import { cpSync, existsSync, mkdirSync, readdirSync, readFileSync, renameSync, rmSync, statSync } from "node:fs";
import { homedir } from "node:os";
import { basename, dirname, isAbsolute, join, relative, resolve } from "node:path";
import {
  DefaultPackageManager,
  type PathMetadata,
  type ResolvedResource,
} from "../../../../../../packages/coding-agent/src/core/package-manager.ts";
import { SettingsManager, type PackageSource } from "../../../../../../packages/coding-agent/src/core/settings-manager.ts";
import { parseFrontmatter } from "../../../../../../packages/coding-agent/src/utils/frontmatter.ts";

const SKILLS_DIR = "skills";
const SKILLS_DISABLED_DIR = "skills-disabled";

export interface SkillSettingsEntry {
  path: string;
  enabled: boolean;
  toggleable: boolean;
  name: string;
  description: string;
  scope: string;
  source: string;
}

interface MovableSkillLocation {
  baseDir: string;
  fromPath: string;
  isDirectory: boolean;
  currentlyDisabled: boolean;
}

interface SkillScanTarget {
  baseDir: string;
  scope: string;
}

function createManagers(repoRoot: string, agentDir: string) {
  const settingsManager = SettingsManager.create(repoRoot, agentDir);
  const packageManager = new DefaultPackageManager({
    cwd: repoRoot,
    agentDir,
    settingsManager,
  });
  return { settingsManager, packageManager };
}

function resolveSkillFilePath(pathValue: string): string {
  const resolved = resolve(pathValue);
  if (resolved.endsWith("SKILL.md")) return resolved;
  const skillFile = join(resolved, "SKILL.md");
  return existsSync(skillFile) ? skillFile : resolved;
}

function normalizeSkillPath(pathValue: string): string {
  return resolveSkillFilePath(pathValue);
}

function readSkillMeta(pathValue: string): { name: string; description: string } {
  const skillFile = resolveSkillFilePath(pathValue);
  const fallbackName = basename(dirname(skillFile));
  if (!existsSync(skillFile)) {
    return { name: fallbackName, description: "" };
  }
  try {
    const content = readFileSync(skillFile, "utf8");
    const { frontmatter } = parseFrontmatter<{ name?: string; description?: string }>(content);
    return {
      name: String(frontmatter.name || fallbackName),
      description: String(frontmatter.description || ""),
    };
  } catch {
    return { name: fallbackName, description: "" };
  }
}

function isSkillToggleable(metadata: PathMetadata, skillPath: string): boolean {
  if (metadata.origin === "package") return false;
  if (metadata.source?.startsWith("npm:")) return false;
  if (skillPath.includes("/node_modules/") || skillPath.includes("\\node_modules\\")) return false;
  return metadata.origin === "top-level" && metadata.source === "auto";
}

function getSkillScanTargets(repoRoot: string, agentDir: string): SkillScanTarget[] {
  const targets: SkillScanTarget[] = [
    { baseDir: agentDir, scope: "user" },
    { baseDir: join(repoRoot, ".pi"), scope: "project" },
    { baseDir: join(homedir(), ".agents"), scope: "user" },
  ];

  const userAgents = join(homedir(), ".agents");
  let dir = resolve(repoRoot);
  const gitRoot = (() => {
    let current = dir;
    while (true) {
      if (existsSync(join(current, ".git"))) return current;
      const parent = dirname(current);
      if (parent === current) return null;
      current = parent;
    }
  })();

  dir = resolve(repoRoot);
  while (true) {
    const agentsBase = join(dir, ".agents");
    if (resolve(agentsBase) !== resolve(userAgents)) {
      targets.push({ baseDir: agentsBase, scope: "project" });
    }
    if (gitRoot && dir === gitRoot) break;
    const parent = dirname(dir);
    if (parent === dir) break;
    dir = parent;
  }

  const seen = new Set<string>();
  return targets.filter((t) => {
    const key = resolve(t.baseDir);
    if (seen.has(key)) return false;
    seen.add(key);
    return true;
  });
}

function collectSkillFilesInDir(dir: string, piRootMarkdown = false): string[] {
  const entries: string[] = [];
  if (!existsSync(dir)) return entries;

  const walk = (currentDir: string, isRoot: boolean): void => {
    let dirEntries: ReturnType<typeof readdirSync>;
    try {
      dirEntries = readdirSync(currentDir, { withFileTypes: true });
    } catch {
      return;
    }

    for (const entry of dirEntries) {
      if (entry.name === "SKILL.md") {
        const fullPath = join(currentDir, entry.name);
        try {
          if (statSync(fullPath).isFile()) entries.push(fullPath);
        } catch {
          /* ignore */
        }
        return;
      }
    }

    for (const entry of dirEntries) {
      if (entry.name.startsWith(".") || entry.name === "node_modules") continue;
      const fullPath = join(currentDir, entry.name);
      let isDir = entry.isDirectory();
      let isFile = entry.isFile();
      if (entry.isSymbolicLink()) {
        try {
          const stats = statSync(fullPath);
          isDir = stats.isDirectory();
          isFile = stats.isFile();
        } catch {
          continue;
        }
      }
      if (piRootMarkdown && isRoot && isFile && entry.name.endsWith(".md")) {
        entries.push(fullPath);
        continue;
      }
      if (isDir) walk(fullPath, false);
    }
  };

  walk(dir, true);
  return entries;
}

function resolveMovableSkill(skillFilePath: string, baseDir: string): MovableSkillLocation | null {
  const skillFile = resolve(skillFilePath);
  const activeRoot = join(baseDir, SKILLS_DIR);
  const disabledRoot = join(baseDir, SKILLS_DISABLED_DIR);

  for (const [root, currentlyDisabled] of [
    [activeRoot, false],
    [disabledRoot, true],
  ] as const) {
    const rel = relative(root, skillFile);
    if (rel.startsWith("..") || isAbsolute(rel)) continue;

    const parentRel = relative(root, dirname(skillFile));
    if (parentRel === ".") {
      return { baseDir, fromPath: skillFile, isDirectory: false, currentlyDisabled };
    }

    const topSegment = rel.split(/[/\\]/)[0];
    if (!topSegment) continue;
    const fromPath = join(root, topSegment);
    if (!existsSync(fromPath)) continue;
    return {
      baseDir,
      fromPath,
      isDirectory: statSync(fromPath).isDirectory(),
      currentlyDisabled,
    };
  }

  return null;
}

function findMovableSkill(pathValue: string, repoRoot: string, agentDir: string): MovableSkillLocation | null {
  const skillFile = resolveSkillFilePath(pathValue);
  for (const { baseDir } of getSkillScanTargets(repoRoot, agentDir)) {
    const found = resolveMovableSkill(skillFile, baseDir);
    if (found) return found;
  }
  return null;
}

function moveSkillBetweenDirs(location: MovableSkillLocation, enabled: boolean): string {
  const activeRoot = join(location.baseDir, SKILLS_DIR);
  const disabledRoot = join(location.baseDir, SKILLS_DISABLED_DIR);
  const destRoot = enabled ? activeRoot : disabledRoot;
  mkdirSync(destRoot, { recursive: true });

  const name = basename(location.fromPath);
  const destPath = join(destRoot, name);
  if (resolve(location.fromPath) === resolve(destPath)) {
    return location.isDirectory ? join(destPath, "SKILL.md") : destPath;
  }
  if (existsSync(destPath)) {
    throw new Error(`目标已存在: ${destPath}`);
  }

  movePath(location.fromPath, destPath);
  return location.isDirectory ? join(destPath, "SKILL.md") : destPath;
}

function movePath(fromPath: string, destPath: string): void {
  try {
    renameSync(fromPath, destPath);
  } catch (err) {
    const code = err && typeof err === "object" && "code" in err ? String(err.code) : "";
    if (code !== "EXDEV") throw err;
    cpSync(fromPath, destPath, { recursive: true });
    rmSync(fromPath, { recursive: true, force: true });
  }
}

function stripSkillPatternPrefix(entry: string): string {
  if (entry.startsWith("!") || entry.startsWith("+") || entry.startsWith("-")) {
    return entry.slice(1);
  }
  return entry;
}

function entryMatchesSkillPatterns(entry: string, patterns: Set<string>): boolean {
  const stripped = stripSkillPatternPrefix(entry);
  for (const pattern of patterns) {
    if (stripped === pattern) return true;
    if (stripped.endsWith(`/${pattern}`)) return true;
    if (pattern.endsWith(stripped)) return true;
  }
  return false;
}

function patternsForSkillFile(skillFile: string, baseDir: string): Set<string> {
  const patterns = new Set<string>();
  for (const dirName of [SKILLS_DIR, SKILLS_DISABLED_DIR]) {
    const root = join(baseDir, dirName);
    const rel = relative(root, skillFile).replace(/\\/g, "/");
    if (rel.startsWith("..") || isAbsolute(rel)) continue;
    patterns.add(`${SKILLS_DIR}/${rel}`);
    const top = rel.split("/")[0];
    if (top && top !== rel) patterns.add(`${SKILLS_DIR}/${top}`);
    if (rel.endsWith("/SKILL.md")) {
      patterns.add(`${SKILLS_DIR}/${dirname(rel)}`);
    }
  }
  return patterns;
}

function removeLegacySkillPatterns(
  settingsManager: SettingsManager,
  skillFilePath: string,
  repoRoot: string,
  agentDir: string,
): void {
  const skillFile = normalizeSkillPath(skillFilePath);
  const patterns = new Set<string>();
  for (const { baseDir } of getSkillScanTargets(repoRoot, agentDir)) {
    for (const p of patternsForSkillFile(skillFile, baseDir)) {
      patterns.add(p);
    }
  }

  const cleanList = (entries: string[]): string[] =>
    entries.filter((entry) => !entryMatchesSkillPatterns(entry, patterns));

  const globalSettings = settingsManager.getGlobalSettings();
  const cleanedGlobal = cleanList([...(globalSettings.skills ?? [])]);
  if (cleanedGlobal.length !== (globalSettings.skills ?? []).length) {
    settingsManager.setSkillPaths(cleanedGlobal);
  }

  const projectSettings = settingsManager.getProjectSettings();
  const cleanedProject = cleanList([...(projectSettings.skills ?? [])]);
  if (cleanedProject.length !== (projectSettings.skills ?? []).length) {
    settingsManager.setProjectSkillPaths(cleanedProject);
  }

  const cleanPackages = (packages: PackageSource[], setter: (pkgs: PackageSource[]) => void): void => {
    let changed = false;
    const updated = packages.map((pkg) => {
      if (typeof pkg === "string") return pkg;
      if (!pkg.skills?.length) return pkg;
      const cleaned = cleanList([...pkg.skills]);
      if (cleaned.length === pkg.skills.length) return pkg;
      changed = true;
      const next = { ...pkg, skills: cleaned.length > 0 ? cleaned : undefined };
      if (!next.skills && !next.extensions && !next.prompts && !next.themes) {
        return pkg.source;
      }
      return next;
    });
    if (changed) setter(updated);
  };

  cleanPackages([...(globalSettings.packages ?? [])], (pkgs) => settingsManager.setPackages(pkgs));
  cleanPackages([...(projectSettings.packages ?? [])], (pkgs) => settingsManager.setProjectPackages(pkgs));
}

function toggleSkillByMove(
  pathValue: string,
  enabled: boolean,
  repoRoot: string,
  agentDir: string,
  settingsManager: SettingsManager,
): string {
  const location = findMovableSkill(pathValue, repoRoot, agentDir);
  if (!location) {
    throw new Error("仅支持切换 skills 目录下的 skill");
  }

  let newPath = normalizeSkillPath(pathValue);
  if (enabled && location.currentlyDisabled) {
    newPath = normalizeSkillPath(moveSkillBetweenDirs(location, true));
  } else if (!enabled && !location.currentlyDisabled) {
    newPath = normalizeSkillPath(moveSkillBetweenDirs(location, false));
  }

  removeLegacySkillPatterns(settingsManager, newPath, repoRoot, agentDir);
  return newPath;
}

function mapSkillEntry(resource: ResolvedResource): SkillSettingsEntry {
  const meta = readSkillMeta(resource.path);
  const toggleable = isSkillToggleable(resource.metadata, resource.path);
  return {
    path: normalizeSkillPath(resource.path),
    enabled: resource.enabled,
    toggleable,
    name: meta.name,
    description: meta.description,
    scope: resource.metadata.scope || "",
    source: resource.metadata.source || "",
  };
}

function mapDisabledSkillEntry(skillPath: string, scope: string): SkillSettingsEntry {
  const meta = readSkillMeta(skillPath);
  return {
    path: normalizeSkillPath(skillPath),
    enabled: false,
    toggleable: true,
    name: meta.name,
    description: meta.description,
    scope,
    source: "auto",
  };
}

function collectDisabledSkillEntries(repoRoot: string, agentDir: string): SkillSettingsEntry[] {
  const entries: SkillSettingsEntry[] = [];
  for (const { baseDir, scope } of getSkillScanTargets(repoRoot, agentDir)) {
    const disabledDir = join(baseDir, SKILLS_DISABLED_DIR);
    const piRootMarkdown =
      resolve(baseDir) === resolve(agentDir) || resolve(baseDir) === resolve(join(repoRoot, ".pi"));
    for (const skillPath of collectSkillFilesInDir(disabledDir, piRootMarkdown)) {
      entries.push(mapDisabledSkillEntry(skillPath, scope));
    }
  }
  return entries;
}

function pathsMatch(a: string, b: string): boolean {
  const left = normalizeSkillPath(a);
  const right = normalizeSkillPath(b);
  if (left === right) return true;
  return resolve(a) === resolve(b);
}

function mergeSkillEntries(resolved: SkillSettingsEntry[], disabled: SkillSettingsEntry[]): SkillSettingsEntry[] {
  const merged = [...resolved];
  for (const entry of disabled) {
    if (!merged.some((item) => pathsMatch(item.path, entry.path))) {
      merged.push(entry);
    }
  }
  return merged.sort((a, b) => a.name.localeCompare(b.name));
}

export async function listSkillSettings(repoRoot: string, agentDir: string): Promise<SkillSettingsEntry[]> {
  const { packageManager } = createManagers(repoRoot, agentDir);
  const resolved = await packageManager.resolve(async () => "skip");
  const active = resolved.skills.map(mapSkillEntry);
  const disabled = collectDisabledSkillEntries(repoRoot, agentDir);
  return mergeSkillEntries(active, disabled);
}

export async function setSkillEnabled(
  repoRoot: string,
  agentDir: string,
  pathValue: string,
  enabled: boolean,
): Promise<SkillSettingsEntry> {
  const { settingsManager, packageManager } = createManagers(repoRoot, agentDir);
  const resolved = await packageManager.resolve(async () => "skip");
  const match = resolved.skills.find((resource) => pathsMatch(resource.path, pathValue));
  const disabledOnly = collectDisabledSkillEntries(repoRoot, agentDir).find((entry) =>
    pathsMatch(entry.path, pathValue),
  );

  if (match && !isSkillToggleable(match.metadata, match.path)) {
    throw new Error("npm 包内的 skill 由包管理器控制，无法在此禁用");
  }
  if (!match && !disabledOnly) {
    throw new Error("未找到对应 skill");
  }
  if (!findMovableSkill(pathValue, repoRoot, agentDir)) {
    throw new Error("仅支持切换 skills 目录下的 skill");
  }

  const newPath = toggleSkillByMove(pathValue, enabled, repoRoot, agentDir, settingsManager);
  const meta = readSkillMeta(newPath);
  const scope = match?.metadata.scope || disabledOnly?.scope || "";
  const source = match?.metadata.source || disabledOnly?.source || "auto";

  return {
    path: newPath,
    enabled,
    toggleable: true,
    name: meta.name,
    description: meta.description,
    scope,
    source,
  };
}