, defaultSource: GitBundleSource): GitBundleSource {
  const repoUrl = bundle.repoUrl ?? resourceBundleRef.repoUrl;
  const ref = optionalNonEmpty(bundle.ref);
  if (ref) return { repoUrl, ref };
  const commitId = optionalNonEmpty(bundle.commitId);
  if (commitId) return { repoUrl, commitId };
  if (repoUrl === defaultSource.repoUrl) return defaultSource;
  if (defaultSource.ref) return { repoUrl, ref: defaultSource.ref };
  if (defaultSource.commitId) return { repoUrl, commitId: defaultSource.commitId };
  return { repoUrl, ref: "HEAD" };
}

async function checkoutGitSource(checkoutRoot: string, source: GitBundleSource): Promise<GitCheckout> {
  const checkoutPath = path.join(checkoutRoot, stableHash(gitSourceIdentity(source)).slice(0, 16));
  await mkdir(checkoutPath, { recursive: true });
  await git(["init"], checkoutPath);
  await git(["remote", "remove", "origin"], checkoutPath, { allowFailure: true });
  await git(["remote", "add", "origin", source.repoUrl], checkoutPath);
  if (source.ref) {
    await git(["fetch", "--depth", "1", "origin", source.ref], checkoutPath);
    await git(["checkout", "--detach", "FETCH_HEAD"], checkoutPath);
  } else if (source.commitId) {
    await git(["fetch", "--depth", "1", "origin", source.commitId], checkoutPath);
    await git(["checkout", "--detach", source.commitId], checkoutPath);
  } else {
    throw new AgentRunError("schema-invalid", "gitbundle source must include repo ref or commit", { httpStatus: 400 });
  }
  const actualCommit = (await git(["rev-parse", "HEAD"], checkoutPath)).stdout.trim();
  if (source.commitId && actualCommit !== source.commitId) throw new AgentRunError("infra-failed", "gitbundle checkout did not land on requested commit", { httpStatus: 500, details: { expectedCommit: source.commitId, actualCommit } });
  const treeId = (await git(["rev-parse", "HEAD^{tree}"], checkoutPath)).stdout.trim();
  return { repoUrl: source.repoUrl, commitId: actualCommit, ...(source.commitId ? { requestedCommitId: source.commitId } : {}), ...(source.ref ? { requestedRef: source.ref } : {}), checkoutPath, treeId };
}

function gitSourceIdentity(source: GitBundleSource): JsonRecord {
  return { repoUrl: source.repoUrl, commitId: source.commitId ?? null, ref: source.ref ?? null };
}

async function materializeGitBundles(workspacePath: string, resourceBundleRef: ResourceBundleRef, defaultSource: GitBundleSource, defaultCheckout: GitCheckout, checkoutFor: (source: GitBundleSource) => Promise<GitCheckout>): Promise<MaterializedGitBundle[]> {
  const items: MaterializedGitBundle[] = [];
  for (const [index, bundle] of resourceBundleRef.bundles.entries()) {
    const gitSource = bundleGitSource(bundle, resourceBundleRef, defaultSource);
    const checkout = gitSource === defaultSource ? defaultCheckout : await checkoutFor(gitSource);
    const source = resolveBundlePath(checkout.checkoutPath, bundle.subpath, `bundles[${index}].subpath`);
    const target = resolveWorkspaceTargetPath(workspacePath, bundle.targetPath, `bundles[${index}].target_path`);
    let sourceStat;
    try {
      sourceStat = await stat(source);
    } catch (error) {
      throw new AgentRunError("schema-invalid", `gitbundle subpath ${bundle.subpath} is not readable`, { httpStatus: 400, details: { index, subpath: bundle.subpath, error: fileErrorSummary(error), valuesPrinted: false } });
    }
    await mkdir(path.dirname(target), { recursive: true });
    await rm(target, { recursive: true, force: true });
    await cp(source, target, { recursive: true, force: true, dereference: false });
    items.push({ name: bundle.name ?? null, repoUrl: checkout.repoUrl, commitId: checkout.commitId, requestedCommitId: bundle.commitId ?? resourceBundleRef.commitId ?? null, requestedRef: checkout.requestedRef ?? null, subpath: bundle.subpath, targetPath: bundle.targetPath, sourceKind: sourceStat.isDirectory() ? "directory" : "file", sourceBytes: sourceStat.isFile() ? sourceStat.size : null });
  }
  return items;
}

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

async function prepareGitBundleTools(workspacePath: string, env: NodeJS.ProcessEnv): Promise<{ binPath?: string; event: JsonRecord }> {
  const sourceBinPath = path.join(workspacePath, "tools");
  const installedBinPath = optionalNonEmpty(env.AGENTRUN_RESOURCE_BIN_PATH);
  const runtimeBinPath = installedBinPath ?? sourceBinPath;
  let entries;
  try {
    entries = await readdir(sourceBinPath, { withFileTypes: true });
  } catch (error) {
    if (error && typeof error === "object" && "code" in error && (error as { code?: unknown }).code === "ENOENT") return { event: { count: 0, names: [], binPath: null, sourceBinPath: null, installedBinPath: null, installed: false, valuesPrinted: false } };
    throw error;
  }
  const names: string[] = [];
  const items: JsonRecord[] = [];
  if (installedBinPath) await mkdir(installedBinPath, { recursive: true });
  for (const entry of entries) {
    if (!entry.isFile()) continue;
    const filePath = path.join(sourceBinPath, entry.name);
    const text = await readFile(filePath, "utf8");
    const firstLine = text.split(/\r?\n/u, 1)[0] ?? "";
    if (!firstLine.startsWith("#!")) continue;
    await chmod(filePath, 0o755);
    if (installedBinPath) {
      const targetPath = path.join(installedBinPath, entry.name);
      if (targetPath !== filePath) {
        await cp(filePath, targetPath, { force: true, dereference: false });
        await chmod(targetPath, 0o755);
      }
    }
    names.push(entry.name);
    items.push({ name: entry.name, sha256: sha256Text(text), bytes: Buffer.byteLength(text, "utf8"), shebang: firstLine.slice(0, 80), valuesPrinted: false });
  }
  return {
    ...(names.length > 0 ? { binPath: runtimeBinPath } : {}),
    event: {
      count: names.length,
      names,
      items,
      binPath: names.length > 0 ? pathSummary(runtimeBinPath) : null,
      sourceBinPath: pathSummary(sourceBinPath),
      installedBinPath: installedBinPath ? pathSummary(installedBinPath) : null,
      installed: Boolean(installedBinPath && names.length > 0),
      valuesPrinted: false,
    },
  };
}

async function materializePromptRefs(checkoutPath: string, refs: NonNullable<ResourceBundleRef["promptRefs"]>): Promise<{ items: MaterializedPromptRef[]; event: JsonRecord }> {
  const items: MaterializedPromptRef[] = [];
  const eventItems: JsonRecord[] = [];
  let totalBytes = 0;
  for (const ref of refs) {
    const promptPath = resolveBundlePath(checkoutPath, ref.path, `promptRefs.${ref.name}.path`);
    const required = ref.required === true;
    let text: string;
    try {
      text = await readFile(promptPath, "utf8");
    } catch (error) {
      if (required) throw new AgentRunError("prompt-unavailable", `required resource prompt ${ref.name} is not readable`, { httpStatus: 400, details: { name: ref.name, path: ref.path, error: fileErrorSummary(error), valuesPrinted: false } });
      eventItems.push({ name: ref.name, path: ref.path, inject: "thread-start", required, status: "missing", valuesPrinted: false });
      continue;
    }
    const bytes = Buffer.byteLength(text, "utf8");
    if (bytes > maxPromptRefBytes) throw new AgentRunError("prompt-too-large", `resource prompt ${ref.name} exceeds the per-file size limit`, { httpStatus: 400, details: { name: ref.name, path: ref.path, bytes, maxPromptRefBytes, valuesPrinted: false } });
    totalBytes += bytes;
    if (totalBytes > maxInitialPromptBytes) throw new AgentRunError("prompt-too-large", "assembled resource prompt exceeds the total size limit", { httpStatus: 400, details: { totalBytes, maxInitialPromptBytes, valuesPrinted: false } });
    const sha = sha256Text(text);
    items.push({ name: ref.name, path: ref.path, inject: "thread-start", required, text, bytes, sha256: sha });
    eventItems.push({ name: ref.name, path: ref.path, inject: "thread-start", required, status: "materialized", sha256: sha, bytes, valuesPrinted: false });
  }
  return {
    items,
    event: {
      count: refs.length,
      materializedCount: items.length,
      names: items.map((item) => item.name),
      items: eventItems,
      totalBytes,
      valuesPrinted: false,
    },
  };
}

async function discoverGitBundleSkills(workspacePath: string): Promise<{ items: MaterializedSkillRef[]; skillsDir?: string; event: JsonRecord }> {
  const skillsDir = path.join(workspacePath, ".agents", "skills");
  let entries;
  try {
    entries = await readdir(skillsDir, { withFileTypes: true });
  } catch (error) {
    if (error && typeof error === "object" && "code" in error && (error as { code?: unknown }).code === "ENOENT") return { items: [], event: { count: 0, materializedCount: 0, names: [], skillsDir: null, items: [], valuesPrinted: false } };
    throw error;
  }
  const items: MaterializedSkillRef[] = [];
  const eventItems: JsonRecord[] = [];
  for (const entry of entries) {
    if (!entry.isDirectory()) continue;
    const aggregateAs = entry.name;
    const manifestPath = path.join(skillsDir, aggregateAs, "SKILL.md");
    let manifestText: string;
    try {
      manifestText = await readFile(manifestPath, "utf8");
    } catch (error) {
      eventItems.push({ name: aggregateAs, path: `.agents/skills/${aggregateAs}/SKILL.md`, required: true, aggregateAs, status: "missing", error: fileErrorSummary(error), valuesPrinted: false });
      continue;
    }
    const bytes = Buffer.byteLength(manifestText, "utf8");
    const sha = sha256Text(manifestText);
    const summary = skillSummary(manifestText);
    items.push({ name: aggregateAs, path: `.agents/skills/${aggregateAs}/SKILL.md`, aggregateAs, required: true, registryPath: manifestPath, manifestBytes: bytes, manifestSha256: sha, summary });
    eventItems.push({ name: aggregateAs, path: `.agents/skills/${aggregateAs}/SKILL.md`, aggregateAs, required: true, status: "materialized", manifestSha256: sha, manifestBytes: bytes, registryPath: pathSummary(manifestPath), summary, valuesPrinted: false });
  }
  return {
    items,
    skillsDir,
    event: {
      count: entries.filter((entry) => entry.isDirectory()).length,
      materializedCount: items.length,
      names: items.map((item) => item.name),
      skillsDir: pathSummary(skillsDir),
      items: eventItems,
      valuesPrinted: false,
    },
  };
}

function assembleInitialPrompt(promptRefs: MaterializedPromptRef[], skills: MaterializedSkillRef[]): InitialPromptAssembly | undefined {
  if (promptRefs.length === 0 && skills.length === 0) return undefined;
  const sections: string[] = [
    "AgentRun initial runtime instructions. These instructions are assembled from ResourceBundleRef promptRefs and gitbundle skill directories for the first thread-start turn only.",
  ];
  for (const prompt of promptRefs) {
    sections.push([`## Resource Prompt: ${prompt.name}`, `path: ${prompt.path}`, prompt.text].join("\n"));
  }
  if (skills.length > 0) {
    const lines = [
      "## Resource Skills",
      "The following required runtime skills are mounted in the current workspace. Use these bundle skills instead of default model skill guesses.",
      ...skills.map((skill) => `- ${skill.name}: ${skill.summary || "No summary provided."} manifest=.agents/skills/${skill.aggregateAs}/SKILL.md source=${skill.path} required=${skill.required}`),
    ];
    sections.push(lines.join("\n"));
  }
  const text = sections.join("\n\n");
  const bytes = Buffer.byteLength(text, "utf8");
  if (bytes > maxInitialPromptBytes) throw new AgentRunError("prompt-too-large", "assembled initial prompt exceeds the total size limit", { httpStatus: 400, details: { bytes, maxInitialPromptBytes, promptRefCount: promptRefs.length, skillCount: skills.length, valuesPrinted: false } });
  return {
    text,
    summary: {
      available: true,
      bytes,
      sha256: sha256Text(text),
      promptRefCount: promptRefs.length,
      promptRefNames: promptRefs.map((item) => item.name),
      skillCount: skills.length,
      skillNames: skills.map((item) => item.name),
      valuesPrinted: false,
    },
  };
}

function skillSummary(text: string): string {
  const frontmatter = /^---\s*\n([\s\S]*?)\n---\s*/u.exec(text);
  if (frontmatter) {
    const descriptionLine = frontmatter[1]?.split(/\r?\n/u).find((line) => /^description\s*:/iu.test(line));
    if (descriptionLine) return trimSummary(descriptionLine.replace(/^description\s*:\s*/iu, "").trim().replace(/^['"]|['"]$/gu, ""));
  }
  const line = text.split(/\r?\n/u).map((entry) => entry.trim()).find((entry) => entry.length > 0 && !entry.startsWith("#") && entry !== "---");
  return trimSummary(line ?? "");
}

function trimSummary(value: string): string {
  const normalized = value.replace(/\s+/gu, " ").trim();
  return normalized.length > skillSummaryChars ? `${normalized.slice(0, skillSummaryChars)}...` : normalized;
}

function sha256Text(text: string): string {
  return createHash("sha256").update(text, "utf8").digest("hex");
}

function fileErrorSummary(error: unknown): JsonRecord {
  const record = typeof error === "object" && error !== null ? error as { code?: unknown; message?: unknown } : {};
  return { code: typeof record.code === "string" ? record.code : null, message: typeof record.message === "string" ? redactText(record.message).slice(0, 300) : null };
}

async function git(args: string[], cwd: string, options: { allowFailure?: boolean } = {}): Promise<{ stdout: string; stderr: string }> {
  const child = spawn("git", args, { cwd, stdio: ["ignore", "pipe", "pipe"] });
  let stdout = "";
  let stderr = "";
  child.stdout.setEncoding("utf8");
  child.stderr.setEncoding("utf8");
  child.stdout.on("data", (chunk) => { stdout += String(chunk); });
  child.stderr.on("data", (chunk) => { stderr += String(chunk); });
  const result = await new Promise<{ code: number | null; signal: NodeJS.Signals | null }>((resolve, reject) => {
    child.on("error", reject);
    child.on("close", (code, signal) => resolve({ code, signal }));
  }).catch((error: unknown) => {
    throw new AgentRunError("infra-failed", `failed to start git: ${error instanceof Error ? error.message : String(error)}`, { httpStatus: 503 });
  });
  if (result.code !== 0 && !options.allowFailure) {
    throw new AgentRunError("infra-failed", `git ${args[0] ?? "command"} failed with code ${result.code}`, { httpStatus: 502, details: { stderr: redactText(stderr.slice(-4000)), stdout: redactText(stdout.slice(-1000)), signal: result.signal } });
  }
  return { stdout, stderr };
}

function resolveBundlePath(checkoutPath: string, relativePath: string, fieldName: string): string {
  const resolved = path.resolve(checkoutPath, relativePath);
  const root = path.resolve(checkoutPath);
  if (resolved !== root && !resolved.startsWith(`${root}${path.sep}`)) throw new AgentRunError("schema-invalid", `${fieldName} escaped checkout`, { httpStatus: 400 });
  return resolved;
}

function resolveWorkspaceTargetPath(workspacePath: string, relativePath: string, fieldName: string): string {
  const resolved = path.resolve(workspacePath, relativePath);
  const root = path.resolve(workspacePath);
  if (resolved === root || !resolved.startsWith(`${root}${path.sep}`)) throw new AgentRunError("schema-invalid", `${fieldName} escaped workspace`, { httpStatus: 400 });
  return resolved;
}

function pathSummary(value: string): JsonRecord {
  const parts = value.split(/[\\/]+/u).filter(Boolean);
  return { absolute: path.isAbsolute(value), basename: parts.at(-1) ?? null, depth: parts.length, fingerprint: stableHash(value).slice(0, 16), valuePrinted: false };
}